XV INTERNATIONAL SCIENTIFIC CONGRESS SUMMER SESSION 12 - 15.09.2018, VARNA, BULGARIA

2018

MACHINES TECHNOLOGIES MATERIALS 2018

VOLUME IV MATERIALS

ISSN 2535-0021 (Print) ISSN 2535-003X (Online)

ORGANIZER SCIENTIFIC-TECHNICAL UNION OF MECHANICAL ENGINEERING BULGARIA The FEDERATION OF THE SCIENTIFIC ENGINEERING UNIONS (FSEU) in Bulgaria is a professional, scientific - educational, non- governmental, non-political non-profit association of legal entities - professional organizations registered under the Law on non-profit legal entities, whose members are engineers, economists and other specialists in the field of science, technology, economy and agriculture. FSEU performed bilateral cooperation with similar organizations from many countries. FSEU brings together 19 national associations - Scientific and Technical Unions / STU /, 34 territorial associations, which have more than 15 000 professionals across the country. FSEU is a co-founder and member of the World Federation of Engineering Organizations (WFEO). FSEU a member of the European Federation of National Engineering Associations (FEANI), and a member of the Standing Conference of engineering organizations from Southeast Europe / CO.PICEE /, Global Compact, European Young Engineers (EYE). The Federation has the exclusive right to give nominations for the European Engineer (EUR ING) title. Contacts: 108 Rakovsky Str., Sofia 1000, Bulgaria web: www.fnts.bg e-mail: [email protected] INTERNATIONAL SCIENTIFIC CONFERENCE MACHINES. TECHNOLOGIES. MATERIALS

12-15.09.2018, VARNA, BULGARIA

PROCEEDINGS

YEAR II, ISSUE 4 (11), SOFIA, BULGARIA 2018

VOLUME IV MATERIALS

ISSN 2535-0021 (PRINT) ISSN 2535-003X (ONLINE)

PUBLISHER:

SCIENTIFIC TECHNICAL UNION OF MECHANICAL ENGINEERING

108, Rakovski Str., 1000 Sofia, Bulgaria tel. (+359 2) 987 72 90, tel./fax (+359 2) 986 22 40, [email protected] www.mtmcongress.com

INTERNATIONAL EDITORIAL BOARD

Chairman: Prof. DHC Georgi Popov Vice Chair: Prof. Dr. Eng. Tsanka Dikova Members: Prof. Mihail Aurel Titu RO Acad. Ivan Vedyakov RU Prof. Mladen Velev BG Acad. Yurij Kuznetsov UA Prof. Mohamed El Mansori FR Prof. Aleksander Mihaylov UA Prof. Movlazade Vagif Zahid AZ Prof. Anatoliy Kostin RU Prof. Nikolay Dyulgerov BG Prof. Adel Mahmud IQ Prof. Oana Dodun RO Prof. Ahmet Ertas TR Prof. Olga Krivtsova KZ Prof. Andrzej Golabczak PL Prof. Peter Kostal SK Prof. Boncho Bonev BG Prof. Raul Turmanidze GE Prof. Gennady Bagluk UA Prof. Renato Goulart BR Prof. Detlef Redlich DE Prof. Roumen Petrov BE Prof. Dipten Misra IN Prof. Sasho Guergov BG Prof. Dmitry Kaputkin RU Prof. Seiji Katayama JP Prof. Dmitry Dmitriev UA Prof. Sergej Dobatkin RU Prof. Eugene Eremin RU Prof. Sergej Nikulin RU Prof. Ernest Nazarian AM Prof. Stefan Dimov UK Prof. Juan Alberto Montano MX Prof. Svetan Ratchev UK Prof. Esam Husein KW Prof. Svetlana Gubenko UA Prof. Ilir Doci KO Prof. Sveto Cvetkovski MK Prof. Ivo Malakov BG Prof. Tale Geramitchioski MK Prof. Katia Vutova BG Prof. Vadim Kovtun BY Prof. Krasimir Marchev USA Prof. Viktor Vaganov RU Prof. Leon Kukielka PL Prof. William Singhose USA Prof. Lyudmila Ryabicheva UA Prof. Yasar Pancar TR Prof. Milan Vukcevic ME Prof. Wu Kaiming CN

C O N T E N T S

MATERIALS

REINFORCED WITH FULLERENES COMPOSITES BASED ON METALLIC MATRICES Prof. Dr. O.Sizonenko, Prof. Dr. S.Prokhorenko, Dr. A.Torpakov ...... 331

INVESTIGATION OF HARDENING PROCESSES OF CORROSION-RESISTANT COATINGS DEPOSITED BY A FLUX-CORED WIRE WITH NITRIDE-BORIDE ALLOYING Prof. Dr. Econ. Kuznetsova O., Prof. Dr. Eng. Eremin E., Cand. Eng. Makarov V., graduate student Losev A., graduate student Borodihin S...... 335

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF P/M TITANIUM MATRIX COMPOSITES REINFORCED WITH TiB Prof., Dr. Sc. Bagliuk G., M. Sc. Stasiuk O...... 338

PRODUCTION PROCESS OF POWDER PERMEABLE MATERIALS MADE OF SPHERICAL BRONZE POWDERS BY PRESSING Prof., Dr. Eng., Cor. Member of NAS of Belarus Ilyushchanka A., PhD of Eng., Doc. Kusin R.A., Head of the Lab. Charniak I.N., Res. Kusin A.R., Res. Zhehzdryn D.I...... 343

TRIBOLOGICAL STUDIES FOR COMMERCIALLY PURE GRADE 4 TITANIUM WITH DIFFERENT MICROSTRUCTURES, WITH AND WITHOUT COATING Lead. Res., Dr. Semenov V.I., Lead. Res., Prof. Raab G.I., Prof., Dr. Huang S.-J., PhD Stud. Bogale D.A., Head of Lab. Charniak I.N...... 347

INVESTIGATION OF THE EFFECT OF DIAMETERS OF POLYACRYLONITRILE NANO FIBER WITH CARBON NANOTUBE ON MECHANICAL PROPERTIES Assist.Prof.Dr..Gürol Ö., Assoc.Prof.Dr..Kevser D...... 352

INVESTIGATION OF ELECTRICAL CONDUCTIVITY AND HYDROPHOBIC/HYDROPHILIC INTERACTION OF PAN + PMMA COMPOSITE NANOFIBERS WITH AG NANOWIRE PRODUCED BY ELECTROSPINNING METHOD Assoc.Prof. Dr..Kevser D, Mechanical Engineering.. Mustafa Husseın Bahaulddın B...... 356

INVESTIGATION OF THE EFFECT OF PRODUCTION PARAMETERS ON POLYSTYRENE NANO FIBER FORMATION FOR 12 WT %, 14 WT % AND 16 WT % Assist. Prof. Dr. Yusuf Y., Assist. Prof. Dr. A.Serhat E. Assoc. Prof. Dr. Kevser D., Mech. Engineer. Büşra M., Chemist.Hasan Ö...... 360

RULE-BASED MAMDANI-TYPE FUZZY MODELING OF PERFORMANCE OF HYDROXY (HHO) DRY CELL WITH 12x12 PLATE COMBINATION Assist. Prof. Dr..Ali Serhat E., Assist. Prof. Dr. Yusuf Y., Mech. Engineer..Burak Buğra Ç., Mech. Engineer ..Taylan P., Assoc.. Prof. Dr..Kevser D...... 364

ANALYSIS AND FRACTURE OF ALUMINIUM ALLOY COMPONENTS USED FOR SPINNING OF CHEMICAL FIBER Assoc. Prof. Kandrotaitė Janutienė R. PhD, Lect. Mažeika D. PhD ...... 368

PERSPECTIVE COMPOSITE MATERIALS FOR GENERAL AND SPECIAL MECHANICAL ENGINEERING Ph.D. Khantimerov S.M., M.Sc. Khantimerova Yu.M., M.Sc. Garipov R.R., Dr. Suleimanov N.M...... 372

THE COMPRESSION NATURE OF THE „WURTZITE BORON NITRIDE-DIAMOND” SINTERED UNDER HIGH PRESSURE I.I. Buzhanska, V.M. Volkogon, S.K. Avramchuk, Yu.O. Fedoran, A.V. Kravchuk, V.S. Antonyuk ...... 374

MECHANICAL PROPERTIES OF PARTS OF PLA-NATURAL AS A FUNCTION OF THE TEMPERATURE OF THE 3D PRINTING BY FDM METHOD Chief Assist. Prof. Yankov E...... 376

THE COMPATIBILITY FACTOR IN MATERIAL SCIENCE OF MIXED ENGINEERING NANOBLENDS Assoc. prof. cand. eng. Avdeychik S., Assoc. prof. cand. eng. Sarokin V., Senior lecturer Antonov A., Prof. dr. eng. Struk V...... 380

ELECTROPLATING WITH TUNGSTEN AND TUNGSTEN-MOLYBDENUM ALLOYS FROM METAPHOSPHATE- CONTAINING HALIDE-OXIDE AND OXIDE MELTS Prof., D.Sc. Malyshev V., Prof., D.Sc. Kushchevska N., Prof., D.Sc. Bagliuk G., Ph.Dr. Shakhnin D.B., Prof., Ph.Dr. Paprotskaya O.,Ph.Dr. Zaliubovskyi M...... 383

TUNGSTEN AND MOLYBDENUM CARBIDES OBTAINING BY ELECTROLYSIS OF SALT MELTS Prof., D.Sc. Malyshev V., Prof., D.Sc. Kushchevska N., Prof., D.Sc. Bagliuk G., Ph.Dr. Shakhnin D., Ph.Dr. Paprotskaya O., M.Sc. Kurovskyi V...... 386

ION PLAZMA NITRIDING OF FERRITIC STEEL AISI 430 F MSc Naziv Jashari, Prof. Dr Cvetkovski. S. PhD., Prof. Dr Ş. Hakan Atapek PhD., Prof. Dr Şeyda Polat PhD., Dr Gülşah Aktaş Çelik ...... 389

ADHESION AND PHYSICO-MECHANICAL CHARACTERISTICS OF COATINGS OF CHROMIUM CARBONITRIDE, GENERATED ON STEEL SUBSTRATES Phd Chekan N.M., Ass.prof, dr.Eng. Auchynnikau Y.V., Phd Akula I.P., Ass.prof. Phd Eisymont Y.I., Pinchuk T.I...... 393

EFFECT OF DYNAMICAL AGING IN SLM Ti-6Al-4V ALLOYS Davidov D. PhD., Prof. Kazantseva N. Dr.of Sci., Ezhov I. PhD Student, Fefelov A. PhD., Merkushev A., Afanasyev S. PhD...... 397

MACHINES. TECHNOLOGIES. MATERIALS. 2018

REINFORCED WITH FULLERENES COMPOSITES BASED ON METALLIC MATRICES

Prof. Dr. O.Sizonenko1, Prof. Dr. S.Prokhorenko2, Dr. A.Torpakov1, Dr. D.Żak2, Dr. Y.Lypian1, MSc. R.Wojnarowska-Nowak 2,, Prof. Dr. J.Polit2 and Prof. Dr. E.M.Sheregii2

1 Department of Disperse Systems Pulse Treatment, Institute of Pulse Processes and Technologies, National Academy of Science of Ukraine, Mykolaiv 54018, Ukraine 2 Center of Microelectronics and Nanotechnology, University of Rzeszow, 1 Pigonia Str., 35-959 Rzeszow, Poland

[email protected]

Abstract. A new technological approach to obtain anti-friction dispersion-hardened by nanoparticles materials based on of TiC – AlC – and FeC alloys with inclusions of the Cn0 (n=6 or 7) phases which characterized by high heat resistance, strength and durability for use in aircraft and rocket technology, is presented. Elemental powders of Al–Ti–С and Fe–Ti–С systems are used as base objects for development of new composite materials by high voltage electric discharge treatment in kerosene (dispersion, activation and synthesis). In effect, as shown micro-Raman data, these systems contain refractory components (fullerenes, carbides), MAX-phases of Ti-Al-C system with increasing thermo-stability, strength and wear resistance while maintaining ductility how can it be predicted.

Keywords: HIGH VOLTAGE ELECTRIC DISCHARGE; COMPOSITE MATERIAL; RAMAN SCUTTERING; FULLERENCE.

1. Introduction. temperatures, developed within the channel, lead to rapid (from 500 up to 2000 m/s) expansion of channel and appearance of Considerable number of fabrication methods have been shock waves, transformed into acoustic with wide frequency proposed to develop metal matrix composites containing carbon specter, powerful hydro flows, cavitation, electromagnetic and 18,19 nano-materials, nanotubes for example, using the liquid-state thermal fields Studies have shown that the dispersion process -10 18 techniques1-6 as well as solid-state techniques7-13. Spraying involves the shock wave with a front of 10 m thickness (or processes6-8, squeeze casting9, disintegrated melt deposition10,11 compression wave, depending on circuit parameters), cavitation, processes (also electrolytic12) and milling fabrication13-16 have destruction of particles during their collision with the rigid wall been introduced to fabricate the composite at temperatures above of the chamber and their mutual attrition throughout the chamber the melting temperature of the matrix. On the other hand, metal during expansion and collapse of the vapor-gas cavity in varying matrix composites containing such carbon nanoparticles as degrees. Use of a hydrocarbon liquid as the working medium fullerenes are less known, although the properties of these objects during processing of powder mixtures avoids their oxidation with predominant sp2 bonding17 extend their use also in without substantially reducing the hydrodynamic characteristics 2 composites. of the discharge. The case of using a hydrocarbon liquid with sp - Dispersion-hardened composites, based on titan-iron- hybridization (kerosene) is characterized by carbon of graphite 3 carbon alloy systems are widely used in aviation and aerospace type short-range order, and the case of using a fluid with sp - industry due to the properties combining characteristics for hybridization (dodecane, cyclohexane, hexane), by a diamond- 20-23 metals (significant ductility and fracture toughness) and ceramics like . Therefore, it is advisable to use kerosene as the working (high strength, high thermal resistance and elastic modulus). If fluid at HVED treatment of metal powders. The processes they could consist of titanium and iron carbide matrix and occurring in the consolidation of micropowder particles have hardening inclusions –as fullerenes (C60 and C70) decreasing significant influence on the properties of the material. coefficient of friction, such nano-composition besides large Application of method of sintering, such as a spark-plasma strength will be characterized by high thermal resistance in the sintering (SPS), which allow the preservation of the ultrafine wide range of temperatures and low coefficient of friction. structure of the initial powders, leads to the possibility of Therefore, method to obtain such composite would be obtaining high-density powder composites with improved irreplaceable. physical and mechanical properties as well as SPS allows A new method of the metal matrix composites containing purposeful control of grain growth speed and thereby generate carbon nanoparticles preparing – high voltage electric discharge nanostructured microheterogeneous structure of multifunctional treatment in kerosene (dispersion, activation and synthesis) is composite materials with high physical-mechanical and 20 proposed in present work. performance properties . Besides that, high pressure zone The measured micro-Raman scattering confirm the present of enables the formation of fullerene particles. Last one is fullerenes in fabricated composites while mechanical properties particularly important the last one is especially important because shown considerable increasing of strength and wear resistance. of the huge mechanical strength of fullerenes and their property to lower the coefficient of friction22. 2. High voltage electric discharge method. 2.1. The experimental complex

Electric discharge treatment is unique complex method of The experimental complex of HVED (see electrical scheme impact combining the physical and mechanical action and it is Fig.1), located at the Institute of Pulse Processes and based on utilizing high voltage electric discharge (HVED) in Technologies, National Academy of Science of Ukraine, was liquid. HVED in liquid is essentially an electric explosion, used for studies. As shown below, the connection between characterized by rapid energy excretion (during microseconds) in sufficiently strong and stable. The enzyme catalytic activity is initially small volume of discharge channel, paved by streamer, also confirmed, which means that the method applied to construct appeared under the influence of high electric potential between the nanobiosystem was effective. the opposing electrodes. HVED allows obtaining dense low temperature plasma18; its temperature reaches up to 5.104 °C. The high energy concentration, high pressures (about 1 GPa) and

331 MACHINES. TECHNOLOGIES. MATERIALS. 2018

Fig. 1. Electrical scheme of HVED

b)

a) b) c)

c) Fig. 3. The 75%Fe–25%Ti mixture. a) - Distribution of particles percentage F(d) by diameter values (1– initial mixture; 2– after HVED treatment with di/dt = 13 GA/s; 3– di/dt = 19 GA/s; 4– di/dt= 24 GA/s), b)- Mixtures micro-photo-graphs: initial mixture, c)– after HVED treatment with WsΣ = 25 MJ/kg and d) e) di/dt = 24 GA/s. The high modulus (ceramic) TiC (with homogeneity area Fig. 2. a) - working chamber: I – isolator; F – anode; K– up to TiC0,92) and FeC (with size varying from 10 up to 600 nm) kerosene; P – research powder, b) - pressure scale, c, d, e) phases are synthesized at this time. Worth noting that maximum pressure wave peaks during HVED treatment with single amount of powder with ~ 3 µm diameter (~ 30 %) was obtained discharge energy of 1, 0.5 and 0.25 kJ, respectively. after treatment with maximal considered current rise rate of Since at the high voltage electric discharge (HVED) di/dt=24 GA/s (see Fig.3a, curve 4). Most of initial mixture pressure in the discharge channel reaches 1GPa particles had irregular fragmental shape (see Fig.3b), but after (Fig.2 a,b,c,d,e) the temperature in the discharge channel can processing they have shape, close to spherical (see Fig.3c) – this reach 50 000K and at the interface between the plasma channel shows, that they were synthesized due to impact of discharge and environment it is down to 1000 K, the transition layer channel current (ablation and electric erosion). Thus, due to the thickness is 2 mm, pyrolysis of kerosene, with the formation of combined action of simultaneously mechanical (forced solid carbon and atomic and molecular hydrogen gas, is compaction during processing), spark plasma (electric discharge possible24,25. between particles), plasma (local heating after the breakdown of For example, treatment of 75%Fe–25%Ti powder mixtures the oxide films on the surface of powder particles) it is possible to receive composite material with improved physical and was performed with specific energy of WsΣ=const =25 MJ/kg, which ensures synthesis of necessary amount of carbon for performance properties at sufficiently low temperature compared formation of stoichiometric Ti carbide. Current rise rate varied to traditional approaches. from 13 up to 24 GA/s, which provided different intensity of 3. The Raman scattering results. pressure waves impact (see Fig.1d,e,f). Frequency of pulses passing was f = 0,6 Hz. In order to control the chemical composition of components during SPS, the Raman spectroscopy analysis was 2.2. Distribution of particles by diameter values. applied using micro-Raman system based on Renishow inVia Mean diameter of powder particles after treatment in all spectrometer. In Fig.4, micro-Raman (with spatial resolution of 1 studied modes decreased from 80 to ~3 µm (see Fig. 3a). µm) spectrum of individual grain (is shown in center in Fig. 3c) for the 75%Fe – 25%Ti mixture obtained by HVED treatment is presented. The sharp strong line at 1583 cm-1, observed on the 26 curve in Fig. 4, is attributed to C70 molecules , undoubtedly -1 while the line at 1355 cm is close to the one related to the C60 molecules. The deviation from the classic position will be explained later in Table 1. In Fig. 5 the detail results about micro-Raman spectra refer to individual grains of the 50% Al – 50% Ti powder are given.

a)

332 MACHINES. TECHNOLOGIES. MATERIALS. 2018

d) Fig. 4. Raman spectra: blue for above mixture; red for C60 and C70 mixture [26]. The shape of the spectra is changed with each step but two lines at 1355 cm-1 as well as at 1596 cm-1 are clearly shown on each presented in Fig. 5 spectra. A large variety of the Cn fullerene molecules could be attributed to the wide line at about 1360 cm-1 -1 (see Table 1) while line at about 1590 cm , is referred to C70, and is the strongest one in the 24 point. The lines observed in the region from 2300 cm-1 to 3000 cm-1 refer, probably, to Ti–C alloy (with the exception of the line at 2720 cm-1, which is certainly the overtone of the line at 1355 cm-1) and the lines observed in the region from 500 cm-1 to 900 cm-1 – to Al – C alloy.

4. Conclusion.

Therefore, the new method of the metal matrix-carbon nanoparticles composite fabrication based on the HVED treatment of the initially prepared powder is proposed. Proposed method of preparation of powders for consolidation differs from known methods7-16 by the fact that hardening particles are not mechanically added to powder mixture, but are instead

Fig. 5. Mapping of Raman spectra on researched grains of the 50% Al – 50% Ti nanoparticles composite. (a) – the map of the surface of powder; (b) – Raman spectra obtained for the points on map: 8, 13, 18 and 24.

Table 1. Identification of the lines observed in the Raman spectra (s-strong, m-medium, w-weak)

Position of line or Raman spectrum designation: point number group of lines on the map, line pattern (w - weak, m - Identification References (cm-1) medium, s – strong) 1s,2(w),8(w), 10(w),13(w),14(w), (18-22) 1 148 – 154 Al – C alloy 12,14,15 (w) 2 208 – 213 5(w),6(w), (10-12)(w), (14-16)(w), (20-21) w Al (Ti)– C alloy 12,14,15

333 MACHINES. TECHNOLOGIES. MATERIALS. 2018 3 256 – 267 1-3w, 8w, 13w, (16-18)w, 21w Al (Ti)– C alloy 12,14,15 1-3, (5-7)m, 8(-10)s, 13s, 17s,18s, 21m, 23s, 4 415 – 428 Al (Ti)– C alloy 12,14,15, 26 24m, 25w 1-3, 6s, 7m, 8s, 9, 10, 13s, 14, 17s,18s, 21, 5 608 –613 Al (Ti)– C alloy 12,14,15, 27 (23 – 25)m 4, (5–9)s, 10 – 14, 15s, 16, 19s, 6 820 – 840 Al C 12 (20-22)m, 23s, 24s, 25m 4 3 C60 including Fe or Al 7 1355 – 1359 (1-8)m, (9-16)s, (19-22)s, 24sm, 25s atoms and other 15, 26, 27 allotropic C forms (1-3)m, (4-6)s, 7m, 8m, (9-16)s, 17w 18w, 8 1594 – 1596 C 26, 27 (19-22)s, 24s, 25s 70 overtone of line at 1355 9 2700 – 2720 (3-7)w, (8 – 16)w, (19-25)w 28, 29 cm-1 10 2930 – 2950 3m, 4m, (5-7)w, (9 – 16)w, (19-25)w Ti – C alloy 28, 29 11 2320 (1-4)w, (5-7)s, 8w, 9s, (10-16)m, Ti – C alloy 28, 29 synthesized during HVED treatment of “kerosene – Fe Raman spectra of obtained composites have shown (Al) – Ti powder mixture” disperse system with its simultaneous presence of fullerenes C70, as well as other allotropic forms of grinding, fullerenes, which allows us to predict strong thermo-stability in which can be used for creation of composite materials with the wide temperature region, strength and wear resistance while increased mechanical and performance characteristics. maintaining ductility also.

5. References

1 T. Tokunaga, K. Kaneko, K. Sato, Z. Horita. Scripta Materialia, 19 D. Golberg, Y. Bando, O. Stéphan, and K. Kurashima, Appl. 58 735 (2008). Phys. Lett. 73, 2441 (1998). 2 F. A. Khalid, O. Befort, U. E. Klotz, B. A. Keller, P. Gasser, S. 20 O. N. Sizonenko, A. I. Vovchenko, International virtual journal Vaucher, Acta Materialia, 51, 4575 (2003). for science, technics and innovations for the industry, 8, 41 3 S. R. Bakshi, V. Singh, S. Seal, A. Agarwal, Surface and (2014). Coatings Technology, 203, 1544 (2009). 21 Z. A. Munir, U. Anselmi-Tamburini, M. Ohyanagi, Journal of 4 S. R. Bakshi, V. Singh, K. Balani, D. G. McCartney, S. Seal, A. Materials Science, 41, 763 (2006). Agarwal, Surface and Coatings Technology, 202, 5162 (2008). 22 E. Osawa, Perspectives of Fullerene Nanotechnology, Springer 5A. K. Keshri, K. Balani, S. R. Bakshi, V. Singh, T. Laha, S. Science & Business Media, 2002, 375 p. Seal, A. Agarwal, Surface and Coatings Technology, 203, 23 R. Saito, M. Hofmann, G. Dresselhaus, A. Jorito and M. S. (2009). Dresselhaus, Advances in Physics, 60, 413 (2011) 6 H. Uozumi, K. Kobayashi, K. Nakanishi, T. Matsunaga, K. 24 O. N. Sizonenko, E. G. Grigoryev, A. D. Zaichenko, N. S. Shinozaki, H. Sakamoto, T. Tsukuda, C. Masuda, M. Yoshida, Pristash, A. S. Torpakov, Y. V. Lypian, V. A. Tregub, A. G. Materials Science and Engineering A, 495, 282 (2008). Zholnin, A. V. Yudin, and A. A. Kovalenko, High Temp. Mater. 7 C. S. Gon, J. Wei, L. C. Lee, M. Gupta, Composites Science Proc. 36, 891 (2017). and Technology, 68, 1432 (2008). 25O. N. Sizonenko, G. A. Baglyuk, E. I. Taftai, A. D. Zaichenko, 8 M. Paramsothy, S. F. Hassan, N. Srikanth, M. Gupta, Applied E. V. Lipyan, A. S. Torpakov, A. A. Zhdanov, N. S. Pristash, Science and Manufacturing, 40, 1490 (2009). Powder Metall. Met. Ceram. 52, 247 (2013). 9 D. K. Lim, T. Shibayanagi, A. P. Gerlich, Materials Science and 26 D. S. Bethune, G. Meijer *, W. C. Tang, H. J. Rosen, W. G. Engineering A, 507, 194 (2009). Golden, H. Seki, C. A. Brown, M. S. de Vries, Chemical Physics 10 A. M. K. Esawi, M. A. El Borady, Composites Science and Letters, 179, 175 (1991) Technology, 68, 486 (2008). 27 O. Chernogorova, I. Potapova, E. Drozdova, V. Sirotinkin, A. 11 H. J. Choi, G. Kwon, G. Lee, D. Bae, Scripta Materialia, 59, V. Soldatov, A. Vasiliev, and E. Ekimov, Appl. Phys. Lett., 104, 360 (2008). 043110 (2014) 12L. A. Yolshina, R.V. Muradymov, I. V. Korsun, G. A. 28K.J. Cai, Y.Zheng, P. Shen, S. Y. Chen, CrystEngComm, 24 Yakovlev, S. V. Smirnov, J. Alloys and Compounds, 663, 449 (2014). (2016). 29 K. J Cai, Y. Zheng, P. Shen and S. Y. Chen. CrystEngComm, 13A. M. K. Esawi, K. Morsi, A. Sayed, A. A. Gaward, P. Borah, 16, 5466 (2014) Materials Science and Engineering A, 508, 167 (2009). 14 H. J. Choi, J. H. Shin, D. H. Bae, Composites Part A: Applied Science and Manufacturing, 43, 106 (2012). 15K. Choi, J. Seo, D. Bae, H. Choi, Trans. Nonferrous Met. Soc. China, 24, 47 (2014). 16 R. Pérez-Bustamante, C. D. Gómez-Esparza, I. Estrada-Guel, M. Miki-Yoshida, L. Licea-Jiménez, S. A. Pérez-García, R. Martinez-Sánchez, Materials Science and Engineering A, 508, 159 (2009). 17 M.S. Dresselhaus, G. Dresselhaus, and P.C. Eklund, Science of Fullerenes and Carbon Nanotubes, Academic Press, NewYork, NY/San Diego, CA, 1996. 18 R. Deves, D. Aspimvall, J. Simao, H.G.Lee. Electric Al, Materials Word, 11 16 (2003).

334 MACHINES. TECHNOLOGIES. MATERIALS. 2018 INVESTIGATION OF HARDENING PROCESSES OF CORROSION-RESISTANT COATINGS DEPOSITED BY A FLUX-CORED WIRE WITH NITRIDE-BORIDE ALLOYING

ИССЛЕДОВАНИЕ ПРОЦЕССОВ УПРОЧНЕНИЯ КОРРОЗИОННО-СТОЙКИХ ПОКРЫТИЙ, НАПЛАВЛЕННЫХ ПОРОШКОВОЙ ПРОВОЛОКОЙ С НИТРИДНО-БОРИДНЫМ ЛЕГИРОВАНИЕМ

Prof. Dr. Econ. Kuznetsova O.1, Prof. Dr. Eng. Eremin E.2, Cand. Eng. Makarov V.3, graduate student Losev A.4, graduate student Borodihin S.5 Faculty of Humanities Education 1, Machine-building institute 2,4,5, Faculty of Transport, Oil and Gas 3 – Omsk State Technical University, Russia

Abstract: This study explores the metal of a coating deposited by a high-chromium flux-cored wire alloyed with a BN-TiB2-ZrB2 complex. We investigated the changes in the durometric properties and fine structure of the coating after tempering and subsequent quenching. It is shown that the hardening of the metal of such a coating after quenching consists in the formation of a complex composite structure with an iron-chromium martensitic matrix, a large amount of eutectic and particles of hardening complexes, which leads to an increase in hardness and wear resistance. It has been established that phase transformations in the metal of such a coating are caused by the formation of an eutectic component based on chromium and iron borides, a framework structure and a large number of dispersed titanium nitride particles up to 2.5 μm in size. KEYWORDS: SURFACING, FLUX-CORED WIRE, CHROMIUM STEEL, BORIDE COMPOUNDS, HEAT TREATMENT, MARTENSITE, HARDNESS, STRUCTURE, WEAR RESISTANCE.

1. Introduction required to conduct the tempering of the deposited metal, and then, Different methods of coating application are important for after mechanical treatment, its quenching. increasing the group of characteristics of parts of machine-building The hardening processes of this coating and its final properties have production, determining their service life and reliability in not been studied. operation. One of such methods of coating application, widely used Thus, the aim of the work is to explore the changes in the at present, is the surfacing of working surfaces of parts with flux- durometric properties and fine structure of such a coating after cored wires. tempering and subsequent hardening. Thus, for the surfacing of parts for various purposes in petrochemical production widely used flux-cored wires containing 2. Objects and methods of research from 13 up to 25% chromium [1]. Using them makes it possible to As the research object we chose the metal obtained by surfacing obtain coatings with high corrosion resistance. However, such with a flux-cored wire containing 15% Cr, 0.5% BN, 1.25% TiB2, coatings have low abrasion resistance when working in friction 0.5% ZrB2. The metal was studied after thermal treatment under the conditions. At the same time, the introduction of various alloying conditions established earlier: tempering at 800 °С for 2 hours and elements into the flux-cored wires makes it possible to increase the quenching at 1020 °С. hardness and wear resistance of the deposited coatings. Surfacing was carried out on plates of St3 steel with a size of It is common knowledge that high and stable mechanical and 200×50×10 mm with an experimental flux-cored wire of 2.4 mm operational properties of steels can be obtained by combining solid- diameter in argon in three layers. Surfacing mode: current strength solution hardening and hardening by second-phase particles 230 A; voltage 24 V; the rate of surfacing is 20 m / hr. (carbides, nitrides, borides, intermetallics) in an iron-based matrix. Metallographic studies of the deposited metal were carried out on One of such effective methods of hardening the metal is alloying it an optical microscope АXIO Observer A1m (Carl Zeiss). The with boron [2-4]. To achieve this, boron compounds such as microstructure was detected by chemical etching in a reagent of the ferroboron, boron carbide, chromium diboride, titanium diboride following composition: CuSO4 – 4 g; HCl – 20 ml; H2O – 20 ml. should be used when surfacing. Previous studies made by authors Durometric studies were carried out on metal samples after have established a positive effect of titanium and zirconium surfacing and thermal treatment with a hardness tester ТК-2 by the diborides on the wear resistance of chromium-nickel martensitic- method of Rockwell and microhardness tester Shimadzu HMV-2 aging steels surfaced with flux-cored wires [5-7]. by the Vickers method. A wide application for alloying austenitic and austenitic-ferritic Electron microscopy examination was carried out with a raster-type corrosion-resistant steels has found nitrogen [8-10]. Nitrogen electron microscope JEOL JSM-6610-LV with add-on device Inca- improves the ability of deformation hardening, significantly 350 of energy-dispersive analysis (EDA). increases the wear resistance of steel and its ability to resist the Investigations of the fine structure of the metal were carried out on spread of cracks. Nitrogen has also found application for alloying foils using a transmission electron microscope EMV-100L at an steels with a martensitic structure. Such a steel is stronger than the accelerating voltage of 100 kV. steel with carbon and it has a higher wear resistance values than, for example, the well-known Hadfield steel [8]. It should be noted that 3. Results of the experiments and discussion nitrogen is usually introduced into the melt by the use of nitrided The metal of the coating obtained with a flux-cored wire having chromium or ferrochrome. 0,5% BN, 1,25% TiB2, 0,5% ZrB2 in the state after surfacing has a The use of boron nitride for these purposes, which is an electronic hardness of 52-57 HRC starting from the second layer. The carbon analogue due to the similarity of a number of properties, is microhardness of the structural components of such a metal is 617- also of great interest [11]. 648 HV for the matrix, 764-847 HV for the eutectic and 1128-1247 The authors have shown the perspective of surfacing with a flux- HV for the strengthening phases [7]. cored wire doped with a BN-TiB2-ZrB2 complex [7]. However, the It has been established that the microhardness of the structural carried out researches refer only to the metal coatings in the state components of such a surfaced metal after tempering of the coating after surfacing. At the same time, the hardness of such coatings is under investigation has changed significantly (Fig. 1, Tab. 1). quite high, which makes it difficult to machine them. Therefore, it is

335 MACHINES. TECHNOLOGIES. MATERIALS. 2018 Table 3. Microhardness HV 0,01* and HV 0,05 of structural components of the metal with borides after quenching Puncture № HV 1* 1015 2* 558 3 617 4 636 5 756 6 688 7 612 8* 1045 9* 882 10 656 Figure 1. The microstructure of the coating metal and the 11 624 measurement ranges of the structural constituents of the metal with 12 841 borides after tempering

Table 1. Microhardness HV 0,01* and HV 0,05 of structural The microhardness of the structural constituents of the metal components of the metal with borides after tempering deposited by the flux-cored wire with borides has increased Puncture № HV significantly after quenching to 558-688 HV for the matrix, 756-882 1 357 HV for the eutectic and 1015-1045 HV for the hardening phases. Electron microscopic studies of the structure make it possible to 2 608 establish the laws of hardening of such a metal after its quenching. 3 629 The results of transmission electron microscopy of the fine structure 4* 783 of the metal after quenching are shown in Fig. 3. Such a metal is a 5 386 supersaturated α-solid solution with a developed and closed 6 366 eutectic. Its structure characterizes by a large number, a special 7 603 morphology and chemical composition of the eutectic and 8 408 intermediate phases. In addition to the martensitic matrix, eutectics 9* 593 and strengthening phases take place. At high magnifications, the σ 10 371 phase is detected (Fig. 3, b). 11 384 12 675

As it can be seen, the microhardness of the structural constituents of the metal with borides after tempering has significantly decreased to 357-408 HV for the matrix, to 593-629 HV for the eutectics and to 675-783 HV for the strengthening phases. After quenching, the deposited coating metal has a complex composite structure with a martensitic matrix, a large amount of eutectic and reinforcing phase particles. The hardness of such a metal reaches a maximum value of 54 HRC (Tab. 2).

Table 2. Hardness distribution over the cross-section of the coating metal with borides after quenching Hardness distribution over deposited metal Basic Fusion layers, HRC metal zone 1 2 3 4 (a) 10 16,5 52 54 53 51 9 15,5 51 53 54 52

Dyurometric studies showed significant differences in the microhardness of the structural constituents of the coating metal after quenching (Fig. 2, Tab. 3).

(b) Figure 3. The microstructure of the coating metal deposited by the flux-cored wire with borides after quenching obtained by TEM: (a) fine structure (х 18000); (b) microdiffraction Figure 2. The measurement ranges and the microhardness values of the structural constituents of the metal with borides after quenching The results of scanning electron microscopy of the metal with borides are shown in fig. 4.

