International virtual journal for science, technics and innovations for the industry MACHINES TECHNOLOGIES MATERIALS SSN 1313-0226 I / 2014 12 Issue VIII YEAR Published by Scientific technical Union of Mechanical Engineering MACHINES, TECHNOLOGIES, MATERIALS INTERNATIONAL VIRTUAL JOURNAL 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.mech-ing.com/journal ISSN 1313-0226 YEAR VIII ISSUE 12 / 2014 EDITORIAL BOARD Editor-in-chief: Prof. Dr. Mitko Mihovski – Chairman of the Scientific Council of the STUnion of Mechanical Engineering AKADEMIC CONCEPTIONAL BOARD EDITORIAL COUNCIL Acad. Vassil Sgurev Prof. D.Sc. Georgi Popov Acad Yachko Ivanov Prof. D.Sc. Alexander Skordev Acad Vladimir Klyuev Prof. D.Sc. Nikola Rashkov Acad. Rivner Ganiev Prof. D.Sc. Dimitar Stavrev Corr. mem. Georgi Mladenov Prof. D.Sc. Hristo Shehtov Corr. mem. Dimitar Buchkov Prof. Dr. Todor Neshkov Corr. mem. Stefan Hristov Prof. Dr. Dimitar Damianov Corr. mem. Venelin Jivkov Prof. Dr. Kiril Arnaudov Corr. mem. Anatoliy Kostin Prof. Dr. Snejana Grozdanova Corr. mem. Edward Gorkunov Prof. Dr. Vassil Georgiev Assoc. Prof. Lilo Kunchev EDITORIAL BOARD – EXPERTS AND REVIEWERS FROM BULGARIA FOREIGN MEMBERS Prof. D.Sc. Nyagol Manolov PD. D. PE Assoc. Prof D.Midaloponlas Prof. D.Sc. Vitan Galabov Prof. Dr. Athanasios Mihaildis Prof. D.Sc. Emil Momchilov Prof. Amos Notea Prof. D.Sc. Emil Marinov Prof. Dr. Eng. Airon Kubo Prof. D.Sc. Dimitar Katzov Prof. Dr. Eng Georg Dobre Prof. D.Sc. Stavri Stavrev Prof. Dr. Dimitrov Dimitar Prof. D.Sc. Georgi Raychevski Prof. Dr. Mohora Cristina Prof. D.Sc. Ivan Yanchev Prof. Dr. Popa Marcel Prof. D.Sc. Marin Stoychev Prof. Dr. Sobczak Jerzy Prof. D.Sc. Roman Zahariev Prof. Dr. Tamosiuniene Rima Prof. D.Sc. Vassil Mihnev Prof. Alexander Dimitrov Prof. D.Sc. Valentin Abadjiev Prof. dr. Marian Tolnay Assoc. Prof. Dimitar Stanchev Prof. dr. Mikolas Hajduk Assoc. Prof. Milcho Angelov Assoc. Prof. Mihail Mihovski Assoc. Prof. Radi Radev The current issue and the first issue of journal and Assoc. Prof. Georgi Todorov the conditions for publication can be find on Assoc. Prof. Simeon Petkov l Assoc. Prof. Petar Dobrev www.mech-ing.com/journa Assoc. Prof. Nikolay Piperov CONTENTS SURFACE MORPHOLOGY OF PURE TITANIUM AFTER ANODIZATION Dikova Ts. ...................................................................................................................................................................................... 3 USER EVALUATIONS: APPLYING A COST-BENEFIT APPROACH TO HUMAN COMPUTER INTERACTIONS Katz A. ........................................................................................................................................................................................... 8 PRODUCTION OF ALUMINA NANOPARTICLES (AL2O3) USING PULSED LASER ABLATION TECHNIQUE IN ETHANOL SOLUTION Adel K. M. ................................................................................................................................................................................... 12 COMPARISON BETWEEN PROJECT MANAGEMENT AND SOFTWARE PROJECT MANAGEMENT Ivanova M. ................................................................................................................................................................................... 16 THERMOMECHANICAL STRENGTHENING AND STABILITY OF AUSTENITIC Cr18Ni10N STEEL Kaputkina L.M., A. G. Svyazhin, D.E. Kaputkin, I. V. Smarygina, V. E. Kindop ..................................................................... 20 IN-SITU STRESS-STRAIN TESTING OF STEELS IN CO2-CONTAINING SALINE SOLUTIONS Pfennig A., S. Trenner, M. Wolf, C.-P. Bork .............................................................................................................................. 23 ROBUST BI-CRITERIA APPROACH TO OPTIMIZE THE COMPOSITION AND PROPERTIES OF TITANIUM ALLOY Tontchev N., Y. Kalev ................................................................................................................................................................ 26 ANALYSIS OF THE APPROACHES FOR IMPROVEMENT OF THE ENERGY EFFICIENCY OF ELECTRIC RESISTANCE FURNACES Dimitrov B., O. Zhekov ............................................................................................................................................................... 31 CREATING AND RESEARCHING SUSTAINABLE DESIGN OF CORRUGATED CARDBOARD FURNITURE WITH ADVANCED TECHNOLOGICAL MEANS Dovramadjiev T., P. Bratanov, K. Cankova, G. Jecheva ............................................................................................................. 