DOCSLIB.ORG

Design Concepts of Gaseous Detonation Guns for Thermal Spraying

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Design Concepts of Gaseous Detonation Guns for Thermal Spraying ɌȿKA. COMMISSION OF MOTORIZATION AND ENERGETICS IN AGRICULTURE – 2013, Vol. 13, No.4, 82-91 Design concepts of gaseous detonation guns for thermal spraying Yuriy Kharlamov1, Maksym Kharlamov2 1Volodymyr Dahl East Ukrainian National University, Molodizhny bl., 20ɚ, Lugansk, 91034, Ukraine, e-mail: [email protected] 2E.O. Paton Electric Welding Institute 11 Bozhenko St., Kiev, 03680, Ukraine, e-mail: [email protected] Received September 12.2013: accepted October 10.2013 S u m m a r y . Presented a structural analysis of gaseous processes have exposed that higher detonation guns for spraying powder coatings and the performance and lifetime coatings can be possible variants of their operational cycle. The basic principles for the design of high detonation-gas plants produced if the feedstock particles are for spraying powder coatings, including the concept of a accelerated to a high velocity and heated prior valveless devices, are formulated. to impact on the substrate to be coated [4, K e y w o r d s . Gaseous detonation, coating deposition, 13, 27]. operational cycle. Almost in parallel to plasma spraying, Union Carbide (now Praxair Surface INTRODUCTION Technologies, Inc., Indianapolis. IN) marketed the trademarked D-Gun producing premium In spite of competing processes coatings, especially metallic and cermet ones, (chemical vapor deposition (CVD), physical which have long been the goal of all other vapor deposition (PVD), etc.) and certain coating processes, i.e., higher density, drawbacks, thermal spray process sales are improved corrosion barrier, higher hardness, increasing regularly (almost by 10% per year better wear resistance, higher bonding and since 1990 [6]). The growth will probably cohesive strength, almost no oxidation, thicker continue, because spraying techniques are coatings, and smoother as-sprayed surfaces. relatively harmless to the environment and the However, the detonation gun (D-Gun) process full potential of thermal spraying as an was available only as a service [12]. alternative to more conventional coating Historically, the two fundamental modes techniques (e.g., hard chromium) for of combustion, namely flame and detonation, processing "multimaterials" or for free forming have found a wide variety of applications in and repairs is still undiscovered. However, this human activities. It is a slow flame that has development could be enhanced with been extensively utilized in propulsion, power increased quality of coatings and process engineering, material science, and chemical reliability. It demands improved process technology, while detonations were used understanding and on-line control with a real basically for military purposes. As the time closed-loop control. Decades of research knowledge in detonation physics and and development in thermal spray (TS) chemistry is continuously advancing, one DESIGN CONCEPTS OF GASEOUS DETONATION GUNS FOR THERMAL SPRAYING 83 inevitably arrives at the time when this detonation-gas plants for spraying of powder knowledge is to be used for constructive coatings. purposes as well to help humanity at large. Detonation is a very attractive phenomenon from the viewpoint of the thermodynamic BASIC PRINCIPLES OF GASEOUS efficiency of chemical energy conversion into DETONATION GUNS thermal and kinetic energy. Once this The detonation-spraying technique is advantage of detonation is capitalized cyclic. In a D-Gun, detonation is initiated in a properly, considerable benefits are expected to tube that serves as the combustor. The be achieved in terms of fuel consumption, detonation wave rapidly traverses the chamber manufacturing and operational costs, pollutant resulting in a nearly constant-volume heat emissions, etc. [1, 3, 20]. addition process that produces a high pressure For a long time, D-Gun technology has in the combustor and provides the formation of been the reference standard in producing high velocity impulse flow, which used for metallic and cermet coatings. However, as it powder heating and acceleration. A typical was available only as a service, no research duty cycle of detonation-gas spraying of work was published on the process. With the coatings and its main parameters are shown in transformations that occurred in the former Fig. 1. USSR, Russian equipment and literature on To facilitate the description and analysis the subject became available in the mid 1990s of basic physicochemical phenomena involved [19]. in the working cycle, nine principal steps will Gas detonation can be used to generate be considered: (1) filling the detonation gun thrust in engines, to induce force or destruction barrel with a fresh charge of combustible gas actions on objects located both inside and mixture (GF), (2) powder doze feeding into outside the device, to heat and accelerate DC (barrel) (PF), (3) creation of condensed particles, to rapidly