336 MACHINES. TECHNOLOGIES. MATERIALS. 2018 This boride eutectic is characterized by 900-1050 HV micro- hardness and a large number of dispersed carbonitrides inclusions of the type (Fe, Ti, Cr, Zr)CN from 0.5 µm to 2.5 µm. The research has shown that adding the high chromium flux-cored wire of the boron nitride, titanium diboride and zirconium diboride allows getting a new deposited composite metal. This metal has high hardness, which is due to the complex hardening owing to the formation of martensite in the carbonitride and carboborite phases matrix. In addition, carboboride eutectic located in the frame between the martensite crystals appears in the deposited metal structure, takes some load of the contact interaction and spreads it out on large surface area. This increases the tearing resistance of the deposited metal operating under abrasion conditions. However, a) zirconium and titanium form fine dispersed hardly soluble high strength nitrides that increase the wear resistance of the deposited metal, increasing viscosity and reducing fragility.

4. Conclusion The hardening of the metal of corrosion-resistant coatings deposited with a flux-cored wire alloyed with the BN-TiB2-ZrB2 complex after quenching consists in the formation of a complex composite structure with an iron-chromium martensitic matrix, a large amount of eutectic and particles of hardening complexes, which leads to an increase in hardness and wear resistance. Phase transformations in the metal of such a coating are caused by the formation of an eutectic component based on chromium and iron borides, a framework structure and a large number of dispersed titanium nitride particles up to 2.5 μm in size. The obtained results can be recommended for developing the technology for surfacing corrosion-resistant coatings on parts of petrochemical production.

5. Acknowledgement This research was made possible by a grant from the Russian Foundation for Basic Research (project No. 16-48-550523).

6. Literature

1. (1979) The surfacing materials of the CMEA member countries: catalogue. Kiev, Moscow: VINITI. 2. Lyakishev, N. P., Pliner, Yu. L., Lappo, S. I. (1986) Boron- containing steels and alloys. Moscow: Metallurgiya Publ. 3. Zhong, L., Xiang, C., Yan-xiang L., Kai-hua, H. (2009) High b) boron iron-based alloy and its modification. In: J. of Iron and Steel Figure 4. Scanning electron microscopy of the metal with borides: Research, International, Issue16 (3), 37–42. a) image of the microstructure with the scanning areas location; 4. Raghavan, V. (2003) B – Cr – Fe – Ti (Boron – Chromium – Iron – b) distribution of elements along the scan line Titanium). In: Journal of Phase Equlibria, Issue 24 (5), 459–460. 5. Yeremin Ye. N., Losev, A. S. (2014) Mechanical properties and From energy dispersive analysis data reflecting the quantitative thermal stability a maraging steel with borides, deposited with a distribution of elements along the cut of a straight line in the form flux-cored wire. In: Welding International, Issue 28 (6), 465–468. of concentration spectrograms (Fig. 4, b) and spectra of the local 6. Eremin, E. N. (2013) Using boride compounds in flux-cored point analysis (Table. 4) follows that the metal structure of wires for depositing maraging steel. In: Welding International, Issue represents the iron-chromium martensitic matrix with an eutectic 27 (2), 144–146. component, formed on the basis of boride (Fе, Cr)2B having a 7. Eremin E. N., Losev A. S., Borodikhin S. A., Ivlev K. Ye. skeletal character. (2017) Effect of the boride-nitride hardening on the structure and properties of chromium steel deposited with a flux-cored wire. In: Table 4. Chemical composition of coatings deposited with flux Oil and Gas Engineering (OGE-2017) AIP Conf. Proc., Issue 1876, cored wire with borides 020071-1–020071-6.

8. Kostina M. V., Bannikh O. A., Blinov V. M. (2000) Chrome- B,% N, % C, % Cr, % Fe, % Ti, % Zr, % plated corrosion-resistant steel, alloyed with nitrogen, a new class of structural steels. In: J. Technology of metals, Issue 10, 2–12.

Spectrum 9. Schino A. Di, Barteri M., Kenny J. V. (2003) Grain size 1 18.55 0 13.22 17.26 50.97 0 0 dependence of mechanical, corrosion and tribological properties of 2 0 0 17.55 12.21 70.24 0 0 high nitrogen stainless steels. In: Journal of Materials Science, 3 0 14.65 18.39 8.86 36.24 18.59 3.27 Volume 38, Issue 15, 3257–3262. 4 16.08 0 11.81 18.51 53.60 0 0 10. Spadele М. О. (2005) New nitrogen-containing austenitic stainless steels with high strength and ductility. In: Metallurgy and 5 0 13.18 15.45 6.35 49.82 14.56 0.64 heat treatment of metals Volume 11 (605), 9–13. 11. Kurdyumov A. V., A. N. Pilyankevich, (1979) Phase transformations in carbon and boron nitride. Kiev: Naukova Dumka Publ.

337 MACHINES. TECHNOLOGIES. MATERIALS. 2018 MICROSTRUCTURE AND MECHANICAL PROPERTIES OF P/M TITANIUM MATRIX COMPOSITES REINFORCED WITH TiB

Prof., Dr. Sc. Bagliuk G., M. Sc. Stasiuk O. Institute for Problems of Materials Science, National Academy of Science of Ukraine, Kyiv, Ukraine E-mail: [email protected]

Abstract: The results of the estimation for the influence of titanium diboride content in the initial powder mixture on the basic mechanical properties at the tests on tension and compression are presented. It is shown that the porosity of sintered at 1250 0C preforms from TiH2-TiB2 powder mixture increases with increasing of titanium diboride content in the initial charge, which is due to the manifestation of the Frenkel effect at sintering. The values of tensile strength, hardness and elastic modulus, despite some porosity growth of the sintered alloy, increase with the addition of 5 % of TiB2 powder, while increasing the content of the high modulus component in the mixture to 10 % leads to decrease in the level of these characteristics. The plasticity of sintered alloys monotonically decreases with increasing of the boride component content. At compression tests, the yield point and the compressive strength increase monotonically with increase in TiB2 content, despite the increase in porosity of the latter, due to a significantly lower effect of porosity on the value of the resistance to deformation in compression compared with tension. The use of hot forging of sintered powder preforms leads to increase of strength properties and hardness of the composites. Keywords: POWDER, TITANIUM, BORIDE, HYDRIDE, COMPOSITE, STRENGTH, POROSITY, SINTERING, HOT FORGING.

1. Introduction Titanium matrix composites (TMCs) reinforced with high strength and high stiffness particles/whiskers have generated extensive research interests due to their low cost, ease of fabrication as well as excellent mechanical properties. They have been found a wide range of applications in various fields for commercial automotive, aerospace and advanced military applications, owing to unique properties which include high specific strength, specific combination of good mechanical properties and high temperature durability and specific fatigue resistance (high cycle fatigue) [1]. A number of reinforcements have been suggested/used including Ti Si , CrB, B C and SiC and TiC [1–6]. The 5 3 4 a reinforcements usually need to be stiffer than the matrix, have a similar thermal expansion coefficient to the matrix and to be also chemically stable. Among the ceramic reinforcements TiB are of particular interests since they are well compatible with titanium matrix even at high temperatures and its high hardness and elastic modulus [7-9]. Technological schemes for manufacturing of the titanium matrix composites are based mainly on the use of powder metallurgy techniques [8-10]. At the same time, one of the most effective ways for production of titanium based sintered materials is the use of titanium hydride powders as raw materials instead of titanium powder, which provides a significant activation of diffusion processes during sintering due to the increased density of the crystal b lattice of hydride. As well as the possibility occurs of additional Fig. 1. The morphology of the initial TiH2 (a) and TiB2 (b) powders purification of the interphase boundaries at the expense of atomic hydrogen released during the decomposition of titanium hydride The mixtures of titanium hydride and 5 or 10 % (mass.) [11-13], which leads to higher achievement of complex physical titanium diboride powders were blended in a ball mill and then and mechanical characteristics obtained alloys. The economic consolidated at 650 MPa to obtain compacts, which were then 0 efficiency of TiH2 using is also due to its lower cost compared to sintered at 1250 C for 4 hour in vacuum. As the base material for pure titanium powders. the comparative assessment of high-modulus component effect on Besides that, for providing of dense (practically non-porous) the alloys characteristics, the compacts made from the titanium material the hot forging of porous preforms is one of the most hydride were sintered without the use of reinforcing TiB2 additives efficient processes of powder metallurgy. in the initial mixture. The aim of this article was to study the regularities of the The density and porosity of the blanks after consolidation and structure and phase formation at sintering and effect of hot forging sintering were determined by the method of hydrostatic weighing. on mechanical properties of titanium based composites reinforced Some of the sintered samples were then heated for 10 min. in with TiB. argon and hot forged on the mechanic arc-type stator press in the semiclosed die (fig. 2). 2. Materials and experimental procedure Mechanical tensile and compression tests of the produced For experimental investigations of mixture composition composites were carried out at room temperature using the Instron influence the on the structure and phase composition of the 3376 machine. pseudoallys, the mixtures of titanium hydride and titanium diboride The fracture structure of the samples after the mechanical tests TiB2 powders (fig.1) were prepared. was studied using fractographic analysis. The study of materials The dispersion composition of the powders was determined microstructure was carried out using scanning electron microscope using the Malvern Mastersizer 2000 laser analyzer.

338 MACHINES. TECHNOLOGIES. MATERIALS. 2018

TESCAN VEGA 3. The Vickers hardness was measured on a are present in the alloy. The initial TiB2 phase on the radiographs of Wolpert hardness meter. the sintered alloys are not identified.

Fig. 2. The experimental die for hot forging: 1 - the top plate; 2 - upper semimatrix; 3 - lower semimatrix; 4 - lower support plate; 5 - support plate; 6 - elastic element; 7 - lower punch; 8 - stampable blank; 9 - upper and lower fixing flanges

Investigation of physical processes occurring during the heating of powder compacts took place on an automated dilatometric Fig. 3. X-ray pattern of the alloy, sintered from the mixture complex [14]. The X-Ray Diffraction (XRD) analysis of the of TiН2+TiВ2 powders samples was performed using DRON-3M diffractometer with CoKα radiation in the range of angles from 20 to 130 degrees. The sample The estimation of component composition of the initial powder during the analysis were rotated around its axis. The analysis of mixture influence on the amount of the sintered specimens porosity XRD data was performed by standard methods using the ASTM under the same sintering conditions showed that material porosity card index. increases with increasing of titanium diboride content. While the porosity of titanium made from TiH2 powder without reinforcing additives does not exceed 1,5 %, the specimens sintered from 3. The results and discussion mixture with 10% TiB2 have already a significant porosity of about The estimation of the initial powders granulometric composition 7,5 % (fig. 4, a). showed that average size of the titanium diboride particles did not Increasing of the sintered samples porosity with incorporation exceed 10 microns, whereas the maximum of the distribution curve of the titanium diboride into the mixture composition can be for the particles of the titanium hydride powder was about 30-40 explained by the effect of secondary pore formation. Since the Ti microns (Fig. 3). diffusion coefficient in boron is negligible compared to boron in titanium diffusion coefficient [15], in the process of sintering practically one-sided diffusion of boron atoms into titanium matrix occurs with the formation of needle-like TiB particles, while the flow of vacancies diffuses in the opposite direction, which leads to the formation of secondary porosity (the Frenkel effect) [16]. The presence of residual porosity makes its effect on the level of the main mechanical characteristics of the alloy. Despite the generally hardening nature of the TiB reinforcing phase in the metal matrix composite, when the content of the latter is increased in the initial powder mixture, competition occurs between the effects of reinforcing of the matrix phase (which leads to an increase in the hardness and strength of the sintered alloy), and reducing of these characteristics values due to the presence of residual porosity. Thus, from fig. 4, b it can be seen that sintered samples obtained from titanium hydride without the use of the reinforcing phase have the tensile strength value of about 650 MPa with the elongation of Fig. 3. Particles size distribution of the used TiH2 and TiB2 powders: 1 - initial powders; 2 - powders after ultrasonic treatment ~10 %. These values are comparable to the standards for technically pure titanium (Grade 4). Incorporation of 5 % TiB2 powder in the Sintering process of titanium hydride based powder mixtures is mixture, despite some porosity growth of the sintered alloy in accompanied by the emission of atomic hydrogen contained in the comparison with pure titanium, leads to increase in the composite titanium hydride crystalline lattice, which is an effective metal strength up to 750÷800 MPa (fig. 4, b), but it is accompanied by a cleaner from unwanted admixtures such as oxygen and chlorine. decrease in plasticity to 2÷3 % (fig. 4, c). During high-temperature sintering hydrogen is almost completely With an increase of the high-modulus component content in the removed from titanium and the hydride is converted into sintered, mixture to 10 %, the negative effect of increasing porosity prevails technically pure titanium with residual content of hydrogen in the over the reinforcing effect and the value of ultimate stress limit of alloy at the level of 0.005 %. the latter decreases to 620 MPa. Furthermore, such increase of TiB2 As it is shown in [7, 13], in the process of sintering of mixtures content in the mixture and, accordingly, TiB phase content in the of titanium powder with titanium diboride, TiB2 particles at high sintered material, also leads to a catastrophic reduction of its plastic temperatures actively interact with the titanium matrix phase by the characteristics, which does not exceed 0,5 %. reaction ТіВ2+Ті2ТіВ with the release of titanium monoboride Similar regularity concerning the effect of titanium diboride particles. content in the mixture on composite strength appears as well for the The the X-ray diffraction analysis results of the sintered parameters of the elastic modulus (fig. 4,e) and hardness (fig. 4,d). samples from the TiН2+TiВ2 mixture (fig. 3) indicate that in the Typical tensile curves for technically pure titanium and alloy, in addition to the main titanium matrix phase, the TiВ phase composites with different contents of TiB reinforcing phase are with orthorhombic lattice and the presence of traces of titanium presented at fig. 5. Comparison of «σ-ε» diagrams type for materials compounds with boron of another concentration (Ti3B4 and Ti2B5), with different contents of high modulus component showed their

339 MACHINES. TECHNOLOGIES. MATERIALS. 2018 significant difference due to their significantly different plasticity. stresses, is characteristic. In the composite obtained from mixture For deformation curve of titanium sintered without borides with 5 % TiB2, the length of this area significantly decreases, and additives, the presence of a large-scale zone of plastic deformation with the increase of titanium diboride content up to 10 %, the view where the deformation grows practically without increasing of "σ-ε" diagram corresponds to those of fragile destruction.

a b

c d

e f Fig. 4. The effect of titanium diboride content in powder mixture on the basic mechanical characteristics of sintered alloys when tested for tensile strength (a, b, c, e), hardness (d) and compression (f)

increase in the TiB2 content in the mmixture despite the increase of porosity. This regularity, obviously, is due to considerably less influence of material porosity on the value of the compressing strength compared with the tensile strength due to decrease in porosity value during blanks upsetting, which is also confirmed by the results of theoretical works [17]. The analysis of the sintered specimens microstructure (fig. 6) showed that in the process of sintering, the titanium diboride inclusions actively interacts with the titanium matrix, resulting in formation of titanium monoboride particles, which mainly have a needlelike shape with cross section size of 1÷5 μm and a length of 10÷25 μm. Fig. 5. Typical deformation curves for sintered composites It is well known that one of the most effective methods for at tensile tests improving the basic mechanical and operational properties of sintered powder materials is to reduce porosity and provide Taking into account fundamentally different mechanisms of favorable conditions for the intensification of intergranular tensile deformation for the investigated alloys of various component diffusion processes between powder particles. In order to realize compositions, it is obviously of interest to compare their mechanical these effects, approaches are widely used, based on the employment characteristics when tested for compression. As in can be seen from of hot forging of porous powder preforms [18-21]. fig. 4,f, unlike tensile tests, in case of compression tests the value of both proportional limit and yield point monotonically grow with

340 MACHINES. TECHNOLOGIES. MATERIALS. 2018 leads to a decrease in the level of these characteristics. The plasticity of sintered alloys monotonically decreases with increasing content of the boride component. 4. Unlike tensile tests, at compression tests values of limit of proportionality and yield point increase monotonically with an increase of TiB2 content despite the increase in porosity of the latter. 5. The use of hot forging of sintered powder preforms leads to increase of strength properties and hardness of the composites.

a b

c d Fig. 6. Microstructure of the composites made from powder a mixtures with 5 % (a, c ,d) and 10 % (b) ТіВ2

Comparative estimation of the effect of porous preforms hot forging on the basic mechanical characteristics of the composite had shown, that this kind of treatment of sintered billets significantly increased the values of both proportional limit and yield point (fig. 7,a), and the hardness of the material (fig. 7,b). It is noteworthy that the effect of hot forging to a large extent is shown for a composite obtained from the mixture with a higher content of titanium diboride (10%). The observed regularity is due to the following reasons. As it was shown above (fig. 4a), the increase the content of boride component in the alloy composition results in a corresponding increase of the composite porosity after sintering as well as associated with the latter mechanical characteristics (fig. 4,b,d,e). At the same time, the use of hot forging b provides obtaining of practically non-porous (with porosity of 0,5 ÷ Fig. 7. The effect of titanium diboride content in powder mixture on 1,0 %) powder materials. Thus, after hot forging, the effect of proportional limit and yield point at compression testing (a) and residual porosity on the properties of the alloy, which is manifested hardness (b) for sintered materials, is eliminated, and the mechanical characteristics of such alloys will be determined (at the same other conditions) mainly by the content of the high modulus boride 5. References component, the dispersion of the structure and the state of the 1. Titanium´ 2003: Science and Technology: Proc. of 10th intergranular boundaries. World Conf. On Titanium, 13-18 July 2003. - Gamburg, Germany. Taking into account the known influence of hot forging on the Vol. 1-5. - 3425 p. structure dispersion and the intensification of intergranular 2. Wang H.W., Qi J.Q., Zou C.M., Zhu D.D., Wei Z.J. diffusion, we can conclude that the increase in the properties of the High-temperature tensile strengths of in situ synthesized TiC/Ti- alloy with a minimal content of the boride component (5% TiB2), alloy composites // Materials Science and Engineering, A. - 2012. - with a small initial porosity after sintering (≈1.5%) is due mainly to Vol. 545. - P. 209-213. these factors, whereas for the billets with 10 % TiB2 significant 3. Rahoma H.K.S., Wang X.P., Kong F.T., Chen Y.Y. , Han increase in properties is due as well to the effect of removing J.C., Derradji M. Effect of (α+β) heat treatment on microstructure residual porosity during forging. and mechanical properties of (TiB+TiC)/Ti-B20 matrix composite // Materials & Design. - 2015. - Vol. 87. - P. 488–494. 4. Conclusion 4. Poletti C., Balog M., Schubert T. Production of titanium 1. Sintering of the samples made from a powder mixture TiH2- matrix composites reinforced with SiC particles // Composites TiB2 is accompanied by active interaction of diboride particles with Science and Technology. – 2008. – V.68. – P. 2171-2177. titanium matrix, as a result of which the the formation of needle-like 5. Li S., Kondoh K., Imai H., Chen B., Jia L., Umeda J. titanium monoboride particles in the titanium matrix phase takes Microstructure and mechanical properties of P/M titanium matrix place. composites reinforced by in-situ synthesized TiC-TiB // Materials 2. Porosity of the sintered samples increases with the increase Science and Engineering: A. - Vol. 628, 2015. - P. 75–83. of titanium diboride content in the initial mixture from 1.5 % for 6. Sumida M., Kondoh K. In-Situ synthesis of Ti-matrix samples without boride inclusions, to 7.5 % for materials with 10 % composite reinforced with dispersed Ti5Si3 particles via spark TiB2 due to development of Frenkel effect at sintering. plasma sintering // Materials Transactions. – 2005. – Vol. 46, 3. The values of tensile strength, hardness and elastic No.10. – P. 2135-2141. modulus, despite some porosity growth of the sintered alloy, 7. Li, B. S.; Shang, J. L.; Guo, J. J.; Fu, H. Z. Formation of increase with the insertion of 5 % of TiB2 powder into the mixture, TiBw reinforcement in in-situ titanium matrix composites // J. while increasing the content of the high modulus component to 10% Mater. Sci. – 2004. - Vol. 39. - P. 1131-1133.

341 MACHINES. TECHNOLOGIES. MATERIALS. 2018 8. Ma, Z. Y.; Tiong, S. C.; Gen, L. In-situ Ti-TiB metal- matrix composite prepared by a reactive pressing process // Scr. Mater. – 2000. – Vol. 42. – P. 367-373. 9. Баглюк Г. А., Івасишин О. М., Стасюк О. О., Саввакін Д. Г. Вплив компонентного складу шихти на структуру та властивості спечених титаноматричних композитів з високомодульними сполуками // Порошковая металлургия. – 2017 . – № 1/2. – С. 59-68. 10. Gorsse, S.; Chaminade, J. P.; Le Petitcrops, Y. In situ preparation of titanium base composites reinforced by TiB single crystals using a powder metallurgy technique // Composites, Part A. – 1998 – Vol. 29 . – P. 1229-1234. 11. Ивасишин О. М., Демидик А. Н., Саввакин Д. Г. Использование гидрида титана для синтеза алюминидов титана из порошкових материалов // Порошковая металлургия. – 1999. – № 9/10. – С. 63-70. 12. Баглюк Г.А., Супрун О.В., Мамонова А.А. Особливості структуроутворення при термічному синтезі багатокомпонентних сполук із порошкових сумішей на основі системи TiH2-Fe-Si-Mn-C(В4С) // Наукові нотатки. – 2017. – Вип. 58. - C.27-35. 13. Івасишин О.М., Баглюк Г.А., Стасюк О.О., Саввакін Д.Г. Особливості структуроутворення при спіканні порошкових сумішей системи TiH2-TiВ2 // Фізика і хімія твердого тіла. – 2017 . – т.18, № 1. – С. 15-20. 14. Ивасишин О. М., Черепин В. Т., Колесник В. Н., Гуменяк Н. М., Автоматизированный дилатометрический комплекс // Приборы и техника эксперимента. – 2010. – № 3. – С. 147-151. 15. Fan Z., Guo Z. X., Cantor B. The kinetics and mechanism of interfacial reaction in sigma fibre-reinforced Ti MMCs // Composites Part A: Applied Science and Manufacturing - 1997.- P. 131-140. 16. Сторожук Н.В., Гусак А.М. Конкуренция эффектов Френкеля и Киркендалла при взаимной диффузии // Металлофизика и новейшие технологии. - 2014. - Т. 36, № 3. - С. 367-374. 17. Михайлов О.В., Штерн М.Б. Учет разносопротивляемости растяжению и сжатию в теориях пластичности пористых тел // Порошковая металлургия. – 1984. – № 5. – С. 17÷23. 18. Дорофеев В.Ю. Структура и свойства порошкового материала, формируемого при горячей штамповке с элементами выдавливания // Порошковая металлургия. -1985. - №7. –С.23-27. 19. Баглюк Г.А. Влияние деформационных параметров на структуру и свойства горячештампованных порошковых материалов // Обработка металлов давлением. – 2011. – № 1(26). – С. 139÷145. 20. Баглюк Г.А. Повышение эффективности уплотнения пористых заготовок за счет интенсификации сдвиговых деформаций // Реологія, структура, властивості порошкових та композиційних матеріалів. Збірник наук. праць. –Луцьк: РВВ ЛДТУ, 2004. –С.35-48. 21. Павлов В.А., Носенко М.И. Влияние горячей деформации на формирование структуры и свойств порошковых металлов // Порошковая металлургия. – 1988. - №2. – С.16-20.

342 MACHINES. TECHNOLOGIES. MATERIALS. 2018 PRODUCTION PROCESS OF POWDER PERMEABLE MATERIALS MADE OF SPHERICAL BRONZE POWDERS BY PRESSING

ПРОЦЕСС ПОЛУЧЕНИЯ ПОРОШКОВЫХ ПРОНИЦАЕМЫХ МАТЕРИАЛОВ ИЗ СФЕРИЧЕСКИХ ПОРОШКОВ БРОНЗЫ МЕТОДОМ ПРЕССОВАНИЯ

Prof., Dr. Eng., Cor. Member of NAS of Belarus Ilyushchanka A.1, 2, PhD of Eng., Doc. Kusin R.A.3, Head of the Lab. Charniak I.N.2, Res. Kusin A.R. 2, Res. Zhehzdryn D.I.2 State research and production powder metallurgy association1 – Minsk, Republic of Belarus State Scientific Institution “Powder metallurgy institute” 2 – Minsk, Republic of Belarus Belarusian state agriculture technical university 3 – Minsk, Republic of Belarus Е-mail: [email protected], [email protected], [email protected], [email protected], [email protected]

Abstract: The process of producing powder permeable materials made of spherical bronze powders by tin-phosphorous pressing method has been investigated. A technique for producing experimental samples based on the granulation of powders by a pore-former has been described. The technology is simple to carry out and it does not require complex equipment. Products have a satisfactory set of properties.

KEYWORDS: POWDER PERMEABLE MATERIALS, PORE-FORMER, GRANULATION, PRESSING, PROPERTIES

1. Introduction fraction (minus 315+200) μm, carbamide powder CO(NH2)2 The methods for powder permeable materials molding are divided (analytic grade) were used as initial materials. The process of into two groups: and applying pressure. As a rule, when using producing the samples included the preparation of a charge, spherical powders for the production of porous permeable products, granulation, pressing and sintering. a molding method without applying pressure is used. The simplest Granulation was carried out by carbamide dissolution in distilled method is the sintering of a freely poured powder [1, 2]. water, mixing the resulting solution with fine-dispersed bronze, Compared with non-spherical powders, products made of spherical drying the charge in CNEF 4.5.4.5/34-1 drying oven at a powders have a more uniform porosity and high permeability [3, 4]. temperature of 60-80 °C with constant stirring. The formed granules For the production of permeable materials, spherical powders of were scattered on a device of grain composition 029 with separation tin-phosphorous bronze of grade BrO10F1 are most widely used, of the required fractions of the obtained charge (bronze powder which are well sintered by the method of free pouring at relatively granulated with a pore-former carbamide). low temperatures (790-870 °C) in reducing and neutral atmospheres After pressing, the samples were sintered for 1 hour in an endogas or in a vacuum. The products from these powders have a high atmosphere in a laboratory electric furnace with preliminary complex of filtering and physical-mechanical properties. A tooling removal of carbamide by withstanding at a temperature of 250 °C from corrosion-resistant steels of grades Х18Н10, Х18Н9, Х30 is for 0.5 hour. The porosity in accordance with GOST 18898-89, the used for sintering the products. One set of tooling can withstand coefficient of permeability in accordance with GOST 25283-93, the from 50 to 100 cycles of sintering. However, corrosion-resistant pore sizes in accordance with GOST 26849-86 and the ultimate steels are poorly treated and expensive. This significantly affects shear stress, calculated by dividing the shear force by the area of the the cost of porous products. sheared surface, were determined in the produced samples. Therefore, it seems relevant to consider the possibility of producing porous filter materials made of BrO10F1 powder by pressing, 2. Experiment results and discussion secondly, to justify the possibility of producing powder permeable It is obvious that the main technological factors influencing the materials from the powders with a fraction of 200-315 μm with properties of the produced powder permeable materials during the properties corresponding to materials produced from powders with preparation of the charge are the size of the initial bronze powder Dp larger fractions. and the volume ratio of carbamide (pore-former) and bronze However, molding with applying pressure is mainly used in the powders Vpor/Vbr. As noted above, a fraction of the bronze powder manufacture of products made of powders with a non-spherical (minus 315+200) μm was chosen for the study. The charge was shape particles, and does not require the introduction of binding prepared in five compositions: Vpor/Vbr: 0.1; 0.3; 0.6; 0.9; 1.2, since materials. at a ratio of less than 0.1, the pore-former does not have a significant The purpose of this work is to study the process of producing effect on the structure of powder permeable material, and at a ratio powder filter materials by pressing granular spherical bronze more than 1.2, the strength of the produced powder permeable powders of grade BrO10F1 by means of a pore-former. materials is significantly reduced. When molding, i.e. static pressing in a mold, the key factor is the pressing pressure p. A study of the 2. Research material. morphology of the surface of particles of bronze powder and It is common knowledge that spherical powders are not pressed granules of granular bronze powder by a carbamide pore-former was without special additives (binders), which can be used as pore- carried out using MIRA scanning electron microscope with formers and plasticizers [2, 5]. In this paper, the molding capacity EDX X-act X-ray microanalyzer, Tescan, Czech Republic. The of a spherical powder of tin-phosphorous bronze is ensured by microscope is shown in Figure 1. granulating the metal powder by a pore-former, i.e. carbamide (urea, CO(NH2)2). It follows from the works [6-10] that carbamide has a number of advantages: it does not contaminate products with decomposition impurities; it is well soluble in water; it is widely used. It should be noted that carbamide was previously used as a filler. Its use as a binder in the molding of powder permeable materials from spherical powders of tin-phosphorous bronze by the pressing method has not been previously met. Samples in the form of a disk with a diameter of 30 mm and a thickness of 3 mm were produced by a pressing method to study the process of producing powder permeable materials from spherical Fig. 1 MIRA scanning electron microscope with EDX X-act X-ray bronze powders [11-13]. Bronze powder of grade BrO10F1 of microanalyzer, Tescan, Czech Republic

343 MACHINES. TECHNOLOGIES. MATERIALS. 2018 Photographs of the morphology of the powder surface and granules The pressing pressure, on the one hand, was chosen from the are shown in Figures 2 and 3. condition of achieving the strength of the compact, ensuring its safety during the preparatory work related to sintering (moving, placing in the boat, etc.); on the other hand, the porosity and coefficient of permeability are significantly decreased at high pressures making it unreasonable to use the resulting product as powder permeable material. Proceeding from this, the pressing pressure was chosen to be 50, 90, 130 MPa.

Figures 4-7 show the experimental dependences of P, k, dpore, av on the ratio of urea volume to the volume of bronze powder at various pressing pressures.

Fig. 2 Photographs of morphology of the surface of bronze powder of brand BrO10F1 of fraction (minus 315+200) μm

Fig. 4 Dependence of the porosity on the volume ratio of the pore-former and the metal powder

k1013, м2

a)

Fig. 5 Dependence of the coefficient of permeability on the volume ratio of the pore-former and the metallic powder

b)

а) with increasing × 20; b) with increasing ×300

Fig. 3 Photographs of the morphology of the surface of particles of bronze powder granulated by a carbamide Fig. 6 Dependence of the average pore size on the volume ratio of the blowing agent and the metal powder

344 MACHINES. TECHNOLOGIES. MATERIALS. 2018

str., МРа

c)

Fig. 7 Dependence of the ultimate shear strength on the volume а) Vpor/Vbr = 0,3; b) Vpor/Vbr = 0,6; c) Vpor/Vbr = 1,2 ratio of the pore-former and the metal powder Fig. 8 Microstructure of the samples of powder filter material made The analysis of the obtained data in Figures 1-4 makes it possible to of tin-phosphorous bronze powder of a fraction from 315 to 200 μm conclude that the use of the pore-former allows to significantly with different contents of carbamide pore-former at a pressing regulate the range of the main properties of powder permeable pressure of 90 MPa material: porosity from 0.32 to 0.52; average pore size from 60 to 197 μm; coefficient of permeability from 250×10-13 to -13 2 The most promising is the use of the developed method for mass 1450×10 m . It is obvious that the use of other fractions more pressing of small asymmetric products or long tubular filtering extends this range. products by radial isostatic pressing. The latter is very difficult to Analysis of the photographs of the sample fractures (Figure 8) produce by other methods, especially with a small diameter: rolling made by MIRA scanning electron microscope (Figure 1) has of plates in this case is impossible, and sintering in the mold is showed that the samples of powder permeable material made by economically impractical and is related to unacceptable pressing from the tin-phosphorous bronze powder of the fraction technological complications. from 315 to 200 μm with different contents of the carbamide pore- former have a well developed biporous pore structure (Figure 8). 3. Conclusion As a result of the research, the process of manufacturing powder permeable materials was developed by pressing a granular spherical bronze powder of grade BrO10F1. It is established that the pressing of a granular powder of spherical bronze makes it possible to produce powder permeable materials with a wide range of regulated properties.

4. References

[1] Jones, V. Fundamentals of Powder Metallurgy, Moscow: Mechanical Engineering, (1965), pp. 31-48. (V. Jones). (in Russia).

[2] Vityaz, P. Filtering materials: properties, fields of application, manufacturing technology, Minsk: SRI PM with PP, (1999), p. 304 (P. Vityaz, V. Kaptsevich, R. Kusin). (in Russia).

[3] Belov, S. Porous materials in mechanical engineering, Moscow: а) Mechanical engineering, (1981), p. 248 (S. Belov). (in Russia).

[4] Fedorchenko, I. Powder metallurgy, Materials, technology, properties, fields of application, Reference book, Kiev, Naukova Dumka, (1985), p. 625 (I. Fedorchenko, I. Franzevich, etc.) (in Russia).

[5] Balshin, M. Scientific fundamentals of powder metallurgy and fiber metallurgy, Moscow, Metallurgizdat, (1972), p. 335 (M. Balshin). (in Russia).

[6] Kusin A. Optimization of the process of producing porous powder materials at the pressing of metal powders with pore- formers, New materials, equipment and technologies in industry, Materials of the Republican Sc.-Techn. Conf. of Post-graduate students, Undergraduates and Students, Mogilev, GUVPO Belarussian-Russian University, (2004), p. 46. (A. Kusin) (in b) Russia).

345 MACHINES. TECHNOLOGIES. MATERIALS. 2018 [7] Kostornov, A. Compaction features of metal powder mixtures [11] Kusin R. Powder of filtering materials gained from porogene with a pore-former, Powder Metallurgy, (1983), V.6, pp. 10-14. granulated spherical powder of tin-phosphorus bronze by molding (A. Kostornov, L. Lunin, N. Fedorova, L. Chernyshev) (in Russia). with the application of pressure, Powder Metallurgy, Republican interdepartmental collection of scientific works, Editorial Board: P. [8] Lunin, N. Effect of joint milling and mixing of a pore-former Vityaz (Ch. Ed.) and colleagues, Minsk, Belaruskaya Navuka, with a metal powder on the structure of a porous material, Powder (2007), Issue 30, pp. 167-169. (R. Kusin and etc). (in Russian). Metallurgy, (1983), V. 4, pp. 15-18. (N. Lunin, V. Sheremet, A. Kostornov, N. Slaptsova). (in Russia). [12] Kusin R. Perspective methods for creating gradient permeable structures, Porous filtering materials: technologies and products [9] Bokan, G. Influence of a pore-former on the properties of thereof: Records of the IV International Symposium, Minsk, 30-31 porous powder materials made of corrosion-resistant steel powder, October, 2011, Nat. Acad. of Sciences of Belarus. Editorial Board: Powder Metallurgy, (1999), Issue 22, pp. 112-115. (G. Bokan, I. P. Vityaz (Ch. Ed.) and colleagues. Minsk: Belaruskaya Navuka, Valkovich, M. Kaptsevich, and etc.). (in Russia). (2011) pp. 81-91. (R. Kusin). (in Russian).

[10] Nekrasov, B. Fundamentals of General Chemistry, Vol. 1, 3rd [13] Vityaz, P. Modern Processes of Producing Two-Layer Filtering ed., corrected, Moscow, Chemistry, (1974), p. 656 (B. Nekrasov). Materials, Powder Metallurgy and Metal Ceramics, January 2014, (in Russia). V. 52, Issue 9-10, pp 514-522. (P. Vityaz and etc.).

346 MACHINES. TECHNOLOGIES. MATERIALS. 2018 TRIBOLOGICAL STUDIES FOR COMMERCIALLY PURE GRADE 4 TITANIUM WITH DIFFERENT MICROSTRUCTURES, WITH AND WITHOUT COATING

ТРИБОЛОГИЧЕСКИЕ ИССЛЕДОВАНИЯ НА ТЕХНИЧЕСКИ ЧИСТОМ ТИТАНЕ GRADE 4 С РАЗЛИЧНОЙ МИКРОСТРУКТУРОЙ С ПОКРЫТИЕМ И БЕЗ ПОКРЫТИЯ

Lead. Res., Dr. Semenov V.I.1, +, Lead. Res., Prof. Raab G.I.1, Prof., Dr. Huang S.-J.2, PhD Stud. Bogale D.A.2, Head of Lab. Charniak I.N.3

1Ufa State Aviation Technical University, Ufa, Russia 2 National Taiwan University of Science and Technology, Taipei, Taiwan 3State Scientific Institution "Institute of Powder Metallurgy", Minsk, Belarus +corresponding author, e-mail: [email protected]

Abstract. The paper presents experimental data on the tribological properties of commercially pure titanium with different microstructures with and without coating. As a result of the conducted experiments, it was established that the integral value of the friction coefficient, as well as its adhesion component, are structurally sensitive parameters. It is noted that the ultrafine-grained structure, obtained as a result of intense plastic deformation, contributes to the reduction of the coefficient of friction, as well as to the increase of the load-bearing capacity of tribo-conjugation.

