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Pierre Fauchais - One of the best experts on this subject based on the ideXlab platform.
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Al2O3-ZrO2 Finely Structured Multilayer Architectures from Suspension Plasma Spraying
Journal of Thermal Spray Technology, 2017Co-Authors: Olivier Tingaud, Jean François Coudert, Vincent Rat, Alain Denoirjean, Ghislain Montavon, Pierre FauchaisAbstract:Suspension Plasma Spraying (SPS) is an alternative to conventional atmospheric Plasma Spraying (APS) aiming at manufacturing thinner layers (i.e., 10-100 lm) due to the specific size of the feedstock particles, from a few tens of nanometers to a few micrometers. The staking of lamellae and particles, which present a diameter ranging from 0.1 to 2.0 lm and an average thickness from 20 to 300 nm, permits to manufacture finely structured layers. Moreover, it appears as a versatile process able to manufacture different coating architectures according to the operating parameters (suspension properties, injection configuration, Plasma properties, spray distance, torch scan velocity, scanning step, etc.). However, the different parameters controlling the properties of the coating, and their interdependences, are not yet fully identified. Thus, the aim of this paper is, on the one hand, to better understand the influence of operating parameters on the coating manufacturing mechanisms (in particular, the Plasma gas mixture effect) and, on the other hand, to produce Al2O3-ZrO2 finely structured layers with large varieties of architectures. For this purpose, a simple theoretical model was used to describe the Plasma torch operating conditions at the nozzle exit, based on experimental data (mass enthalpy, arc current intensity, thermophysical properties of Plasma forming gases, etc.) and the influences of the spray parameters were determined by mean of the study of sizes and shapes of spray beads. The results enabled then to reach a better understanding of involved phenomena and their interactions on the final coating architectures permitting to manufacture several types of microstructures.
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Latest Researches Advances of Plasma Spraying: From Splat to Coating Formation
Journal of Thermal Spray Technology, 2016Co-Authors: Pierre Fauchais, Michel Vardelle, Simon GoutierAbstract:The Plasma spray process with solid feedstock, mainly ceramics powders, studied since the sixties is now a mature technology. The Plasma jet and particle in-flight characterizations are now well established. The use of computer-aided robot trajectory allows Spraying on industrial parts with complex geometries. Works about splat formation have shown the importance of: the substrate preheating over the transition temperature to get rid of adsorbates and condensates, substrate chemistry, crystal structure and substrate temperature during the whole coating process. These studies showed that coating properties strongly depend on the splat formation and layering. The first part of this work deals with a summary of conventional Plasma Spraying key points. The second part presents the current knowledge in Plasma Spraying with liquid feedstock, technology developed for about two decades with suspensions of particles below micrometers or solutions of precursors that form particles a few micrometers sized through precipitation. Coatings are finely structured and even nanostructured with properties arousing the interest of researchers. However, the technology is by far more complex than the conventional ones. The main conclusions are that models should be developed further, Plasma torches and injection setups adapted, and new measuring techniques to reliably characterize these small particles must be designed.
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What Do We Know, What are the Current Limitations of Suspension Plasma Spraying?
Journal of Thermal Spray Technology, 2015Co-Authors: Pierre Fauchais, Michel Vardelle, Armelle Vardelle, Simon GoutierAbstract:Nano-structured coatings should exhibit better properties than micro-structured coatings because of a high volume fraction of internal interfaces. Since the mid-nineties a large body of works have been devoted to suspension and solution Plasma Spraying for the deposition of finely and even nanometer-structured coatings. The aim of this paper is to take stock of our present knowledge in the field of suspension Plasma Spraying that is, at the moment, essentially used for oxide ceramic coatings. It will first tackle the injection of the suspension in the Plasma jet and the behavior of nano or sub-micro-meter particles processed in the Plasma jet core involving the liquid breakup and vaporization that releases the solid particles from the solvent droplets. It will, then, deal with the Plasma torches and liquid feeding systems available to suspension Spraying. It will finally discuss the key characteristics of suspensions (solvent, dispersant, and particle morphologies), designing of coating microstructure, and potential industrial applications, with the developments requested to cope with these applications.