burn the fuel, “phlegmatizing gas plug” between ignition etc. [19]. point and gas mixer (GP), (4) ignition of gas The development of detonation spraying mixture (Ig), (5) DC purging of residual gases is accompanied by broadening its industrial (Pr), (6) deflagration to detonation transition use [16]: deposition of coatings on aircraft (DDT), (7) impulse burn-out of the fresh engines and parts, jigs and fixtures [2], charge (B), (8) interaction of the powder strengthening of cumulative punches [8, 9], particles with an impulse flow of combustion improvement of wear resistance of work items products and two phase outflow from barrel re-adjustable dies [15], creation of a new (AP), (9) interaction of the gas-powder stream metal-working tools [17], hardening of with the substrate and single layer coating abrasive wheels, balancing of rotor systems formation (CF). [18], improvement of resistance to abrasion In the most general case the gaseous [21], etc. detonation gun (GDG), as an auto-oscillatory There are many different D-Gun designs system, has a block diagram shown in Fig.1. [14,23,24,28]. Unfortunately, the available The oscillatory system can also be represented literature contains no reliable data on the as a sequence of systems of the GDG itself and reliability of these devices and the comparative of the environment receiving the powder being analysis of their structural characteristics. processed (the product being coated, cooling Compared to HVOF or plasma spray chamber, etc.). The behavior (state) of the processes, much work, some of which is in environment may affect parameters of the progress, is necessary to better understand the working cycle because of the effect of phenomena of the D-gun process [10, 11]. feedbacks on the controllers and actuators. The aim of this work is to develop the Growing pressure to improve the performance basic principles of structural analysis and of D-Guns, as of IC engines, has resulted in synthesis of structures of high efficiency development of improved control systems [5]. 84 YURIY KHARLAMOV, MAKSYM KHARLAMOV Fig. 1. A typical duty cycle of detonation-gas spraying and its main parameters Fig. 2. Block diagram of gaseous detonation gun for thermal spraying DESIGN CONCEPTS OF GASEOUS DETONATION GUNS FOR THERMAL SPRAYING 85 The steps of an impulse burn-out of the the barrel first drops below atmospheric combustible mixture and formation of an pressure (because of the inertia of the flow) impulse heterogeneous stream are governing and then equalizes. The combustion chamber steps and depend greatly on the quality of is again filled with a fresh charge, and the barrel filling. Repetition of cycles causes the process is repeated. Thus, vibration burning fresh charge to contain a certain amount of with discontinuous oscillations (relaxation or combustion products and powder from the non-resonance burning) occurs in the barrel. preceding spraying cycle. The gases and The regularities in the burn-out of the powder, on the one hand, reduce the mass of a combustible mixture and in the outflow of fresh charge and, on the other hand, adversely combustion products from the barrel are the affect the processes of burn-out and formation scientific fundamentals to be considered in an of an impulse heterogeneous stream efficient development of spray-coating themselves. It is therefore natural to attempt to production processes [26]. However, this step reduce the fraction of residual gases and of the working cycle has not yet been studied powder in a fresh charge. Also the flow of a sufficiently. The most urgent issues for further working medium (purging gas, fresh investigations should include the following: combustible mixture or gas suspension of the the effect of design characteristics and the initial powder) has a limited time to overcome geometric configuration of the barrel, ignition the resistance of inlet paths, to contact heated chamber and other pre-barrel spaces on the surfaces etc. All this changes the density of the development and conditions of the working medium and hence also the mass of combustible mixture burn-out, outflow of charge capable of filling a barrel of detonation products and heat exchange with predetermined dimensions, the degree of barrel the barrel walls, the composition and filling, the spatial distribution of fresh charge properties of combustion products and their components in the barrel. The barrel-filling change during mixture burn-out and gas processes have been poorly studied. outflow from the barrel, the optimization of After the barrel has been filled, an the design characteristics of detonation- ignition source operates, installed in the spraying plants
Load more

Recommended publications
  • View/Download PDF of This Article, the File Size