KEY WORDS: COEFFICIENT OF FRICTION; SHEAR STRENGTH OF ADHESION BONDS, HARDNESS, INTENSE PLASTIC DEFORMATION, MICROARC OXIDATION, ION-PLASMA SPRAYING.

Introduction different microstructures with and without coatings are of practical According to the expert assessment, the use of strain-hardened interest. commercially pure titanium in the field of medicine (as implants, tools, fasteners, etc.) is promising [1]. This is largely due to the fact 1.1. Methods to evaluate the integral quantity of the friction that commercially pure titanium has a high biocompatibility, coefficient and its adhesive component bioinertness, hypoallergenicity and is also non-toxic [2 - 5]. The applied deformation processing technologies make it possible to For tribological studies, the two schemes are shown in Fig. 2. achieve a high-strength state due to the formation of ultrafine- grained (UFG) microstructure, which contributes to a significant increase in mechanical and functional properties [6, 7]. There are known works on the production of semi-products from commercially pure titanium for medical use with ultrafine- grained (UFG) structure, produced by high pressure torsion (HPT) [8 - 10], with subsequent application of a coating from titanium nitride [8, 9] and diamond-like carbon with zirconium [10]. At the same time, high strength of the material with improved tribological properties is achieved, but the samples have very small dimensions – a diameter of up to 5 - 8 mm and a thickness of less than 1 mm - а) b) which create significant limitations for their widespread use. In Fig. 2. Reciprocal test scheme: a) 1 - spherical indenter; 2 - the addition, it is difficult to conduct tribological tests on such samples. test sample; a test scheme for determining the shear strength of Thus, for engineering applications, of great interest are adhesion bonds and the molecular component of the friction technologies that make it possible to produce bulk (large-sized) coefficient: b) 1 - spherical indenter; 2 and 3 are test samples. nanostructured materials with unique physico-mechanical, performance and functional properties [1, 2, 11 - 14]. These The first scheme for reciprocating motion (Fig. 2a) was used technologies are based on the methods of equal-channel angular to estimate the friction coefficient in pairs "commercially pure pressing (ECAP) [11, 14, 15], in particular, the ECAP-Conform titanium Grade 4 - chromium steel of composition Fe-1.5Cr-1.0C". process for the formation of UFG structures in large-sized long- This scheme was implemented on the tribometer "Nanovea TRB- length metallic materials (the principle is shown in Fig. 1). 1" (Fig. 3).

Fig. 3. Tribometer "Nanovea TRB-1"

Fig. 1 Principle of the ECAP-Conform process for producing long- For the tests we used samples in the form of a parallelepiped length semi-finished products with ultrafine-grained structure with a length of 25 mm and a section of 9.5 x 9.5 mm. For the indenter, we used bearing steel of composition Fe-1.5Cr-1.0C with For large-sized samples, many aspects related to the study of a spherical contact surface with a diameter of 3 mm. The test functional properties, in particular tribological ones, remain open, conditions are as follows: temperature – room temperature; the depending on the structural state of commercially pure titanium. In displacement amplitude at a normal load of 5 N was 20 mm at addition, comparative tribological studies of the material with 5000 cycles. Speed of movement was 30 cycles per min.

347 MACHINES. TECHNOLOGIES. MATERIALS. 2018 The second scheme (Fig. 2, b) was used to evaluate the shear strength of adhesive bonds and the molecular component of the The high sensitivity of measurements is ensured by the friction coefficient. The test samples were made in the form of absence of additional supports of the upper and lower samples. parallelepipeds with a section of 9.5 x 9.5 mm and a thickness of 5 The standard values of the radius (r=2.5 mm) of the spherical mm, a spherical indenter with a sphere radius of 2.5 mm - from specimen (indenter) and the compressive force ensure that the high-speed tool steel of composition Fe-6W-5Mo. Tests to h determine the shear strength of adhesion bonds were carried out on conditions .0 02  2.0 (where h is the penetration a one-ball adhesion tester by the scheme shown in Fig. 2, b. In Fig. r 4 shows a general view of the equipment for evaluating the strength depth), which mainly covers the range of the ratio of the of adhesion bonds. microasperity depth to the radius at the vertex, characteristic for external friction. In this case, the pressure at the contact site can be considered as uniformly distributed (with an error of no more than 10%). The deformation of a spherical specimen that is harder than a plane sample is neglected.

1.2. Determinations of the friction coefficient under elastic contact conditions

The results of tribological tests according to the first scheme (Fig. 2, a) in the following friction pairs: "commercially pure Grade 4 titanium without coating - chromium steel of composition Fe-1.5Cr-1.0C"; "Commercially pure Grade 4 titanium with IPS coating - chromium steel of composition Fe-1.5Cr-1.0C"; Fig. 4. Equipment for determining the shear strength of adhesion "Commercially pure titanium Grade 4 coated with MAO - bonds chromium steel of composition Fe-1.5Cr-1.0C" in Fig. 5. The material under investigation was of different microstructure: The tests were carried out at a temperature of 20 ° C on a one- coarse (CG) after annealing and ultrafine-grained (UFG) after six ball adhesion tester [16]. This method is based on the physical cycles of severe plastic deformation by the method of equal- model, which in the first approximation reflects the actual channel angular pressing (ECAP) combined with Conform conditions of friction at the local contact. (ECAP-Conform). According to this model, the spherical indenter 1 (simulating a single asperity of the contact spot of rubbing solid bodies), compressed by two plane-parallel samples 2 and 3 (with high accuracy and cleanliness of the contacting surfaces) rotates under load around its own axis. The force F expended on the rotation of the indenter is mainly due to the shear strength of the adhesion bonds. The initial roughness of the contact surfaces of the test samples and indenter in both test schemes was 0.06-0.16 μm on the Ra scale. The test samples used for both schemes had a coarse-grained (CG) and ultrafine-grained (UFG) structure, obtained in the first case after annealing at 600 ° C for 1.5 hours and, in the second case, Fig. 5. Dependence of the friction coefficient on the number of after six cycles of severe plastic deformation (SPD) processing by cycles (the number without a prime corresponds to the material ECAP- Conform. with a CG structure, the number with a prime corresponds to the For comparative tests via both schemes, one group of samples material with a UFG structure): 1 - 1 '- commercially pure was without surface treatment (without coating), TiC coating was titanium Grade 4; 2 - 2 '- commercially pure titanium Grade 4 applied by ion-plasma spraying (IPS) to the surface of the other with IPS coating (TiC); 3 - 3 '- commercially pure Grade 4 group of samples, and the surface of the third group of samples was titanium with a coating obtained by the MAO technology (TiO). treated by micro-arc oxidation (MAO) with producing of titanium oxide TiO. As it can be seen from the presented graph, the values of the The shear strength of adhesive bonds (MPa) was determined friction coefficient obtained for annealed samples, both coated and from the relationship: uncoated, are higher (curves 1, 2 and 3) than for samples after 6 (1) cycles of SPD processing by ECAP-Conform (Curves 1 ', 2' and 3 M '). And it is noted that the greatest effect, in terms of reducing the  .0 75  , n 3 friction coefficient from the deformation-induced increase in  d 2,1      strength, is observed on uncoated samples (curves 1 - 1 '). For the  2    sample with a CG microstructure, after 5000 cycles of action on the surface of the test specimen during reciprocating motion where d1,2 are the diameters of indents on the tested samples, mm; according to the scheme shown in Fig. 2, a, the friction coefficient М is the moment of the indenter's rotation, N mm. is about 0.6, while for the UFG sample after 6 cycles of the SPD processing it decreases, approximately, to 0.4, which is an The adhesive (molecular) component of the friction coefficient important indicator. was determined as: For samples with different microstructures with applied  п , (2) coatings, the effect of a sharp decrease in the friction coefficient is fM  рr not observed (curves 2 - 2 'and 3 - 3'). But, nevertheless, we can see some decrease. Most probably, this is due to the fact that the coating itself has a greater effect on the tribological properties of where pr – is the normal pressure, МPа (3) Р commercially pure titanium, rather than the changes in the рr  2  d  rheological properties of the substrate on which it is applied. It was π   2,1   2  noted that the TiO2 coating formed on the surface of commercially   pure titanium by its treatment with MAO technology is most where Р is the force of sample compression, N. preferable from the point of view of reducing the friction

348 MACHINES. TECHNOLOGIES. MATERIALS. 2018 coefficient (curves 3 - 3 '). In addition, it should be noted that in the material under study in the annealed state with CG and UFG case of using this coating, a much shorter run-in area is observed, microstructures, with different surface preparation. especially on a material with a UFG microstructure. This property, The full-scale experiment was carried out on samples from due to the high tribological properties of the MAO coating, is very commercially pure titanium with different microstructures and important and attractive for medical implants that are in frictional different types of surface preparation. For the indenter, we used contact. tool steel of composition Fe-6W-5Mo. Samples with a CG Fig. 6 shows the friction paths after testing samples with microstructure were prepared by annealing at 600 ° C for 1 hour. different surface preparation. The UFG microstructure was obtained as a result of the 6-cycle The lowest values of the friction coefficient, as already noted SPD processing by ECAP-Conform via route Bc with a rotation by above, are observed on a sample whose surface is treated with 90 ° around the longitudinal axis of the workpiece after each MAO technology to form titanium oxide TiO2. processing cycle. The average grain size was about 300 nm. In addition, samples with CG and UFG microstructures were coated with a TiC coating by ion-plasma spraying (IPS) and oxide TiO2 obtained using micro arc oxidation (MAO) technology. The tests were carried out at room temperature without lubricants. Fig. 7 shows the imprints after exposure to the indenter on the samples.

Fig. 6. Friction paths obtained during the tribological tests according to the scheme of linear reciprocating motion: a - commercially pure titanium Grade 4 without coating with a CG structure; b - commercially pure titanium Grade 4 with a CG structure with IPS coating (TiC); c - commercially pure titanium Grade 4 with a CG structure with a coating obtained by the MAO Fig. 7. Imprints from the indenter after its impact on CG samples technology (TiO); d, e, f - the same with a UFG structure (3 times from commercially pure titanium Grade 4 with different surface magnification). treatments: a - without coating; b - with TiC coating deposited by

ion-plasma spraying; c - with TiO2 coating, obtained by MAO From the analysis of Fig. 6 it can be seen that the similarity of technology; and on UFG samples: d - without coating; e - coated the friction paths on samples from commercially pure titanium with TiC; f - with TiO2 coating, obtained by the MAO technology. Grade 4 without coating (a) and with ion-plasma coating (TiC) (b) (10 times magnification) is observed. Apparently, this is due to the fact that under the accepted conditions of the physical experiment, intensive abrasion From the figures shown, it is seen that in the indentation of the coating and baring of the substrate material (commercially craters on the surface of the sample without coating (a), exposed pure titanium Grade 4) occurs. The friction path shown in Fig. 6, c surfaces are observed due to the formation of adhesive bridges and formed on a sample with TiO coating, obtained by MAO with the indenter material. On the surface of the sample with TiC technology, is a smooth trace without any breaks. This indicates the coating deposited by ion-plasma spraying, (b) there can also be preservation of the integrity of the investigated coating and its high seen exposed areas (light fragments in the photo) caused by the strength. adhesive interaction of the materials of the sample and indenter. The visual analysis of the friction paths during tribological The most even and clean impression was obtained on a sample tests on samples with a UFG microstructure and an applied coating with TiO coating (c) obtained by MAO technology. For samples (see Figure 6, d, e) provided approximately the same results as we with a UFG microstructure (see Fig. 7, d, e f), under the same can observe on samples with a CG microstructure (see Figure 6, b, surface treatment of commercially pure titanium approximately the c). The friction paths on the samples with CG and UFG same effects are observed, as for samples with a CG structure. The microstructures without coating are somewhat different. Thus, on a main difference between these samples is only the smaller sample with a UFG microstructure (Fig. 6d), the trace is more diameters of the craters under the same normal load, which is due "blurred" in comparison with the friction track on a sample with a to the greater hardness of the material under study after SPD CG microstructure (Fig. 6a). Most probably, the "blurring" of the processing by ECAP. As a consequence, a higher hardness friction path on the UFG sample is associated with a higher strength determines the greater load-bearing capacity of the tribocoupling. obtained as a result of SPD processing by ECAP-Conform. As a result of the tribological tests and processing of the Thus, from the point of view of tribological efficiency, the obtained data using formulae (1) and (3), the shear strength of most interesting is the TiO2 coating obtained by the microarc adhesion bonds was plotted versus normal pressure, as shown in oxidation method, as well as the material (in this case, Fig. 8. commercially pure titanium Grade 4) with a UFG microstructure.

1.3. Evaluation of the strength of adhesive bonds and determination of the adhesive component of the friction coefficient

Of great interest is the study of the shear strength of adhesion bonds as a function of pressure. Knowing the results of these studies, it is possible to calculate the adhesion component of the Fig. 8. Effect of pressure on the shear strength of adhesive bonds friction coefficient by formula (2). Figures 7 and 8 show the results for samples with different microstructures: 1 - CG (without of the evaluation of the shear strength of adhesive bonds of the coating); 2 - UFG (without coverage); 3 – CG with TiC; 4 - UFG with TiC; 5 – CG with TiO2; 6 - UFG with TiO2.

349 MACHINES. TECHNOLOGIES. MATERIALS. 2018 Table 1 presents the results of a comparative evaluation of the tribological properties of the MAO coating, is very important and tribological characteristics in the friction contact "steel indenter attractive for medical implants that are in frictional contact; from tool steel of composition Fe-6W-5Mo - commercially pure 2. The friction path formed on a TiO2-coated sample obtained titanium" with different microstructure and surface preparation. using MAO technology is a smooth trace without any breaks. This indicates the preservation of the integrity of the investigated Table 1. Influence of the structural state of commercially pure coating and its high strength; titanium and coatings on the tribological characteristics under 3. The most acceptable type of surface treatment of extreme loading conditions commercially pure titanium Grade 4, from the point of view of Tribological characteristics obtaining high tribological properties with relatively low values of Structural state and shear strength of adhesive bonds and high load-bearing capacity of p ,  ,  /  surface treatment type rn nn nn  0, tribocoupling, is TiO2 oxide coating deposited by microarc МPа МPа prn МPа oxidation in combination with severe plastic deformation by 1. CG microstructure 1605 376 0,235 0,208 43 ECAP-Conform; (without coating) 4. The correlation dependence between the values of the 2. UFG microstructure 1988 376 0,189 0,166 47 complex parameter of plastic frictional contact and the strength of (without coating) adhesive bonds is established for the friction pairs "material under 3. CG microstructure with study - tool steel of composition Fe-6W-5Mo", which is described 2158 447 0,207 0,189 39 TiC by a single dependence in a temperature range of 20-450 °C; 4. UFG microstructure 5. The temperature range of frictional interaction is defined for a 2311 266 0,115 0,112 8 with TiC number of investigated materials; 5. CG microstructure with 6. A regression formula is obtained, reflecting the analytical 2480 189 0,076 0,064 31 TiO2 dependence of the experimentally obtained results; 6. UFG microstructure 7. The dependence between the adhesion component of the 2937 221 0,075 0,061 42 with TiO2 friction coefficient and the structural state of the deformed where  is the coefficient of molecular bond strengthening under the action material in friction pairs "commercially pure titanium - steel of of compressive stresses, τ0 is the shear strength of adhesive bonds in the composition Fe-6W-5Mo" in plastic contact is established. From absence of normal load. this dependence, it follows that the strength of adhesion bonds and the molecular component of the friction coefficient are structurally Analyzing the tabular values and graphical dependences shown sensitive characteristics. in Fig. 8, it was established that the lowest shear strength of adhesion bonds is observed on samples with both CG and UFG ACKNOWLEDGEMENTS structures coated with titanium oxide using MAO technology. In This research was supported by the Ministry of Education and this case, the bearing capacity of the UFG material is higher than Science of the Russian Federation under grant agreement that of the material with a CG microstructure (see Fig. 8, curves 5 No. 14.586.21.0059 and 6). As it can be seen from the presented results, the greatest (unique project identifier RFMEFI58618X0059). shear strength of adhesion bonds is observed on a coarse-grained material without coating (curve 1). The TiC coating on the substrate with a CG structure (curve 3) demonstrates slightly lower shear REFERENCES: strength of adhesive bonds and a higher load-bearing capacity. 1. Internet resource: http://studbooks.net/2286625/matematika_ Under the considered conditions, the lowest shear strength of himiya_fizika/ primenenie_ titana_meditsine adhesive bonds is in the contact pair "steel indenter from tool steel 2. Valiev R.Z., Estrin Y., Horita Z., Langdon T.G., Zehetbauer of composition Fe-6W-5Mo - commercially pure titanium Grade 4 M.J., Zhu Y.T. Producing bulk ultrafine-grained materials by with oxidized surface using MAO technology" (curves 5 and 6). severe plastic deformation // JOM-2006. 58, No4, p33. Moreover, in all variants of the test samples, a high load-bearing 3. Valiev R.Z. Nanostructuring of Metals by Severe Plastic capacity is observed for a material with a UFG microstructure Deformation for Advanced Properties// Nature Materials, 2004, (curves 2, 4 and 6) compared to a similar surface treatment on Vol. 3, pp. 511-516. samples with a CG microstructure (curves 1, 3, and 5). This 4. Lowe T.C. and Valiev R.Z. The use of severe plastic observation is associated with the deformation-induced increase in deformation techniques in grain refinement // JOM. – 2004. – v. the strength of the material under study - commercially pure 56. – N10. – P.64-68 titanium Grade 4. 5. Proposal of novel ultra-high straining process for bulk materials Correlating results were obtained both in the determination of - development of the Accumulative Roll-Bonding (ARB) – process the integral value of the friction coefficient and in the evaluation of / Saito Y., Utsunomiya H., Tsuji N. and Sakai T. // Proc. of ICAA- the adhesion component of the friction coefficient. 6. – 1998. – Aluminum alloys. – V.3. – P.2003-2008 Thus, it can be stated that, from the considered options, the 6. R.Z. Valiev, I.V. Alexandrov. Nanostructured Materials most acceptable type of surface treatment for commercially pure Produced by Severe Plastic Deformation. Moscow: Logos, 2000. titanium, from the point of view of obtaining high tribological 272 p. (in Russian). properties with relatively low shear strengths of adhesive bonds and 7. R.Z. Valiev. Fabrication of nanostructured metals and alloys high load-bearing capacity of the tribocoupling, is TiO2 oxide with unique properties by means of severe plastic deformation coating deposited by microarc oxidation in combination with severe techniques. Rossiiskie Nanotekhnologii – 2006, Vol.1, №1-2, p. plastic deformation processing, in particular, by ECAP-Conform. 208-216 (in Russian).

8. Chuan Ting Wanga, Nong Gaob, Mark G. Gee etc. Processing CONCLUSIONS: of an ultrafine-grained titanium by high-pressure torsion: An 1. The coating itself has a greater effect on the tribological evaluation of the wear properties with and without a TiN properties of commercially pure titanium, and not the change in the coating//Journal of the mechanical behavior of biomedical rheological properties of the substrate on which it is applied. It was materials 17 (2013) 166–175 noted that the TiO2 coating formed on the surface of commercially 9. Chuan Ting Wang, Nong Gao, Mark G. Gee, etc. Tribology pure titanium by its treatment with MAO technology is the most testing of ultrafine-grained Ti processed by high-pressure torsion preferable from the point of view of reducing the friction with subsequent coating//J Mater Sci. DOI 10.1007/s10853-012- coefficient. It is established that in the case of using this coating, a 7110-y much shorter run-in area is observed, especially on a material with a 10. Chuan Ting Wang, Ana Escudeiro, Tomas Polcar etc. UFG microstructure. This property, conditioned by the high Indentation and scratch testing of DLC-Zr coatings on ultrafine-

350 MACHINES. TECHNOLOGIES. MATERIALS. 2018 grained titanium processed by high-pressure torsion//Wear (2013) 14. Equal-channel angular pressing of metallic materials: advances Elsevier 1-7. and areas of development (Thematic selection of papers edited by 11. Valiev R.Z., Estrin Y., Horita Z., Langdon T.G., Zehetbauer V.M Segal, S.V. Dobatkin, R.Z. Valiev) // Russian Metallurgy M.J., Zhu Y.T. Producing bulk ultrafine-grained materials by severe 2004, № № 1, 2. plastic deformation // JOM-2006. 58, No4, p33. 15. G.I. Raab, R.Z. Valiev, Equal-channel angular pressing of 12. Valiev R.Z. Nanostructuring of Metals by Severe Plastic long-length billets. Izvestiya Vuzov. Tsvetnaya Metallurgiya - Deformation for Advanced Properties// Nature Materials, 2004, 2000 -№5, p.50-53 (in Russian). Vol. 3, pp. 511-516. 16. L.Sh. Shuster. Adhesive Interaction of Solid Metallic Bodies. – 13. Russian Federation patent № 2181776 Stee treatment method. Ufa: Gilem. 1999. – 198 p. (in Russian). Zaripova R.G., Kajbyshev О.А., Salishchev G.A., Farkhutdinov K.G., publication date 27.04.2002.

351 MACHINES. TECHNOLOGIES. MATERIALS. 2018 INVESTIGATION OF THE EFFECT OF DIAMETERS OF POLYACRYLONITRILE NANO FIBER WITH CARBON NANOTUBE ON MECHANICAL PROPERTIES

Assist.Prof.Dr..Gürol Ö.1, Assoc.Prof.Dr..Kevser D1

1Selcuk University, Department of Mechanical Engineering, Konya/TURKEY Email:[email protected], [email protected],

Abstract: In this study, pure polyacrylonitrile (PAN) nano fiber (8 wt. %) and PAN nano fiber with multi-walled carbon nanotubes (MWCNT) were prepared. The content of MWCNT was (1, 3 and 5 wt.%). Electrospin device was used in nanofiber production. Nano diameters of the produced nanofibers were examined by Scanning electron microscopy (SEM). The nanofiber samples were cut 0.5 cm wide and 2 cm long. These samples were subjected to a tensile test on the Shimadzu device. The effect of nanofiber diameters on mechanical properties was investigated. All the MWCNT based composite nanofibers presented larger diameters than those of pure PAN nanofibers. The maximum stress value (76.60 kN) was found to be at PAN nanofiber with 1% MWCNT (average nano fiber diameter is 369.45 nm).

KEYWORDS: CARBON NANOTUBE, ELECTROSPINNING, MECHANICAL PROPERTIES, NANOFIBERS

1. Introduction 2. Material and Method

Until now electrospinning has been considered to be relatively the simplest process for producing materials at nano-scale. However, 2.1. Fabrication of pure PAN nanofibers and PAN it has been stipulated that the physic behind it is not easy to nanofibers with MWCNT understand since the properties of the electrospun nanofibers can be significantly influenced by many parameters. Electrospun nanofibers Electrospinning is a unique approach using electrostatic forces present unique properties such as a high surface area to volume ratio, to produce fine fibers. Polymer solution or the melt that has to be lightweight, high porosity, good thermal, mechanical, electrical and spun is forced through a syringe pump to form a pendant drop of flexibility properties. Materials obtained from electrospinning the polymer at the tip of the capillary. High voltage potential is technique can find a wide range of applications, notably in electronic, applied to the polymer solution inside the syringe through an medicine, environment protection, energy conversion and storage, and immersed electrode, thereby inducing free charges into the polymer so on [1]. Electrospin-produced nanofibers are generally preferred as solution. These charged ions move in response to the applied additives and fillers [2, 3, 4]. electric field towards the electrode of opposite polarity, thereby The hexagonal ring structure of CNT is used as a strengthening transferring tensile forces to the polymer liquid. At the tip of the element since it develops mechanical characteristics. CNT not only capillary, the pendant hemispherical polymer drop takes a cone like increases the mechanical properties but also the electrical and thermal projection in the presence of an electric field. And, when the conductivity values. For this reason, CNT is added to the polymer in applied potential reaches a critical value required to overcome the the process of obtaining nanofibers by electrospinning. These surface tension of the liquid, a jet of liquid is ejected from the cone materials are always preferred due to their physicochemical properties tip [8]. [5]. Ju et al. [6] reported that thinner nanofibers could be produced The equipment and chemicals used in this study for the with the preference of the electrospin method, and that the CNT- preparation of the solutions, production and characterization of added solution generally had high electrical conductivity when nanofibers are listed in the Table 1. compared to the CNT-free solution. This method is a unique technique for producing nanofibers with CNT added to provide non- Table 1. List of materials woven structure. However, the success of this method depends on the distribution of CNT among the nanofibers. Equipments or chemicals Description Nanotubes are categorized as single-walled nanotubes (SWNTs) Polyacronitrile (PAN), From the Sigma and multi-walled nanotubes (MWNTs). Individual nanotubes 150,000g/mol of (Mw) Aldrich Co. naturally align themselves into "ropes" held together by van der Waals N, N- Dimethylformamide From the Sigma forces, more specifically, pi-stacking. Multi-walled nanotubes anhydrous, 99.8% Aldrich Co. (MWNTs) consist of multiple rolled layers (concentric tubes) of MWCNT, 20 nm %99.9 From Nanografi graphene. There are two models that can be used to describe the With 0.8ml as structures of multi-walled nanotubes. In the Russian Doll model, Stainless steel needles sheets of graphite are arranged in concentric cylinders, e.g., a (0,8) inner diameter single-walled nanotube (SWNT) within a larger (0,17) single-walled Digital balance nanotube. In the Parchment model, a single sheet of graphite is rolled Syringe pump in around itself, resembling a scroll of parchment or a rolled Magnetic fish newspaper. The interlayer distance in multi-walled nanotubes is close Collector to the distance between graphene layers in graphite, approximately 3.4 Magnetic stirrer Å. The Russian Doll structure is observed more commonly. Its High voltage power supply individual shells can be described as SWNTs, which can be metallic Masks or semiconducting. Because of statistical probability and restrictions Gloves on the relative diameters of the individual tubes, one of the shells, and Scissors thus the whole MWNT, is usually a zero-gap metal [7]. In this study, PAN nano fiber and PAN nano fiber with MWCNT SEM were prepared. The content of multi-walled nanotube is (1, 3 and 5 Tensile test wt.%). Investigation of the effect of diameters of polyacrylonitrile TEM nano fiber with carbon nanotube on mechanical properties (at Selcuk Universtiy condition).

352 MACHINES. TECHNOLOGIES. MATERIALS. 2018

All the electrospinning solutions were prepared in the same way, the used procedure can be presented as follows (Fig.1):

 Weigh the required amount of chemicals (PAN and DMF) using the digital balance,

 Homogenization of PAN/DMF mixture using magnetic stirrer for 3 hours,

 Once the second step is successfully achieved, weigh the mass of the obtained homogeneous solution using again the

digital balance,

 According to the quantity of mass obtained in the third step, Fig.2 Electrospinning experimental setup calculate the required amount of MWCNT in relation to their respective percentage which must be introduced in the previous PAN/DMF solution, 2.2. Tensile Tests of PAN Nanofiber and PAN Nanofiber with MWCNT  Pour the required amount of MWCNT in the PAN/DMF solution, The morphology of the fabricated PAN nanofibers and PAN nanofibers with MWCNT was characterized by SEM (Zeiss Evo  Homogenization of the new PAN/DMF/ MWCNT mixture LS10). In Fig. 3 show the SEM images of the fabricated PAN using magnetic stirrer for an hour, nanofiber/PAN composite nanofibers with different MWCNT concentration (1, 3 and 5wt.%) performed at 15 kV. The fibers  Once the sixth step is successfully achieved then, withdraw diameter increased from 210.45 nm for pure PAN fibers to 369.45 the solution from the magnetic stirrer until it reaches the nm, 330.3 nm and 241.75 nm for MWCNT composite nanofibers room temperature, containing 1, 3, and 5 wt. % MWCNT, respectively. It is important to note that the average diameter of MWCNT based nanofibers decreased with the increase of MWCNT contents in the The last step is pouring the solution in the syringe.  electrospinning solution.

Fig. 1. Preparation and electrospinning process of 8 wt. % PAN polymer content solution (a) DMF, (b) PAN, (c) solution of PAN and DMF on the magnetic stirrer, (d) MWCNT, (e) solution of PAN and DMF with MWCNT on the magnetic stirrer, (f) solution of PAN and DMF with MWCNT was waiting at the room temperature

After the homogenization process, in each case the solution was brought to the room temperature. Then, the prepared electrospinning solutions were poured into a 2.5 mL syringe pump with 0.8 mm as inner diameter in order to proceed with the electrospinning setup. The applied voltage was 15 kV. The needle to the collector distance was Fig.3. Comparison of average diameter of the fabricated pure 12 cm. The solution flow rate maintained at 2 mL/h.Rotating speed PAN nanofibers and PAN/MWCNT composite nanofibers for was 112.5 rpm. The electrospinning process was carried out (Fig. 2). concentration of components (wt. %) 353 MACHINES. TECHNOLOGIES. MATERIALS. 2018 The samples were cut 0.5 cm wide and 2 cm long. These samples were subjected to a tensile test on the Shimadzu device. Tensile tests were performed by Shimadzu AGS-X hydraulic desktop test device at room temperature. Situations before of tensile test of samples at Figs. 4a-7a and situations during of tensile test of samples at Figs. 4b- 7b and situations after of tensile test of samples at Figs. 4c- 7c were presented.

Fig. 9. Variation of maximum stress in the function of fibers average diameters

2.3. Determination of Thermal Conductivity for PAN Nanofiber and PAN Nanofiber with MWCNT

The P.A. Hilton H-940 test station was used to determine for the thermal conductivity of the materials (Fig.10). Initially, the system was expected to enter the steady state condition (approximately 20 minutes). After the system entered steady state condition, 2.2 W power was given to the system. Then the temperature values obtained from six different points (1, 2, 3, 7, 8 and 9) were recorded. The samples were placed to the middle of the experimental set shown in Fig. 10b (section h-c) and measurements were made.

Fig. 4-7. The situations of samples in the tensile test

Fig. 8 reports the variation of stress in terms of the change of the strain of PAN nanofiber and PAN/MWCNT composite nanofibers. Generally speaking, we have found that the stress increased with the nano fibers diameters.

Fig. 8. Variation of stress in the function of strain (%)

In Fig. 9., the results on maximum stress are compared for nanofibers diameters. All the MWCNT based composite nanofibers presented larger diameters than those of pure PAN nanofibers. Fig.10. a) The experimental setup for thermal conductivity b) Schematic diagram for measurement of thermal conductivity [9]

354 MACHINES. TECHNOLOGIES. MATERIALS. 2018

When MWCNT is added to the PAN, the thermal conductivity is 3. Conclusions increased (Fig.11). According to the PAN sample, it was found that the thermal conductivity increased 135.95 % for 1% MWCNT In this study, the effect of diameters of PAN/(PAN+MWCNT) addition, 137.4729 % for 3% MWCNT addition and 168.70 % for 5% nano fiber on mechanical properties has been investigated as a MWCNT addition. function of the incorporated content. Different MWCNT contents (1,

3 and 5 wt. %) were added separately in the electrospinning solutions consisted of PAN and dimethylformamide. Nano diameters of the produced nanofibers were examined by SEM. The average diameter of MWCNT based nanofibers decreased with the increase of MWCNT contents in the electrospinning solution. However, the average nano diameter of PAN nanofiber with MWCNT is higher than the average nano diameter of pure PAN. When all the results were compared to each other, the highest stress value was obtained with 1 wt. % of MWCNT-based PAN fiber and the stress value was 76.60 kN (average fiber diameter = 369.45 nm). In other words, compared to pure PAN nanofiber, an increase of 405.29 % was observed in the stress value of fiber containing 1 wt. % of MWCNT. Taken together, the findings suggested that fibers with low content of MWCN led to higher stress. The study showed that the incorporation of MWCNT in the electrospinning solution led to an increase of thermal conductivity values of the electrospun nanofibers.

4. References Fig. 11. Variation of thermal conductivity in the function

of concentration of components [1] Mpukuta, O.M., Investigation of electrical conductivity

of nanofibers (PAN) containing nanoparticles (Graphene, Copper,

Silica) produced by electrospinning method, Master of Science Transmission electron microscopy (TEM) works with the principle Thesis, Selcuk University, Department of Mechanical of imaging high-energy electrons passing through a sample that is Engineering. quite thin. As a result of the interaction of electrons with the sample, the resulting image is magnified. In this study, Jeol JEM-2100 (UHR) [2] Dersch, R., Steinhart, M., Boudriot, U., Greiner, A. device was used for TEM images (Fig. 12). Fig. 13 shows TEM image Wendorff, J., 2005, Nanoprocessing of polymers: applications in of PAN/ MWCNT. medicine, sensors, catalysis, photonics, Polymers for Advanced Technologies, 16 (2-3), 276-282.

[3] Kim, G., Lach, R., Michler, G., Pötschke, P. Albrecht, K., 2006, Relationships between phase morphology and deformation mechanisms in polymer nanocomposite nanofibres prepared by an electrospinning process, Nanotechnology, 17 (4), 963.

[4] Heikkilä, P. Harlin, A., 2009, Electrospinning of polyacrylonitrile (PAN) solution: Effect of conductive additive and filler on the process, Express Polymer Letters, 3 (7), 437-445.

[5] Chinnappan, A., Lee, J. K. Y., Jayathilaka, W. Ramakrishna, S., 2018, Fabrication of MWCNT/Cu nanofibers via electrospinning method and analysis of their electrical conductivity by four-probe method, International Journal of Hydrogen Energy, 43 (2), 721-729.

[6] Ju, Y.W., Choi, G.R., Jung, H.R. Lee, W.J., 2008, Electrochemical properties of electrospun PAN/MWCNT carbon nanofibers electrodes coated with polypyrrole, Electrochimica Fig. 12. Jeol JEM-2100 (UHR) TEM device [10] Acta, 53 (19), 5796-5803.

[7] https://en.wikipedia.org/wiki/Carbon_nanotube

[8] Önal, G., Erdal MO, Dincer K. 2017, Investigation of electrical conductivity of polyacrylonitrile (PAN) nanofibers/nano particule (Ag, Cu, CNT and GNR), Nano Hybrids and Composites, Vol. 16.

[9] Zain-ul-Abdein, M., Azeem, S. ve Shah, S. M., 2012, Computational investigation of factors affecting thermal conductivity in a particulate filled composite using finite element method, International Journal of Engineering Science, 56, 86-98.

[10] Anonim, 2018, iltek, https://www.selcuk.edu.tr/ileri_arge/tr: [02.06.2018].

Fig. 13. TEM image of PAN/MWCNT 355 MACHINES. TECHNOLOGIES. MATERIALS. 2018

INVESTIGATION OF ELECTRICAL CONDUCTIVITY AND HYDROPHOBIC/HYDROPHILIC INTERACTION OF PAN + PMMA COMPOSITE NANOFIBERS WITH AG NANOWIRE PRODUCED BY ELECTROSPINNING METHOD

Assoc.Prof. Dr..Kevser D1, Mechanical Engineering.. Mustafa Husseın Bahaulddın B1

1Selcuk University, Department of Mechanical Engineering, Konya/TURKEY Email:[email protected], [email protected]

Abstract: In this study, the electrical conductivities and hydrophobic/hydrophilic properties of Polyacrylonitrile (PAN) + Polymethyl methacrylate (PMMA) composite nanofibers reinforced with nanowires were be investigated. The nanofibers are produced by the electrospin method. Their electrical conductivities and their hydrophobic/ hydrophilic properties were examined. The maximum the electrical conductivity value is 0.00298 S/cm at PAN + PMMA composite nanofibers with Ag nanowires (5 wt. %). The the biggest static contact angle occurred in PAN+PMMA composite nanofibers with 1 wt. % Ag nanowire. The static contact angles of all PAN + PMMA composite nanofibers with Ag nanowire were found to be bigger than those of PAN + PMMA composite nanofibers.