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Specific Measurements of In-Flight Droplet and Particle Behavior and Coating Microstructure in Suspension and Solution Plasma Spraying
Journal of Thermal Spray Technology, 2015Co-Authors: Pierre Fauchais, Simon Goutier, Michel Vardelle, Armelle VardelleAbstract:© 2015, ASM International.The Plasma Spraying of suspensions of sub-micro- or nano-sized particles and of solutions of chemicals precursors produces finely structured coatings that have generally enhanced properties compared to conventional Plasma-sprayed coatings. However, most techniques used in conventional Plasma Spraying are no more adapted to experimentally observe the behavior of the liquid feedstock in the Plasma jet and investigate the effect of the operating conditions on liquid fragmentation in droplets, solid particles released by solvent evaporation or formed from the chemical precursors. Also, specific techniques have to be used to study the coating formation and characterize its microstructure. This paper aims to present the main techniques developed or adapted, up to now, to study the Plasma-liquid feedstock interactions and characterize the coatings achieved by suspension and solution Plasma Spraying.
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D.C. Plasma Spraying
Thermal Spray Fundamentals, 2014Co-Authors: Pierre Fauchais, Joachim V R Heberlein, Maher I. BoulosAbstract:In Plasma Spraying, an electric arc generates Plasma within a Plasma torch. The arc is struck between a cathode (usually a rod or button-type design) and a cylindrical anode nozzle, and the Plasma gas is injected at the base of the cathode, heated by the arc, and exits the nozzle as a high temperature, high velocity jet (see Fig. 7.1). Figure 2.1 presents the details of coating generation by Plasma Spraying.
Alain Denoirjean - One of the best experts on this subject based on the ideXlab platform.
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Al2O3-ZrO2 Finely Structured Multilayer Architectures from Suspension Plasma Spraying
Journal of Thermal Spray Technology, 2017Co-Authors: Olivier Tingaud, Jean François Coudert, Vincent Rat, Alain Denoirjean, Ghislain Montavon, Pierre FauchaisAbstract:Suspension Plasma Spraying (SPS) is an alternative to conventional atmospheric Plasma Spraying (APS) aiming at manufacturing thinner layers (i.e., 10-100 lm) due to the specific size of the feedstock particles, from a few tens of nanometers to a few micrometers. The staking of lamellae and particles, which present a diameter ranging from 0.1 to 2.0 lm and an average thickness from 20 to 300 nm, permits to manufacture finely structured layers. Moreover, it appears as a versatile process able to manufacture different coating architectures according to the operating parameters (suspension properties, injection configuration, Plasma properties, spray distance, torch scan velocity, scanning step, etc.). However, the different parameters controlling the properties of the coating, and their interdependences, are not yet fully identified. Thus, the aim of this paper is, on the one hand, to better understand the influence of operating parameters on the coating manufacturing mechanisms (in particular, the Plasma gas mixture effect) and, on the other hand, to produce Al2O3-ZrO2 finely structured layers with large varieties of architectures. For this purpose, a simple theoretical model was used to describe the Plasma torch operating conditions at the nozzle exit, based on experimental data (mass enthalpy, arc current intensity, thermophysical properties of Plasma forming gases, etc.) and the influences of the spray parameters were determined by mean of the study of sizes and shapes of spray beads. The results enabled then to reach a better understanding of involved phenomena and their interactions on the final coating architectures permitting to manufacture several types of microstructures.