    INVESTIGATION OF STRUCTURE AND PROPERTIES OF THERMAL COATINGS OF WC—Co—Cr SYSTEM PRODUCED BY HIGH-VELOCITY METHODS OF SPRAYING Yu.S. BORISOV, E.A. ASTAKHOV, A.P. MURASHOV, A.P. GRISHCHENKO, N.V. VIGILYANSKAYA and M.V. KOLOMYTSEV E.O. Paton Electric Welding Institute, NASU 11 Bozhenko Str., 03680, Kiev, Ukraine. E-mail: [email protected] Spraying of coatings of WC—9Co—4Cr powder was performed by high-velocity procedures of thermal spraying, using the methods of detonation, supersonic air-gas plasma (SAGP) and oxy-fuel HVOF spraying. Microstructure and properties of produced coatings were investigated. Analysis of results of the coating structure examination showed that during spraying with these methods the dense coatings are formed, consisting of inclusions of tungsten carbide, uniformly distributed in Co—Cr matrix. Porosity of coatings is less than 1 %. Microhardness of SAGP- and HVOF-sprayed coatings is 11.0—11.7 GPa. As to the values of microhardness these coatings are superior to those of the galvanic chromium (10 GPa). Microhardness of the detonation coating is 8.5 GPa. The cause of decrease in hardness of the detonation coating is a partial loss of carbon and appearance of oxide inclusions in it, that is caused by the oxidizing medium of the detonation products. By the complex of characteristics of hardness, adhesion strength (more than 50 MPa) and porosity the coatings of WC—9Co—4Cr system, sprayed by SAGP and HVOF methods, are advantageous as compared with the galvanic chrome-plating. Among the investigated methods of high-velocity thermal spraying of coatings of WC—9Co—4Cr system the SAGP method is characterized by the highest efficiency (15 kg/h).
    [Show full text]
  • Microhardness Improvement by Using Thermal Sprayed Ni and Al Coatings by Detonation Gun
    e-ISSN (O): 2348-4470 Scientific Journal of Impact Factor (SJIF): 5.71 p-ISSN (P): 2348-6406 International Journal of Advance Engineering and Research Development Volume 5, Issue 04, April -2018 MICROHARDNESS IMPROVEMENT BY USING THERMAL SPRAYED NI AND AL COATINGS BY DETONATION GUN Mukesh kumar1, Mohd Vaseem2, Rajesh Kumar3 1Mechanical Engineering, Quantum University, Roorkee, India 2Mechanical Engineering, Quantum University, Roorkee, India 3Enginear, Welding/NDT, Engineeres India Limited RRFCL, Telagana, India Abstract - The present work was undertaken to increase the hardness of aluminium and nickel based coatings deposited by Detonation spray technique. The experimental work included deposition of Al2O3-TiO2 and Ni-Cr overlays of around 400 micron coating thickness, so as to achieve appropriate adhesion strength and hardness by using detonation gun spray technique (DS). Characterization of samples was made for further studies viz. as sprayed condition & post coating treatment. One of the hardfaced samples was subjected to post spray treatments of nitriding and compaction heat-treatment at 565° C for 2.5 hours and allowed to furnace cool, while another set of samples of both types of coatings was subjected to compaction at 12kN for 15 minutes. Systematic microstructural characterization of the coatings in the as-sprayed, nitrided conditions were carried out which included microhardness techniques in order to understand the effect of post treatment on the microstructure of these coatings. It is found that the microhardness values of base metal are enhanced almost three times after hardfacing/coatings with the Al2O3-TiO2 & Ni-Cr, using DS, which further enhanced after post treatment of nitriding and compaction.
    [Show full text]
  • Application Notes Metallographic Preparation of Thermal Spray Coatings
    Metallographic preparation of thermal spray coatings Application Notes Thermal spraying was invented in the early 1900s using zinc for „metallizing” substrates for corrosion protection. The development of the plasma spray gun in the late 50s and 60s made it commercially viable to use high temperature materials such as ceramics and refractory metals for coating materials. In addition to fl ame and plasma spraying, today thermal spray methods include high velocity and detona- tion spraying using a multitude of different spray materials for the most diverse and demanding applications. Thermal spray coatings are applied to a substrate to give a specifi c surface quali- ty, which it originally does not have. Thus Metallography of thermal spray coatings the bulk strength of a part is given by the can have several purposes: substrate, and the coating adds superior - To defi ne, monitor and control spraying surface qualities such as corrosion, wear conditions for quality control or heat resistance. - For failure analysis Therefore thermal spray coatings are wide- - For developing new products. ly used in the aerospace and power gene- ration industry for new and refurbished The procedure normally involves coating sections and parts for jet engines and a test coupon to defi ne and optimize the gas turbines, compressors and pumps. process for the part to be sprayed. Sec- The properties of some coatings can only tions of this test coupon are then metal- be fabricated by thermal spraying, using lographically prepared and examined to mainly metals, ceramics, carbides and assess coating thickness, size and distribu- composites as well as mixtures of various tion of porosity, oxides and cracks, adhe- materials.