KEYWORDS: ELECTRICAL CONDUCTIVITY, ELECTROSPINNING, HYDROPHOBIC/HYDROPHILIC, NANOFIBERS

1. Introduction prepared. PAN + PMMA composite nanofibers, which have been reinforced with nanoparticles, have been produced. Pure PAN + Nanotechnology is science, engineering, and PMMA composite nanofiber and Ag nano wire PAN + PMMA the technology conducted at the nanoscale, which is about 1 to 100 electrical conductivity and hydrophobic / hydrophilic properties of nanometers. Nanoscience and nanotechnology are the study and the composite nanofiber were investigated. application of extremely small things and can be used across all the other science fields, such as chemistry, biology, physics, materials 2.Material and Method science, and engineering [1]. A nanofiber is a fiber with a diameter of 100 nanometers or less. The properties of nanofibers have caused In this study, PAN, PMMA, DMF, Ag nano wire were used.A researchers and companies to consider using this material in several PAN with an average molecular weight (Mw) of 150,000 g/mol, A fields. A survey of the applications of nanofibers: Researchers are PMMA with an average molecular weight (Mw) of 350,000 and N, using nanofibers to capture individual cancer cells circulating in the N-Dimethylformamide anhydrous, 99.8% were purchased from the blood stream. They use nanofibers coated with antibodies that bind Sigma Aldrich Co. to cancer cells, trapping the cancer cell for analysis. Nanofibers can Polyacrylonitrile: PAN molecule has strong polar nitrile groups. stimulate the production of cartilage in damaged joints [2]. It is relatively insoluble in nature. PAN based carbon fibers possess Electrospinning is most widely chosen tool for synthesizing very high strength compared to other polymeric precursors. When one-dimensional (1D) nanostructures which include ribbons, fibers, subjected to heat treatment, it can produce high carbon yield giving filled and hollow tubes from the fact that it‟s quite simple, easy to rise to thermally stable, highly oriented, graphite like molecular use and relatively inexpensive technique. The unique features of structure. Generating carbon-fiber from PAN based fiber is a such as-spun nanofibers are one-dimensional morphology, combination of three processes-- namely stabilization, carbonization extraordinary length, large surface area and highly porous structures and graphitization [9]. [3, 4, 5]. Electrospin production of polymer composite nanofibers is a remarkable work in recent years. The superior properties exhibited by polymer nanofibers make them suitable for many applications. Some of the studies on nanofibers have been presented below. Bahrambeygi et al. investigated the sound absorption behavior of PAN nanofibers, nano clay, multi-walled carbon nanotubes and polyurethane combination. Bahrambeygi et al. Reported that the nanoparticle provided a significant improvement in sound absorption and had more positive results in multi-walled carbon nanotubes [6]. Fig.1. Skeletal formula of the PAN Piperno et al. [7] produced nanofibres with various percentages of PMMA. They have characterized the morphological structure and chemical composition of the nanofibers they have produced. Ozek et Poly(methyl methacrylate) : PMMA, also known al. (2015) produced nanofibers with polyacrylonitrile (PAN) as acrylic or acrylic glassas well as by the trade polymers using the electrospin method, the most common method of names Crylux, Plexiglas, Acrylite, Lucite, and Perspex among several obtaining nanofibers. They have found that nanoclay-doped PAN others, is a transparent thermoplastic often used in sheet form as a nanofibers can be used as an alternative adsorbent [8]. lightweight or shatter-resistant alternative to glass. The same material In this study, the electrical conductivities and hydrophobic / can be used as a casting resin, in inks and coatings, and has many hydrophilic properties of (PAN + PMMA) / (PAN + PMMA + Ag other uses. PMMA is a strong, tough, and lightweight material. It also nano wire) composite nanofibers were investigated. First, 8% by has good impact strength, higher than both glass and polystyrene; weight of a solution consisting of PAN + PMMA + DMF was however, PMMA's impact strength is still significantly lower than prepared. Pure PAN + PMMA composite nanofiber was produced polycarbonate and some engineered polymers [10, 11, 12]. from this solution. After various proportions (1%, 3% and 5%) of silver nanowires + PEN + PMMA + in solution of DMF was

356 MACHINES. TECHNOLOGIES. MATERIALS. 2018 solvent. Then, solution was stirred using a magnetic stirrer device at 70°C and 500 rpm for three hours so as to obtain a homogeneous

electrospinning solution. Once the homogenization process ended, the solution samples were waiting to the room temperature. In order to proceed with the electrospinning setup, the solution sample was

poured into syringe of 2.5 mL and 0.8 mm as inner diameter. Then, the electrospinning process was carried out. The applied voltage was 20 kV. The needle to the collector distance was 12 cm. The solution

flow rate maintained at 2 mL/h.Rotating speed was 112.5 rpm Fig.2. Skeletal formula of the PMMA (Fig.5).

N,N-Dimethylformamide anhydrous, 99.8% : N,N- Dimethylformamide (DMF) is the commonly employed solvent for chemical reactions. DMF is a useful solvent employed for the isolation of chlorophyll from plant tissues. It is widely employed reagent in organic synthesis. It plays multiple roles in various reactions such as solvent, dehydrating agent, reducing agent as well as catalyst. N,N-Dimethylformamide is a polar solvent commonly used in organic synthesis. It also acts as a multipurpose precursor for formylation, amination, aminocarbonylation, amidation and cyanation reactions [13].

Fig.3. Chemical formula of N,N-Dimethylformamide anhydrous, 99.8% Fig.5. Electrospinning experimental setup

Ag nano wire : Silver nanowires are useful in a wide variety of conductive, optical and anti-microbial applications such as Fabrication of PAN+PMMA/Ag nanowires composite touchscreen displays, medical imaging and sterile clothing [14]. nanofibers : In the same fashion, three samples of solution containing 8 wt. % of PAN+PMMA and % 92 of DMF as solvent were prepared under the same conditions and stirred in the similar conditions as it was done for each previous solution. Ag nanowires were added in the (PAN+PMMA)/DMF electrospinning solution at different rates (1, 3, 5 wt. %) (Fig. 6).

Fig. 4. The nanowires used in this study

2.1.Fabrication of PAN + PMMA Composite

Nanofibers/ PAN + PMMA Composite Nanofibers with Ag nanowires

In this study, four types of solutions were prepared. These are pure PAN+PMMA composite nanofibers 8 % and PAN+PMMA composite nanofibers 8 % with Ag nano wires (1 %, 3 %,5 %) by weight. The pure PAN+PMMA composite nanofibers and PAN+PMMA composite nanofibers with Ag nanowires were fabricated by electrospinning technique. The procedure for preparing pure PAN + PMMA and PAN+PMMA with Ag nano wires electrospinning solution is described below.

Fabrication of pure PAN+PMMA composite nanofibers : Firstly, PAN+PMMA/ DMF solution with polymer content of 8 wt Fig. 6. Pictures of PAN+PMMA/Ag nanowires composite nanofibers. % by mass were prepared. In order to prepare the electrospinning (a) 1 wt. % Ag nanowires (b) 3 wt. % Ag nanowires, (c) 5wt. % Ag solutions, the PAN+PMMA sample was dissolved in its DMF nanowires

357 MACHINES. TECHNOLOGIES. MATERIALS. 2018 2.2. Determination of Electrical Conductivity for composite nanofibers with Ag nanowires, respectively. As can be PAN+PMMA Composite Nanofibers/ seen from the Fig. 7 higher electrical conductivity were obtained at high Ag nanowires contents (5wt. %). PAN+PMMA Composite Nanofibers with Ag nanowires 2.3. Determination of Hydrophobic/Hydrophilic

It is well known that one of the subatomic particles of an atom Interaction for PAN+PMMA Composite is the electron. The electrons carry a negative electrostatic charge Nanofibers/ PAN+PMMA Composite Nanofibers and under certain conditions can move from atom to atom. The with Ag nanowires direction of movement between atoms is random unless a force causes the electrons to move in one direction. This directional movement of electrons due to an electromotive force is what is Nonpolar molecules that repel the water molecules are said to be known as electricity. Electrical conductivity is a measure of how hydrophobic; molecules forming ionic or a hydrogen bond with the well a material accommodates the movement of an electric charge. It water molecule are said to be hydrophilic. This property of water was is the ratio of the current density to the electric field strength. important for the evolution of life. Hydrophobic interaction plays the Electrical conductivity is a very useful property since values are most critical roles in the formation of the lipid bilayer of the cell affected by such things as a substances chemical composition and membrane and the folding of proteins and nucleic acids; therefore, the stress state of crystalline structures [15, 16]. hydrophobic interaction is the foundation for the existence of life A four-point probe device (ENTEK Elk. FPP-460 with Pt [18]. The contact angle () is the angle, conventionally measured probes) was used to measure the electrical conductivity of through the liquid, where a liquid–vapor interface meets nanofibers at room temperature. The used four point probe device is a solid surface [19]. illustrated in Fig. 6 [17]

Fig. 8. The contact angle for hydrophobic/hydrophilic [20]

Fig. 6. Four-point probe device (ENTEK Elk. FPP-460) The hydrophobic/hydrophilic of PAN+PMMA composite nanofibers/ PAN+PMMA composite nanofibers with Ag nanowires were investigated using the contact angle measurement device The results on electrical conductivity of pure PAN + PMMA (Dataphysics instruments GmbH, model OCA15EC, version 1.3). composite nanofibers and PAN + PMMA composite nanofibers with Ag nanowires (1, 3, 5 wt. %) are compared in Fig 7.

Fig. 9. OCA15EC with single-direct dosing system [21]

Fig. 10. shows the average static contact angles of pure PAN + PMMA composite nanofibers and PAN + PMMA composite nanofibers with Ag nanowires (1, 3, 5 wt. %) for left and rigth side. It has been found that all PAN + PMMA composite nanofibers with Ag Fig. 7. Comparison of electrical conductivity of nanofibers. nanowire have bigger static contact angles. The biggest static contact (a) Pure PAN+PMMA composite nanofiber, (b) PAN+PMMA angle () occurred in PAN+PMMA composite nanofibers with 1 wt. composite nanofibers with 1 wt. % Ag nanowire, (c) PAN+PMMA % Ag nanowire ( is 132.14o for left and right side). composite nanofibers with 3 wt. % Ag nanowire (d) PAN+PMMA composite nanofibers with 5 wt. % Ag nanowire

Electrical conductivity values found from the four-point probe technique were 0.000837 S/cm for pure PAN+PMMA nanofibers and 0.00089, 0.00261 and 0.00298 S/cm for PAN + PMMA

358 MACHINES. TECHNOLOGIES. MATERIALS. 2018 Advanced Technologies. 2011;22(3):326-38.

[5] Bhattarai P., Keshar B., Rajesh T., Basnet B., Sharma S., Electrospinning: How to Produce Nanofibers Using Most Inexpensive Technique? An Insight into the Real Challenges of Electrospinning Such Nanofibers and Its Application Areas, International Journal of Biomedical And Advance Research, ISSN: 2229-3809 (Online) Journal DOI:10.7439/ijbar CODEN:IJBABN.

[6] Bahrambeygi H., Sabetzadeh N., Rabbi A., Nasouri K., Mousavi A., Mohammad S. Babaei R., Nanofibers (PU And PAN) And Nanoparticles (Nanoclay And Mwnts) Simultaneous Effects On Polyurethane Foam Sound Absorption, J Polym Res, 2013, 20:72.

[7] Piperno S., Lozzi L., Rastelli R., Passacantando M., Santucci S., PMMA Nanofibers Production By Electrospinning. Applied Surface Science, 2006, 252, 5583-5586.

[8 ] Özek S., Çiftci Ş., Göde F., Aksoy S., Aksoy S., Synthesis and Characterization of PAN Nanofiber Added Nanoclay SDU Journal of Science, 2015, 107-117.

[9]https://www.sigmaaldrich.com/catalog/product/aldrich/181315?lan g=en®ion=TR&gclid=EAIaIQobChMI1NiCifjX3AIVVOaaCh3g nQTTEAAYASAAEgK8ZPD_BwE.

[10] Polymethylmethacrylate (PMMA, Acrylic) Archived 2015-04- 02 at the Wayback Machine.. Makeitfrom.com. Retrieved 2015-03- 23.

[11] Zeng, W. R., Li, S. F., Chow, W. K. Preliminary Studies on Burning Behavior of Polymethylmethacrylate (PMMA). Journal of Fig. 10. Comparison of the average static contact angles for left Fire Sciences. 2002, 20 (4): 297–317. and rigth side. (a) Pure PAN+PMMA composite nanofiber, (b) PAN+PMMA composite nanofibers with 1 wt. % Ag nanowire, [12] https://en.wikipedia.org/wiki/Poly(methyl_methacrylate). (c) PAN+PMMA composite nanofibers with 3 wt. % Ag nanowire, (d) PAN+PMMA composite nanofibers with 5 wt. % Ag nanowire [13]https://www.sigmaaldrich.com/catalog/product/SIAL/227056?lan g=en®ion=TR&gclid=EAIaIQobChMIp- 3.Conclusions m9xIjY3AIV16SaCh3GpQ8IEAAYASAAEgLjyvD_BwE.

In this study, the electrical conductivities and [14]https://www.sigmaaldrich.com/catalog/product/aldrich/739421?la hydrophobic/hydrophilic properties of PAN + PMMA composite ng=en®ion=TR. nanofibers/ PAN + PMMA composite nanofibers with nanowires were investigated. The maximum the electrical conductivity value is [15]https://www.ndeed.org/EducationResources/CommunityCollege/ 0.00298 S/cm at PAN + PMMA composite nanofibers with Ag Materia ls/Physical_ Chemical/Electrical.htm. nanowires (5 wt. %). The the biggest static contact angle occurred in PAN+PMMA composite nanofibers with 1 wt. % Ag nanowire. [16] Dincer K., Waisi B., Ozdemir M. O., Pasaogullari U., McCutcheon J., Experimental Investigation of Proton Exchange Acknowledgments Membrane Fuel Cells Operated with Nanofiber and Nanofiber/Nanoparticle, World Academy of Science, Engineering Financial support of experimental study from the research fund and Technology International Journal of Chemical, Molecular, of the Selcuk University under Grant No. BAP 18201065 is Nuclear, Materials and Metallurgical Engineering, 2015, Vol:9, gratefully acknowledged. In addition, this study constitutes part of the No:12. ongoing Master thesis of Mustafa Husseın Bahaulddın Bahaulddın. [17] Mpukuta O.M., Investigation of Electrical Conductivity of 3. References Nanofibers (PAN) Contining Nanoparticles (Graphene, Copper, Silica) Produced by Electrospinning Method, The Graduate School [1] https://www.nano.gov/nanotech-101/what/definition. of Natural and Applied Science of Selcuk University, The Degree of Master of Science In Mechanical Engineering, Master of Science [2] UnderstandingNano.com, Nanofibers: Uses and Applications of Thesis, 2018, Department of Mechanical Engineering. Nanofibers. [18] National Nanotechnology Infrastructure Network, Serving [3] Grant CD, Schwartzberg AM, Smestad GP, Kowalik J, Tolbert Nanoscale Science, Engineering & Technology, The Water Race: LM, Zhang JZ. Characterization of nanocrystalline and thin film Hydrophobic & Hydrophilic Surfaces.

TiO2 solar cells with poly(3-undecyl-2,2′-bithiophene) as a sensitizer and hole conductor. Journal of Electroanalytical Chemistry. [19] https://en.wikipedia.org/wiki/Contact_angle. 2002;522(1):40-8. [20]http://info.alchemy-spetec.com/blog/hydrophobic-vs-hydrophilic- [4] Dai Y, Liu W, Formo E, Sun Y, Xia Y. Ceramic nanofibers polyurethanes. fabricated by electrospinning and their applications in catalysis, environmental science, and energy technology. Polymers for [21] http://www.dataphysics.de.

359 MACHINES. TECHNOLOGIES. MATERIALS. 2018 INVESTIGATION OF THE EFFECT OF PRODUCTION PARAMETERS ON POLYSTYRENE NANO FIBER FORMATION FOR 12 WT %, 14 WT % AND 16 WT %

Assist. Prof. Dr. Yusuf Y.1, Assist. Prof. Dr. A.Serhat E.1 Assoc. Prof. Dr. Kevser D.1, Mech. Engineer. Büşra M.1, Chemist.Hasan Ö.1

1Selcuk University, Department of Mechanical Engineering, Konya/TURKEY Email: [email protected], [email protected]

Abstract— Polystyrene (PS) is a versatile plastic used to produce a wide variety of consumer products. It is used as a hard, solid plastic, mostly as food packaging and laboratory products. When polystyrene is mixed with various colorants, additives or other plastic materials, it is used to make electronic parts, automobile parts, toys, pots and equipments and more. Polystyrene is a vinyl polymer. It is structurally a long hydrocarbon chain with a phenyl group attached to the carbon atom. Polystyrene is produced by free radical vinyl polymerization from monomer styrene. In this study, the effect of production parameters on the formation of PS nanofibers was investigated. For this purpose, solutions were prepared at various mixing ratios (12 wt %, 14 wt % and 16 wt %) consisting of PS + dimethylformamide (DMF). The nanofiber structure was determined from these solutions. Electrospin method was used in production of nanofibers.

KEYWORDS: ELECTROSPIN METHOD, NANO FIBER, POLYSTYRENE.

1.Introduction  Melt spray method Nanoscience and nanotechnology are the study and  Laser evaporation method application of extremely small things and can be used across all the  Electrospin method other science fields, such as chemistry, biology, physics, materials science, and engineering. The ideas and concepts behind In this study, electrospin method was used. Nanoscience and nanotechnology started with a talk entitled “There’s Plenty of Room at the Bottom” by physicist Richard Fig.1. illustrates the broad domains of polymer nanofibers that Feynman at an American Physical Society meeting at the California are being actively researched on. About 50% of the papers are Institute of Technology (CalTech) on December 29, 1959, long focused on the electrospinning process development and before the term nanotechnology was used. In his talk, Feynman characterization of fibers. Others are focused on innovative use of described a process in which scientists would be able to manipulate polymer nanofibers for a variety of applications in medicine, and control individual atoms and molecules. Over a decade later, in biotechnology, and engineering [4]. his explorations of ultra precision machining, Professor Norio Taniguchi coined the term nanotechnology. It wasn't until 1981, with the development of the scanning microscope that could "see" individual atoms, that modern nanotechnology began [1]. Nanotechnology is also being applied to or developed for application to a variety of industrial and purification processes. Purification and environmental cleanup applications include the desalination of water, water filtration, waste water treatment, groundwater treatment. In industry, applications may include construction materials, military goods, and nano-machining of nano-wires, nano-rods, few layers of graphene, etc. Also, recently a new field arisen from the root of nanotechnology is called nanobiotechnology [2].

2.Nanofiber

Nanofibers are fibers with diameters in the nanometer range. Nanofibers can be generated from different polymers and hence Fig. 1. Potential applications of polymer nanofibers. Polymer have different physical properties and application nanofibers are candidates for a number of applications in medicine, potentials. Polymer chains are connected via covalent biotechnology, and engineering, because of their large surface area bonds. The diameters of nanofibers depend on the type of polymer to volume ratio and unique nanometer scale architecture used and the method of production. All polymer nanofibers are unique for their large surface area-to-volume ratio, high porosity, appreciable mechanical strength, and flexibility in functionalization 3.Electrospinning theory and process compared to their microfiber counterparts [3]. There are 8 methods of producing nanofiber. These are presented below The schematic diagram of the electrospinning is illustrated in  Drawing method Fig.2 [5]. Electrospinning is a unique approach using electrostatic  Phase separation method forces to produce fine fibers. Electrostatic precipitators and  Self attachment method pesticide sprayers are some of the well known applications that  Chemical vapor deposition method (CVD) work similarly to the electrospinning technique. Fiber production  Nano-mold method using electrostatic forces has invoked glare and attention due to its

360 MACHINES. TECHNOLOGIES. MATERIALS. 2018 potential to form fine fibers. Electrospun fibers have small pore size barrier to oxygen and water vapor and has a relatively low melting and high surface area. There is also evidence of sizable static point [9]. Polystyrene is one of the most widely used plastics, the charges in electrospun fibers that could be effectively handled to scale of its production being several million tons per year [10]. produce three dimensional structures. Polymer solution or the melt Polystyrene can be naturally transparent, but can be colored with that has to be spun is forced through a syringe pump to form a colorants. Uses include protective packaging (such as packing pendant drop of the polymer at the tip of the capillary. High voltage peanuts and CD and DVD cases), containers (such as "clamshells"), potential is applied to the polymer solution inside the syringe lids, bottles, trays, tumblers, disposable cutlery [9] and in the through an immersed electrode, thereby inducing free charges into making of models. As a thermoplastic polymer, polystyrene is in a the polymer solution. These charged ions move in response to the solid (glassy) state at room temperature but flows if heated above applied electric field towards the electrode of opposite polarity, about 100 °C, its glass transition temperature. It becomes rigid thereby transferring tensile forces to the polymer liquid. At the tip again when cooled. This temperature behaviour is exploited of the capillary, the pendant hemispherical polymer drop takes a for extrusion (as in Styrofoam) and also for molding and vacuum cone like projection in the presence of an electric field. And, when forming, since it can be cast into molds with fine detail. Polystyrene the applied potential reaches a critical value required to overcome is slow to biodegrade and is therefore a focus of controversy among the surface tension of the liquid, a jet of liquid is ejected from the environmentalists. It is increasingly abundant as a form of litter in cone tip [6, 7]. the outdoor environment, particularly along shores and waterways, especially in its foam form, and also in increasing quantities in the Pacific Ocean [11]. The molecular structure of PS is shown in Fig. 4.

Fig. 2. The schematic diagram of the electrospinning experimental setup

It is essential to adjust electrospinning parameters to obtain uniform nanofibers. The parameters affecting the electrospinning process are represented in Fig. 3 [8].

Fig.4. The molecular structure of PS [11]

N,N-Dimethylformamide is the commonly employed solvent for chemical reactions. DMF is a useful solvent employed for the isolation of chlorophyll from plant tissues. It is widely employed reagent in organic synthesis. It plays multiple roles in various reactions such as solvent, dehydrating agent, reducing agent as well as catalyst. It is a multipurpose building block for the synthesis of compounds containing O, -CO, -NMe2, -CONMe2, -Me, -CHO as functional groups. N,N-Dimethylformamide is a polar solvent commonly used in organic synthesis. It also acts as a multipurpose precursor for formulation, amination, aminocarbonylation, amidation and cyanation reactions [23]. The molecular structure of DM is shown in Fig. 5.

Fig. 3. Parameters affecting the electrospinning process

Fig.5. The molecular structure of DMF [12] 4. Experimental

A PS with an average molecular weight (Mw) of 192000 g/mol In this study, PS and DMF were used. Polystyrene can be solid or and N, N-Dimethylformamide anhydrous, 99.8% were purchased foamed. General-purpose polystyrene is clear, hard, and rather from the Sigma Aldrich Co. all the materials were used as- received brittle. It is an inexpensive resin per unit weight. It is a rather poor without further purification. The experimental setup is shown in 361 MACHINES. TECHNOLOGIES. MATERIALS. 2018 Fig.6. In this study, four types of solutions were prepared. These are 12 %, 14 %, 15 %, 16 % by weight. Then the mixture was stirred in a magnetic stirrer. Once the homogenization process ended, the solution samples were brought to the room temperature. After reaching the room temperature, the prepared electrospinning solutions were poured into a 2.5 mL syringes with 0.8 mm as inner diameter in order to proceed with the electrospinning setup.

Fig. 7. Pictures of PS nanofibers for 12 wt. %

Sample No : 2 (14 wt. % PS polymer content)

At 50 oC and 500 rpm, the solution was stirred for 2 hour Applied voltage (kV) : 15 The mass flow rate : 1 mL / h Distance between pipette and collector : 14 cm Collector Speed : 750 rpm (15%) Result : The homogeneous surface did not occur. Also, in the middle part of the sample, a filamentous structure was observed (Fig. 8).

Fig. 8. Pictures of PS nanofibers for 14 wt. %

Sample No : 3 (15 wt. % PS polymer content)

At 90 oC and 500 rpm, the solution was stirred for 1 hour Applied voltage (kV) : 20 The mass flow rate : 1 mL / h Distance between pipet and collector : 10 cm Collector Speed : 750 rpm (15%) Result : The homogeneous surface did occur. But no nanofibers Fig.6. Experimental setup formed in the middle (Fig. 9).

Sample No : 1 (12 wt. % PS polymer content)

At 50 oC and 500 rpm, the solution was stirred for 1 hour. Applied voltage (kV) : 20 The mass flow rate : 1 mL / h Distance between pipette and collector : 14 cm Collector Speed : 750 rpm (15%) Result : The homogeneous surface did not occur (Fig.7)

Fig. 9. Pictures of PS nanofibers for 15 wt. %

362 MACHINES. TECHNOLOGIES. MATERIALS. 2018

Sample No :4 (16 wt. % PS polymer content) At 90 oC and 500 rpm, the solution was stirred for 1 hour Applied voltage (kV) : 20 The mass flow rate : 0.5 mL / h Distance between pipette and collector : 16 cm Collector Speed : 750 rpm (15%) Result : The homogeneous surface occurred The average diameter of nanofibers PS = 1591 nm (Fig.10).

Fig. 12. Pictures of PS nanofibers for 15 wt. % and sample no : 6

5. Conclusions

In this study, the effect of production parameters on the formation of PS nanofibers was investigated. For this purpose, Fig. 10. Pictures of PS nanofibers for 15 wt. % and sample no : 4 solutions were prepared at various mixing ratios (12 wt %, 14 wt %, 15 wt % and 16 wt %) consisting of PS+DMF. The nanofiber structure was determined from these solutions. Electrospin method was used in production of nanofibers. The homogeneous surface did Sample No : 5 (16 wt. % PS polymer content) not occurred for 12 wt %, 14 wt %, 15 wt % PS polymer content. At 16 wt % PS polymer content, the homogeneous surface occurred. At 90 oC and 500 rpm, the solution was stirred for 1 hour At 16 wt % PS polymer content, it was determined that the average Applied voltage (kV) : 20 nanofiber diameter decreased as the mass flow rate increased. The mass flow rate : 1 mL / h Distance between pipette and collector : 16 cm 5. References Collector Speed : 750 rpm (15%) [1] https://www.nano.gov/nanotech-101/what/definition. Result : The homogeneous surface occurred [2] https://en.wikipedia.org/wiki/Applications of nanotech. The average diameter of nanofibers PS = 1237 nm (Fig.11). [3] https://en.wikipedia.org/wiki/Nanofiber [4][https://www.azonano.com/article.aspx?ArticleID=1280] . [5] Thi Thu Trang Mai, Thi Thu Thuy Nguyen, Quang Duong Le, Thi Ngoan Nguyen, Thi Cham Ba, Hai Binh Nguyen, Thi Bich Hoa Phan, Dai Lam Tran, Xuan Phuc Nguyen and Jun Seo Park, A novel nanofiber Cur-loaded polylactic acid constructed by electrospinning, Adv. Nat. Sci.: Nanosci. Nanotechnol. 3 (2012) 025014. [6]Thandavamoorthy Subbiah, G. S. Bhat, R. W. Tock, S. Parameswaran, S. S. Ramkumar, Electrospinning of Nanofibers, Journal of Applied Polymer Science, Vol. 96, 557-569, 2005. [7] Kevser Dincer, Basma Waisi, M. Ozan Ozdemir, Ugur Pasaogullari, Jeffrey McCutcheon, Experimental Investigation of Proton Exchange Membrane Fuel Cells Operated with Nanofiber and Nanofiber/Nanoparticle, World Academy of Science, Engineering and Technology International Journal of Chemical, Molecular, Nuclear, Materials and Metallurgical Engineering Vol:9, No:12, 2015. Fig. 11. Pictures of PS nanofibers for 15 wt. % and sample no : 5 [8] M. V. Vellayappan,J. R. Venugopal,b S. Ramakrishna, S. Ray, A. F. Ismail, M. Mandal, A. Manikandan, S. Sealg and S. K. Jaganathan, Electrospinning applications from diagnosis to Sample No : 6 (16 wt. % PS polymer content) treatment of diabetes, RSC Adv., 2016, 6, 83638–83655. [9] Common Plastic Resins Used in Packaging. Introduction o to Plastics Science Teaching Resources. American Chemistry At 90 C and 500 rpm, the solution was stirred for 1 hour Council, Inc. Retrieved 24 December 2012. Applied voltage (kV) : 20 [10] Maul, J., Frushour, B. G., Kontoff, J. R., Eichenauer, H., The mass flow rate : 1.5 mL / h Ott, K.-H. and Schade, C. (2007). Polystyrene and Styrene Distance between pipette and collector : 16 cm Copolymers. in Ullmann's Encyclopedia of Industrial Collector Speed : 750 rpm (15%) ChemistryWiley-VCH, Result : The homogeneous surface occurred Weinheim, doi:10.1002/14356007.a21_615.pub2. The average diameter of nanofibers PS = 1190 nm (Fig.12). [11] https://en.wikipedia.org/wiki/Polystyrene. [12]https://www.sigmaaldrich.com/catalog/product/sial/22705 6?lang=en®ion=TR.

363 MACHINES. TECHNOLOGIES. MATERIALS. 2018 RULE-BASED MAMDANI-TYPE FUZZY MODELING OF PERFORMANCE OF HYDROXY (HHO) DRY CELL WITH 12x12 PLATE COMBINATION

Assist. Prof. Dr..Ali Serhat E.1, Assist. Prof. Dr. Yusuf Y.1, Mech. Engineer..Burak Buğra Ç.1, Mech. Engineer ..Taylan P.1, Assoc.. Prof. Dr..Kevser D.1

1Selcuk University, Department of Mechanical Engineering, Konya/TURKEY Email:[email protected], [email protected],

Abstract— The fossil fuels and the natural gas reserves that have undertaken the role of the locomotive of the industrial period are limited. It is also the biggest factor in environmental problems. All these reasons lead to the need for alternative fuels or resources. Hydrogen is the candidate to be one of these alternatives; is an unlimited clean and efficient fuel. Hydrogen may assume the role of carrier in the process of storage of other alternative energy sources. Today, interest in hydrogen energy is increasing. One of the reasons for this is that hydrogen can be produced from renewable energy sources such as water, biomass, wind and sun as well as hydrogen from primary energy sources. There is no polluting gas emissions when hydrogen is used as fuel. The HHO dry cell is a device that converts water into HHO (oxyhydrogen) gas. In this study, performance of HHO dry cell with 12x12 plate combination was experimentally investigated and modeled with a Rule-Based Mamdani-Type Fuzzy (RBMTF) modeling technique. Input parameters are; plate number, time, current; output parameter is mass flow rate. The coefficient of multiple determination (R2=98.5) for the mass flow rate. RBMTF results indicated that RBMTF can be successfully used in HHO dry cell with 12x12 plate combination.

KEYWORDS: FUZZY LOGIC MODELLING, HHO DRY CELL, HYDROGEN,

theory should be seen as a methodology to generalize any specific 1. Introduction theory from crisp to continuous. Fuzzy modeling opens the possibility for straightforward translation of statements in natural language verbal formulation of the observed problem into a fuzzy Hydrogen is the simplest element. An atom of hydrogen consists of system. Its functioning is based on mathematical tools [7]. only one proton and one electron. It's also the most plentiful In this study, performance of HHO dry cell was investigated element in the universe. Despite its simplicity and abundance, experimentally and modeled by fuzzy logic method. The hydrogen doesn't occur naturally as a gas on the Earth - it's always performance parameter is the mass flow rate. The highest value of combined with other elements. Water, for example, is a the mass flow rate was 0.261 x 10-3 kg /h. combination of hydrogen and oxygen (H O). Hydrogen is also 2 found in many organic compounds, notably the hydrocarbons that make up many of our fuels, such as gasoline, natural gas, methanol, 2. Materials and Methods and propane. Hydrogen can be separated from hydrocarbons through the application of heat - a process known as reforming. Currently, most hydrogen is made this way from natural gas. An Hydrocarbon fuel is one of the sources of energy used for electrical current can also be used to separate water into its electrical power generation, heating and transportation in the world. components of oxygen and hydrogen. This process is known But they have negative side effects like polluting emissions, large as electrolysis. Some algae and bacteria, using sunlight as their scale oil spill, etc. Due to its widespread dependence and difficulties energy source, even give off hydrogen under certain conditions [1]. in getting other alternatives the use of hydrocarbon fuel could not In 1918 Charles Frazer, a North American inventor, patented the be eliminated. To mitigate the above problems and to reduce the use first water electrolysis machine act as a hydrogen booster for of hydrocarbon fuel, hydrogen gas can be supplemented. Hydrogen internal combustion engines. Yull Brown, a Bulgarian born gas to air intake of a combustion process will improve flame speed, Australian inventor patented and attempted to popularize Browns lean burn ability and flame quenching distance. But scarcity and Gas as a cutting gas and fuel additive during the 1970’s and 80’s. production cost makes it more difficult to implement. Hydrogen HHO is an enriched mixture of hydrogen and oxygen bonded rich gas produced from electrolysis of water called the Brown’s Gas together molecularly and magnetically. HHO gas is produced in a or HHO could solve the potential difficulties [4, 8]. common-ducted electrolyser & then sent to the intake manifold to Fuzzy inference system consists of a fuzzification interface, a introduce into combustion chamber of the engine. HHO gases will rule base, a database, a decision-making unit, and finally a combust in the combustion chamber when brought to its auto- defuzzification interface. The function of each block is as follows. ignition or self-ignition temperature [2-4]. A rule base containing a number of fuzzy IF–THEN rules, a Zadeh in 1965 introduced fuzzy concept to develop a database which defines the membership functions of the fuzzy sets mathematical framework for imprecisely presented data. It is a used in the fuzzy rules, a decision-making unit which performs the generalized form of interval analysis, where parameters are defined inference operations on the rules, a fuzzification interface which with lower and upper values. In a traditional set theory, an element transforms the crisp inputs into degrees of match with linguistic is defined as a member of a set. If the element is in the set, the values and a defuzzification interface which transforms the fuzzy membership grade is unity, otherwise it is zero. A fuzzy set is an results of the inference into a crisp output. Mamdani's method is the extension of the traditional set theory in which the element has most commonly used in fuzzy inference system, due to its simple certain degree of membership l (0–1) in the set. Fuzzy set structure of 'min-max' operations [9]. establishes relationship between uncertain data and the membership In this study, performance of HHO dry cell with 12x12 plate function l, which ranges from 0 to 1 [5, 6]. combination was experimentally investigated (Fig.1) and modeled Fuzzy logic is a superset of Boolean-conventional logic that has with a RBMTF modeling technique. The experimental setup used in been expanded to handle the concept of partial truth and truth this study is illustrated in Fig.1. values between ―completely true‖ and ―completely false.‖ Fuzzy

364 MACHINES. TECHNOLOGIES. MATERIALS. 2018 system modeling. Let X be input (regression) matrix and g an output vector defined as Eqs. (1) and (2).

where upper script T denotes the transpose. In the Mamdani fuzzy model, both the antecedent and consequent are fuzzy propositions. A general form of linguistic fuzzy if-then rule is given as Eq. (3).

R : if x is A then y is B ; i= 1, 2,…,K (3) i i i

Fig.1. Experimental system where Ri is the rule number, Ai and Bi are the fuzzy sets, x is the antecedent variable representing the input in the fuzzy system, and y is the consequent variable related to the output of the fuzzy In the same way, the used experimental procedure can be presented system [10]. as follows: In this study, numerical parameters of input and output variables were fuzzificated as linguistic variables: very very low  First the plates are assembled. (L1), very low (L2), low (L3), negative medium (L4), medium (L5),  The water outlet of the water tank is connected to the positive medium (L6), high (L7), very high (L8) and very very high water inlet of the HHO cell. (L9) linguistic classes (Fig.3).  The gas inlet pipe of the water tank is fixed to the gas outlet part of the HHO cell.  Place water in the water tank in such a way that each combination of water level is the same.  To supply electricity to the HHO cell, the DC power supply is connected to the electric plates of the HHO cell.  The end of the temperature measuring instrument is attached to the HHO cell plates  The DC power supply is started and the voltage is fixed at 24 volts.  Every minute, the current in the DC power supply, the temperature in the temperature meter, and the mass flow rate of the HHO gas read from the mass flow rate are recorded.  The DC power supply is turned off when the specified time for each experiment is over.  The gas mixture in the HHO cell is drained.

General structure of RBMTF model developed (three input, one- output) is given in Fig. 2. Input parameters are; plate number (PN), time (t), current (C); output parameter is mass flow rate (MFR).