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Tribological performances of YSZ composite coatings manufactured by suspension Plasma Spraying
Surface and Coatings Technology, 2013Co-Authors: Geoffrey Darut, Hélène Ageorges, Alain Denoirjean, Pierre FauchaisAbstract:Nanostructured coatings are more and more considered in scientific literature because of their benefit contributions in improving coating properties such as toughness, wear resistance or thermal properties. In conventional Plasma Spraying, agglomeration of nanometer-sized particles into micrometer-sized feedstock can be injected using a carrier gas to obtain a bimodal structure. Or, since now ten years, a liquid carrier (Suspension Plasma Spray process, SPS) is employed to drive nanometer or sub-micrometer sized particles into the Plasma jet with a limited agglomeration of the particles. With SPS, the reduced microstructural size of coatings improves their tribological properties, especially for ceramic coatings.This study aims at studying yttria stabilized zirconia (YSZ) coatings manufactured by suspension Plasma Spraying. The primary objective of this work is to improve tribological performances of YSZ coatings, which is found to be better when a higher Plasma enthalpy is used to elaborate them. The second objective is to incorporate reinforcements within the YSZ matrix to improve further performances. In that way SiC has been included in the YSZ matrix resulting in a higher wear resistance. © 2012 Elsevier B.V.
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Suspension DC Plasma Spraying of thick finely-structured ceramic coatings: Process manufacturing mechanisms
Surface and Coatings Technology, 2009Co-Authors: Olivier Tingaud, Antoine Bacciochini, Alain Denoirjean, Ghislain Montavon, Pierre FauchaisAbstract:Due to the large volume fraction of the internal interfaces and reduced size of stacking defects, thick (from 20 to 100 μm) nano- or sub-micron structured coatings exhibit better properties than conventional micron structured ones (e.g. higher coefficients of thermal expansion, lower thermal diffusivity, higher hardness and toughness, better wear resistance, among other coating characteristics and functional properties). They could hence offer pertinent solutions to numerous emerging applications, in particular for energy production, energy saving, diffusion and environmental barriers, etc. Suspension Plasma Spraying (SPS) permits to manufacture such finely-structured layers and consists in mechanically injecting within the Plasma flow a liquid suspension of sub-micrometric-sized or nano-sized particles through an injector of diameter of the order of one hundred micrometers. Upon penetration within the DC Plasma jet, two phenomena occur sequentially: droplet fragmentation and then solvent evaporation. Particles are then processed by the Plasma flow (heat and momentum transfers) prior to their impact, flattening and solidification upon the surface to be covered. Compared to Plasma Spraying of micrometer-sized particles (APS), SPS exhibit several major differences : i) a more pronounced sensitivity to electric are root fluctuation requiring to operate the spray gun in a relatively stable mode (take over) unless to process inhomogeneously the suspension which would results in heterogeneous coating structure; ii) a shorter spray distance (since small particles decelerate faster than bigger ones) leading to higher thermal flux transmitted from the Plasma flow to the substrate (5 to 10 times higher than conventional Plasma Spraying); iii) an emphasized thermophoresis effect; iv) a typical cohesive structure made of the stacking of granular and flattened particles with low density of stacking defects. This paper aims at presenting recent developments carried-out on this process in terms of process optimization and coating manufacturing mechanisms. © 2008 Elsevier B.V. All rights reserved.
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Suspension Plasma Spraying: Process parameters and resulting coating architecture
PPPS-2007 - Pulsed Power Plasma Science 2007, 2007Co-Authors: Jean François Coudert, Hélène Ageorges, Vincent Rat, N. Caron, Alain Denoirjean, Ghislain Montavon, Pierre Fauchais, S. AlexandreAbstract:Due to the large volume fraction of the internal interfaces, finely structured coatings (nano- or submicronsized) should exhibit better properties than the ones structured at a microscale. Suspension Plasma Spraying (SPS) appears as a technology permitting to manufacture such coatings and consisting in injecting within a Plasma jet a liquid suspension of solid particles. Compared to Plasma Spraying of micron-sized particles, SPS exhibit several major differences: i) a more pronounced sensitivity to arc root fluctuations requiring to adapt operating parameters; ii) a shorter spray distance; iii) a higher thermal flux transmitted from the Plasma jet to the substrate. Several operating parameters, including suspension characteristics and suspension injection parameters, play relevant roles in the suspension processing and the resulting coating architecture. © 2007 IEEE.