    [Show full text]
  • Properties of WC–10%Co–4%Cr Detonation Spray Coating Deposited on the Al–4%Cu–1%Mg Alloy
    materials Article Properties of WC–10%Co–4%Cr Detonation Spray Coating Deposited on the Al–4%Cu–1%Mg Alloy Marina Samodurova 1, Nataliya Shaburova 2,* , Olga Samoilova 2, Ahmad Ostovari Moghaddam 2 , Kirill Pashkeev 1, Vladimir Ul’yanitckiy 3 and Evgeny Trofimov 2 1 Resource Center for Special Metallurgy, South Ural State University, 76 Lenin Av., Chelyabinsk 454080, Russia; [email protected] (M.S.); [email protected] (K.P.) 2 Department of Materials Science, Physical and Chemical Properties of Materials, South Ural State University, 76 Lenin Av., Chelyabinsk 454080, Russia; [email protected] (O.S.); [email protected] (A.O.M.); [email protected] (E.T.) 3 Laboratory of Synthesis of Composite Materials, Institute of Hydrodynamics, M.A. Lavrent’ev SB RAS, 15 Lavrent’ev Av., Novosibirsk 630090, Russia; [email protected] * Correspondence: [email protected] Abstract: One of the methods of local improvement of the wear resistance of aluminum alloy parts is the deposition of hard tungsten carbide-based coatings on the surfaces subjected to intense external influence. This paper is devoted to the characterization of the WC–10Co–4Cr (wt.%) coating deposited on an Al–4Cu–1Mg (wt.%) alloy by the detonation spray method. In comparison with the common thermal spray techniques like High Velocity Oxygen Fuel (HVOF) or Atmospheric Plasma Spraying (APS), the heat input delivered to the substrate during detonation spray is significantly lower, that is especially important in case of coating deposition on aluminum alloys. The paper presents the Citation: Samodurova, M.; results of morphology investigation, microstructure, phase composition, microhardness, and cohesive Shaburova, N.; Samoilova, O.; strength of deposited carbide-based detonation spray coating.
    [Show full text]
  • SHS Powders for Thermal Spray Coating†
    SHS Powders for Thermal Spray Coating† T. Talako*, A. Ilyuschenko and A. Letsko Powder Metallurgy Institute1 Abstract The possibilities of preparing advanced powders for thermal spraying functional coatings by the method of self-propagating high-temperature synthesis are discussed in this review. Besides important economical and ecological benefits, the method allows the formation of powders with improved or unique structure and properties in size ranges and with an external morphology suitable for different thermal spray processes. A number of novel powders and recent achievements are presented. Keywords: self-propagating high-temperature synthesis, powder, thermal spray coating ent, depending on the spraying process, the operat- Introduction ing conditions, the desired properties of the final Modern industrial technologies call for the devel- coating, etc. Besides the intrinsic material properties, opment of novel materials with improved properties, the technical requirements for the TS feedstock pow- lower costs and environmentally suitable processes. ders include good flowability and sprayability. They Surface engineering that attempts to create func- are greatly affected by the particle size, shape and tional layers on the surface is obviously the most morphology as well as particle size distribution. That economical way to provide high performance to is why thermal spray feedstock powder production machinery and equipment. Among the wide range processes must be reliable and flexible, while remain- of available methods (including varieties of atomistic ing as inexpensive as possible. and particulate deposition, bulk coatings wetting Self-propagating high-temperature synthesis (SHS) processes and surface modification), thermal spray or combustion synthesis, discovered by A.G. Mer- coatings offer the most versatile solutions.