Fig. 3. Fuzzy membership functions for three input variables and one output variable: (a) PN fuzzy set graphic, (b) t fuzzy Fig.2. Designed RMBTF structure set graphic, (c) C fuzzy set graphic, (d) MFR fuzzy set

A fuzzy model expresses a complex system in the form of graphic fuzzy implications. Mamdani model can be built by using these implications (linguistic relationships) and observed data. The Mamdani-based fuzzy models use excessive number of rules for

365 MACHINES. TECHNOLOGIES. MATERIALS. 2018 3. Results and Discussion

HHO gas has substantial advantages when compared to the gasoline due to its high diffusivity. First two of these advantages is rate of formation of homogenous mixture is greater since HHO diffuses faster in mixture. Secondly, HHO can dilute quite fast under circumstances of leakage. Several researches show that 1866 litres of HHO gas is obtained from 1 liter of water, after ignition, the HHO gas returns to original volume after combustion [11, 12]. The HHO dry cell with 12x12 plate was tested in this study for temperature, current, mass flow rate (Figs. 4-6). According to the experimental results;

 The highest temperature value was found at 5 minutes in the 12-9 plate combination.  The highest temperature value was measured as 25.5 oC.  The highest temperature value occurred at 1.01 A.  The temperature increased when the current increased. Fig.5. The current values for time  The mass flow rate increased when time increases.  The highest value of the mass flow rate was 0.261 x 10-3 kg /h. This value was measured in a 9 plate combination and on the 1st minute.

Fig.6. The mass flow rate values for time The purpose of this study is to model the performance of the HHO dry cell using experimental data by the RBMTF modeling technique. The performance parameter is mass flow rate. In Table 1 Fig.4. The temperature values for time shows the comparison of experimental data with RBMTF for the mass flow rate.

Table 1. Comparison of experimental (EXP.) data with RBMTF for the variation of time with mass flow rate (MFR) for plate number (PN)

Time (min.) MFR (kg/h) MFR (kg/h) MFR (kg/h) MFR (kg/h) MFR (kg/h) Debi (kg/h) (minute) PN = 1 (EXP.) PN = 2 (EXP.) PN=3 (EXP.) PN=1 RBMTF PN=2 RBMTF PN=3 BMTF 1 0.014 x 10-3 0.022 x 10-3 0.04 x 10-3 0.015 x 10-3 0.021 x 10-3 0.05 x 10-3 2 0.015 x 10-3 0.023 x 10-3 0.047 x 10-3 0.016 x 10-3 0.024 x 10-3 0.048 x 10-3 3 0.016 x 10-3 0.025 x 10-3 0.061 x 10-3 0.017 x 10-3 0.026 x 10-3 0.062 x 10-3 4 0.016 x 10-3 0.023 x 10-3 0.082 x 10-3 0.017 x 10-3 0.024 x 10-3 0.084 x 10-3 5 0.016 x 10-3 0.023 x 10-3 0.093 x 10-3 0.018 x 10-3 0.024 x 10-3 0.095 x 10-3 Time (min.) MFR (kg/h) MFR (kg/h) MFR (kg/h) MFR (kg/h) MFR (kg/h) MFR (kg/h) PN=4 (EXP.) PN=5 (EXP.) PN=6 (EXP.) PN=4 RBMTF PN=5 RBMTF PN=6 BMTF 1 0.064 x 10-3 0.089 x 10-3 0.009 x 10-3 0.065 x 10-3 0.09 x 10-3 0.010 x 10-3 2 0.095 x 10-3 0.109 x 10-3 0.01 x 10-3 0.093 x 10-3 0.119 x 10-3 0.012 x 10-3 3 0.108 x 10-3 0.115 x 10-3 0.008 x 10-3 0.109 x 10-3 0.125 x 10-3 0.009 x 10-3 4 0.11 x 10-3 0.124 x 10-3 0.007 x 10-3 0.12 x 10-3 0.124 x 10-3 0.008 x 10-3 5 0.09 x 10-3 0.115 x 10-3 0.009 x 10-3 0.10 x 10-3 0.116 x 10-3 0.0011 x 10-3 Time (min.) MFR (kg/h) MFR (kg/h) MFR (kg/h) MFR (kg/h) MFR (kg/h) MFR (kg/h) PN=7 (EXP.) PN=8 (EXP.) PN=9 (EXP.) PN=7 RBMTF PN=8 RBMTF PN=9RBMTF 1 0.14 x 10-3 0.027 x 10-3 0.261 x 10-3 0.15 x 10-3 0.0278 0.263 x 10-3 2 0.16 x 10-3 0.027 x 10-3 0.258 x 10-3 0.17 x 10-3 0.027x 10-3 0.259 x 10-3 3 0.16 x 10-3 0.028 x 10-3 0.257 x 10-3 0.17 x 10-3 0.029x 10-3 0.258 x 10-3 4 0.14 x 10-3 0.026 x 10-3 0.247 x 10-3 0.15 x 10-3 0.027 x 10-3 0.248 x 10-3 5 0.15 x 10-3 0.027 x 10-3 0.25 x 10-3 0.16 x 10-3 0.028 x 10-3 0.26 10-3

366 MACHINES. TECHNOLOGIES. MATERIALS. 2018

4.Conclusions Financial support of experimental study from the research fund of In this study, a HHO dry cell with 12x12 plate was investigated the Selcuk University under Grant No. BAP 17402018 is gratefully experimentally and modeled by RBMTF. According to the acknowledged. experimental results; the highest value of the mass flow rate is 0.261 x 10-3 (kg /h). This value was measured in a 12-9 plate combination and on the 1st minute. 5. References The comparison between experimental data and fuzzy logic is done using statistical methods such as the R2 are defined as follows [1] (Eq.1), https://www.renewableenergyworld.com/hydrogen/tech.html. [2] R. Cameron, Effects of on-board HHO and water injection in a diesel generator, Bachelor of Engineering Research Project, University of Southern Queensland Faculty of Engineering and Surveying, 2012. [3] S. Yadav Milind, S.M. Sawant, Investigations on oxyhydrogen gas and producer gas as alterntive fuels on the performance of twin cylinder diesel engine, International Journal of Mechanical Engineering and Technology (IJMET), vol.2, pp.85-93, 2011. [4] Abdullah Işıktaş, Kevser Dincer, Ali Verim, Osman where n is the number of data patterns, yp,m indicates Türkmen, Sadık Ata, Experimental Investigation and Fuzzy Logic  Modelling of Performance Hydroxy Dry Cell with Different Plate the predicted, tm,m is the actual value of one data point m, and t m,m Combination, International Journal of Intelligent Systems and is the mean value of all actual data points [13].In this study, the Applications in Engineering, IJISAE, 2016, 4 (Special Issue), 18–22, R2=98.5 is for the mass flow rate and RBMTF can be successfully 2016. used in HHO dry cell with 12x12 plate combination. [5] Shakhawat, C., Tahir, H., & Neil, B. (2006). Fuzzy rule- based modelling for human health risk from naturally occurring Acknowledgment radioactive materials in produced water, Journal of Environmental Radioactivity, 89, 1–17. [6] M. Tosun, K. Dincer, S. Baskaya, Rule-based Mamdani- type fuzzy modelling of thermal performance of multi-layer precast concrete panels used in residential buildings in Turkey, Expert ignition engine, International Journal of Innovative Research in Systems with Applications 38 (2011) 5553–5560. Science, Engineering and Technology, vol.2, pp. 393-404, 2013. [7] K. Dincer , S. Tasdemir , S. Baskaya , I. Ucgul & B. Z. [9] M. Bölgen, Fuzzy logic and data mining technıques in Uysal, Fuzzy Modeling of Performance of Counter flow Ranque- evaluating of credit risks of companies, Master Thesis, Graduate Hilsch Vortex Tubes with Different, Geometric Constructions, School of Numerical Heat Transfer, Part B, 54: 499–517, 2008. Natural and Applied Sciences of Dokuz Eylül University, [8] E. Leelakrishnan, N. Lokesh, H. Suriyan, Performance and Turkey, 2010. emission characteristics of Brown’s gas enriched air in spark [10] Sadık Ata, Kevser Dincer, Fuzzy logic modeling of performance proton exchange membrane fuel cell with spin method coated with carbon nanotube, international journal of hydrogen energy 42 (2017) 2626-2635. [11] Sakthıvel, S., 2014, An Experimental Assessment of Performance and Exhaust Emission Characteristics by Addition of Hydroxy (HHO) Gas in Twin Cylinder C.I. Engine, International Journal of Innovative Research in Science, Engineering and Technology, Vol. 3(2), pp. 60-65. [12] Yusuf YILMAZ, Sadık ATA, Gürol ÖNAL, Abdullah IŞIKTAŞ, Kevser DINCER, A Fuzzy Logıc Approach For The Estımatıon Of Performance Hydroxy Dry Cell With Different Plate Combınatıon, Selcuk Univ. J. Eng. Sci. Tech., v.6, n.1, pp. 70-87, 2018. [13] Onal, G., Dincer, K., Yayla, S., Yılmaz, Y., Ersoyoğlu, A.S. Pt/C Coating for Proton Exchange Membrane Fuel Cell (PEMFC) and Rule-Based Mamdani-Type Fuzzy Modeling of PEMFC Performance, International Journal of Mining, Metallurgy & Mechanical Engineering, 3(3), 122-128, 2015.

367 MACHINES. TECHNOLOGIES. MATERIALS. 2018 ANALYSIS AND FRACTURE OF ALUMINIUM ALLOY COMPONENTS USED FOR SPINNING OF CHEMICAL FIBER

Assoc. Prof. Kandrotaitė Janutienė R. PhD1, Lect. Mažeika D. PhD1 Faculty of Mechanical Engineering and Design – Kaunas University of Technology1, Lithuania E-mail: [email protected], [email protected] Abstract: An aim of a research was to determine the reasons of fracture of aluminium alloy components used for spinning of chemical fibres and to improve spinning process by selecting material with better performance. Keywords: ALUMINIUM ALLOY, FRACTURE, MICROSTRUCTURE

1. Introduction EN ISO 6892-1:2009 standard in Tinius Olsen H50KT universal testing machine. The purpose of the aluminum alloy rods used by a producer of Table 1: Chemical composition of aluminum alloy used for current chemical fibers is to tighten and direct the fiber spun on the reel tensioners (% wt) (Fig. 1). During the operation, the rods are constantly vibrating, i.e. Equivalent of Sample Elements, % cyclically loaded. In the event of a break, the part should be alloy grade replaced by a new one, therefore the downtime occurs in production Al Si Mg Cu Mn Zn Ni Fe of chemical fiber. Bal. 0.695 1.07 0.293 0.089 0.015 0.005 0.207 Rod 6061 Ø3 mm Pb Bi Cr Ti Sn V Ca Be (AlMg1SiCu) 0.005 -- 0.165 0.011 0.022 -- 0.007 0.014

Table 2: Mechanical properties of current tensioners material R , Dimensions of sample R , MPa p0.2 A, % Z, % m MPa Ø3 mm × 50 mm 408 321 21.5 50 The fracture surface and microstructure of aluminum alloy used for the current tensioners was examined by optical microscope optical microscope Nikon equipped with video camera Nikon DS-2 16 MP and objectives Nikon TU Plan Fluor 10×/0.30 and Nikon TU Plan Fluor 100x/0.90. Trying to order different grades of aluminum alloy it was found out that in the producer’s area just two grades were available – 6060 a and 6063. Therefore, these two grades were compared with the current one seeking to choose the material with better performance. 3. Results and Discussion 3.1. Analysis of chemical composition of system Al-Mg-Si According to EN standards, the 6XXX numbering indicates that these are heat treatable wrought alloys of Al-Mg-Si system, which are also found in the literature under the name of "avials" (aviation alloys) [1]. Avials are low-alloyed with magnesium and silicon (sum of alloying elements 1-2%); these alloys also contain small additives of chrome and manganese. By forming the dispersed phases of Mg2Si, Al6Mn, Al7Cr, alloying components decrease the grain size microstructure and raise the temperature of the b c recrystallization. Copper addition increases the strength of avials, Fig. 1 Spinning machines for production of chemical fibers: a) general but reduces the corrosion resistance of the alloys [2]. Al-Mg-Si view; b) workplace of spinning on reel; c) fiber tensioner made of aluminum alloys are deformable – their properties can be improved by heat alloy. White arrows show tensioners investigated treatment and deformation. The producer decided to decrease the risk of the downtimes by In order to find as much information as possible about the alloys choosing material with better performance for the parts. of interest, German and Russian aluminum alloy analogues were The aim of the work was to analyze the reasons of fracture of also reviewed (Table 3). The equivalent of the aluminum alloy 6063 the parts and to choose other aluminum alloy which could maintain was not found in DIN or GOST standards. more cycles of vibrations during the production of chemical fibers. The chemical composition of the aluminum alloys is regulated by the European Union standard EN 573. The chemical composition 2. Methodology of alloys is given in Table 4, which is comparable to the currently Determination of chemical composition and analysis of used grade. mechanical properties showed that the current tensioners have been Table 3: Aluminum alloys equivalents manufactured from the rod of aluminum alloy 6061 (according to EN 573 DIN 1712, 1725 GOST 11069, 4784 EN) (1 and 2 Tables). No. Grade No. Grade No. Grade 6060 AlMgSi 3.3206 AlMgSi0.5 1310 AД31 Chemical composition was determined according LST CR 6061 AlMgSiCu 3.3214 AlMg1SiCu AД33 10320-2006 standard by optical emission spectrometer ARC-MET 6063 AlMg0.7Si - - - - 8000. Tension strength and yield point were examined according

368 MACHINES. TECHNOLOGIES. MATERIALS. 2018 Table 4: Comparison of aluminum alloys chemical composition (according alloying elements precipitates from the solid solution in the form of DIN EN 573-3:2009-08) [3] small particles (chemical compounds). These strengthening Impurity Fe Cu Mn Cr Zn Ti particles improves mechanical properties of the alloy. Aluminum Alloy Si Mg Al Other Max of max max max max max max Total alloys are most often treated for artificial aging (T6). The strength each of the aluminum alloy is higher than after natural aging (T4). 0.3- 0.1- 0.35- 6060 0.1 0.1 0.05 0.15 0.1 Bal. - 0.05 0.15 0.6 0.3 0.6 The mechanical properties of aluminum alloys after different 0.4- 0.15- 0.8- 0.04- 6061 0.7 0.15 0.25 0.15 Bal. - 0.05 0.15 0.8 0.4 1.2 0.35 thermal treatment are regulated by standard EN 755. The 0.2- 0.45- characteristics of the mechanical properties presented in the 6063 0.35 0.1 0.1 0.1 0.1 0.1 Bal. - 005 0.15 0.6 0.9 standard are indicated by "the possible minimum". Maximum Currently used alloy values of mechanical characteristics are not regulated. Table 5 0.005Ni shows the mechanical characteristics of the aluminum alloys 6061 0.695 0.207 0.293 0.089 1.07 0.165 0.015 0.011 97.50 0.005Pb - - 0.022Sn investigated: tensile strength Rm, yield strength Rp0.2, relative elongation A and relative contraction Z. 3.2 Alloying of system Al-Mg-Si Table 5: Comparison of mechanical properties of aluminum alloys (according EN 755-2:2016) [4] Magnesium increases the strength of aluminum alloy. One A percent magnesium increases tensile strength R by about 30 MPa. R R A 50 m Heat Diameter, m p0.2 mm Grade MPa MPa % HBW Magnesium increases the vibrational durability of the alloy, as well. treat. mm % The grade 6061 has the maximum magnesium content and the grade min max min max min min 6060 has the lowest content. T4 ≤ 150 120 - 60 - 16 14 50 Silicon forms reinforcing phases inside the microstructure of the 6060 T5 ≤ 150 160 - 120 - 8 6 60 T6 ≤ 150 190 - 150 - 8 6 70 avials, i.e. compounds of Mg2Si. These particles are several T4 ≤ 200 180 - 110 - 15 13 65 micrometers in size or smaller; hard, strong, in avials acting as a 6061 reinforcing material. 0.5-0.6% of silicon improves welding T6 ≤ 200 260 - 240 - 8 6 95 performance. According to the EN standard, the maximum content T4 ≤ 150 130 - 65 - 14 12 50 of silicon is in the 6061 alloy, in comparison of three grades 6063 T5 ≤ 200 175 - 130 - 8 6 65 T6 ≤ 150 215 - 170 - 10 8 75 investigated. Currently used alloy Manganese and chromium increase the strength of avials. 6061 3 408 321 21.5 - - Alloys of Al-Si-Mg system that contain these elements become hardened by highly dispersed phases [Al6Mn, α-(Al-Si-Mn), Al7Cr], Comparing the properties of the investigated aluminum alloys, which increase the temperature of the recrystallization of plastically it is obvious that the highest strength corresponds to 6061 alloy, and deformed products and inhibit grain growth. In the 6061 alloy, the the lowest – to 6060 alloy. Also, one can see how the strength of the amount of manganese and chromium is allowed maximum, in the alloys varies depending on the heat treatment method: the second place is 6063, and in the third – 6060. maximum strength is achieved after solid solution treatment and artificial aging (T6). However, the maximum plasticity after the Zinc, titanium and chromium reduce the possibility of corrosion same heat treatment corresponds to alloy 6063. under stress. In addition, just 0.4-0.8% zinc increases the yield strength of the aluminum alloy. Mechanical properties of the material are usually characterized by the standard values R and R . However, the high strength and The small amount of copper that occurs in the alloys m p0.2 yield limits sometimes show how the material will behave under the investigated, and is almost all dissolved in the solid solution, real conditions, especially when cyclical loads act. However, slightly increases the strength of it, but its higher content (0.05- aluminum alloys showing high R and R values, do not exhibit 0.1%) decreases resistance to corrosion, especially intercrystalline. m p0.2 significant strength. The reason of this can be the defects of the real The iron impurity has the most degraded effect to aluminum product when operating under real conditions. The defects may alloys – it practically does not dissolve in aluminum, but forms include mechanical surface defects: cracks, scratches, surface fragile intermetallic phases, therefore, the amount of iron has to be roughness; metallurgical: oxides, rough intermetallic phases, as small as possible. According to standard EN 573, the maximum chemical elemental heterogeneity. All defects in the material act as iron content in alloy 6061 may be up to 0.7%, but only 0.207% was stress concentrators around which stresses may exceed the found in the currently used alloy according to the chemical material's yield point or strength limit [5]. composition analysis. In alloys 6060 and 6063, the iron content is There are always cracks (or surface irregularities) on the surface more restricted to 0.3-0.35%. of metallic components in real construction. Each material has its 3.3 Mechanical properties and heat treatment of Al-Mg-Si own period of slow crack propagation, during which the component alloys can be operated. And only when the crack reaches a critical size, its further expansion occurs very quickly until a complete break. The The mechanical properties of aluminum alloys depend fracture period during which the cracks develop slowly indicates the particularly on the chemical composition, but even more on the heat performance, functionality and durability of the product. This treatment of the alloy. During heat or thermomechanical treatment, period may vary between different materials. Very often, materials the strength, hardness and plasticity of aluminum alloys can vary a with high mechanical characteristics Rm and Rp0.2, weakly resist the few times. The most common thermal treatment methods, labeled in propagation of a crack, and materials with lower characteristics accordance with EN 755: counteract much better.  T4 –solid solution treated and naturally aged; The lifetime of the material can be assessed by the impact strength test. The higher the impact strength, the better the  T5 – cooled from an elevated temperature shaping process and artificially aged; durability of the material. Unfortunately, the standard 5 × 5 × 100 mm specimens are required to evaluate impact strength and  T6 – solid solution treated and artificially aged. therefore not suitable for wire. After quenching, the aluminum alloy is in a state of a solid The impact strength of an aluminum alloy can be increased in solution, which is saturated with dissolved alloying elements. the following ways: Mostly plastic and soft. During the further aging, the excess of

369 MACHINES. TECHNOLOGIES. MATERIALS. 2018 1. Reducing the amount of iron in the aluminum alloys. Best of all, when its content does not exceed 0.1-0.3%, and even better, when it is a hundred percentage points. Reducing the amount of iron, the amount of insoluble and very fragile intermetallic phases [Al3Fe, α-(Al-Fe-Si), α-(Al-Fe-Si-Mn), etc.] reduces as well, resulting an increase of the impact strength of the alloy. Iron dissolves in aluminum up to 0.062%, all the excess is precipitated in fragile intermetallic phases. 2. By super-aging of aluminum alloys to ensure that coherent bonding that occurs between the matrix and the intermetallic phases become destroyed. According to EN standard, this would be a heat treatment method labeled by T7, i.e. the products are treated to a solid solution and super-aged (stabilized). The strength of these products is slightly lower than after the solution treated and artificially aged with the purpose to obtain the maximum strength a (T6), but the impact strength of such treated alloys is higher. 3.4 Analysis of fracture and microstructure of aluminum alloy rods A fracture analysis of the broken rod surface showed that the type of fracture is fatigue (Fig. 2). Fatigue fracture occurs in several stages. Metal decomposition starts with a defect on the surface – it can be corrosion-damage, crack, scratch, non-metallic insert, solid, fragile, intermetallic phase, etc. As the components investigated are loaded cyclically, the material's fatigue resistance and surface quality are very important. The origin of the fracture (surface defects), the propagation of the crack and the area of the final fracture are indicated by arrows. As the component is vibrating during exploitation, i.e. deformed in different directions, surface tensile stresses have induced the defects to propagate until the final break. b

c Fig. 3 Analysis of the microstructure of the broken aluminum rod: the Fig. 2 Determination of fatigue fracture of the aluminum rod defects found at or near the surface (a), (b), and (c) After microstructural analysis, it became obviously that the surface is rich in defects: possible corrosion damages, non-metallic inserts (Fig. 3). The amount of non-metallic inclusions was found to be a little; these inclusions would be the most damaging when accidentally appears at the surface. A cross-section of the specimen was examined for the surface defects. Deformable Al-Mg-Si alloys contain low amounts of alloying elements, usually the sum of all alloying elements does not exceed 1-2%. Aluminum alloys 6060, 6061 have a phase composition of α (solid solution) + Mg2Si (hardening phase) [6], which is obtained after solution treatment and aging (artificially aging results higher mechanical properties than natural). Such a structure is visible observing the metallographic sample, made from the wire provided by the company (Fig. 4). Fig. 4 Microstructure of currently used aluminum alloy: composition of solid solution and hardening disperse particles Mg2Si

370 MACHINES. TECHNOLOGIES. MATERIALS. 2018 4. Conclusions 5. References Following the investigation of the fracture and microstructure of 1. Krishna Reddy, L. Principles of Engineering Metallurgy. New the currently used aluminum rods and the literature analysis on Al- Age International, 2007, 260 p. Mg-Si aluminum alloys, the following conclusions were formulated: 2. Žvinys, J. Structural Alloys. II T. Non-ferrous metals. Kaunas, Technology, 2000, 665 p. 1. The cause of the breakage of the currently used aluminum 3. DIN EN 573-3:2007-11. Aluminium and aluminium alloys rods is fatigue. If the suppliers of aluminum alloys provide Chemical composition and form of wrought products – Part 3: information about the fatigue resistance, this characteristic should Chemical composition and form of products. 30 p. be taken into account. 4. EN 755-2:2016 Aluminium and aluminium alloys – Extruded 2. Comparing the chemical composition of alloys 6060, 6061 rod/bar, tube and profiles - Part 2: Mechanical properties. 58 p. and 6063, it is obvious that 6061 has a higher Mg and Si content, and these elements form hardening particles. Also, this alloy has a 5. Б. А. Колачев, В. И. Елагин, В. А. Ливанов. Металловедение high content of manganese and chromium, which strengthens и термическая обработка цветных металлов и сплавов. Москва, alloys. The second place according to the amount of alloying МИСИС, 2001, 413 с. elements takes alloy 6063. 6060 alloy is the least alloyed aluminum 6. William F. Hosford. Materials for Engineers. Chapter 8 – alloy. Alloys 6060 and 6063 have more limited iron content than an Nonferrous Metals, Cambridge University Press, 2014, pp. 85-94. alloy 6061, which can form fragile intermetallic phases. Also, alloys 6060 and 6063 have less copper, and therefore they are more resistant to corrosion. This is important because the parts are in an environment of increased corrosion.

3. Comparing the mechanical properties of alloys, the maximum strength and yield point presents the alloy 6061. The alloy 6063 stands at the second place. However, the alloy 6063 has a plasticity greater than 6061, therefore, considering the theory outlined in section 3.3, it is likely that the tensile strength of alloy 6063 will be sufficient.

4. Comparing the mechanical properties of alloys after thermal treatment, it is obvious that the maximum strength is achieved after solution treatment and artificial aging (treatment T6) During the heat treatment process, the alloying elements precipitate from the solid solution that strengthen the alloy.

Recommendation: From the two possible aluminum alloy grades 6060 and 6063, it was suggested alloy 6063 more alloyed by silicon and magnesium and presenting higher strength and plasticity (compared to 6060) after thermal treatment of T6.

371 MACHINES. TECHNOLOGIES. MATERIALS. 2018 PERSPECTIVE COMPOSITE MATERIALS FOR GENERAL AND SPECIAL MECHANICAL ENGINEERING

Ph.D. Khantimerov S.M.1,2, M.Sc. Khantimerova Yu.M.2, M.Sc. Garipov R.R.1, Dr. Suleimanov N.M.1 Zavoisky Physical‑Technical Institute, FRC Kazan Scientific Center of RAS, Russia 1 New Structures & Technologies, LLC 2 [email protected] Abstract: The work considers the use of carbon nanotubes to enhance the functional characteristics of polymer materials. The results on studies of the electrophysical properties of polymers doped with carbon nanotubes are presented and prospects for the use of such materials are discussed. Keywords: ELECTROCONDUCTIVE POLYMER COMPOSITES, DOPING, CARBON NANOTUBES, MODIFICATION

1. Introduction varying between 9 and 20 nm. The fringe spacing is 0.34 nm. Such nanotubes are characterized by a large number of broken chemical The production of new equipment, special-purpose bonds necessary for the attachment of external molecular groups. constructions with a high functional properties requires the An ABS-1035, produced by PJS company Kazanorgsintez development of new materials or the improvement of traditionally (Kazan, Russia) was used as polymer matrix. used ones. An effective solution ща these problems is based on the development of new composite materials doped by micro- and For the production of composite samples based on ABS doped nanostructures. Carbon nanotubes (CNTs), which have a complex by carbon nanotubes, a specially developed technique including of unique physical-chemical properties, can be considered as one of thermochemical and ultrasonic treatment was used [6]. A series of the most promising types of modifiers [1]. Such CNT-based fillers ABS/CNTs composites with varied amounts of CNTs (0.125, 0.25, make it possible to vary both the strength characteristics of 0.5, 1 wt.%) were prepared. polymers and in a wide range the electrical conductivity of the polymer matrix [2, 3]. This greatly expands the possible The concentration dependence of electrical conductivity of a applications of composite materials. Due to their electronic composite material based on ABS and functionalized carbon properties and high aspect ratio (the ratio of length to diameter) of nanotubes was measured by using four-probe van der Pauw method carbon nanotubes, their addition to the polymer matrix in an amount at ambient temperature. of 0.2% causes an increase in the electrical conductivity of the resulting composite by 8-10 orders of magnitude. In this case, the 3. Results and Discussion percolation nature of the conductivity of the material appears, Figure 1 shows the samples of a polymeric composite material according to which, with a small content of the conductive additive, based on ABS and functionalized carbon nanotubes with different charge transfer occurs through a small number of conducting concentrations. The concentration dependence of electrical channels formed upon the contact of the additive particles. conductivity of ABS/CNTs composites is presented on Fig.2. Despite of all the attractiveness of using carbon nanostructures to create promising composites, there is a number of problems that prevent their wide application. One of them is the problem of obtaining nanocomposites based on carbon nanotubes with their uniform distribution in the matrix and the need for the formation of covalent bonds between the surface of nanotubes and polymer. Without further modification, CNTs tend to form agglomerates. In addition, the graphene surface of a nanotube can form only weak van der Waals bonds with a polymer matrix, which inhibits the Fig.1 Samples of a polymeric composite material based on ABS and achievement of useful properties in polymer composite materials. In functionalized carbon nanotubes with different concentrations. order to better disperse the modifier in the matrix, and also to form covalent bonds between the matrix and the nanoparticles, the functionalization of nanotubes is used [4, 5]. It should be noted that the final properties of the composite material doped with carbon nanotubes depend significantly on a number of factors. A key element in creating composites with given properties is a fundamental understanding of the mechanism of composites formation in the interaction of constituent components, basic and alloying. In the case of CNTs used as the doping component, the determining factor is their morphology, electronic structure, concentration, surface state, in particular, the presence of functional groups interacting with the matrix medium. The purpose of this paper is to study the concentration dependence of electrical conductivity of a composite material based on ABS-plastic and functionalized carbon nanotubes. 2. Materials and Methods As carbon nanotubes conical carbon nanotubes were used. Conical carbon nanotubes were grown by pyrolysis of granular Fig.2 Concentration dependence of electrical conductivity of polyethylene. These nanotubes are several microns in length, with ABS/CNTs composites. outer diameters ranging between 40 and 50 nm and inner channels

372 MACHINES. TECHNOLOGIES. MATERIALS. 2018 It can be seen from Fig. 2 that the increase in the electrical 5. References conductivity is nonmonotonic: its sharpest change was observed in 1. Wang, C., Z.-X. Guo, S. Fu, W.Wu, D. Zhu. Prog. Polym. a narrow range of filler concentrations, which allows to consider a Sci., V. 29, 2004, P. 1079–1141. dielectric-metal transition or a percolation transition when the 2. Carbon nanotubes - current progress of their polymer amount of the conducting particles in a material equals to the composites, InTech, 504 p., 2016. percolation threshold. 3. da Costa, E.F., A.A. Skordos, I.K. Partridge, A. Rezai. Thus, in this paper the manufacturing of a composite material Composites Part A: Applied Science and Manufacturing, V. 43, with controlled electrical conductivity based on ABS and carbon №4, 2012, P. 593–602. nanotubes is shown. The developed electrically conductive 4. Vesali, N.M., A.A. Khodadadi, Y. Mortazavi, et al. World composite material based on polymers and CNTs can be used, for Academy of Science, Engineering and Technology, V.49, 2009, P. example, in the manufacturing of conductive pastes and adhesives, 177-179. as electrically conductive liners and plates in modern composite 5. Abuilaiwi, F.A., T. Laoui, M. Al-Harthi, and M.A. Atieh. machine parts in general and special engineering. The Arabian Journal for Science and Engineering, V. 35, № 1C, 2010, P. 37-48. 4. Acknowledgements 6. Patent Ru №2602798. The present study is supported by IVF RT (contract №13/82/2018).

373 MACHINES. TECHNOLOGIES. MATERIALS. 2018 THE COMPRESSION NATURE OF THE „WURTZITE BORON NITRIDE- DIAMOND” SINTERED UNDER HIGH PRESSURE

I.I. Buzhanska1, V.M. Volkogon1, S.K. Avramchuk1, Yu.O. Fedoran1, A.V. Kravchuk1, V.S. Antonyuk2, I.M.Frantsevich Institute for Problems of Materials Science of the National Academy of Sciences of Ukraine, Kyiv1 National Technical University of Ukraine, «Igor Sikorsky Kyiv Politechnic Institute», Kyiv.2

Abstract: The results of experimental studies of the compression process during the sintering under high pressure conditions of wurtzite boron nitride and diamond powders mixture of submicron sizes obtained by different technologies are given. It is determined that the compaction level at obtaining compositions depends on the dispersion and nature of the diamond component. Interaction of wurtzite boron nitride with diamond proceeds more intensively with diamonds of dynamic synthesis, but it is accompanied by their partial graphitization. KEY WORDS: WURTZITE BORON NITRIDE, DIAMOND, DISPERSION, SINTERING, DENSITY.

Introduction. The density of the sintered samples was determined by A considerable amount of work is devoted to obtaining hydrostatic weighting method using the WLR-200 analytical scales composite polycrystalline materials on the basis of superhard phases with a maximum weighing range of 200 g and an accuracy of ± 0.15 of boron and carbon nitride. In experiments [1-4] mixtures of boron mg. and carbon nitride were used, in which one of the components was Discussion of research results. used in the state of thermodynamic stability under high pressure An analysis of the density measurements of sintered conditions. samples of the "wurtzite boron nitride-diamond" system composite However, the production of composites from such material suggests the following. mixtures requires very high barometric parameters for sintering and According to studies of the compression nature of the direct phase transformations in dense modifications of components initial mixture during the sintering of composite materials, it is with a layered crystalline lattice, therefore, in [1], when composite observed its dependence on the origin and dispersion of the from a mixture of hexagonal boron nitride and diamond was diamond component. obtained, to decrease barothermal parameters, catalytic impurities Despite the fact that the samples density from mixtures of were used. boron nitride and diamonds of different origin in the initial state In addition, a number of papers [3-5] reported the before the temperature action had approximately the same value, the obtaining of "CBN-diamond" composite materials when graphite- compression nature of compositions is significantly different. like boron carbonitride powders [3, 4], a mixture of diamond and The samples density containing diamonds of static graphite-like boron nitride [5] or diamond and sphalerite boron synthesis of 1/0 μm at the initial stage of sintering under nitride [6, 7] were used. nonisothermal conditions already after 3 ... 5 s significantly exceeds In view of the fact that any data on the nature of the the characteristics of the composition with diamonds of explosive 3 compression of said powder systems under the influence of high synthesis (ρst = 2.68 ... 2.84 g/cm against ρdyn = 2 , 16 ... 2.31 pressures and temperatures, there are no studies in this direction that g/cm3). are of scientific interest. In the whole range of temperatures at all stages of The purpose of the research is to study the peculiarities sintering over τ = 60s, a gradual increase in sample density to a of formation in conditions of high static pressures and temperatures maximum value of ρ = 3.412 g/cm3 is observed. of polycrystalline composite materials in the system "wurtzite boron Figure 1 shows the compression kinetics of the powder nitride - diamond". composition "wurtzite boron nitride - diamond" at sinterng under Methods of experimental research. As the main high pressure conditions. component of a powder system mixture for the composite material production, the wurtzite boron nitride powder, which meets the requirements of TUU 75-12006.7-98, was used. The main fraction of particles had a size in the developed plane of 0.1 ... 5 microns. According to electron microscopic studies, the powders were fragmented at two levels: the size of the first-level fragments was 0.5 ... 1.0 μm, and the second level was 50 ... 100 nm or less. Diamond powders of different dispersion and origin were used as the second component of the mixture to produce the composite material - a catalytic synthesis of submicron sizes of 0.1/0 μm and dynamic nanosized range 0.005 ... 0.012 μm. To study the compression kinetics and contact interaction between the system components, wurtzite boron nitride and diamond at sintering under high pressure, a mixture of their powders was prepared in a quantitative weight ratio of 90:10, from which pressed samples of a cylindrical shape. Figure 1. Compression kinetics of a powder composition, The obtained samples in the high-pressure apparatus of at sintering under high pressure conditions (p = 8 GPa): BNw + the "toroid" type were subjected to high pressure p = 7.7 GPa and static synthesis diamonds at Т = 1500ºС (1); Т = 1600ºС (2); Т = temperatures T = 1500 ... 1800 °C at an interval of 100 °C for 5, 15, 1700ºС (3); Т = 1800ºС (4) and 30, 60 and 120 seconds. BNw + dynamic synthesis diamonds at Т = 1500ºС (5); The temperature control was carried out in accordance Т = 1600ºС (6); with the schedule of thermocouples previously obtained in the Т = 1700ºС (7); Т=1800ºС (8). coordinates "power of heating – temperature". The maximum density of the sintered composition "BNw - At the beginning of the sintering process, the instant of 3 heating was taken - non-isothermal conditions prior to the Explosive Synthesis Diamond" was ρ = 3.256 g/cm , and the nature establishment of a quasi-stationary thermal regime. of its change, depending on the sintering duration, is similar to

374 MACHINES. TECHNOLOGIES. MATERIALS. 2018 composition with static synthesis diamonds, but the sample density The fast packing compression state (initial stage) of at all stages of sintering is significantly lower. sample is determined by the cooperative plasticity, which This is due to the fact that already at Т = 1000 ºС there is determines by the anisotropy of the lattice of wurtzite boron nitride a graphitization of dynamic synthesis diamonds[8] and, according and the insignificant energy of the basic packaging defects and the to the data of X-ray analysis [9], at T = 1600 ºС the main part (~ disordering of the initial BNw due to the accumulation of basic 70%) is completely graphitized, while the other (~ 30%) forms a defects in the packaging, which is accompanied by an increase in solid solution with boron nitride during the phase transformation of plasticity [13]. the wurtzite modification of BN into sphalerite [10]. Cooperative deformation affects the formation nature of It is the porosity that occured as a result of the phase samples density, due to the next stage of structure formation - transformation of diamonds into graphite, which determines the dissolution of the material. characteristics of the sintered composition samples with the Conclusion. indicated density indices, and its volume corresponds to the mass The results of the conducted studies indicate that the fraction of diamonds that have been graphitized. dispersion and nature of diamonds in the composition of the wurtzite It was shown in [11] that at sintering diamond powders boron nitride determine the characteristics of the polycrystalline with particle sizes smaller than 0.3 μm already at a temperature T = material compression during the sintering under high pressure 1600 ºС, as a result of their graphitization, the amount of conditions. In the presence of static synthesis diamonds of submicron counterweight in the pores of the samples is comparable to the sizes, the compression process of the powder system during sintering value of the external pressure (p = 8 GPa). corresponds to the general laws for wurtzite boron nitride in its pure Accordingly, the results of our X-ray diffraction analysis form. of the matrix component of the composite based on wurtzite boron For composition with dynamic synthesis diamonds, the level nitride are obtained. of components compression of the composition is limited by partial graphitization, which is approximately 30% of the initial amount of the The level of phase transformation BN → BN in the w sf diamond component. composition of the explosive synthesis diamond under the same barothermic conditions, lower than the compositions based on static References: 1 Мазуренко А.М. Синтез поликристаллического композита алмаз – synthesis diamonds, due to pressure drop in the pores of the КНБ и его свойства / А.М. Мазуренко, Л.И. Ракицкая, Э.В. graphite, which is applied to the total pressure in the volume of Ракицкий, А.А. Леусенко // Выездное заседание секции научного samples and contributes to the intensification of the phase совета ГКНТ СССР «Получение и обработка материалов transformation of BNw → BNg in the case of discrepancy in the воздействием высоких давлений». Сб. науч. тр., 19-23 сентября volume of samples of the thermodynamic stability conditions of 1988. – Минск: Ураджай, 1990. – С. 171 – 175. high pressure nitride boron phases. 2 Itoh H. Reaction sintering of cubic boron nitride using volatile catalysts It is significant that for both systems of composition the / H. Itoh, H. Takao, H. Iwahara // J. Amer. Ceram. Soc. – 1993. – 76, maximum density of sintered samples is achieved at the temperature №11. – P. 2889 – 2895. 3 Sasaki T. 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Iwahara et al. // J. of the Japan Society of Powder and Powder Metallurgy. – 1989. – 36, №6. – P. 756 – 758. 7 Кидалов С.В. К вопросу о получении и свойствах сверхтвердых кристаллических материалов в системе бор – углерод – азот / С.В. Кидалов, Ф.М. Шахов, В.М. Давиденко, В.А. Яшин // Письма в ЖТФ. – 2011. – том 37, №6. – С. 8 – 14. 8 Даниленко В.В., Петруша И.А., Олейник Г.С., Даниленко Н.В. Эволюция структуры компакта при спекании нанодисперсных алмазов в условиях высоких давлений. // Сверхтвердые материалы. – 1998.– №4. – С. 58 – 61. 9 Особенности фазовых превращений в системе «BNв - алмаз» в зависимости от характеристик алмаза при ее спекании в условиях высоких давлений / В.М. Волкогон, С.К. Аврамчук, Figure 2. Compression characteristics of powder А.В. 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Волкогон, С.К. mechanisms change in accordance with the evolution of the Аврамчук, А.В. Котко // Сверхтвердые материалы. – 2010, №5. – С. structural and phase state in the system of particles. 51 – 60.