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Suspension Plasma Spraying of Zirconia coatings: Process and coating structure
18th International Symposium on Plasma Chemistry Kyoto: Japan, 2007Co-Authors: Olivier Tingaud, R. Etchart-salas, Jean François Coudert, Hélène Ageorges, Vincent Rat, Alexis Grimaud, Alain DenoirjeanAbstract:Summary form only given. Due to the large volume fraction of the internal interfaces, coatings structured at the nanoscale should exhibit better properties than conventional coatings structured at the microscale. However, when processing by thermal Plasmas such feedstock, several questions arise: (i) how feeding the Plasma jet with nanosized powders? (ii) how keeping their nanostructured structures when melting them? (iii) how controlling the growth of coating's grain? Suspension Plasma Spraying (SPS) appears as a technology permitting to circumvent those difficulties. It consists in mechanically injecting within the Plasma flow a liquid suspension of particles of average diameter varying between 0.1 and 1 mum through an injector of diameter in the order of one hundred micrometers. Upon penetration within the DC Plasma jet, two phenomena occur sequentially: droplet fragmentation and then evaporation (lasting, in average, two orders of magnitude longer than fragmentation). Particles are then processed by the Plasma flow prior their impact, spreading and solidification upon the surface to be covered. Compared to Plasma Spraying of micron-sized particles, SPS exhibit several major differences: (i) a more pronounced sensitivity to arc root fluctuations requiring to adapt operating parameters in order to operate the spray gun in its take over mode unless to have inhomogeneous process of the suspension by the Plasma: (ii) a shorter spray distance since small particles decelerate faster than bigger ones; (iii) a higher thermal flux transmitted from the Plasma flow to the substrate, between 5 to 10 times higher than the heat flux transmitted in conventional Plasma Spraying. In consequence, coatings manufactured by SPS differ from conventional coatings by: (i) a more pronounced sensitivity to the particle size distribution: narrow-sized ones are absolutely required to produce dense layers; (ii) lamella characteristic dimensions smaller than the ones encountered in conventio-\nnal Plasma Spraying (with lower flattening ratio due to lower particle Reynolds numbers upon impact) with almost no peripheral splashing (due to lower particle adjusted Sommerfeld numbers upon impact); (iii) lower residual stress levels within lamellae which limit the development of intralamellar cracks; (iv) a denser structure with almost no pore connectivity. This paper aims at presenting the SPS of alumina coatings in terms of: (i) suspension characteristics on the coating architecture; (ii) process optimization, emphasizing the predominant role of the arc root fluctuations on the coating architecture; (iii) resulting coating architectures, in particular in terms of their pore network architecture.
Detlev Stöver - One of the best experts on this subject based on the ideXlab platform.
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characteristics of ceramic coatings made by thin film low pressure Plasma Spraying lpps tf
Journal of Thermal Spray Technology, 2012Co-Authors: Andreas Hospach, Georg Mauer, Robert Vasen, Detlev StöverAbstract:The thin film low pressure Plasma spray process (LPPS-TF) has been developed with the aim of efficient depositing uniform and thin coatings with large area coverage by Plasma Spraying. At high power input (~150 kW) and very low pressure (~100 Pa) the Plasma jet properties change considerably and it is even possible to evaporate the powder feedstock material providing advanced microstructures of the deposits. This relatively new technique bridges the gap between conventional Plasma Spraying and physical vapor deposition. In addition, the resulting microstructures are unique and can hardly be obtained by other processes. In this paper, microstructures made by LPPS-TF are shown and the columnar layer growth by vapor deposition is demonstrated. In addition to the ceramic materials TiO2, Al2O3 or MgAl2O4, the focus of the research was placed on partially yttria-stabilized zirconia. Variations of the microstructures are shown and discussed concerning potential coating applications.