35 NUMERICAL SIMULATION AND EXPERIMENTAL INVESTIGATION OF EQUAL-CHANNEL ANGULAR PRESSING OF POROUS POWDER BILLETS Ryabicheva L., D. Usatyuk, A. Dyadichev .................................................................................................................................. 37 PULSED DISCHARGE TECHNOLOGIES OF PROCESSING AND OBTAINMENT OF NEW MATERIALS (Review) Sizonenko O., A. Vovchenko ...................................................................................................................................................... 41 THE ROLE OF SEVERE PLASTIC DEFORMATION IN THE FORMATION OF HIGH ELECTRICAL PROPERTIES OF ALUMINUM ALLOY Raab G.I., E. I. Fakhretdinova ...... .............................................................................................................................................. 45 DISSIMILAR WELDING AUSTENITIC STAINLESS STEEL S316 WITH FERRITIC STRUCTURAL STEEL GRADE 300NZS Cvetkovski S., D. Brkovski .......................................................................................................................................................... 48 COMBINED APPROACH FOR MODELING OF MANUFACTURING EXECUTION SYSTEMS Antonova I. D. .............................................................................................................................................................................. 52 SURFACE MORPHOLOGY OF PURE TITANIUM AFTER ANODIZATION Assoc. Prof. Dr Dikova Ts. Faculty of Dental Medicine, Medical University of Varna, Varna, Bulgaria E-mail: [email protected] Abstract: Present paper deals with the investigation of the surface morphology of pure titanium after anodization. Round samples of CP Ti were anodized at different voltages (16V, 20V, 25V, 30V and 40V) in an electrolyte containing 0.5 wt.% HF. The process duration varied from 30min to 7 hours. The samples’ surface was observed and EDX analysis was made by SEM. Surface morphology of CP Ti after anodization is defined by the surface roughness before anodization, electrolyte type and process parameters – voltage and duration. It was established that the surface of pure titanium after 3h-7h anodization at all voltages characterizes with large number of craters increasing the surface micro-roughness. At short-term processes only pores with about 2µm diameter were observed. Depending on the regimes used different oxide nanostructures were observed. After short-term anodization in lower voltages the titanium surface was covered with nanodots, nanorods and nanoflakes. Increasing the voltage up to 25 V led to originating of nano-tubular structure in some areas and sponge-like nano-structure at 30 V and 40 V. Increasing the process duration caused increase of the proportion of nanotubes and sponge- like structure to that of nanorods. Keywords: PURE TITANIUM, ANODIZATION, SURFACE MORPHOLOGY, TITANIUM OXIDE NANOTUBES AND NANOSTRUCTURES 1. Introduction range of 5-30V [3-5]. It was found that the diameters of the nanotubes were determined by applied voltage while the final An implant is an artificial structure whose purpose is to replace length of the tubes was independent of the anodization time. The or stabilize damaged body functions and include many different thickness of the formed tubular-structure oxide layer can be from a types such as hip and knee joints, spinal implants, dental implants few hundred nanometers up to a few microns by controlling pH and etc. [1]. The principal requirements of all medical implants are electrolytes. corrosion resistance, biocompatibility, bioadhesion, As the geometry and roughness of the surface strongly biofunctionality, processability and availability. The design of influences on the implant’s biocompatibility, the aim of the present implants could be divided in four levels: macro-design, mini-design, paper is to investigate the surface morphology of pure titanium after micro-design and nano-design. The last two aspects refer to the anodization in water solution of HF at different regimes. surface roughness at micro-level and to the molecular organization of the implant surface at nano-level. From that point of view, the surface topography of the implant should consists of hierarchical 2. Experimental methods structure, composed of micro- and nano-components, which mimic Round samples with dimensions 24mm x 3mm (diameter x the structure of the natural bone [2,3]. thickness) were made of commercially pure (CP) Ti Grade-2 Pure titanium is preferable material for production of implants (99,5%). The samples’ surface was grinded with sandpaper 300, because its mechanical properties and elastic modulus are close to 600 and 800. After grinding they were ultrasonically cleaned that of the bone tissues. Its good corrosion resistance and consecutively in acetone, ethanol and deionized water for 15 min in biocompatibility