    [Show full text]
  • Detonation Thermal Spraying Process of Metal
    Technology Lappeenranta/Imatra Degree Programme in Mechanical Engineering and Production Technology Specialisation Andrey Vinogradov Detonation thermal spraying process of metal- ceramic coating of the inner body of a regulating valve for maintenance of turbine condensate level in a deaerator for a nuclear power plant Bachelor’s Thesis 2015 1 Abstract Andrey Vinogradov Detonation thermal spraying process of metal-ceramic coating of the inner body of a regulating valve for maintenance of turbine condensate level in a deaerator for a nuclear power plant, 41 pages, 3 appendices Saimaa University of Applied Sciences Technology Lappeenranta Degree Programme in Mechanical Engineering and Production Technology Bachelor’s Thesis 2015 Instructors: Lecturer Jukka Nisonen, Saimaa University of Applied Sciences Managing Director Zelenin Y.V., main process engineer Shvedov N.G., process engineer Karpenko D., Center of Scientific-Technical Service "Prometey" The objective of the research was to examine a process of metal-ceramic deto- nation spraying, technology and realization of the procedure and its features for the given component. The work was commissioned by main process engineer Shvedov N. G. This study was carried out at the Center of Scientific-Technical Service "Prometey". The information was gathered from internal documentation of the enterprise, manuals, literature and by interviewing process engineers. As a result of this thesis the detonation coating process was investigated for a particular unit – the regulating valve. All the stages and requirements were pre- sented. The results can be applied to any detonation coating case or surface treatment matter where complex approach is necessary. Keywords: coating, valve, deposition, spraying, mixture, powder, assembly, component, aluminum oxide, spraying gun, surface, nozzle, plunger, process.
    [Show full text]
  • Classic and Advanced Ceramics: from Fundamentals to Applications. Robert B
    Robert B. Heimann Classic and Advanced Ceramics From Fundamentals to Applications Robert B. Heimann Classic and Advanced Ceramics Related Titles Aldinger, F., Weberruss, V. A. Volume 4: Applications Advanced Ceramics and 2012 Future Materials Hardcover ISBN: 978-3-527-31158-3 An Introduction to Structures, Properties and Technologies Öchsner, A., Ahmed, W. (eds.) 2010 Hardcover Biomechanics of Hard Tissues ISBN: 978-3-527-32157-5 Modeling, Testing, and Materials 2010 Riedel, R., Chen, I-W. (eds.) Hardcover Ceramics Science and ISBN: 978-3-527-32431-6 Technology 4 Volume Set Krenkel, W. (ed.) Hardcover Ceramic Matrix Composites ISBN: 978-3-527-31149-1 Fiber Reinforced Ceramics and their Applications Volume 1: Structures 2008 Hardcover 2008 ISBN: 978-3-527-31361-7 Hardcover ISBN: 978-3-527-31155-2 Öchsner, A., Murch, G. E., de Lemos, M. J. S. (eds.) Volume 2: Properties Cellular and Porous Materials 2010 Hardcover Thermal Properties Simulation and Prediction ISBN: 978-3-527-31156-9 2008 Hardcover ISBN: 978-3-527-31938-1 Volume 3: Synthesis and Processing 2010 Hardcover ISBN: 978-3-527-31157-6 Robert B. Heimann Classic and Advanced Ceramics From Fundamentals to Applications The Author All books published by Wiley-VCH are carefully produced. Nevertheless, authors, editors, and Prof. Dr. Robert B. Heimann publisher do not warrant the information Am Stadtpark 2A contained in these books, including this book, to 02826 Görlitz be free of errors. Readers are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate. Library of Congress Card No.: applied for British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library.