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columnar structured thermal barrier coatings tbcs by thin film low pressure Plasma Spraying lpps tf
Journal of Thermal Spray Technology, 2011Co-Authors: Andreas Hospach, Georg Mauer, Robert Vasen, Detlev StöverAbstract:The very low-pressure Plasma Spray (VLPPS) process has been developed with the aim of depositing uniform and thin coatings with coverage of a large area by Plasma Spraying. At typical pressures of 100-200 Pa, the characteristics of the Plasma jet change compared to conventional low-pressure Plasma-Spraying processes (LPPS) operating at 5-20 kPa. The combination of Plasma Spraying at low pressures with enhanced electrical input power has led to the development of the LPPS-TF process (TF = thin film). At appropriate parameters, it is possible to evaporate the powder feedstock material providing advanced microstructures of the deposits. This technique offers new possibilities for the manufacturing of thermal barrier coatings (TBCs). Besides the material composition, the microstructure is an important key to reduce thermal conductivity and to increase strain tolerance. In this regard, columnar microstructures deposited from the vapor phase show considerable advantages. Therefore, physical vapor deposition by electron beam evaporation (EB-PVD) is applied to achieve such columnar-structured TBCs. However, the deposition rate is low, and the line-of-sight nature of the process involves specific restrictions. In this article, the deposition of TBCs by the LPPS-TF process is shown. How the evaporation of the feedstock powder could be improved and to what extent the deposition rates could be increased were investigated.
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Study on instant droplet and particle stages during suspension Plasma Spraying (SPS)
Surface and Coatings Technology, 2008Co-Authors: Holger Kassner, Robert Vaßen, Detlev StöverAbstract:Suspension Plasma Spraying (SPS) is a new process in the field of the atmospheric Plasma Spraying (APS). The SPS process uses a heterogeneous mixture of liquids and particles. Thus it is possible to process particles with a size between ten to a few hundred nanometres. This leads to completely new or at least improved material features and structures. Notwithstanding the process and the involved mechanisms that lead from a suspension droplet to a molten ceramic droplet and its influence on the generated coating are not yet completely understood. Because of the liquid in the suspension and much smaller particles the process in the Plasma is much more complex compared to the APS process. Based on empiric studies including in-flight monitoring of the particles as well as splat and coating analyses a new schematic of the single stages during suspension Plasma Spraying and their influence on the coating structure will be introduced. © 2008 Elsevier B.V. All rights reserved.
Olivier Tingaud - One of the best experts on this subject based on the ideXlab platform.
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Al2O3-ZrO2 Finely Structured Multilayer Architectures from Suspension Plasma Spraying
Journal of Thermal Spray Technology, 2017Co-Authors: Olivier Tingaud, Jean François Coudert, Vincent Rat, Alain Denoirjean, Ghislain Montavon, Pierre FauchaisAbstract:Suspension Plasma Spraying (SPS) is an alternative to conventional atmospheric Plasma Spraying (APS) aiming at manufacturing thinner layers (i.e., 10-100 lm) due to the specific size of the feedstock particles, from a few tens of nanometers to a few micrometers. The staking of lamellae and particles, which present a diameter ranging from 0.1 to 2.0 lm and an average thickness from 20 to 300 nm, permits to manufacture finely structured layers. Moreover, it appears as a versatile process able to manufacture different coating architectures according to the operating parameters (suspension properties, injection configuration, Plasma properties, spray distance, torch scan velocity, scanning step, etc.). However, the different parameters controlling the properties of the coating, and their interdependences, are not yet fully identified. Thus, the aim of this paper is, on the one hand, to better understand the influence of operating parameters on the coating manufacturing mechanisms (in particular, the Plasma gas mixture effect) and, on the other hand, to produce Al2O3-ZrO2 finely structured layers with large varieties of architectures. For this purpose, a simple theoretical model was used to describe the Plasma torch operating conditions at the nozzle exit, based on experimental data (mass enthalpy, arc current intensity, thermophysical properties of Plasma forming gases, etc.) and the influences of the spray parameters were determined by mean of the study of sizes and shapes of spray beads. The results enabled then to reach a better understanding of involved phenomena and their interactions on the final coating architectures permitting to manufacture several types of microstructures.