375 MACHINES. TECHNOLOGIES. MATERIALS. 2018 MECHANICAL PROPERTIES OF PARTS OF PLA-NATURAL AS A FUNCTION OF THE TEMPERATURE OF THE 3D PRINTING BY FDM METHOD

МЕХАНИЧНИ СВОЙСТВА НА ИЗДЕЛИЯ ОТ PLA-NATURAL КАТО ФУНКЦИЯ ОТ ТЕМПЕРАТУРАТА НА 3D ПРИНТИРАНЕ ПО МЕТОДА FDM

Chief Assist. Prof. Yankov E.

1University of Ruse, Dept. Material Science and Technology, Ruse, 8 Studentska Str., Bulgaria1 E-mail: [email protected]

Abstract: The objective of this study is to investigate the influence of extruding temperature TE on the mechanical properties of PLA- Natural printing samples using fused deposition modeling (FDM) technology. Yield strength Re0.2, Tensile stress Ra, Young’s modulus E, Elongation ε, impact strength KCU, hardness HSD are examined as functions of the Te in the range 180 – 240 °C with 10°C increment. Standard tensile test samples, were printed using 3D printer JennyPrinter4 Z370. All samples were builded with the following parameters: nozzle diameter 0.2 mm, layer thickness 0.1 mm, speed 20 mm/min, table temperature 60 °C. Five samples were tested for each mechanical property. The ambient air temperature during the tensile test was 23° and humidity 68 %. One-dimensional stretching tests were carried out on a machine INSTRON, impact strength – by Sherpy test, hardness by Shore method. The results of the research showed that TE significantly influences on the mechanical properties of PLA printing samples. Optimal temperature range is 200-220 °C.

Keywords: 3D printing, Additive manufacturing (AM), FDM, PLA-Natural, Mehanical testing, Extruding temperature, Design of experiments (DoEs)

1. Увод специално разработен метод за изпитване на пластмаси. Изпитването на едномерен равномерен опън при този режим се 3D принтирането се счита за една от ключовите технологии осъществява с постоянна скорост 1 mm/min. Якостта на опън за бъдещото прецизно производство с цел да се Rm е в границите от 44.5 MPa до 46.4 MPa, относителната облагодетелстват различни отрасли в машиностроенето, деформация ε е в границите от 1.75 % до 2.42 %, горна граница разработването на продукти, биомедицинските иновации на провлачване Rе от 25 МРа до 30.7 МРа и модул на строителството, и т.н. [1-5] Причините за нарастващите еластичност в границите от 1.87 GPa до 2.2 GPa. Получените приложения на 3D принтирането се дължат главно на намалено стойности на механичните показатели в условията на доставка тегло, намален разход на материали, висока точност и по-малък отговарят на известните данни за PLA-Natural [15]. цикъл за производство. Освен това, изключителна важно за 3D За целите на изследването са използвани пробни тела за принтирането е получените детайли да могат да поддържат едномерен опън и ударна жилавост (БДС EN ISO 527-2:2002 и същите или дори по-добри механични и технологични качества съответно СИВ 1491:1979) са показани съответно на фиг.1. на материалите и качество на получаваните продукти, каквито се постигат чрез конвенционалните производствени методи [6- 10]. Изследвания на колективи показват различаващи се механични показатели и свойства [11-14]. Причини за това могат да са крият в режима на принтиране (температура на екструдиране, скорост на принтиране, скорост на екструдиране, стратегията на изграждане, стратегия на запълване диаметър на екстрадиращата дюза и др.) и вида на материала (чист или с определено количество примеси, като оцветители, втвърдители свързващи вещества и др.). Целта на това изследване е да се установи влиянието на един от ключовите параметри на режима на принтиране - температурата на екструдиране (ТЕ) в интервала 180 - 240 °С върху механичните показатели (якост на опън, относително удължение, модул на Юнг, горна граница на провлачване, твърдост, ударна жилавост), както и на връзката между линиите и слоевете на изграждане при 3D принтиране на пробни тела от материал PLA –Natural. Настоящото проучване е част от началния етап на по-широки и задълбочени изследвания на факторите влияещи върху качеството на 3D принтирани изделия от различни материали. Фиг. 1. Пробни тела за едномерен опън ударна жилавост. 2. Методика не експеримента Цифровите модели са разработени с CAD система SolidWork, като се запазват в подходящ формат за 3D Изследванията в настоящата работа са проведени с нишков принтиране - *.OBJ с възможно най-малки размери на материал PLA-Natural диаметър 1.75 mm навит на ролка. Преди мрежовите елементи. Пробните тела са реализирани на 3D провеждане на изследванията материалът бе проверен по принтер „3D Jenniprinter4 Z370“ затворен тип с помощта на отношение на механичните му свойства. От нишката бяха софтуер продукт за преподготовка за 3D принтиране - отрязани 5 проби с дължина 160 mm. Всяка проба бе изпитана Simplify3D v.3.1.0. В софтуерния продукт са зададени на универсална изпитвателна машина Instron 3384 (фиг.3.а) със параметрите за принтиране на всички пробните тела: диаметър

376 MACHINES. TECHNOLOGIES. MATERIALS. 2018 на дюзата 0.25 mm, скорост на движение по ос X и Y 20 екструдиране оказва чувствително влияние върху механичните mm/min, дебелина наслоя 0.1 mm, компенсация за свиване след показатели на получаваните проби. От диаграмата се вижда, че изстиване 0.6 %, плътност на запълване 100 %, стратегия на при най-ниската температура на екструдиране 180 °С якостта изграждане линейно чрез периодично редуване на слоеве, в на опън е ниска – 17.4 МРа, а пластичността достига най- които изграждането е под ъгъл съответно -45° и +45° спрямо високи стойности 8 %. С нарастване на ТЕ якостта нараства, а оста X (фиг.2.а и 2.б), температура на работната маса - 60 °С. пластичността намалява. До температура до 220 °С якостта нараства непрекъснато и достига максимална стойност при тази температура - 29 MPa. Относителната деформация много слабо намалява при 190 °С (7.8 %) но значително спада - на 5 % при 200 °С, след което слабо се влияе от повишението на температурата до 220°С, като относителното удължение е 4.4 %. С повишение на ТЕ над 220° якостта спада на 24.91 MPa при 230 °С, като едновременно с това се повишава относителното а) б) удължение – 7.3 %. Тези стойности на механичната якост са Фиг. 2. Стратегия на изграждане при 3D принтиране: а) първи типична за температури на екструдиране в интервала 190 - 200 слой -45°, б) втори слой + 45°. °С. Същевременно относителната деформация нараства и доближава стойности характерни за 190 °С. При 240 °С якостта За целите на изследването са принтирани по 5 броя пробни на опън 28 MPa е много близка до тази при 220 °С. тела при температура на екструдиране (TE) - 180 °С, 190 °С, 200 Относителната деформация, обаче, рязко спада на 2,2 % - най- °С, 210 °С, 220 °С, 230 °С и 240 °С. малката стойност от всички изследвани проби. Изпитването на пробните тела е проведено с универсална изпитвателна машина Instron 3384 (фиг.3.а), като методът на изпитване е същият използван при изпитването на изходния материал. За коректно определяне на механичните характеристики: механична якост, горна граница на провлачване, модул на еластичност (модул на Юнг) и относителна деформация, в разработената методика се въвеждат размерите на пробите преди и след изпитване.

Фиг. 4. Диаграма на истинските напрежения и деформации. Обобщените механичните характеристики от проведения едномерен опън са нанесени в табл.1 (максималните стойности на всеки параметър са оцветени в тъмно зелен цвят, а минималните в тъмно червен цвят). Стойностите на показателите, които са най-близки до усреднената стойност са представени без оцветяване. а) б) Table 1. Механични свойства на PLA -Natural след 3D принтиране Фиг. 3. Уредби за изпитване а) универсална изпитвателна машина Механични свойства на PLA -Natural след 3D принтиране Instron-338; б) чук на Шарпи. Ударна Ударната жилавост се определяше чрез механичен Температура Условна Якост на Относителн Модул на жилавост Твърдост на граница на махалоударна машина - чук на Шарпи (фиг.3.б). За всяка опън деформация Юнг по Шарпи по Шор екструдиране провлачване температура на принтиране бяха изпитвани по пет Rm(MPa) ε (%) Е (GPa) KCU (HSD) ТЕ (°С) R (MPa) последователни пробни тела, а получените осреднени e (J/сm²) стойности са нанесени в табл.1(СТ на СИВ 1491:1979). 180 12.585 17.40 8 1.405 7.321 72 Твърдостта на пробните тела е измервана с механичен 190 14.924 24.22 7.8 1.586 6.148 78 твърдомер (дуромер) на Шор-D за пластмаси (БДС EN ISO 200 16.684 24.93 5 1.733 5.515 77 868:2006). Твърдостта се определяше върху областта на 210 17.511 26.77 4.1 1.856 5.152 79 захващане на пробите за едномерен опън при плавно 220 18.272 29.01 4.38 1.889 6.231 83 натоварване с 5 kg и време на задържане 10 s. Механична 230 15.104 24.91 7.3 1.818 5.597 83 твърдост от десет последователни измервания за всяка проба са 240 19.962 28.09 2.17 1.7 4.890 80 осреднени и нанесени в табл.1. Относно модула на Юнг (Е) резултатите показват, че с нарастване на температурата на екструдиране той се повишава 3. Резултати и анализ от 1.4 GPa при 180 °С достига максимална стойност 1.9 GPa От проведеното изпитване на едномерен опън за всяка една при 220 °С (табл.1 и фиг.5). Нарастването на модула в този температура са снети индикаторните диаграми и построени температурен интервал е чувствително – 35 %. По нататъшното съответните криви на уякчаване. За целите на анализа от всяка повишение на температурата води до понижаване модула на група криви на уякчаване при дадена температура е избрана Юнг, като достига стойност 1,7 GPa при 240 °С. Повишаването една крива – представител, която отговаря на средните на модула на Юнг до 220 °С води естествено към по-висока стойности на механичните показатели. На фиг. 4 са показани якост на опън в този интервал. представителните криви на уякчаване за седемте температури Изследването на едномерен опън показа, че при всички на изследване. Както може да се очаква температурата на температурни режими на принтиране материалът няма

377 MACHINES. TECHNOLOGIES. MATERIALS. 2018 проявена физическа граница на провлачване (фиг.4). Предвид принтиране са ниски за създаване на достатъчно силни връзки на това е определена условната граница при степен на (кохезия) между повърхностите на отделните нишки. С оглед деформация Re0.2. Подобно на измененията на разгледаните на това изследването потвърждава, че температурата 180 °С не дотук параметри Rm и Е, условната граница на провлачване е подходяща за целите на създаване на изделия от PLA с добри нараства с повишаване на ТЕ до 220 °С (табл.1). Интересна механични свойства. С не голямо повишение на температурата особеност тук, обаче, е че след известно понижение на Re0.2 – на 190 °С може да се забележи, че дължината и количеството при 230 °С – 15.104 MPa, тя рязко се повишава при 240 °С на на изтеглените нишки в областта на разрушение намаляват. 19,962 MPa (фиг. 5), надвишавайки стойността и при 220 °С - Това е показателно за положителното влияние на повишението 18.272 MPa. на температурата върху силите на свързване (кохезия) между слоевете и редовете на изграждане. Изследванията на ударната жилавост показаха, че с повишаване на температурата на екструдиране до 210 °С тя Разрушението на пробите от едномерен опън при намалява от 7.32 до 5.15 J/cm2. С повишаване на температурата температурите 200 – 230 °С има друг характер – липсва на 220 °С ударната жилавост слабо се повишава до 6.23 J/cm2 образуване на шийка, няма преориентиране на нишките в след което с нарастване на температурата до 240 С продължава зоната на разрушение, не е налично изтегляне на нишки, което да спада и достига стойност 4.89 J/cm2. свидетелства за по-добра кохезия и разкъсването протича по едно от направлението на разположение на нишките - 45°. Този характер на изменение на ударната жилавост е Характерът на разрушение е типичен за крехко разрушение. резултат от нарастващата якост на опън в интервала от 180 - При изпитването на ударна жилавост в този температурен 210°С и намаляването на пластичността. Нарастването на интервал също така разрушението е крехко без изтегляне на ударната жилавост в интервала от 210 - 230°С е следствие от нишки в зоната на разрушение. За разлика от ниските нарастването на пластичността и слабото изменение на якостта температури 180 °С и 190 °С в зоната на разрушение е на опън в същия температурен интервал. Характерна особеност въвлечен по-малко обем от пробата. в интервала 220 - 230 °C e тенденцията на намаляване на ударната жилавост при нарастване на пластичността и слабо При максималната температура на екструдиране 240 °С намаляване на якостта на опън. Тази особеност може да се разрушението при едномерен опън вече не протича под 45° дължи на разликата във височините на пробите - 1.5 mm за изцяло, както при пробите принтирани при по-ниските едномерен опън и 10 mm за ударна жилавост, която неизбежно температури 200 – 230 °С. тъй като разрушението в началния води да различни температурни условия на изграждането им в етап протича независимо от направлението на изграждане. Но процеса на принтирането. При това температурата на разрушението има същия крехък характер. В зоната на екструдиране по-всяка вероятност оказва влияние и върху разрушение на пробите за ударна жилавост при тази силата на молекулните връзки. температура не се наблюдава по-различна картина от тази при по-ниските температури 200 – 230 °С. Получените резултати от изследванията на опън и ударна жилавост показват, че има известна корелация между якостта на опън, относителното удължение и ударната жилавост в температурния интервал 180 – 220 °С. С нарастване на температурата към 230 °С има спадане на якостта на опън, на горната граница на провлачване и на ударната жилавост при същевременно нарастване на пластичността. Вероятно това се дължи на настъпилите по-големи промени във вътрешната структура на полимера, които водят до понижаване на якостните показатели, въпреки създалите се по-силни кохезионни връзки между нишки и слоеве при 230 °С.

Фиг.5. Зависимости на Rm, ε, E, Rm0.2, KCU и HSD от температурата на екструдиране.

Изследванията на твърдостта във функция от ТЕ показват подобен характер на изменението й, както при механични показатели Rm и E, с максимум 84 HSD между - 220- 230 °С (фиг.5). Следва да се отбележи, че при ниските температури на екструдиране 180 °С, 190 °С и при 230 °С се получава по- голямо разсейване на твърдостта (±2 HSD). На фиг.6 и фиг.7 е показан характерът на разрушение съответно при едномерен опън и при изпитване на ударна жилавост в зависимост от температурата на екструдиране в изследваният интервал 180 - 240 °С. От фиг.6 се вижда, че при температури 180 и 190 °С се образува шийка характерна за пластично разрушение на материала. Това е свързано с установената по-голяма пластичност при тези проби. По- подробният анализ на зоната на разрушение показва известно преориентиране на принтираните нишки. По повърхностите на разрушение се наблюдават отделни разкъсани нишки от материала. Този ефект е още по-силно изразен при пробите изпитани на ударна жилавост (фиг. 7). В пробите при 180 и 190 Fig.6. Представителните изпитани проби от едномерен опън °С ясно се вижда как под действие на ударното натоварване част от нишки се издърпва, което е показател за слабата връзка (спояване) между тях. Очевидно тези температури на

378 MACHINES. TECHNOLOGIES. MATERIALS. 2018 Литература: 1. Kreiger M., Pearce J., Environmental impacts of distributed manufacturing from 3-D printing of polymer components and products, Materials Research Society Symposium Proceedings (2013). 2. Dikova Ts., Dzhendov Dzh., Katreva Iv., Tonchev. Ts., Study the precision of fixed partial dentures of Co-Cr alloys cast over 3D printed prototypes, March 2018 Archives of Materials Science and Engineering 1(90): pp. 25-32, DOI: 10.5604/01.3001.0012.0610. 3. Cuiffo, М., Snyder J., Elliott A., Romero N., Kannan S. and Halada G., Impact of the Fused Deposition (FDM) Printing Process on Polylactic Acid (PLA) Chemistry and, Structure, Fig.7. Представителните проби изпитани на ударна жилавост. Appl. Sci. 2017, 7, 579; doi:10.3390/app7060579. 4. Pawel Grobelny, Lukasz Furmanski, Stanislaw Legutko, Сравнението на получените механични свойства след 3D Investigations of Surface Topography of Hot Working Tool Steel принтиране показва, че якостните показатели са по-ниски от Manufactured with the Use of 3D Print, MATEC Web Conf. тези на изходния материал, а пластичността е по висока: 137 02004 (2017), DOI: 10.1051/matecconf/201713702004. якостта на опън е по-ниска - с 43.5 %, горна граница на 5. Dong, Y., Milentis, J. & Pramanik, А., Additive manufacturing of провлачване – с 41 %, модул на еластичност – с 13 %, а mechanical testing samples based on virgin poly (lactic acid) относителното удължение нараства с 174 % (изменението в % е (PLA) and PLA/wood fibre composites, Advances in изчислено в температурния интервал 190 – 230 °С от Manufacturing, March (2018) Volime 6: pp.71-82. представителните данни в табл.1, а за изходния материал – https://doi.org/10.1007/s40436-018-0211-3. осреднените стойности). 6. Minev E, Yankov E, Minev R. The RepRap 3D printers for metal casting pattern making – capabilities and application, On

Innovative Trends in Engineering and Science (SFITES) 4. Заключение Kavala, Greece (2015), pp. 122-127. 7. Dikova T, Dzhendov D, Katreva I, Pavlova D, Tonchev T, Разработените методи за 3D принтиране на стандартни Doychinova M, Geometry and Surface Roughness of Polymeric пробни тела и за изпитване на пластмаси на едномерен Samples Produced by Stereolithography, Int. Journal Machines, равномерен опън осигуряват възможност за надеждна оценка Technologies, Materials. 2017; 4:201-205. на механичните свойства. Разработените методики на 8. Tontchev N. Materials Science, Effective solutions and изпитване и изследване дават възможност за обективна оценка Technological variants, LAMBERT Academic Publishing, на влиянието на температурата на екструдиране (ТЕ). В 2014.142 p. изследвания диапазон от температури 180 – 240 °С е 9. Yankov E., M. Nikolova, V. Zaharieva. Modern Methods for установено значително влияние на ТЕ върху механичните Measuring Temperature, Stresses, and Strains in the Field of свойства. С повишаване на ТЕ от 180 °С до 220 °С якостта на Micro- and Nanotechnologies. IN: 56th Mechanical опън нараства с 40 %, горната граница на провлачване с 31 %, Engineering and Machine-Building Technologies, Science модула на Юнг с 26 %, а относителното удължение със Conference of Ruse University, Bulgaria, 2017, pp. 66-76, стойност 8 % при 180 °С спада с 49 % до температура 210 °С ISBN 1311-3321. след което се повишава с 7.3 % при 230 °С, като при 240 °С има 10. Дикова Ц., Фактори, оказващи влияние върху качеството минимална стойност 2 %. В резултат на тези изменения на Co-Cr дентални сплави, отлети с 3D принтирани характерът на разрушение с повишение на ТЕ се променя от модели. Foundry 2017;1(1):58-62. пластичен в крехък. Ударната жилавост в температура 180 °С 11. Wittbrodt B., Pearce J., The effects of PLA color on material има максимална стойност -7.32 J/cm2 и се понижава до 5.15 properties of 3-D printed components, Additive Manufacturing- J/cm2с повишаване на температурата до 210 °С, след което 8 (2015). слабо се повишава на 6.23 J/cm2 при 220 °С. Твърдостта по 12. O.H. Ezeh, L. Susmel, On the fatigue strength of 3D-printed Шор с нарастване на температурата от 180 °С до 230 °С polylactide (PLA), Procedia Structural Integrity, Volume 9, нараства от 72 до 83 HSD единици. Ниските температури 180 2018, Pages 29-36, ISSN 2452-3216, °С и 190 °С водят до слаба кохезия между нишките и слоевете https://doi.org/10.1016/j.prostr.2018 .06.007. на принтиране, с нарастване на температурата кохезията се 13. Decuir F., Phelan K., Hollins B., Mechanical strength of 3-D подобрява. Оптималният температурен интервал за принтиране printed filaments, Proceedings - 32nd Southern Biomedical на PLA-Natural по FDM метода е 200 - 220 °С. Engineering Conference, SBEC 2016 (2016). 14. Yue Ding, Bo Lu, Pingli Wang, Gexia Wang, Junhui Ji, PLA-

PBAT-PLA tri-block copolymers: Effective compatibilizers for Благодарност: promotion of the mechanical and rheological properties of PLA/PBAT blends, Polymer Degradation and Stability, Volume The study was supported by contract of University of Ruse 147, 2018, Pages 41-48, ISSN 0141-3910, “Angel Kanchev”, № BG05M2OP001-2.009-0011-С01, " Support https://doi.org/10.1016/j.polymdegradstab.2017.11.012. for the development of human resources for research and innovation 15. https://de.wikipedia.org/wiki/Polylactide. at the University of Ruse “Angel Kanchev”. The project is funded with support from the Operational Program " Science and Education for Smart Growth 2014 - 2020" financed by the European Social Fund of the European Union.

379 MACHINES. TECHNOLOGIES. MATERIALS. 2018 THE COMPATIBILITY FACTOR IN MATERIAL SCIENCE OF MIXED ENGINEERING NANOBLENDS

ФАКТОР СОВМЕСТИМОСТИ В МАТЕРИАЛОВЕДЕНИИ СМЕСЕВЫХ МАШИНОСТРОИТЕЛЬНЫХ НАНОКОМПОЗИТОВ

Assoc. prof. cand. eng. Avdeychik S.1, Assoc. prof. cand. eng. Sarokin V.2, Senior lecturer Antonov A.2, Prof. dr. eng. Struk V.2 Molder, ltd 1 – Grodno, Belarus, Faculty of Innovative Technologies of Mechanical Engineering 2 – Yanka Kupala State University of Grodno, Belarus, e-mail: [email protected]

Abstract: Features of the structure of blends obtained by thermomechanical blending of thermoplastic components with different molecular structure are considered. The possibility of formation of structures with different levels of ordering (from heterophase structure with a pronounced boundary between the components to the macrogomogeneous structure with high compatibility of matrix and modifying components) is shown. Under injection of nanosize particles with different chemical composition into the blends, a synergistic effect of simultaneously increasing the parameters of tensile stress-strain and tribotechnical characteristics of items and its resistance to thermal oxidation is achieved. Nanosize particles in the active state perform the function of a physical compatibilizer, forming a cross-linked structure with physical bonds in the volume of the composite. The engineering nanoblends with increased performance parameters have been developed. KEYWORDS: NANOBLENDS, COMPATIBILITY, NANOSIZE PARTICLES, SYNERGISTIC EFFECT, PHYSICAL COMPATIBILIZER

1. Introduction 2. Research methods In the brand assortment of engineering materials a blends based For the research we used polymer materials widely applied in on thermoplastic components with different chemical composition, engineering for the production of functional products of various structure, molecular weight are occupied a special place. Managing design versions – polyamide 6 (PA 6) and polyethylene the compatibility parameters of the components of blends by using terephthalate (PET) produced at JSC Grodno Azot and JSC Mogilev special technologies for producing composites or functional Khimvolokno. To modify the matrix components were used ingredients that regulate the intensity of interfacial interaction aliphatic polyamides PA 11, PA 12 in the industrial supply state, processes (compatibilizers) can be form a structure with set-up fine-grained particles of carbon-containing components (colloidal parameters of the organization that ensures the achievement of the graphite preparation KGP C-1, carbon nanotubes CNT, products of required performance characteristics of the products under given explosive synthesis – charge) and layer silicates – mica (phlogopite) conditions of their application [1-3]. and talc. The components were blended using a twin-screw extruder At the same time, the structure of the blend in the depending on (Compex), a material cylinder of an injection molding machine with operational requirements for the products varies according to the a screw extruder (Demag, Battenfeld), and a fluidized bed coating homogeneity parameters – from the macrogomogeneous with the plant. The parameters of stress-strain, tribological and adhesive pronounced phases of the matrix and modifying components [3] to characteristics of composites were evaluated by using standard the macrohomogeneous one, in which, as a result of complete techniques on solid samples and coatings. thermodynamic compatibility, the modifying component in the matrix is dissolved [1, 2]. Both fundamentally different types of 3. Results and discussions structure of blends have their own peculiarities in the implementation of the specified parameters of performance Analysis of the physical and mechanical characteristics of characteristics, have found wide application in engineering practice blends obtained by thermomechanical blending of thermoplastic and are not antagonists. Therefore, further development of scientific components PA6 + PET shows its nonmonotonic dependence on ideas on the mechanisms and kinetics of the formation of the chemical composition (Fig. 1). In the range of small concentrations structure of blends with a given level of ordering is have of the modifier (up to 0.5-1.0 wt. %) the effect of increasing the considerable interest for materials science and technology of tensile strength, bending and wear resistance is observed. Earlier, polymeric functional materials. At the same time, both main types similar effects were noted for thermoplast-thermoplast of blends with different levels of thermodynamic compatibility of composites [3]. The effect of increasing the strength and components are characterized by the commonness of the basic tribological characteristics is probably due to the formation of features, the most important of which is the structure of the modifying phase reinforcing aggregates (PET and PA, respectively) boundary layers of composites, which largely determines the in the matrix and the processes of copolymerization parameters of the product performance characteristics. In the mechanochemical reactions during the composite formation. This structure of the optimal level of ordering, the boundary layer reactions lead to the formation of a copolymer product with between the components must possess the necessary parameters of increased resistance to external influences. Analysis of the stress-strain characteristics that can be realized only when morphology of the cleavage of samples cooled in liquid nitrogen controlling the intermolecular interaction processes using different confirms the presence of modifying phase aggregates with approaches. In this aspect, studies of the influence of nanosize dimensions of 0.5-10 μm, depending on the ratio of composites in particles on interphase interaction processes are of particular the mixture. PET and PA particles are close to spherical, and PA interest, since their special energy state suggests the possibility of and PET particles are more various in shape and size (Fig. 2). At the forming the structure of boundary layers with increased parameters ratio of components is close to 50:50 wt. % the phase inversion is of characteristics [4, 5]. observed, that to lead to a significant decrease of all parameters of The purpose of this paper is to evaluate the role of nanosize physical and mechanical characteristics. particles of various types in the formation of the structure of blends with different levels of thermodynamic compatibility.

380 MACHINES. TECHNOLOGIES. MATERIALS. 2018 synergistic effect of increasing the parameters of tribological and adhesion characteristics while maintaining high values of the parameters of stress-strain characteristics, estimated by the criterion σt ≥ 62-65 MPa is achieved.

Fig. 1 Dependence of the tension (1), bending (2) stress and abrasion factor (3) on the content of PA 6 in PET Fig. 3 Dependence of the wear value of blends based on PA 6 on the time for the "finger-disk" test at p = 2.8 MPa, V = 1.1 m/s: 1 – PA 6; 2 – Thus, the traditional technology of thermomechanical blending PA 6 + PTFE (90:10); 3 – PA 6 + talc (90:10); 4 – PA 6-L-FG30; 5 – provides the production of composite materials based on PA 6 and PA 6 + mica (90:10) PET with high service characteristics. Such materials can be To control the compatibility parameters of components in successfully used as binary matrices for engineering materials of composites based on aliphatic polyamides, carbon-containing various functional purposes include tribotechnical. The advantage particles of various production technologies – KGP C-1, CNT, of combined PA/PET matrices is a higher resistance to moisture and charge, were used. operating factors compared to polyamides, which causes an increase The data in Tables 1 and 2 show the effectiveness of the action in the operational range of their use. of highly dispersed particles in blends based on aliphatic When introducing layered silicates into the composite PA 6 / polyamides. A probable mechanism of modifying effect of carbon- PET mixture, it is possible to control the compatibility parameters containing modifiers is the formation of physical adsorption bonds of the components due to the influence of the factor of their in the transition layer of the composite according to the ideas increased energy activity [4]. presented in [4]. Table 1: Parameters of stress-strain characteristics of blends based on the aliphatic polyamides (bending tests). Chemical composition of blend, Characteristics value wt. % E, МPа σb, МPа εb, % PA6,6(84,5%) + PA6(10%) + 2984,7 114,7 6,7 PA12(5%) + KGP С1(0,5%) PA6,6(84,5%) + PA6(10%) + 2797,8 109,7 6,1 PA12(5%) + CNT(0,5%) PA6,6(84,5%) + PA6(10%) + 2850,5 115,1 6,8 PA12(5%) + шихта(0,5%) a) b) Table 2: Parameters of stress-strain characteristics of blends based on the aliphatic polyamides (tensile tests). Chemical composition of blend, Characteristics value wt. % σt, МПа εt, % ПА6,6(84,5%) + ПА6(10%) + 78,84 3,9 ПА12(5%) + КГП С1(0,5%) ПА6,6(84,5%) + ПА6(10%) + 54,19 2,1 ПА12(5%) + УНТ(0,5%) ПА6,6(84,5%) + ПА6(10%) + 77,78 3,8 ПА12(5%) + charge(0,5%)

c) d) Under injection of nanodispersed carbon-containing particles into the composite, which are mainly located in the interspherilite Fig. 2 A typical view of cleavage in liquid nitrogen of PA 6 (a), PET (b) regions, the effect of increasing the resistance to thermal-oxidative and composite materials PA 6 + 10 wt. % PET (c) and PA 6 + 50 wt. % PET (d) destruction increases due to the formation of additional physical bonds of the adsorption type (Fig. 4). Modification of matrix polymers and blends (PA 6/PET) by In our opinion, the significant contribution of carbon-containing layered silicates significantly increased their wear resistance and particles to the resistance to thermal oxidative aging of composites significantly reduced the coefficient of friction during operation based on aliphatic polyamides is due to the energy state of without the supply of external lubrication (Fig. 3). It is obvious that nanoscale particles, which facilitates the formation of during the blend formation is taking place the thermal degradation intermolecular physical bonds with the active centers of the of silicate microparticles with the formation of nanosize plate macromolecule and a decrease in their activity in the processes of aggregates [4], into the interlayer space of which the affinity for oxygen. macromolecules of the matrix and modifying components penetrate. Thus, nanosize carbon-containing particles serve as a physical The energy state of the plate aggregates determines the compatibilizer, contributing to the formation of a more perfect formation of a cross-linked structure with physical bonds that composite structure at different levels of organization. contribute to the increase of the operational characteristics A similar effect of the structuring effect of nanosize particles parameters. such as natural minerals (clays, zeolites) and diamond processing The carried out researches have allowed to develop blends products is established in the works of Prof. A.A. Okhlopkova and PA 6 + 10 wt. % PET and PET + 10 wt. % PA 6. Under introduced co-workers [6] for the modification of polytetrafluoroethylene. into the matrices 5-20 wt. % dispersed particles of mica the

381 MACHINES. TECHNOLOGIES. MATERIALS. 2018 4. Conclusions The established regularities in the formation of the structure of blends based on thermoplastic polymers made it possible to develop composite materials for the manufacture of items of various metal- polymer systems – coatings for friction joints of cardan shafts and turning chucks, elements of shutoff and control valves used in low pressure pipelines [7]. The established regularities can be realized with the use of industrial technological equipment – mixers, extruders, injection molding machines. That allows using the obtained data in practical material science. 5. References 1. Kuleznev, V. N. (2013). Polymer blends and alloys. St. Petersburg: Nauchnye osnovy i tekhnologii, 214 p. 2. Paul, D. R. and Bucknall, C. B., eds. (2009). Polymer Fig. 4 Dependence of the tensile strength parameter on the time of thermal blends. Volume 1: Formulation. St. Petersburg: Nauchnye osnovy i oxidation at 423 K (150 °C) for composites: tekhnologii, 616 p. (translated into Russian). 1 – PA 6.6-L; 3. Struk, V. A. (1988). Tribochemical concept of antifriction 2 – PA6.6 (94 %) + PA6 (5 %) + PA12 (1 %); materials based on the tonnage produced polymer binders: Doctoral 3 – PA6.6 (90 %) + PA6 (5 %) + PA12 (5 %); (candidate of tech sciences) dissertation research, Gomel, 325 p. 4 – PA6.6 (85 %) + PA6 (10 %) + PA12 (5 %); 5 – PA6.6 (84.5 %) + PA6 (10 %) + PA12 (5 %) + KGP C-1 (0.5 %); 4. Avdeychik, S. V., Struk, V. A., Antonov, A. S. (2017). The 6 – PA6.6 (84.5 %) + PA6 (10 %) + PA12 (5 %) + CNT (0.5 %); nanostate factor in the material science of polymer nanocomposites. 7 – PA6.6 (84.5 %) + PA6 (10 %) + PA12 (5 %) + charge (0.5 %) Sааrbrücken : LАP LАMBERT Аcаd. Publ., 468 p. 5. Avdeychik, S. V., Struk, V. A., Sarokin, V. G., Thus, the modification of blends based on aliphatic polyamides Antonov, A. S. (2016). The features of nanodimension realization by nanoscale particles of different chemical composition, structure for polymer matrix composites, Journal “Nanomaterials and and production technology makes it possible to realize the Nanostructures − XXI Century”, Vol. 7, Iss. 2., P. 37-44. synergistic effect of increasing the parameters of stress-strain, 6. Okhlopkova, А. А. Physicochemical principles of creating adhesion, tribotechnical characteristics and resistance to the action tribotechnical materials based on polytetrafluoroethylene and of thermal-oxidative operating media. The mechanism for the ultrafine ceramic : Doctoral (candidate of tech sciences) dissertation realization of the synergistic effect is due to the interaction of active research, Yakutsk, 269 p. centers of nanoscale particles with the centers of polymeric 7. Antonov, A., Avdeychik, S., Sarokin, V., Struk, V., macromolecules with the formation of adsorption type bonds [3-5]. Vorontsov, A., Mikhailova, L. (2017). Nanocomposite materials The formation of such bonds changes the intensity of intermolecular based on thermoplastic blends for the technological equipment with interaction in composites based on mono- and blend matrices, a long service life, Journal “Nonequilibrium phase transformations : which is manifested in the transformation of the structure of the Mаtеrial science”, Iss. 3., P. 92-94. composite at the intermolecular, supramolecular and interphase levels. Due to multi-level structural modification, resistance to the influence of operational factors, including to the processes of tribotechnical interaction in metal-polymer systems and elevated temperatures in the air environment, increases.