    [Show full text]
  • Mechanical Characterization of Composite Coatings Formed by Reactive Detonation Spraying of Titanium
    metals Article Mechanical Characterization of Composite Coatings Formed by Reactive Detonation Spraying of Titanium Sergey Panin 1,2,3,* ID , Ilya Vlasov 2,3, Dina Dudina 4,5 ID , Vladimir Ulianitsky 4, Roman Stankevich 3, Igor Batraev 4 and Filippo Berto 6 1 College of Physics, Jilin University, Changchun 130022, China 2 Institute of Strength Physics and Materials Science SB RAS, Tomsk 634055, Russia; [email protected] 3 Department of Materials Science in Mechanical Engineering, National Research Tomsk Polytechnic University, Tomsk 634050, Russia; [email protected] 4 Laboratory of Detonation Flows, Lavrentyev Institute of Hydrodynamics SB RAS, Novosibirsk 630090, Russia; [email protected] (D.D.); [email protected] (V.U.); [email protected] (I.B.) 5 Department of Mechanical Engineering and Technologies, Novosibirsk State Technical University, Novosibirsk 630073, Russia 6 Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway; fi[email protected] * Correspondence: [email protected]; Tel.: +7-3822-286-904 Received: 18 August 2017; Accepted: 5 September 2017; Published: 8 September 2017 Abstract: The structure and mechanical properties of the coatings formed by reactive detonation spraying of titanium in a wide range of spraying conditions were studied. The variable deposition parameters were the nature of the carrier gas, the spraying distance, the O2/C2H2 ratio, and the volume of the explosive mixture. The phase composition of the coatings and the influence of the spraying parameters on the mechanical properties of the coatings were investigated. In addition, nanohardness of the individual phases contained in the coatings was evaluated. It was found that the composition of the strengthening phases in the coatings depends on the O2/C2H2 ratio and the nature of the carrier gas.
    [Show full text]
  • The Effect of Detonation Spraying on the Phase Composition And
    160 Eurasian Journal of Physics and Functional Materials 2020, 4(2), 160-166 The effect of detonation spraying on the phase composition and hardness of Al2O3 coatings B.K. Rakhadilov∗,1,2, D.B. Buytkenov1, D. Kakimzhanov1, R.S. Kozhanova2, G.S. Bektasova1 1S. Amanzholov East Kazakhstan State University, Ust-Kamenogorsk, Kazakhstan 2Limited partnership «PlasmaScience», Ust-Kamenogorsk, Kazakhstan E-mail: [email protected] DOI: 10.29317/ejpfm.2020040207 Received: 07.04.2020 - after revision The article were studied the effect of detonation spraying on the structure and properties of Al 2 O 3 coatings. It was determined that reducing the delay time between shots is leading to increase the hardness and elastic module of Al 2 O 3 coatings. It was found on the basis of X-ray diffraction analysis that the main reason for the increasing in hardness with a decreasing in the delay time between shots is associated with increasing in the volume fraction of α -Al 2 O 3 phase. The studies of X-ray diffraction presented that the highest content of the phase is achieved when the coatings are formed with a delay time between shots of 0.25 s. It was found that increasing in the volume fraction of the α -Al 2 O 3 phase is caused by the secondary recrystallization γ → α , which occurs due to the heating of particles during ◦ coating formation, i.e. due to increasing in temperature above 1100 C in single spots of the coating when they are put each other. Keywords: detonation deposition, aluminum oxide, phase, hardness, coating.
    [Show full text]
  • Structure and Properties of Coatings Formed by Detonation Spraying of Titanium Powder
    MTMNG IOP Publishing IOP Conf. Series: Materials Science and Engineering1234567890 286 (2017) 012025 doi:10.1088/1757-899X/286/1/012025 Structure and Properties of Coatings Formed by Detonation Spraying of Titanium Powder S V Panin1,2,3, I V Vlasov2,3, R V Stankevich3, D V Dudina4,5, V Yu Ulyanitsky4 and I S Batraev4 1Jilin University, 4026 Yatai St, Nanguan Qu, Changchun Shi, 130022, China 2Institute of Strength Physics and Materials Science SB RAS, 2/4, pr. Akademicheskii, Tomsk, 634055, Russia 3National Research Tomsk Polytechnic University, 30, Lenin Avenue, Tomsk, 634050, Russia 4Lavrentyev Institute of Hydrodynamics SB RAS, 15, pr. ac. Lavrentyeva, Novosibirsk, 630090, Russia 5Novosibirsk State Technical University, 20, pr. K. Marksa, Novosibirsk, 630073, Russia E-mail: [email protected] Abstract. Structure and properties of the coatings formed by detonation spraying of titanium powder have been studied at varying the deposition parameters (nature of carrier gas, spraying distance, O2/C2H2 ratio, and the volume of explosive mixture). It is shown that when air is used as the carrier gas the primary strengthening by the titanium oxide phases is realized. When nitrogen is introduced into the explosive mixture, a more complicated mechanism of hardening is realized due to the formation of titanium oxides, carbides, oxynitrides and carbonitrides. The aspects of employing the revealed “rational” modes of the detonation spraying for formation of protective composite coatings based on titanium possessing a complex of improved physical and mechanical properties are discussed. 1. Introduction At present, several coating deposition methods are known and widely used in the industry. One of the efficient technologies for restoration, repair and strengthening of machine parts is cold gas-dynamic spraying.