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Suspension DC Plasma Spraying of thick finely-structured ceramic coatings: Process manufacturing mechanisms
Surface and Coatings Technology, 2009Co-Authors: Olivier Tingaud, Antoine Bacciochini, Alain Denoirjean, Ghislain Montavon, Pierre FauchaisAbstract:Due to the large volume fraction of the internal interfaces and reduced size of stacking defects, thick (from 20 to 100 μm) nano- or sub-micron structured coatings exhibit better properties than conventional micron structured ones (e.g. higher coefficients of thermal expansion, lower thermal diffusivity, higher hardness and toughness, better wear resistance, among other coating characteristics and functional properties). They could hence offer pertinent solutions to numerous emerging applications, in particular for energy production, energy saving, diffusion and environmental barriers, etc. Suspension Plasma Spraying (SPS) permits to manufacture such finely-structured layers and consists in mechanically injecting within the Plasma flow a liquid suspension of sub-micrometric-sized or nano-sized particles through an injector of diameter of the order of one hundred micrometers. Upon penetration within the DC Plasma jet, two phenomena occur sequentially: droplet fragmentation and then solvent evaporation. Particles are then processed by the Plasma flow (heat and momentum transfers) prior to their impact, flattening and solidification upon the surface to be covered. Compared to Plasma Spraying of micrometer-sized particles (APS), SPS exhibit several major differences : i) a more pronounced sensitivity to electric are root fluctuation requiring to operate the spray gun in a relatively stable mode (take over) unless to process inhomogeneously the suspension which would results in heterogeneous coating structure; ii) a shorter spray distance (since small particles decelerate faster than bigger ones) leading to higher thermal flux transmitted from the Plasma flow to the substrate (5 to 10 times higher than conventional Plasma Spraying); iii) an emphasized thermophoresis effect; iv) a typical cohesive structure made of the stacking of granular and flattened particles with low density of stacking defects. This paper aims at presenting recent developments carried-out on this process in terms of process optimization and coating manufacturing mechanisms. © 2008 Elsevier B.V. All rights reserved.
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Suspension Plasma Spraying of Zirconia coatings: Process and coating structure
18th International Symposium on Plasma Chemistry Kyoto: Japan, 2007Co-Authors: Olivier Tingaud, R. Etchart-salas, Jean François Coudert, Hélène Ageorges, Vincent Rat, Alexis Grimaud, Alain DenoirjeanAbstract:Summary form only given. Due to the large volume fraction of the internal interfaces, coatings structured at the nanoscale should exhibit better properties than conventional coatings structured at the microscale. However, when processing by thermal Plasmas such feedstock, several questions arise: (i) how feeding the Plasma jet with nanosized powders? (ii) how keeping their nanostructured structures when melting them? (iii) how controlling the growth of coating's grain? Suspension Plasma Spraying (SPS) appears as a technology permitting to circumvent those difficulties. It consists in mechanically injecting within the Plasma flow a liquid suspension of particles of average diameter varying between 0.1 and 1 mum through an injector of diameter in the order of one hundred micrometers. Upon penetration within the DC Plasma jet, two phenomena occur sequentially: droplet fragmentation and then evaporation (lasting, in average, two orders of magnitude longer than fragmentation). Particles are then processed by the Plasma flow prior their impact, spreading and solidification upon the surface to be covered. Compared to Plasma Spraying of micron-sized particles, SPS exhibit several major differences: (i) a more pronounced sensitivity to arc root fluctuations requiring to adapt operating parameters in order to operate the spray gun in its take over mode unless to have inhomogeneous process of the suspension by the Plasma: (ii) a shorter spray distance since small particles decelerate faster than bigger ones; (iii) a higher thermal flux transmitted from the Plasma flow to the substrate, between 5 to 10 times higher than the heat flux transmitted in conventional Plasma Spraying. In consequence, coatings manufactured by SPS differ from conventional coatings by: (i) a more pronounced sensitivity to the particle size distribution: narrow-sized ones are absolutely required to produce dense layers; (ii) lamella characteristic dimensions smaller than the ones encountered in conventio-\nnal Plasma Spraying (with lower flattening ratio due to lower particle Reynolds numbers upon impact) with almost no peripheral splashing (due to lower particle adjusted Sommerfeld numbers upon impact); (iii) lower residual stress levels within lamellae which limit the development of intralamellar cracks; (iv) a denser structure with almost no pore connectivity. This paper aims at presenting the SPS of alumina coatings in terms of: (i) suspension characteristics on the coating architecture; (ii) process optimization, emphasizing the predominant role of the arc root fluctuations on the coating architecture; (iii) resulting coating architectures, in particular in terms of their pore network architecture.