382 MACHINES. TECHNOLOGIES. MATERIALS. 2018 ELECTROPLATING WITH TUNGSTEN AND TUNGSTEN-MOLYBDENUM ALLOYS FROM METAPHOSPHATE-CONTAINING HALIDE-OXIDE AND OXIDE MELTS

Prof., D.Sc. Malyshev V.1, Prof., D.Sc. Kushchevska N. 1, Prof., D.Sc. Bagliuk G. 2, Ph.Dr. Shakhnin D.B.1, Prof., Ph.Dr. Paprotskaya O. 1, Ph.Dr. Zaliubovskyi M. 1 Institute for Engineering & Technology – University “Ukraine”, Ukraine 1 I.M. Frantsevich’s Institute for Problems in Materials Science of the National Academy of Sciences of Ukraine, Ukraine 2 [email protected] Abstract: The electrochemical behavior of dimeric tungsten complexes in metaphosphate-containing melts is studied potentiometrically and voltammetrically. The electrodeposition of tungsten and tungsten coatings from halide-oxide and oxide melts and the correlation between the properties of deposits and the conditions of electrolysis are investigated. Keywords: ELECTROPLATING, TUNGSTEN, TUNGSTEN-MOLYBDENUM ALLOYS, METAPGOSPHAT, HALIDE AND HALIDE-OXIDE MELTS

1. Introduction derivation of an equation for E(О2) is awkward in this case because of the complex composition of the melt. For the purposes of applied electrochemistry, it is convenient to use cheap, nonaggressive, and non-hygroscopic solvents, such as an equimolar KCl-NaCI composition. The concentration of stable oxygen-containing complex tungsten anions in this melt is sufficient, and the losses due to sublimation are insubstantial. The advantages of such baths are their stability in air and compatibility with aluminum oxide (alundum or corundum), which allows one to work with open electrolyzers with a soluble tungsten anode. Because of its binding in stable complexes, tungsten becomes less noble and, without contact deposition, can be cathodically applied not only to the metals of platinum family (as in purely halide solutions), but also to graphite, copper, and nickel. However, nonadherent coatings of complex composition are electroplated Fig. 1: The dependence of the potential of a platinum-oxygen electrode on from these melts to steel specimens [1-3]. The melts based on 3 the concentration of NaPO3 in a NaCl-KC1-0.35 mol/dm Na2WO4 melt vs. tungstates and molybdates are typical ionic liquids: they are 3 the reference electrodes (1) Pt, O2 / KCl - NaCl - 0.3 mol/dm Na2WO4 and thermally stable, have comparatively low viscosity and melting (2) Pb/Pb2+. - point and relatively high electroconductivity and decomposition In the presence of PO3 ions in a Na2WO4 melt, the following voltage [4, 5]. processes may take place: 2- - 2- 3- 2WO4 +PO3 W2O7 + PO4 , (8) 2. Experimental 2- - 2- 2- 2WO4 + 2PO3 W2O7 + P2O7 . (9) The details of preparing electrolytes, the design of electrodes and cells, and the techniques of the investigation of coatings were Using the same mathematical approach, as we applied in [7] for considered in detail in [6]. deriving an equation for E(О2), we come to a conclusion that in the concentration range studied, reaction (9) actually proceeds with the 2- 2- 3. Result and discussion formation of W2O7 and P2O7 ions. 3.1 Ionic composition of metaphosphate-containing melts In KCl-NaCl-Na2WO4-NaPO3 melts, a noticeable corrosion of tungsten is observed. At Na2WO4 and NaPO3 concentrations of Electromotive forces (EMFs) of the following electrochemical 0.175 and 0.06 mol/l, respectively, and a temperature of 1023 K, it circuits were measured: is about 12.0 to 15.3 g/(m2h). The number of electrons formally Pt, O2|KCl-NaCl-Na2WO4||KCl-NaCl-2.5 mol % PbCl2|Pb, (1) calculated from the value of the pre-logarithmic factor in the Pt, O2|Na2WO4-NaPO3||Na2WO4-0.2WO3|O2, Pt, (2) dE/dlogC dependence is 0.5 to 0.8, which is substantially smaller W|KCl-NaCl-Na2WO4-NaPO3||KCl-NaCl-2.5 mol % PbCl2|Pb,(3) than the value of 1.5 that should correspond to the equation W|Na2WO4-NaPO3||Na2WO4-0.2WO3|O2, Pt. (4) 2- 2- 4W2O7 + 6e W + 7WO4 . (10) According to the conventional hypothesis on the acid-base The EMF of a circuit (4) was measured in a NaPO3 equilibria, the equilibrium in the melts in question is shifted to the concentration range from 1.0 to 10.0 mol %. At a met-aphosphate left in the absence of PO3 ions: 2- 2- 2- concentration lower than 1.0 mol %, tungsten insubstantially 2WO4 W2O7 + O . (5) -7 2 corrodes (at a corrosion rate of 3 to 5 x 10 g/(m h)). At a NaPO3 The introduction of metaphosphate leads to the binding of concentration higher than 1.0 mol %, the corrosion is not practically oxygen ions: observed. An equation for the attained steady-state potential of a 2- - 3- tungsten electrode can be written in the form of Eq. (10). O +PO3 PO4 (6) that is, to the summary reaction Taking into account reaction (9), from the dE/dlog2CNaPO3 2- - 2- 3- 2WO4 + PO3 W2O7 + PO4 . (7) dependence (see Fig. 2), we can estimate the number of electrons per one electrochemically active particle as 1.5. In the concentration 2- The decrease in the activity of O ions upon the introduction of range studied, n = 1.44 to 1.51. This value corresponds to electrode - PO3 ions in a chloride-tungstate melt is confirmed by the increase reaction (10). in the equilibrium potential of the oxygen electrode E(О2) with an - increase in the concentration of PO3 (see Fig. 1), which, by Eq. (6), 3.2 Electroreduction of oxide tungsten (VI) forms in decreases the activity of the reduced oxygen form in the melt. The metaphosphate-containing melts

383 MACHINES. TECHNOLOGIES. MATERIALS. 2018 2- Tungstate ions WO4 are not electrochemically active particles reduction proceeds in one stage, and the product of potentiostatic - in a chloride melt. Upon the introduction of PO3 ions in the melt, electrolysis of the melt at a potential of -1.2 V is metallic tungsten. two waves appear on the voltammograms (see Fig. 3, curve 3) at 2+ The proportionality of the limiting current to the concentration potentials of -0.1 to -0.2 V and -0.3 to 0.5 V vs. a Pb/Pb reference 1/2 - - of sodium metaphosphate, the constancy of the id/V ratio (where id electrode. At a concentration of PO3 in the range 0.01 < [PO3 2- is the limiting current and V is the polarization rate), and the value ]/[WO4 ] < 0.18, the product of potentiostatic electrolysis at the -5 of the kinetic constant id/nFc, which is 8.3 to 9.5 x 10 cm/s for the above potentials is metallic tungsten. An increase in the NaPO3 - 2- steady-state waves, indicate the fact that the electrode process is concentration to [PO3 ]/[WO4 ] >> 0.18 results in the appearance of tungsten phosphides in the products of electrolysis. limited by the diffusion of electrochemically active particles to the electrode. Ditungstate ions, which are formed in reaction (8), become electrochemically active in the summary electrode process (10). Under the steady-state conditions, the slope of the E - log(id - i) dependence varies from 38 to 42 mV at different NaPO3 concentrations, while the number n of electrons, which are transferred in the electrode process, is 5.8 ± 0.3. This means that the charge transfer stage of Eq. (10) is reversible. The number of electrons, which is determined from the half-widths of the peaks in non-steady-state voltammograms according to Matsuda-Ayabe criterion for the NaPO3 concentrations lower than 10 mol % and the polarization rates from 0.04 to 0.2 V/s, equals 5.9 to 6.1.

3.3 Electroplating with tungsten and tungsten-molybdenum alloys from metaphosphate-containing melts

3.3.1. The effect of the electrolysis conditions on the structure of Fig. 2: (1) The dependence of the potential of a tungsten electrode on the tungsten coatings concentration of NaPO3 in a sodium tungstate melt and (2) its representation in logarithmic coordinates. The tungsten coatings were electroplated from KCl - NaCl - Na2WO4 or Na2WO4 baths with NaPO3 admixtures. The effect of the change in Na2WO4 and NaPO3 concentrations, in temperature, cathodic current density, and the duration of electrolysis on the composition and structure of the deposits was investigated, and the optimal conditions with current reversal were found for plating.

3.3.2. The effect of sodium sungstate and metaphosphate concentrations

The tungsten coatings from the KCl - NaCl - Na2WO4 - NaPO3 melts are fit when the aforementioned concentration condition is - 2- met: 0.02<[PO3 ]/[WO4 ]< 0.18. At a Na2WO4 concentration lower than 1 mol %, the deposit is not adherent, and no phosphide can be found in it. At a concentration higher than 10 mol %, the diffraction patterns show the presence of tungsten oxides. At a metaphosphate 2- concentration [PO3]/[WO4 ] > 0.18, tungsten again is deposited with phosphides, and no adherent coating is formed.

Tungsten coatings in a Na2WO4 - NaPO3 melt form at a metaphosphate concentration from 0.5 to 15.0 mol %. Above this limit, along with tungsten, its bronzes form, and the deposit soon begins to grow as dendrites. Fig. 3: The roughness amplitude of tungsten coatings on specimens of (a, curve 2; b, curves 2 and 3) St3 steel and (a, b, curves 7) copper vs. (a) the current density (T = 1.5 h) and (b) the duration of electrolysis (1, 2) at a 3.3.3. The effect of the temperature of electrolysis 2 direct current ic of (7) 10 and (2) 15 A/dm and (3) under reversal conditions Continuous tungsten coatings from a halide-oxide electrolyte 2 2 of plating (ic = 15 A/dm , tc = 25 s, ia = 30 A/dm , and td = 0.5 s): (1) KCl- were obtained at a temperature from 973 to 1073 K and a current NaCl - 2.5 mol % Na2WO4 — 0.35 mol % NaPO3 and (2, 3) Na2WO4 — 5 density of up to 25 A/dm2. At a higher temperature, the system mol % NaPO3. looses its stability, and its volatility increases. At a temperature Cyclic voltammograms (Ec-a = (0.550 ... 0.630) > 0.047 V = below 973 K, only thin (up to 5 µm) tungsten layers can be 3.2RT/2F) and the dependence of the half-peak potentials of the obtained, and the deposit quickly transforms into a powder. At a waves on the polarization rate of the electrode indicate the current density higher than 25 A/dm2, dispersed tungsten powders irreversible character of the electrode process. Modeling electrode are formed. processes [7] allows us to believe that the first wave ion the Continuous tungsten coatings from an oxide electrolyte were voltammogram of a KCl - NaCl - Na WO - NaPO system cor- 2 4 3 obtained at a temperature from 1023 to 1123 K and a current responds to the discharge of tungsten oxychlorides, which are density of up to 40 A/dm2. At a temperature below 1023 K, only formed in reactions 2- - - 2- 3- thin (up to 15 or 20 µm) tungsten layers are formed. At a current WO4 + PO3 + 2C1 WO2Cl2 + O + PO4 , (11) density higher than 40 A/dm2, highly dispersed tungsten powders 2- - - 2- 3- 2 WO4 + PO3 + 4C1 WOCl4 + 2O + PO4 , (12) with a specific surface area of 40 to 50 m /g form. while the second wave appears due to the discharge of ditungstate ions, which are formed in reaction (7). On the voltammograms of 3.3.4. The effect of the cathodic current density and the duration Na2WO4 - NaPO3 melts, a wave corresponding to the reduction was of electrolysis observed at a potential of -1.1 to -1.2 V. The limiting currents were The effect of the cathodic current density, as well as the proportional to the concentration of metaphosphate added rather duration of electrolysis and the reversal conditions of plating, was than to the summary concentration of tungsten in the melt. The

384 MACHINES. TECHNOLOGIES. MATERIALS. 2018

studied in KCl-NaCl — 2.5 mol % Na2WO4 — 0.35 mol % NaPO3 4. Conclusion and Na2WO4 — 5 mol % NaPO3 electrolytes. Adherent, continuous, and nonporous coatings were obtained from the above electrolytes Thus, we studied the electrochemical behavior of tungsten- at temperatures of 923 and 1173 K and current densities of 1 to 15 metaphosphate melts, the electroplating with tungsten from them, and 3 to 25 A/dm2, respectively. and the properties of the coatings. The grains size in the deposit has a minimum depending on the 5. Literature current density, and above 25 A/dm2, the crystallites become substantially larger, while the surface grows rougher. Finally, the [1] Wilkes J.S., A short history of ionic liquids – from molten salts deposit transforms into dendrites. At a current density lower than to neoteric solvents, Green Chem., 4, 2002, 73-80. 2.5 A/dm2, the corrosion rate of a substrate is too large, and no [2] Nishikata A., Numata H., Tsuru T., Electrochemistry of molten adherent coating is formed. salt corrosion, Materials Science and Engineering: A, 146, The deposition rate of tungsten in the studied range of current 1991, 15-31. µ densities is 5 to 15 m/h in a halide-oxide electrolyte and 20 to 45 [3] Malyshev V.V., Gab A.I., Uskova N.N., Soloviev V.V., µ m/h in an oxide electrolyte. The current efficiency of a tungsten Chemistry and Electrochemistry of Tungsten-Containing Ionic coating is up to 60 and 95%, respectively. The time dependences of Melts, Molten Salts Bulletin, 2, 2004, 1-10. the thickness of a coating and its current efficiency are shown in Fig. 5. As the duration of electrolysis increases, the current [4] Malyshev V., Shaknin D., Influence of temperature and the efficiency drops. composition of tungstate–molybdate alloys on the morphology of their electrolytic deposits, Materials Science, 48, 2012, 375- From halide-oxide electrolytes, we obtained adherent 383. continuous tungsten coatings on nickel, copper, graphite, tungsten, and molybdenum. In oxide melts, the coatings were obtained also [5] Gua Y., Liu J., Qu S., Deng Y., Han X., Hua W., Zhong C., on different instrumental steels, hard alloys and nitric-, copper-, or Electrodeposition of alloys and compounds from high- nickel-plated titanium. temperature molten salts, Journal of Alloys and Compounds, 690, 2017, 228-238. 3.3.5. The controlling of the structure of coatings by reversal [6] Malyshev V.V., Soloviev V.V., Chernenko L.A., Rozhko V.N., conditions of plating Management of composition cathodic products in the Profilometric investigation shows that, as the deposit thickens, electrolysis of molybdenum-, tungsten- and carbon-bearing its single-phase fine-crystalline structure transforms into a coarser halogenide-ohide and oxide melts, Materialwissenschaft und one. We tried to prevent the formation of a coarse-grain structure by Werkstofftechnik (Materials Science and Engineering applying reversal conditions of electrolysis. The duration ratio of Technology), 45, 2015, 67-72. the cathodic to anodic period was varied from 15 to 50 at a duration of the anodic period from 0.5 to 3.0 s, and the anodic current [7] Malyshev V.V., Kushkhov H.B., Electrochemical behavior of density was changed from 20 to 50 A/dm2. The following platinum-oxygen and tungsten electrodes in the melt of sodium tungstate-sodium metaphosphate, Ukr. Khim. Zhurn., 63, conditions are optimal for a Na2WO4 - 5 mol % NaPO3 electrolyte 2 2 1997, 115-118. at 1173 K: (ic = 15 A/dm , ia = 30 A/dm , τc = 25 s, and τa = 1.5 s. In this case, relatively smooth coatings of a thickness of up to 0.5 [8] Damaskin B.B., Petrij O.A., Cirlina G.A., Electrochemistry, mm were obtained at the cathode. Koloss, Moscow, 2006.

3.4. Physicochemical properties and performance of tungsten coatings The coatings are light-gray microgranular continuous deposits. By the data of x-ray spectral microanalysis, alien metallic admixtures are contained in an amount of up to 0.02 wt % and do not noticeably affect the structure of coatings. According to standard estimates [8], the pores area in coatings is 0.0 to 0.2%, which is considered as an indication of a practically nonporous coating. The microhardness does not change across the coating and equals 460 to 485 kgf/mm2. The diffusional area of 5 to 20 µm, revealed with the x-ray spectral microanalysis of the cross sections of a specimen, indicates that there is a mutual diffusion of the elements of the coating and the substrate, which provides the proper adherence of the coating. The continuity of the transition from the coating to the substrate was confirmed by stereoscanograms of spallings of the specimens, which concurrently showed a pronounced columnar structure of the deposit. The specimens of steel 45 with a tungsten coating were thoroughly tested in a friction pair with a quenched steel 45 counterbody. As a result of the plating, the wear resistance increased by a factor of 4.5 to 5.7. The specimens of steel 45 with tungsten coatings were tested for abrasive resistance in an electrocorundum 100-µm fraction at a load of 52 ± 0.25 N. Due to the coating, the abrasive resistance increased 2.5 to 4.3 times.

385 MACHINES. TECHNOLOGIES. MATERIALS. 2018 TUNGSTEN AND MOLYBDENUM CARBIDES OBTAINING BY ELECTROLYSIS OF SALT MELTS

Prof., D.Sc. Malyshev V.1, Prof., D.Sc. Kushchevska N. 1, Prof., D.Sc. Bagliuk G. 2, Ph.Dr. Shakhnin D.1, Ph.Dr. Paprotskaya O.1, M.Sc. Kurovskyi V. 2 Institute for Engineering & Technology – University “Ukraine”, Ukraine 1 I.M. Frantsevich’s Institute for Problems in Materials Science of the National Academy of Sciences of Ukraine, Ukraine 2 [email protected] Abstract: Compositions of the products of the electrolysis of melts based on a eutectic mixture of sodium chloride–lithium fluoride and sodium tungstate, which contains molybdenum (VI) and tungsten (VI) oxides, molybdates, tungstates, and carbonates of lithium or sodium, are investigated. It is shown that, depending on the content of melt components, the products of electrolysis are carbon, molybdenum, tungsten, and their bronzes and carbides. The conditions of the deposition of galvanic coatings of molybdenum and tungsten carbides on carbon, nickel, and copper matrices are determined. Keywords: IONIC MELTS, MOLYBDENUM, TUNGSTEN, ELECTROMETALLURGY, SYNTHESIS, CARBIDES, POWDERS, COATINGS

1. Introduction 3. Result and discussion Increased interest in the development of new effective methods 3.1 Halogenide–Oxide Melts for obtaining refractory compounds such as carbides, borides, silicides, alloys, and intermetallic compounds of Groups IV–VIB of Electrochemical reactions on electrodes are described in detail the periodic table is dictated by their use in modern technique. A in [3, 4]. On the cathode, refractory metal and carbon are isolated: 2– 2– comparative analysis of the synthesis of metal-like refractory MO4 + 6e  M + 4O (M is Mo or W), compounds showed that high-temperature electrochemical synthesis 2– 2– (HTES) is one of the most promising but still poorly known CO3 + 4e  C + 3O methods [1–3]. It is based on processes of the electrical separation with their subsequent interaction with the formation of oxides. of metals and nonmetals from ion melts. The absence of information on the theoretical foundations and principles of control The composition of cathode products of the systems under study over these processes made it impossible to perform HTES in is presented in Table 1. The potential for the electrochemical practice. reduction of molybdenum from the molybdate ion at the background of the NaCl–LiF melt is 0.2 V more positive than the The goal of this study was to investigate the composition of potential for the electrochemical reduction of tungsten from the cathode products of carbon-containing melts based on the eutectic tungstate ion and almost coincides with the potential for the mixture of sodium chloride and lithium fluoride and melts based on electrochemical reduction of carbon from the carbonate ion [3, 4]. sodium tungstate depending on the electrolysis conditions, as well This circumstance, as well as the existence of molybdenum carbide as to fulfill the HTES of galvanic coatings by molybdenum and of the only composition Mo2C, allows us to perform the conditions tungsten carbides [3, 4]. of crystallization of molybdenum carbide in a form of continuous precipitate. Tungsten and carbon form two carbides, WC and W2C. 2. Experimental It is impossible to crystallize WC in a form of a continuous The steady-state and time-dependent current-voltage precipitate, because WC forms at a certain excess of free carbon, characteristics were obtained using a PI-50-1 pulse potentiostat. The which inhibits the growth of electrolytic precipitates. Therefore, in steady-state characteristics were recorded using a DPD-4 two- order to crystallize tungsten carbide in a form of a continuous coordinate recorder, while time-dependent ones were recorded precipitate, more careful control over the electrochemical synthesis using a PO-5122M polarograph. The potentials of equilibria and is necessary, and it should be performed in a mode of obtaining processes were measured with respect to platinum–oxygen W2C [5]. reference electrode [3, 4]. The electrolysis of the NaCl–LiF– Table 1: Composition of cathode products of electrolysis of the melts NaCl– Na2MoO4–Na2CO3 and NaCl–LiF–Na2WO4–Na2CO3 melts was LiF(3:1 wt. fractions)–Na2MoO4–Na2CO3 and NaCl–LiF(3:1 wt. fractions)– performed in containers made from MPG-7 grade graphite. The Na2WO4–Na2CO3. melt was prepared from preliminarily dried chemically pure grade Content of melt components, wt. % Composition and structure of NaCl and LiF and analytical grade Na2MoO4, Na2WO4, and Na2MoO4 Na2WO4 Na2CO3 the cathode precipitate Na2CO3. Impurities were removed from the electrolyte by 1–15 – – Mo coating 2 electrolysis with a cathode current density of 10–15 A/dm until a 15–30 – – Mo–MoO2 precipitate continuous precipitate was stably obtained. Cathodes were nickel, – 1–20 – W coating copper, and steel plates 1  2 cm in size. – 20–30 – W–WO2 precipitate – – 1–30 C powder The precipitates were investigated by X-ray diffraction and 5 – 0.5–2.0 Mo–Mo2C coating metallographic analysis. Microhardness on a transverse slice was 5 – 2–4 Mo2C coating determined using a PMT-3 device with an indenter load of 0.1 kg, 5 – Unadherent Mo C–C 5–10 2 the lattice parameters were measured using a DRON-3 precipitate diffractometer in CuK radiation, and the coating thickness was – 5 0.1–0.2 W–W2C coating measured using a 2IGM multi-turn indicator; in some cases it was – 5 0.2–0.5 W2C coating measured by metallographic analysis. – 5 0.5–1.0 W2C–WC coating – 5 1.0–5.0 WC–C powder

Note: T = 1173 K; cathode is C, Ni, Cu; anode is graphite; and ic = 5.0–7.5 A/dm2.

386 MACHINES. TECHNOLOGIES. MATERIALS. 2018

Experiments at T = 1173 K and cathode current density ic = 8 Table 4: Composition of the cathode products of electrolysis of the Na2WO4– 2 A/dm showed that continuous molybdenum precipitates are formed Li2WO4–Li2CO3 melts at the Na2MoO4 concentration in the melt of ≤15 wt %. At a higher Content of melt components, wt. % Composition and structure of the molybdate content, molybdenum oxides precipitate along with Li2WO4 Li 2CO3 cathode precipitate molybdenum. Continuous tungsten precipitates are obtained at the – 1–15 W2C coating Na2WO4 concentration in the melt of ≤20 wt %; at its higher – 15–30 WC coating concentration, tungsten oxides also co-precipitates. Amorphous – 30–50 C powder carbon powder isolates from the melts containing only carbonate. 10–30 – W coating 5–10 5–10 W2C coating To investigate the influence that other parameters (temperature, 5–10 10–20 WC coating current density, and electrolysis mode) have on the properties and 5–10 20–40 C powder structure of the Mo, W, Mo C, and W C coatings, we selected the 2 2 Note: T = 1173 K; cathode is C, Ni, Cu; anode is graphite; and ic = 0.05– 2 following optimal alloys: NaCl–LiF – 5 wt % Na2MoO4 (Na2WO4), 0.075 A/cm . NaCl–NaF – 5 wt % Na2MoO4 – 2 wt % Na2CO3, and NaCl–LiF – 5 wt % Na WO – 0.4 wt % Na CO . Continuous precipitates were Table 5: Composition of cathode products of electrolysis of the Na2WO4– 2 4 2 3 WO –Li CO melts obtained at T = 1073–1323 K. At lower temperatures, along with 3 2 3 metal or carbide, metal oxides are precipitated. Well-adhered Content of melt components, wt. % Composition and structure of the cathode precipitate continuous pore-free coatings are observed at a current density of WO3 Li 2CO3 2–15 A/dm2 and deposition rate of 2–20 μm/h. The current yield of – 1–15 W2C coating carbide coatings is 40–50%; their depth reaches 30 μm. A low – 15–30 WC coating current yield in the case of carbide coatings is caused by the – 30–50 C powder violation of the growth front of the precipitate as a result of its 5–15 – W coating passivation with lithium oxide, which is formed during the electrode 5–10 10–20 W2C coating 5–10 20–40 WC coating reaction [3, 4]. Further, carbides are precipitated in the form of 5–10 40–60 C powder powder. – 1–15 W2C coating

A coarse-crystalline structure of formed coatings was made Note: T = 1173 K; cathode is C, Ni, Cu; anode is graphite; and ic = 0.05– finer using the reverse of the dc during the electrolysis. The ratio of 0.075 A/cm2. durations of the cathode and anode pulses (τc/τa) varied in the limits Coatings of molybdenum carbide are precipitated from of 30–60, the duration of the anode period was 0.5–1.5 s, and its 2 electrolyte Na2WO4–Li2MoO4–Li2CO3 with the equality (in the current density was 0.15–0.50 A/dm . As a result, we succeeded in limits of 2.5 mol %) of concentrations of lithium molybdate and increasing the thickness of metal coatings to 200 μm and that of lithium carbonate; they should not exceed 10 mol %. At lower carbide coatings to 100 μm. The optimal parameters of the reverse 2 molybdate contents in the precipitate, carbon, molybdenum, and mode were τc = 45 s, τa = 1.5 s, ic = 8–10 A/dm , and ia = 20–30 2 molybdenum carbide were found in the precipitate; and at higher A/dm . contents, molybdenum oxides are observed. At lower carbonate 3.2 Oxide Melts concentrations, molybdenum prevails in the precipitate, and at higher concentrations, mainly free carbon is isolated. Molybdenum In addition to halogenide–oxide carbonate-containing melts for oxide is a more available commercial reagent and the source of the electrochemical deposition of molybdenum, tungsten, and their molybdenum. With its use in this role, the required amount of carbides, we also used oxide tungstate–molybdate–carbonate melts. carbonate is approximately a factor of 2 larger than in the case of The composition of cathode products in the systems under study, the use of lithium molybdate (see Tables 2, 3). depending on the electrolysis conditions, is presented in Tables 2–5. Continuous coatings of molybdenum carbide were obtained at T Table 2: Composition of cathode products of electrolysis of the Na2WO4– 2 = 1073–1223 K and ic > 0.5 A/cm . At T < 1073 K and current Li2MoO4–Li2CO3 melts. densities higher than 0.5 A/cm2, the precipitates are presented by Content of melt components, wt. % Composition and structure of the highly dispersed powders of molybdenum carbide with a specific cathode precipitate Li2MoO4 Li 2CO3 surface up to 30 m2/h. Well-adhered, uniform, continuous, and 1–10 1–10 Mo2C coating absolutely pore-free coatings from electrolyte Na2WO4 – 5 mol % Unadhered C, Mo, Mo C 2.5–5.0 5–10 2 MoO – 10 mol % Li CO at T = 1173 K are observed at cathode precipitate 3 2 3 current densities from 0.01 to 0.10 A/cm2. The deposition rate of 5–10 2.5–5.0 Mo coating coatings in the range of ic under study is 5–25 μm/h; the current 10–20 2.5–5.0 Large MoO crystals 2 yield of molybdenum carbide reaches 80%. The maximum 2.5–5.0 10–20 C powder thickness of the coatings does not exceed 100 μm. – 5–10 WC powder 5–10 – Mo coating The use of the reverse mode of the electrolysis allowed us to Note: T = 1173 K; cathode is C, Ni, Cu; anode is graphite; and ic = 0.05– make the coarse-crystalline structure finer and increase the coating 0.075 A/cm2. thickness to 200 μm. The optimal parameters are as follows: τc/τa = Table 3: Composition of cathode products of electrolysis of the Na WO – 20–40, the duration of the anodic period is 0.5–2.0 s, and the current 2 4 2 MoO3–Li2CO3 melts density is 0.15–0.50 A/cm . Content of melt components, wt. % Composition and structure of the Coatings of tungsten carbide W2C are precipitated from MoO3 Li 2CO3 cathode precipitate electrolyte Na2WO4–Li2CO3 at Li2CO3 concentrations <15 mol %. 1–10 2–20 Mo2C coating At higher amounts of Li2CO3, coatings of tungsten carbide WC are Unadhered C, Mo, Mo C 2.5–5.0 10–20 2 obtained. The powder of free carbon is isolated at the Li CO precipitate 2 3 contents >30 mol %. In the absence of lithium carbide at 5–10 5–10 Mo coating concentrations of Li WO >10 mol %, tungsten coatings are 10–20 5–10 Large MoO crystals 2 4 2 deposited (see Table 4). 2.5–5.0 20–40 C powder – 5–15 WC powder When using tungsten oxide as the tungsten source, the observed 1–5 – Mo coating regularities are similar. The distinction is that the region of isolation 5–10 – Large MoO2 crystals of sodium–tungsten bronzes is observed at WO3 concentrations > Note: T = 1173 K; cathode is C, Ni, Cu; anode is graphite; and ic = 0.05– 30 mol % (see Table 5). 0.075 A/cm2.

387 MACHINES. TECHNOLOGIES. MATERIALS. 2018 The results of investigations of the composition of cathode 5. Literature products of chloride–fluoride molybdenum(tungsten)–carbon- containing molten systems indicate that, in order to deposit the [1] Wilkes J.S., A short history of ionic liquids – from molten salts galvanic coatings by the HTES method, the abovementioned to neoteric solvents, Green Chem., 4, 2002, 73-80. electrolytes can be suggested. The regions of the electrochemical deposition of molybdenum, tungsten, their bronzes and carbides, [2] Nishikata A., Numata H., Tsuru T., Electrochemistry of molten and carbon are determined. The data of Tables 1–5 show that the salt corrosion, Materials Science and Engineering: A, 146, phase composition of the products of electrolysis and characteristics 1991, 15-31. of cathode precipitates are determined by the concentration of the [3] Malyshev V.V., Kushkov H.B., Shapoval V.I., High- carbon source in the melt, namely, lithium and sodium carbonates. Temperature Electrochemical Synthesis of Carbides, Silicides and Borides of VI-A group metals in ionic melts, J. Appl. 4. Conclusion Electrochem., 32, 2002, 573-579. (i) It is shown that cathode products of the electrolysis of the [4] Malyshev V., Gab A., Popescu A-M., Constantin V., melts based on the eutectic mixture of sodium chloride and lithium Electroreduction of Tungsten Oxide (VI) in Molten Salts with fluoride and the melts based on sodium tungstate, in which Added Metaphosphate, Chemical Research in Chinese molybdenum (VI) or tungsten (VI) oxides are dissolved, are Universities, 29, 2013, 771-775. molybdenum, tungsten, their bronzes and carbides, and carbon. [5] Malyshev V., Shakhnin D., Gab A., Gaune-Escard M., Astrelin (ii) It is established that the phase composition of the products I., Chaptes 4.9: Galvanic Coatings of Molybdenum and of electrolysis is determined by the carbonate concentration in the Tungsten Carbides from Oxide Melts: Electrodeposition and melt. Initial Stages of Nucleation, in book: Molten Salts Chemistry (iii) The deposition conditions of galvanic coatings of and Technology, ed. by M. Gaune-Escard, G.M. Haarberg, molybdenum and tungsten carbides on carbon, nickel, and copper Wiley, 2014, 303-317. substrates are determined.

388 MACHINES. TECHNOLOGIES. MATERIALS. 2018 ION PLAZMA NITRIDING OF FERRITIC STEEL AISI 430 F MSc Naziv Jashari1, Prof. Dr Cvetkovski. S. PhD.2, Prof. Dr Ş. Hakan Atapek PhD.3, Prof. Dr Şeyda Polat PhD.3, Dr Gülşah Aktaş Çelik3

State University Tetova, Republic of Macedonia1, Faculty of Technology and Metallurgy – Ss Cyril and Methodius University, Skopje Republic of Macedonia2, Kocaeli University, Kocaeli-Turkey3

[email protected]

Abstract: In this research work, results of the ion plasma nitriding of the ferritic steel AISI 430F are presented . From the raw material solid bar 35 were machined specimens with the following dimension 20x20x15. Prepared specimens were plasma nitrided in the installation ION-20. According to research plan the temperatures of 430, 480 and 530 0C, and nitriding times of 3, 6 and 9 hours were used. Nitriding gas for this experiment was ammonia Pulsed direct current was used for the nitriding. After performing of the ion plasma nitriding process, experimental specimens were subjected to different investigations, mainly microstructural and tribological. Main facilities used for investigations are: device for determination wear resistance “ball-on-disc” (Nanovea), 3D profilometer for surface roughness determination, Optical Microscope Leits and SEM JEOL for microstructural investigations, XRD spectrometer (Rigaku RINT Ultima+) and Vickers microhardness tester for the microhardness measurement. Investigations confirmed that depending of the process parameters different characteristics of nitride layers were obtained. The following characteristic values important for the analysis of the nitride layer was obtained: specific wear rate, volume lost, friction coefficient, width of the wear path, type of wear, type of structure of the nitride layer and maximal hardness of the nitride layer. Performed investigations confirmed that ion plasma nirtriding improve surface properties of the investigate specimens compered with untreated specimen of the raw material. The effect of ion plasma nitriding is directly influenced by the nitriding parameters i.e. temperature and time of the nitriding process. Keywords: PLAZMA NITRIDING, NITRIDING TIME, NITRIDING TEMPERATURE, SPECIFIC WEAR RATE, FRICTION COEFICIENT, WEAR PATH, SURFACE ROUGHNES.

1. Introduction It is well known that stainless steel posses very good properties especially corrosion resistance and excellent plasticity [1-4]. But practical considerations showed that implementation of this steels can be broadened in the new industrial sectors if their surface hardness and wear resistance could be improved. One of the best ways for the realization of this idea is the process of the ion plasma Figure 2 Machined specimens prepared for ion plasma nitriding nitriding as a part of the surface engineering. In order to confirm assumed idea a huge experimental work using new and modern equipment was realized. Table 1 Chemical compositionт of the AISI 430F (DIN X14CrMoS17, WNo 1.4104) elem. % C Si Mn P S Ni Cr Mo 2. Material and investigation standard 0,12 1.0 1.2 0.04 0.03 0.5 18 - 2.1 Material Subject of investigation in this research work is stainless ferritic measured 0.11 0.49 1,0 0.037 0.295 0.28 16.62 0.21 steel AISI 430F. Raw material (figure 1) for the specimens preparation was in the form of solid bars with diameter 35.