    [Show full text]
  • Improving Wear Resistance of Grey Cast Iron Using Detonation Gun Sprayed Coatings: a Review
    www.ijemr.net ISSN (ONLINE): 2250-0758, ISSN (PRINT): 2394-6962 Volume-5, Issue-1, February-2015 International Journal of Engineering and Management Research Page Number: 303-307 Improving Wear Resistance of Grey Cast Iron using Detonation Gun Sprayed Coatings: A Review Gobind1, Jawala Parshad2, Dr. Neel Kanth Grover3 1,2,3Department of Mechanical Engineering, S.B.S.S.T.C, Ferozepur, Punjab, INDIA ABSTRACT finely divided metallic or nonmetallic materials are Materials are precious resources. Different methods deposited in a molten or semi molten condition to form a and techniques are employed to protect the materials from coating. The coating material may be in the form of degradation. As the wear is a surface phenomenon and occurs powder, ceramic-rod, wire, or molten materials [2]. mostly at outer surfaces. Failure of mechanical components As shown in figure 1, Thermal spraying can provide due to wear is the most common and unavoidable problem in thick coatings (approx. thickness range is 20 micrometers automobiles, power generation units (hydro power plants), construction equipments, marine sector, gas and fuel to several mm, depending on the process and feedstock), pipelines and other mechanical processing industries. It not over a large area at high deposition rate as compared to only affects the life of a component but also reduces its other coating processes such performances. Therefore due to heavy economic losses as electroplating, physical and chemical vapor deposition. associated with wear, this problem has attracted the attention Coating materials available for thermal spraying include of the researchers worldwide. To overcome this problem of metals, alloys, ceramics, plastics and composites.
    [Show full text]
  • Thermal Spraying
    Thermal Spraying Thermal Spraying DIN 32530: Thermal spraying comprises processes that feature: - full or partial melting of spraying feedstock (or at least sufficient heat transfer in order to provide a state of high plastic deformation capability) inside or outside a spraying torch - propelling of spray particles onto a prepared substrate surface - substrate surface is (usually) not melted Definition Heat and Momentum Substrate Transfer Spraying gun Energy source -Flame -Arc -Plasma Spraying feedstock -Powder -Wire -Rod Principle of Thermal Spraying Coating formation Thermal Spraying Spraying direction Pores Oxides Heat flux Lateral spreading Contact zones Impact of spray particles on substrates Pore Oxidized particle Not fully molten particle Substrate Formation of thermal spray coatings t = 0.00 µs -50 µm 0 50 t = 0.08 µs t = 0.03 µs -50 µm -50 0 µm 0 50 50 t = 0.13 µs d = 50 µm, v = 200 m/s Spreading of a AlPart. Part. -50 µm 0 50 2 O 3 particle on a substrate t = 0.23 µs -50 µm 0 50 t = 0.62 µs t = 0.36 µs -50 µm -50 0 µm 0 50 50 t = 5.00 µs d = 50 µm, v = 200 m/s Spreading of an AlPart. Part. -50 µm 0 50 2 O 3 particle on a substrate 15 30 45 60 75 > 75 P [MPa] t = 0.04 µs t = 0.10 µs -0.1 0.1 -0.1 0.1 mm mm t = 0.06 µs t = 0.23 µs -0.1 0.1 -0.1 0.1 mm mm t = 0.09 µs t = 0.36 µs -0.1 0.1 -0.1 0.1 mm mm Pressure distribution in an Al2O3 particle during spreading on a steel substrate white dashs: t = 0.62 µs solidification boundary -0.10 0.10 [mm] Temperature [K] t = 3.00 µs -0.10 0.10 > 1550 [mm] > 1300 >1050 t = 10.00 µs -0.10
    [Show full text]