Akira Kobayashi - One of the best experts on this subject based on the ideXlab platform.
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Oxidation mechanism of metal coatings on plastic substrate by gas tunnel type Plasma Spraying
2015Co-Authors: Akira Kobayashi, Fujimoto Koji, Takeuchi Tsunehiro, Zahisham Yusof, Komurasaki Kimiya, Koizumi Hiroyuki, S. YuguswaranAbstract:Plastic components are widely used in many industries like aerospace and auto mobile industries due to its low weight and high corrosion resistance. In this study the metal coatings were formed on plastic substrate by using the gas tunnel type Plasma Spraying. Metal coatings such as Cu, Ni and Ti were successfully deposited on the PET surface by this gas tunnel type Plasma Spraying technique at selective operating conditions. The microstructure and mechanical properties of these coatings were investigated, and those results were discussed. The oxidation of metals during the Spraying processes with respect to Spraying conditions was examined and the results are discussed.
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Metallic glass coatings fabricated by gas tunnel type Plasma Spraying
Vacuum, 2014Co-Authors: S. Yugeswaran, Akira KobayashiAbstract:Abstract Gas tunnel type Plasma Spraying is a renowned technique due to its greater advantages than other conventional Plasma Spraying followed by high speed and high energy density Plasma jet. Furthermore, this is a simple and novel process for producing dense metallic coatings with and without secondary phases such as oxides and intermetallic phases under selective operating parameters. The present work was undertaken to study the formation mechanism and for examining the metallic glass coating properties formed through gas tunnel type Plasma Spraying process. For this purpose, Fe based, Zr based and Ni based metallic glass coatings were individually deposited by gas tunnel type Plasma spray torch at optimum operating conditions with two different input currents (300 and 400 A). Phase and microstructure formations were examined and the results were correlated with the input current. Similarly, mechanical properties and electrochemical corrosion properties of each coating were examined and the results were correlated with the existing phase and the microstructures of the coatings. The examined results revealed that the Fe based metallic glass coatings have relatively less porosity (3–4%) and crystalline phase fraction (9–14%). These coatings also exhibit excellent sliding wear resistance (2.77 × 10 −6 mm 3 /nm −1 ) and electrochemical corrosion resistance against 3.5% NaCl solution.
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Fe-based metallic glass coatings produced by smart Plasma Spraying process
Materials Science and Engineering B-advanced Functional Solid-state Materials, 2008Co-Authors: Akira Kobayashi, Shoji Yano, Hisamichi Kimura, Akihisa InoueAbstract:Abstract Metallic glass has excellent functions such as high toughness and corrosion resistance. Therefore it is one of the most attractive materials, and many researchers have conducted various developmental research works. However, the metallic glass material is expensive and a composite material is preferred for the industrial application. Thermal Spraying method is a potential candidate to produce metallic glass composites. The gas tunnel type Plasma system is useful for smart Plasma processing to obtain high quality ceramic coatings such as alumina (Al2O3) and zirconia (ZrO2) coatings. Also, the gas tunnel type Plasma Spraying can produce metallic glass coatings. In this study, the Fe-based metallic glass coatings were produced by gas tunnel type Plasma Spraying, and the microstructure and some properties were investigated. The amorphous phase of this metallic glass coating was confirmed by the XRD method. The Fe-based metallic glass coatings of about 200 μm in thickness were dense with a Vickers hardness of about Hv = 1100 at Plasma current of 300 A.