Figure 1 Raw material for the specimen preparation

From the experimental bars were machined specimens with the following dimensions 25x25x20. Some of the specimens are shown in the figure 2. а b Chemical composition of the raw material is given in the table 1. Figure 3(а-b) A view of the installation for plasma nitriding ION-20 Prepared specimens were plasma nitrided in the installation ION-20 presented in the figure 3. Glow discharge process using pulsed Working unit of the installation is given in the figure 4. Specimens direct current was implemented process in this research work. As a before nitriding are laid down on the stand which is charged nitriding gas was used pure ammonia. negatively and walls of the chamber have positive charging. Main characteristics of ION-20 plasma nitriding installation are presented in the Table 2.

389 MACHINES. TECHNOLOGIES. MATERIALS. 2018 The main nitriding parameters used in this experiment are presented in the table 3.

Table 2 Technical characteristics of the installation ION-20 used for ion plasma nitriding 1 Size of the nitriding part (xH) mm 500х500 2 Mas of the niriding part kg 80 3 Working temperature 0C 400-600 4 Working gas (ammonia) 5 Working pleasure Pa (0.1-1)·102 6 Maximal flow rate working gas l/h 2 b 7 Voltage 3/380V/50Hz Figure 6 Profilometric testing 8 Power kVA 20 9 Pulsed voltage V 0-800 10 Maximal pule A 25 11 Pulsed factor 0.8 12 Pulsed frequency kHz 10

a

Figure 4 Working part of the installation

Table 3 Nitriding parameters and code of materials b Figure 7 Tribmetar for wear testing Parameters used for the wear test are shown in the table 4, and the view of the specimen after wear test is shown in the figure 8

Table 4 Parameters used for the wear test Normal Testing rate Distance Counter load (N) (m/s) (m) part A view of the specimens after finishing of the nitriding is given in material the figure 5. 5 0.1 180 Al O 2 3

Figure 8 Nitrided specimen – wear path Figure 5 Nitrided specimens In the figure 9 are presented results of the specific wear rate 2.2 Experiments determination in dependence of nitriding time and temperature. Profilometric investigations are performed in order to determine influence of surface roughness on the nitrided specimens after wear test. As first width and depth of the specimens are determined, and after that surface roughness is determined (Figure 6). Tribometar used for the wear test is shown in the figure 7a and its working principle is shown in the figure 7b.

a Figure 9 Specific wear rate in dependence of time and temperature

390 MACHINES. TECHNOLOGIES. MATERIALS. 2018 In the Figure 10 are presented results of friction coefficient determination depending of wear test time. Figure 10a concerns to the raw material and figure 10b concerns to the specimen 2.8. Determination of the friction coefficient in dependence of time is even in the figures 10 (c and d).

Figure 12(a and) Microhardness measurement of the nitrided specimens

Microstructure of the raw material, ferritc steel 430F is given in the Figure 13a, and the microstructure of the nitrided layer is prezented A b in the Figure 13b. EDS analyze across the nitrided layer is shown in the Figure 14. It presents variyng of the nitrogen concentration in the nitrided layer and the base material.

c d Figure 10 (a and b) Determination of friction coefficient for the raw material AISI 430F and nitride specimen 2.8 Figure 10 (c and d) Dependance friction coeficient from time of testing

In the figure 11 (a-c) are given diagrams which present dependence a b of friction coefficient from the distance for the specimens nitrided Figure 13 (a and b) Microstructure of raw material and nitride layer

3, 6 and 9 hour at different temperatures 430, 480 and 530 0C.

Figure 14 EDS analisis of nitrogen in the nitrided layer

a In this research work was analyzed wear path too. Some wear paths are presented in the figure 15.

b

Figure 15 Wear path of the specimen which were susceptible to wear test

For all nitride specimen was made measurement of the width of the wear path. Some examples of the path measurement are given in the Figure 16.

c Figure 11 (a-c) Dependence beetween friction coeficient and time or the specimens nitrided 3, 6 and 9 hour ate different temperatures

Microhardnes determination was performed to all investigated nitrided specimes and raw naterial. Measuring procedure is given in the figure 12a and obtained results for the hardness measurement for the specimen 2.8 are given in the figure 12b. Figure 16 Measurement of the wear path

391 MACHINES. TECHNOLOGIES. MATERIALS. 2018 3. Discussion [11] Li Y., He Y., Xiu J., Wang W., Zhu Y. and Hu B., Wear and Performed investigations showed that through regular choice of the corrosion properties of AISI 420 martensitic stainless steel treated nitriding parameters could be defined conditions which enable the by active screen plasma nitriding, Surface and Coatings Technology 329 (2017) pp. 184-192. best tribological properties on the nitrided specimen’s surface i.e. [12] Devaraju A., Elayaperumal A., Alphonsa J., Kailas S. V. and wear resistance and surface hardness [5-9]. Venugopal S., Microstructure and dry sliding wear resistance General notice is that the best results are obtained for the ion plasma evaluation of plasma nitride austenitic stainless steel type AISI nitriding process for the specimen nitrided at 480 0C for the period 316LN against different sliders, Surface and Coatings Technology of 6 hours. 207 (2012) pp. 406-412. XRD investigations confirmed that microstructure of the nitride [13] Hardell, B. Prakash, Tribological performance of surface layer consists of and precipitates [10-13]. engineered tool steel at elevated temperatures, Int. Journal of Refractory Metals & Hard Materials, 28, (2010), 106-114. Higher temperatures and higher nitriding times influence higher [14] K. Lukaszkowicz, A. Czyzniewski, W. Kwasny, M. thickness of the nitrided layer [14-15]. [15] M. Kalin and J. Jerina, The effect of temperature and sliding It was detected that the curve which give dependence of the friction distance on coated (CrN, TiAlN) and uncoated nitride hot-work tool coefficient and distance consists of increasing part on the beginning steels against an aluminium alloy, Wear, 330-331(2015), p. 371. of testing and flat part after that. [16] J. Eriksson and M. Olsson, Tribological testing of commercial Hardness of the nitrided specimen is much higher than the hardness CrN, (Ti,Al)N and CrC/C PVD coatings – Evaluation of galling and of the raw material. Hardness of the nitride layer is lowering from wear characteristics against high strength steels, Surf. Coat. Technol., 205(2011), No. 16, p. 4045. the surface towards the interior of the specimen.

Changing of the nitrogen concentration is connected with the changing of the surface hardness of the specimens. Generally, it can be said that there is some relationship between specific wear rate, friction coefficient, wear path width, surface roughness and micro hardness. Namely, lower specific rate means lower friction coefficient, lower width of the wear path, higher hardness and lower surface roughness.

4. Conclusion Performed investigations confirmed that ion plasma nitriding improve surface properties of the investigated specimens. Effect of plasma nitriding depends of the nitriding parameters, temperature and time of nitriding. For all nitrided specimens, surface properties are better compared to base material, but it was confirmed that specific wear rate has the best values for the nitriding temperature of 480 0C and nitriding time of 6 hours.

5. Literature [1] McGuire M. F., Stainless steels for design engineers, ASM International, Materials Park, Ohio-USA, 2008. [2] V. Toshkov, Nazif Jashari, S. Cvetkovski, On the Ion Nitriding of Austenitic Steel 316, VIIIth International Metallurgical Congress, Ohrid, 30.05-03.06. 2018 [3] Ş. Hakan Atapek, Nazif Jashari, Sveto Cvetkovski, Şeyda Polat, Gülşah Aktaş Çelik, TRIBOLOGICAL CHARACTERIZATON OF ION PLASMA NITRIDED STAINLESS STEELS, VIIIth [1[ International Metallurgical Congress, Ohrid, 30.05-03.06. 2018 [4] 2. Davis, J. R., ASM specialty handbook: stainless steels, ASM International, Materials Park, Ohio-USA, 1994. [5] Luo Q., Oluwafemi O., Kitchen M. and Yang S., Tribological properties and wear mechanisms of DC pulse plasma nitrided austenitic stainless steel in dry reciprocating sliding tests. Wear 376-377 (2017) pp. 1640-1651 [6] Sung J. H., Kong J. H., Yoo D. K., On H. Y., Lee D. J. and Lee H. W., Phase changes of the AISI 430 ferritic stainless steels after high-temperature gas nitriding and tempering heat treatment. Materials Science and Engineering A 489 (2008) pp. 38-43. [7] ASM Handbook, Heat treating, ASM International, Materials Park, Ohio-USA, 1991. [8] Totten G. E., Steel heat treatment handbook, CRC Press, Boca Raton, 2006. [9] Hutchings I. M., Tribology: friction and wear of engineering materials. Hodder& Stoughton, London-UK, 1992. [10] Prabhudev K. H., Handbook of heat treatment of steels. McGraw-Hill Publishing Company, New Delhi, 1988.

392 MACHINES. TECHNOLOGIES. MATERIALS. 2018 ADHESION AND PHYSICO-MECHANICAL CHARACTERISTICS OF COATINGS OF CHROMIUM CARBONITRIDE, GENERATED ON STEEL SUBSTRATES

АДГЕЗИОННЫЕ И ФИЗИКО-МЕХАНИЧЕСКИЕ ХАРАКТЕРИСТИКИ ПОКРЫТИЙ КАРБОНИТРИДА ХРОМА, СФОРМИРОВАННЫХ НА СТАЛЬНЫХ СУБСТРАТАХ

Phd Chekan N.M.1, Ass.prof, dr.Eng. Auchynnikau Y.V.2, Phd Akula I.P.1, Ass.prof. Phd Eisymont Y.I.2, Pinchuk T.I.3 Physicotechnical Institute, National Academy of Sciences of the Republic of Belarus1, Yanka Kupala State University of Grodno,Grodno, Belarus2, Institute of Powder Metallurgy of the National Academy of Sciences of the Republic of Belarus3 e-mail: [email protected],[email protected]

Abstract. In the present work, the adhesion and physico-mechanical characteristics of heat-resistant vacuum coatings formed on steel substrates are investigated. An increase in the values of adhesion and physico-mechanical parameters of coatings formed from multicomponent compounds is established. The tribotechnical characteristics of coatings based on chromium carbonitride have been studied. KEYWORDS: adhesion, coating, morphology, friction, microhardness

1. Introduction CrCN have good thermal stability, low deposition Chrome coatings are widely used to create temperature, high wear resistance and corrosion resistance. antifriction anti-adhesion layers for various functional The disadvantage is the lack of precise information for the purposes. Wide distribution found coatings on the basis of formation of these coatings, which affects the porosity of the electrolytic chromium in the manufacture of various types of coating and, as a consequence, reduces the corrosion products of automotive and automotive tractors. In works [1- resistance and tribological properties. Further development 3] it was shown that the use of composite coatings based on of studies on the characteristics of vacuum coatings was the chromium modified with ultradisperse clusters of synthetic creation of two-layer systems Cr-CrN, Cr-CrCN. These carbon (UDD) is an effective direction of increasing the life coatings are characterized by increased wear resistance, low of friction units of automobile shock absorbers. Such coefficient of friction and high microhardness in comparison coatings have a higher hardness (by 23-40%), wear with CrN coatings. Usually this system is obtained by resistance (1.6-2.2 times) compared with base chromium and magnetron sputtering. This method gives advantages in can be applied in one cycle without additional grinding and deposition rate and low content of impurities. In addition, polishing of the parts. This allows to significantly reduce the this method allows the creation of thin films with different thickness of the working layer (up to 5-10 microns) while variations in the crystallographic structure and morphology maintaining the main performance characteristics. At the of the structure [7]. Multilayer coatings of Cr-CrN, CrCN are same time, when applying composite chromium coatings of formed by changing the deposition parameters of the coating, small thickness, the role of microdefects caused by the which makes it possible to obtain composite that are gradient presence of aggregates of the solid phase modifier (UDD) in in structure, that is, a layer close to the substrate exhibits the electrolyte solution increases substantially. Therefore, the increased crystallinity and the upper layers are amorphous corrosion resistance of modified UDD coatings decreases [8-9]. One of the main parameters determining the physical significantly with decreasing thickness, which significantly and mechanical characteristics of surface layers, coatings, reduces the efficiency of their use in engineering. Coating and films are surface energy. By surface energy is meant an with a thickness of more than 5-10 microns from the excess of energy in the surface layer at the interface of two modified chromium is economically expedient, so it allows phases in comparison with energy in the volume of two to significantly increase the wear resistance of the modified phases [10]. products, even despite the rather high cost of UDD (1, -1, 5 According to established ideas, the surface layers of US dollars per carat of the modifier). In [4-5], it was solids, whose size does not exceed the action of the radius of proposed to apply the Foleoks fluorine-containing oligomers molecular forces, have a structure different from the structure F-1, F-8 and F-14 to the working surface when creating of the bulk phase of the condensed body. In the structure of a electrolytic coatings, which provides not only a significant solid body, boundary, transition layers are distinguished, increase in the wear resistance of the interface, but also a which can have a significant effect on the values of the corrosive durability of coatings. After 150 hours of soaking surface energy determined experimentally. One of the in salt fog at 600 °C, the test samples have no visible traces methods for determining the surface energy of solid of corrosion damage, while the samples with a base coating substrates is to measure the contact angles of the polar and after 48 hours of testing have a significant number of local non-polar liquids wetting [11]. Based on the values of the corrosion sites. At the same time, the microhardness of the contact angle, it is possible to calculate the value of the coating and its hydrophobicity increase substantially. The surface energy. In the scientific literature there are works use of composite coatings will not only significantly increase showing the relationship between the value of surface energy the service life of shock absorbers, but also significantly and physical characteristics, so in [12] it is proposed to reduce their energy intensity [4-6]. consider surface energy as an additional tool for providing in A promising area in the field of creating chrome space the constancy of positioning, i.e. stationary state of the coatings and compositions based on it is the use of vacuum two contacting parts. This arrangement is recommended to technologies. One of the promising types of these coatings is receive with the help of such a phenomenon as setting effect. chromium nitride (CrN), which is a new alternative in the To create a certain energy state of the contacting parts, in field of protective high-temperature layers. Coatings of CrN, which connections (bridging bridges) arise, it is proposed to

393 MACHINES. TECHNOLOGIES. MATERIALS. 2018 use the technological process. Thus, the process of formation the production of the maximum number of secondary of the energy state of the surface layer of two (and more) electrons. Based on the consideration of the physical aspects parts with predetermined physico-mechanical properties is of secondary electron emission, it was concluded that a 15- controlled [12]. nm gold coating should give optimal secondary electron The purpose of this work was to study the adhesion emission. In the "Sputter coater" installation, the conductive and physico-mechanical characteristics of chromium layer is created by cathode sputtering of gold. The prepared carbonitride coatings formed on steel substrates samples are placed in a scanning electron microscope and 2. Research methodology. imaged at different magnifications. Acceleration voltage is Adhesion characteristics were studied by the scratch analysis one of the main parameters of shooting in EMS. Samples method. Standard equipment used for indenting uses a were sampled at an accelerating voltage of 20 kV. The module for measuring scoring, research of wear and morphology of the samples was studied using a high- profilometry. A feedback system is used to control the resolution scanning electron microscope "Mira" from Tescan applied load, the force acting on the sample, which does not (Czech Republic). The microscope is equipped with depend on the topography of the surface. The pre-scan secondary electron (SE) detectors and back-reflected procedure allows you to measure the actual penetration depth electrons (BSE), which allow for the study of samples in two for a scratch test to characterize the elastic recovery using the modes. When shooting samples in the secondary electron post-scan procedure [13]. Scratch testers are equipped with (SE) mode, the contrast in the image is created by reflecting an easy-to-use software package that allows the user to the electron beam from the sample surface. In the case of an perform a scratch test in a wide variety of test modes, inverse-reflected electron (BSE) detector, the contrast in the including simple scratching, an extended scratch test (with picture is created by the atomic number of the sample pre-scanning and post scan), simple scratch mapping, scratch elements. The type of detector used, the magnification and mapping with different modes, defined by the user. other shooting parameters are indicated in the information Morphological features of coatings formed on the basis of line at the bottom of each frame. The elemental composition refractory metals after determining the adhesion was investigated using an INCA 350 microspectral analyzer characteristics were studied by scanning electron from Oxford Instruments (UK). Defined elements from B to microscopy. U. The minimum detection limit of an element is 0.5%. The Scanning electron microscope is a device with great error of the method is 5-15 relative percent. possibilities, which allow to characterize heterogeneous materials and surfaces at such a high level. In the scanning 3. Research results. electron microscope (SEM), the surface under investigation According to the data presented in Fig. 1a, chromium is irradiated by a thin-focused electron beam, which can carbonitride coatings formed by plasma-chemical methods either rest or unfold in a raster over the surface of the sample. are composite coatings. There is a matrix in which globular As a result of the interaction, secondary electrons, reflected formations with increased nitrogen concentration and a electrons, characteristic X-ray radiation, Auger electrons and reduced carbon concentration are included with respect to the photons of different energies arise. They are produced in content of these chemical elements in the coating matrix. certain volumes (generation areas within the sample) and are used to measure many of its characteristics (composition, surface topography, crystallographic orientation, etc.). The scanning electron microscope is one of the most versatile instruments for studying and analyzing the microstructural characteristics of solids. The main reason for the wide use of SEM is the high resolution in the study of а) massive objects, reaching today 10-15 nm (100-150 Å). One of the important features of SEM is that it allows you to observe the topography of a solid with a resolution and depth of field that is significantly higher than the corresponding parameters of light microscopes. Information in the study of b) the surface is transferred by reflected secondary electrons and other simulating signals. The thickness of the sample is not particularly important, as is the case in transmission electron microscopy, where information is transferred by transmitted electrons that penetrate the sample by no more than 0.1 μm. Dielectric materials are particularly difficult to c) investigate in SEM. When an electron probe hits a dielectric, its absorbed electrons accumulate on its surface because of the absence of a charge flowing to the ground. The accumulation of electrons leads to the appearance of charged regions on the surface of the sample, which during subsequent scanning can irregularly deflect the primary beam, leading to serious distortions. In addition, the presence of a surface charge greatly changes the secondary electron d) emission. From the charging effect, you can get rid of the conductive coating on the surface of the sample. The criterion for choosing the material for deposition is usually

394 MACHINES. TECHNOLOGIES. MATERIALS. 2018 this curve depends on the ratio of the molecular and mechanical components. In the case where the ratio of the coefficient of friction responsible for the molecular component to the friction coefficient responsible for the mechanical component is greater than unity, the minimum of the curve f (N) is shifted to the region of smaller values of N. f) In the region of small loads, the plastic contact [14-15] f is determined mainly by the molecular component of friction.

g)

Figure 3 - Dependence of the friction coefficient of the pair "CrCN-ShKh 15" from the load h) Figure 1 Dependence of the distribution of chemical The decrease in the coefficient of friction with elements in the coatings of chromium carbonitride: a-coating increasing N is due to the fact that N increases faster than the of chromium carbonitride; b-surface area of the coating for increase in the area of the actual contact caused by this which the content of the chemical elements was measured, c- increase, and, as a consequence of the frictional force. That the total distribution of the chemical elements in the CrCN is, an increase in the load by n times entails an increase in the coating, d - the nitrogen distribution in the CrCN coating, f - number of frictional bonds and their dimensions, and, the carbon distribution in the CrCN coating, g - the consequently, an increase in the total shear resistance by a chromium distribution in the CrCN coating, h -iron in the smaller number of times. After reaching the f minimum a coating of CrCN. plastic contact is realized in the main. The position of the

minimum of the curve depends on the ratio of the molecular The presence of iron in CrCN coatings is due to the and mechanical components. In the course of tribological fact that the thickness of the coating is on the order of 2-5 tests of diamond-like coatings, the reverse effect is observed. μm and does not completely shield the steel substrate. The At low loads, the friction coefficient of the CrCN coating structure and chemical composition of the coating have a over steel increases. Then, under loads in the region of 25-30 significant effect on the adhesion and physico-mechanical N, an extremum point is observed. Further increase in the characteristics of the coatings. values of the normal load is accompanied by a significant decrease in the coefficient of friction. Thus, the behavior of the tribotechnical characteristics of chrome coatings differ from the classical views when the normal load changes.

а) 15 ГПа

10

b) 5 Figure 2 - Type of scratch on the CrCN coating obtained by F,H the scratch analysis method. a - a shape of a scratch, b - a 0 fragment of a scratch where there is a full peeling of a 0 0,1 0,2 0,3 0,4 0,5 0,6 covering from a substrate

Coatings of CrCN begin to peel off at values that are in the Figure 4 - Dependence of the change in the microhardness region of 12 - 13 N. The complete peeling of the coating of the CrCN coating formed on 40X steel from the applied from the substrate is observed at values of ~ 23 N. These load on the pyramid values are 1.8-2 times higher than the adhesion characteristics of vacuum chrome coatings. According to the This dependence of the friction coefficient on the load for data of [14-15], the effect of the load on the coefficient of these coatings is explained by the fact that in the structure of friction depends on the type of contact interaction - elastic or CrCN there is a carbon with a high concentration in plastic. In the general case, the function f (N) is comparison with the base chrome coating. The increase in nonmonotonic and is determined by a quadratic function load promotes the diffusion of carbon into the friction zone (Figure 2). It is believed that the position of the minimum of and the formation of a separation film with low shear stress

395 MACHINES. TECHNOLOGIES. MATERIALS. 2018 values, which is expressed by a decrease in the friction Bulgaria; editor: D. Damianov. – Sofia, 2004. – Vol. 2. – rr. coefficient with increasing load. Determination of the 66-67. microhardness of CrCN coatings by the Vickers method 4. Metallopolimernye pokrytiia na osnove leads monotonic decrease in values with increasing load on modifitsirovannogo khroma i ftorsoderzhashchikh the indenter. The microhardness parameters of the coatings oligomerov / A.I. Mamonchik, E.V. Ovchinnikov, S.D. are reduced three times with the load increasing from 0.1 to Leshchik, A.F. Sen'ko // Materialy. Tekhnologii. 0.5 N. Thus, at loads of 0.25-0.5 N, the coating is impressed Instrumenty. - 1998. – T.3, №2. – S.101 into the material of the steel substrate. However, carrying out 5. Tribotekhnicheskie kharakteristiki measurements with these loads makes it possible to establish kompozitsionnykh mnogosloinykh pokrytii [Tekst] / E. V. a modifying effect of high-hard coatings, since the Ovchinnikov, S. D. Leshchik, V. A. Struk, O. V. Kholodilov, microhardness of the steel substrate is no more than 2-3 GPa. D. I. Fedorov // Trenie i iznos. – 2000. – T. 21, № 2. – C. 147-155. 4. Conclusion. 6. Ovchinnikov, E. V. Tonkie plenki Based on the obtained data, it is established that the ftorsoderzhashchikh oligomerov: osnovy sinteza, svoistva i microhardness values of steel substrates are in the range from primenenie [Tekst] / E. V. Ovchinnikov, V. A. Struk, V. A. 2,400 to 3,000 MPa and do not depend on the load on the Gubanov. – Grodno: GGAU, 2007. – 326 s. diamond pyramid. The microhardness values of chromium 7. Kelly PJ, Arnell RD (2000)Magnetron sputtering: a carbonitride coatings decrease monotonically with increasing review of recent developments and applications. Vacuum load on the diamond pyramid. This effect is due to the 56:159–172 indentation of the coating in the structure of the steel 8. Majzoobi GH, Hojjati R, NematianM, Zalnejad E, substrate material. The adhesion characteristics of CrCN Ahmadkhani AR, Hanifepoor E (2010) A new device for coatings are 1.8-2 times higher than the adhesive fretting fatigue testing. Trans Indian Inst Metals 63(2– characteristics of vacuum chrome ones. The tribological 3):493–497 characteristics of CrCN coatings are investigated. It is shown 9. Chunyan Y, Linhai T, Yinghui W, Shebin W, that diffusion of carbon into the friction zone and formation Tianbao L, Bingshe X (2009) The effect of substrate bias of a separation film with low shear stresses is possible, which voltages on impact resistance of CrAlN coatings deposited is expressed by a decrease in the friction coefficient with by modified ion beam enhanced magnetron sputtering. Appl increasing load. Surf Sci 255:4033–4038 10. .Khimicheskii entsiklopedicheskii slovar'. - Pod red. Knuniants I.L. - M.: Sovetstkaia entsiklopediia, 1983. – Bibliography: s.793. 11. Akhmatov A.S. Molekuliarnaia fizika granichnogo 1. Novye materialy i tekhnologii, primeniaemye pri treniia. – M.: «Fizmatgiz», 1963, 472 s. proizvodstve kardannykh peredach [Tekst]/ V. I. 12. Musokhranov M. V., Antoniuk F. I. , Kalmykov V. Kravchenko, V. A. Struk, G. A. Kostiukovich, E. V. V. Poverkhnostnaia energiia i protsess skhvatyvaniia Ovchinnikov // Vestnik Belorussko-Rossiiskogo universiteta. kontaktiruiushchikh poverkhnostei Nauka i Obrazovanie. – 2006. – № 4 (13). – S. 91-99. MGTU im. N.E. Baumana. Elektron. zhurn. 2014. № 11. S. 2. Kompozitsionnye pokrytiia na osnove 45–51. elektroliticheskogo khroma, modifitsirovannogo 13. 1. CSM INSTRUMENTS. Tekhnicheskoe opisanie. ul'tradispersnym uglerodom / S.D. Leshchik, A.I. Mikro Skretch Tester (MST 2) [Elektronnyi resurs] / OOO Mamonchik, V.A. Struk, E.V. Ovchinnikov // Problemy i «Nienshants-Saintifik». – Rezhim dostupa: http://lab- puti realizatsii nauchno-tekhnicheskogo potentsiala voenno- nnz.ru/wp-content/uploads/02-MST2_Technical- promyshlennogo kompleksa: Tezisy dokladov Features_2011-RUS.pdf. – Data dostupa: 29.11.2016. mezhdunarodnoi konferentsii, Kiev, 15-17 marta 2000 g. 14. Tribotekhnicheskii mekhanizm deistviia epilamov Kiev, 2000. – S. 98 - 99.3 . pri trenii. 2. Tribotekhnicheskie kharakteristiki 3. Funktsional'nye nanokompozitsionnye materialy epilamirovannykh materialov / I.I. Garbar [i dr.] // Trenie i dlia konstruktsii kardan-nykh peredach [Tekst] / V. I. iznos. − 1990. − T. 11. − №6. − S. 987-996. Kravchenko, G. A. Kostiukovich, V. A. Struk, E. V. 15. Poplevich, V.I. Zashchitnaia effektivnost' Ovchinnikov // Trans and motoauto’04: Proceedings of ftorirovannykh karbonovykh kislot / V.I. Poplevich // International conference, Plovdiv, 14 – 17 oct. 2004. / Khimiia i tekhnologiia topliv i masel. - 1990.- №8. – S. 22- Scientific-technical union of mechanical engineering of 23.

396 MACHINES. TECHNOLOGIES. MATERIALS. 2018 EFFECT OF DYNAMICAL AGING IN SLM Ti-6Al-4V ALLOYS ЭФФЕКТ ДИНАМИЧЕСКОГО СТАРЕНИЯ В СЛС Ti-6AL-4V СПЛАВАХ Davidov D. PhD. 1, Prof. Kazantseva N. Dr.of Sci.1, Ezhov I. PhD Student 1, Fefelov A. PhD.2, Merkushev A. 2, Afanasyev S. PhD. 1 Institute of Metal Physics, Ekaterinburg, Russia1 Regional Engineering Center of laser and additive technology, Ekaterinburg, Russia2

[email protected] Abstract: The application of the selective laser melting (SLM) method requires knowledge of not only the properties of the material after manufacturing, but also after mechanical loading. The aim of this work is to investigate the strain-rate dependence and microstructure of Ti6Al4V samples manufactured by SLM method with different angles to the building platform. SLM Ti-6Al-4V samples were manufactured using the EOSINT M280 (EOS GmbH) at angles of 0°, 30°, 45°, 90° to the building platform. A medicine Ti6Al4V (ASTM grade 23) powder was used for the study. Tensile tests were performed with an Instron test machine using two strain rates 0.5 mm/min and 2 mm/min at room temperature. It was found the strain-rate dependence in the studied samples. The features of the mechanisms of hardening and softening in an investigated SLM Ti-6Al-V alloy are discussed. KEYWORDS: TITANIUM ALLOY, SLM, 3D PRINTING, MICROSTRUCTURE, STRAIN RATE DEPENDENCE

1. Introduction 3. Results and Discussion Deformation process of metallic materials at high-temperature Figure 1 shows the schema of orientation of the sample to the conditions is competing with non-equilibrium processes associated building platform. with their hardening and softening. An increase in the metal density of dislocations is considered as the main contribution to metal hardening [1]. The experimentally obtained curve of dependence of the deformation resistance σ on the degree of deformation ε may show two different variants of hardening of the deformed materials. In the first case, a wave curve may be observed. The appearance of the waves is associated with the Portwein-Le Châtelier (PLC) effect, which is explained by the occurrence of propagative Fig.1 Schema of the orientation studied samples to the building platform localized bands [2]. In the second case, the curve shows the in EOSINT 280M printer. repeated hardening of the alloy after past appreciable weakening [1]. At the initial (as-build) state, all of the samples had the In the absence of phase transitions, softening of the alloy martensitic HCP α′-structure. Figure 2 presents the structure of the occurs by dynamic return, polygonization and recrystallization [1]. 45° sample. Such structure was found in all of studied samples. Under certain temperature-velocity conditions of deformation, the dynamic deformation aging (DDA) may be occur. DDA effect associated with the increasing of the ductility of the material with increasing of the strain rate in defined range of the temperatures and rates [1]. Increasing in the strain rate usually decreases the mechanical properties of the materials. However, in some cases the effect of dynamical deformation aging was observed in conventional titanium alloys and steels [3-4]. The main purpose of this work is to study the effect of dynamic deformation aging the Ti-6Al-4V alloys manufactured by the selective laser melting.

2. Experimental Fig.2 Structure of 45° sample, scanning electron microscopy. Spherical argon-atomized Ti6Al4V (ELI) (45 µm) powder from In the structure of the as-build samples, we found the pores. TLS Technik was used for study. The chemical composition Spherical pores are characteristic of materials obtained by selective complies with the ASTM B348 (Grade 23) for surgical implant laser melting. Small pores with dimensions of about 4-10 microns applications. Ti-6Al-4V samples were manufactured by 3D printing and pores with sizes up to 30 microns may be observed in the using the selective laser melting (SLM) with the EOSINT M280 structure of the samples (Fig. 3). (EOS GmbH) 3D printing machine equipped with an Ytterbium fiber laser, and operating at 1075 nm wavelength (IPG Photonics Corp.). Standard EOS regime for manufacturing of the titanium alloys was used. SLM Ti-6Al-4V samples were manufactured at angles of 0°, 30°, 45°, 90° to the building platform. Structural studies were done with the QUANTA-200 scanning electron microscope equipped with a Pegasus system for the structural and texture analyses and with an EDAX energy-dispersive spectrometer for the elemental analysis. Tensile tests were performed at room temperature with an Instron test machine using two strain rates: 0.0013 s-1 and 0.0004 s-1. Samples were manufactured in the form of cylinders with a diameter of 12 mm and a length of 55 mm. Samples for mechanical testing were cut from the cylinders in accordance with GOST RF 1497-84. Density of the manufactured Fig.3 Pores in the as-build 45° sample, scanning electron microscopy. samples was defined as 99,7 %. Results of the mechanical testing are presented in the Table 1.

397 MACHINES. TECHNOLOGIES. MATERIALS. 2018 Table 1: Tensile properties of as-built Ti6Al4V samples coarsening and coalescence of the pores in the SLM Ti-6Al-4V Building sample under deformation. UTS, YS, Elongation Strain angle (MPa) (MPa) at break (%) rate, s-1 (grad) 4. Conclusion 45 990 880 6.4 0.0004 1. Structure and deformation process of the SLM 45 1020 940 18.6 0,0013 Ti6A4V (grade 23) samples with a density 99.7% 0 1000 940 14.3 0,0013 were studied. Microstructure of the SLM samples 30 1010 930 16.4 0,0013 showed the presence of pores with the size from 4 to 90 980 890 13 0,0013 30 µm.

Figure 4 presents the strain-stress curves for 45° sample 2. Deformation process in the sample under different deformed at different rates. The dependence of the ductility on the strain rates showed rate dependence of the plasticity strain rate was found in the 45° samples. of the sample. The elongation at the break was also found depending on the orientation of the sample to the building platform. The most elongation was found in the 45° sample. 3. The ductile fracture mechanism of the samples deformed at rapid strain rate (0.0013 s-1) under tension is associated with formation of the deep necking region, which is associated with new pore formation and its coalescence. 4. The sample deformed at standard strain rate (0.0004 s- 1) shows the weak neck formation, which is associated with coarsening and coalescence of the pores. Acknowledgments This work was supported by the Russian Fund of Basic Research Fig.4 Strain-stress curves of 45° sample after deformation at different rates. No 17-03-00084, State programs “Diagnostics” AAAA-A18- 118020690196-3 and “Pressure” No. АААА-А18-118020190104-3. It is known that, the mechanical properties of the Ti6Al4V alloy strongly depend on the structure, heat treatment and the method of References obtaining the samples [5]. As can be seen from the Table 1, the SLM samples grown at an angle of 45° to the building platform 1. Zh.P. Pastukhova, A.G. Rakhshtadt, Yu.A. Kaplun, show the greatest plasticity. Increasing in strain rate up to 0.0004 s-1 Dynamic aging of alloys. Moscow: Metallurgy. (this strain rate is a standard one for deformation of the small (1985). samples) leads to a significant decrease in plasticity of the 45° 2. A. Yilmaz, The Portevin–Le Chatelier effect: a review sample. The results of the mechanical testing at standard strain rate of experimental findings, Sci Technol Adv Mater. are in good correlation with the literature date for SLM Ti-6Al-4V 12(6) (2011) 063001. alloys [5-7]. Usually, the mechanical properties of Ti6Al4V 3. Sang-hyun Cho, Yeon-chuL Yoo, J. J. Jonas. Static obtained by the SLM method are characterized by high yield and dynamic strain aging in 304 austenitic stainless strength (YS), high time resistance (UTS) and low ductility. High steel at elevated temperatures, Journal of materials strength properties and low plasticity are associated with the science letters. 19 (2000) 2019–2022. formation of a martensitic structure at a high rate of crystallization 4. L. Ladani1, J. Razmi and S. Farhan, Choudhury [7]. Mechanical Anisotropy and Strain Rate Dependency Behavior of Ti6Al4V Produced Using E-Beam Structure studies found the different distribution of the pores in Additive Fabrication. J. Eng. Mater. Technol. 136(3), the sample after deformation at different rates (Fig. 5). (2014) 031006. 5. T.H. Becker, M. Beck, and C. Scheffer, (a) (b) Microstructure and mechanical properties of direct metal laser sintered Ti-6Al-4V. South African Journal of Industrial Engineering. 26(1) (2015) 1-10. 6. A. Mertens, S. Reginster, H. Paydas, Q. Contrepois, T. Dormal, O. Lemaire, and J. Lecomte-Beckers, Mechanical properties of alloy Ti–6Al–4V and of stainless steel 316L processed by selective laser melting: Influence of out-of-equilibrium microstructures. Powder Metallurgy, 57(3) (2014) 184-189. Fig.5 SEM structure of the pores in the 45 ° sample after deformation at -1 -1 7. P. Krakhmalev, G. Fredricsson, I.Yadroitseva, N. different rates: (a) - 0.0004 s ; (b) - 0,0013 s . Kazantseva, A. Du Plessis, I.Yadroitsev, Deformation The sample deformed at standard strain rate (0.0004 s-1) shows Behavior and Microstructure of Ti6Al4V the weak neck formation, which is associated with coarsening and Manufactured by SLM, Physics Procedia, 83 (2016) coalescence of the pores (Fig. 5a). In the case of the rapid strain rate 778 – 788. (0.0013 s-1), deformation occurs by formation of the deep necking 8. M.G. Moletsane, P. Krakhmalev, N. Kazantseva, A. region, which is associated with new pore formation and its Du Plessis, I. Yadroitsava & I. Yadroitsev Tensile coalescence (Fig. 5b). The pore behavior under standard rate of properties and microstructure of direct metal laser- deformation was studied in [8]. Authors found the same behavior of sintered TI6AL4V (ELI) alloy, South African Journal the pores in the neck of the sample, which was associated with of Industrial Engineering, 27(3) Special Edition (2016) 110-121.

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