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1
Jeandin, Michel, Dimitris Christoulis, Francois Borit, Marie Helene Berger, S. Guetta, G. Rolland, Vincent Guipont, et al. "Lasers and Thermal Spray." Materials Science Forum 638-642 (January 2010): 174–81. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.174.
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Basically, thermal spray and laser processing can be considered as half brothers since they show many common features due to the use of a (more or less) high-energy source for both. Their combination can therefore be very fruitful and prominent to achieve coatings, which results in their most recent and advanced applications. In the materials processing development story, the laser will thus have moved from cutting to coating. This keynote presentation focuses on the recently-developed coupling of laser processing to cold spray). In this dual process, a cold spray gun is combined to a laser head in a single device, e.g. on a robot. Series of coating experiments using various laser irradiation conditions, primarily pulse frequency, were carried out for Al-based and Ni-based alloys. Laser pre-treatment of the substrate just prior to cold spray, was shown to be beneficial for adhesion of cold-sprayed coatings. Adhesion improvement was exhibited and studied from LASATesting (LASAT for “LAser Shock Adhesion Test”). Incidentally, through LASAT also, the role of lasers in the development of thermally-sprayed coatings can be considered as major. Results are discussed in the light of a TEM (Transmission Electron Microscope) study of the coating-substrate interface with and without laser pre-treatment.
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Raza, Ali, Faiz Ahmad, Thar M. Badri, M. R. Raza, and Khurshid Malik. "An Influence of Oxygen Flow Rate and Spray Distance on the Porosity of HVOF Coating and Its Effects on Corrosion—A Review." Materials 15, no. 18 (September 12, 2022): 6329. http://dx.doi.org/10.3390/ma15186329.
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Thermal spray coating, exceptionally high-velocity oxyfuel (HVOF), improves the corrosion resistance and wear of metal. Coating parameters play a vital role in the properties of the coating. The quality of coating can be increased by selecting appropriate coating parameters. In the case of HVOF, the oxygen flow rate and spray distance are the most significant parameters that directly influence the porosity and corrosion resistance of the coating. Porosity is essential in thermal barrier coatings for low thermal conductivity, but there is a limit of porosity beyond which it can cause failure. Hence, understanding the effects of these parameters is essential to evaluate and further minimize the porosity in order to improve the corrosion resistance and durability of the thermal barrier coating. This article reviews hot corrosion in thermal barrier coatings, the stages of corrosion, the importance of spray parameters, and the effect of the oxygen flow rate and spray distance on the corrosion resistance of HVOF-sprayed coatings. Afterwards, the coating materials, the substrate, the flow rate of oxygen, the spray distance, and the fuel used during the HVOF spraying process from recent articles are summarized. In summary, this review compares the flow rate of oxygen and the spray distance with the corrosion capacity of the coating under different corrosive environments and materials to optimize these parameters for high-quality coating, which would sustain under high temperatures for future applications.
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Ni, Weiliang, Peng Li, Yajun Zhu, Zhigang Di, Liangliang Guo, and Yunqi Liu. "Comparative Study of Anti-Corrosion Properties and Lifespan Prediction Model for Inorganic Zinc-Rich Coating and Thermal-Spray Zinc Coating." Coatings 12, no. 4 (April 8, 2022): 505. http://dx.doi.org/10.3390/coatings12040505.
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On the basis of guaranteeing the reliability of the coating, thermal-spray zinc coating has been verified by the industry to have a lifespan of more than 20 years. It is an anti-corrosion coating with excellent performance. Inorganic zinc-rich coating being a new coating technology has a certain degree of influence on its popularization and application in the field of anti-corrosion; this is due to the lack of relevant comparison data on its anti-corrosion performance and service life. It is necessary to compare and analyze the service life and corrosion resistance of the two coatings, so as to obtain the best application scenarios for the two coatings and provide a reference for the selection of the most economical coating. Based on coating reliability, 7500 h of accelerated salt-spray tests of inorganic zinc-rich coating and of the thermal-spray coating of steel structures were carried out. Electrochemical and salt-spray tests on inorganic zinc-rich coating and thermal-spray zinc coating were carried out. The micro-corrosion morphology, corrosion rate and corrosion mechanism of the two coatings and the factors affecting the corrosion rate were obtained. An interfacial corrosion-thinning and weight-loss equation was established to predict the service life of inorganic zinc-rich coating by comparing it with that of the thermal-spray zinc coating salt-spray test; they suggested that inorganic zinc-rich coating has a longer service life. The results are of practical guiding significance for the selection of a zinc coating and the rapid selection and design of a supporting scheme, and can also provide a reference for the service-life prediction of other types of coatings.
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Gao, Lihua, Fang Jia, and Xiaoliang Lu. "Preparation and Thermal Shock Resistance of Gd2O3 Doped La2Ce2O7 Thermal Barrier Coatings." Coatings 11, no. 10 (September 29, 2021): 1186. http://dx.doi.org/10.3390/coatings11101186.
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As one of the promising thermal barrier coating (TBC) candidates, stoichiometric (La0.8Gd0.2)2Ce2O7 (LGC) coatings were prepared by atmospheric plasma spraying (APS), using (La0.8Gd0.2)2Ce2.5O8 as a spray powder and optimized spray parameters. It was found that spray distance and spray power both play an important role in the phase composition and microstructure of the coating. The LGC coating exhibited lower thermal conductivities than that of La2Ce2O7 (LC) coating, which is ~0.67 W/m·K at 1200 °C. Double-ceramic-layer (DCL) optimum (La0.8Gd0.2)2Ce2O7/YSZ (LGC/YSZ) thermal barrier coating was prepared and its thermal shock behavior was investigated. The LGC/YSZ DCL TBCs had better thermal shock resistance ability than that of LC/YSZ TBCs, which was around 109 cycles at 1100 °C. However, the failure mode was similar to that of LC/YSZ DCL TBCs, which was still layer-by-layer spallation in the top ceramic layer due to the sintering of the ceramic coating.
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Wielage, Bernhard, Thomas Lampke, and Thomas Grund. "Thermal Spraying of Wear and Corrosion Resistant Surfaces." Key Engineering Materials 384 (June 2008): 75–98. http://dx.doi.org/10.4028/www.scientific.net/kem.384.75.
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Thermal spraying is one of the most variable and diverse surface coating techniques concerning materials to be processed as well as possible geometries to be coated. The group of thermal spray processes covers a large parameter field to combine nearly each coating with each base material. Thermally sprayed coatings can be applied very evenly and therefore allow to be applied on final-shaped components. Otherwise, if further treatment or finishing is necessary, thermal spray coatings can be processed by grinding or even milling. Masking during the coating process permits the selective coating of specific surface parts or the application of required geometrically structures, e. q. conductor structures. The main application field of thermal spray coatings is the (combined) wear and corrosion protection of selected component parts.
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Dinh, Văn Chien, Tuan Hai Nguyen, and Khac Linh Nguyen. "Studying Adhesion between a 67Ni18Cr5Si4B Alloy Powder Coating Produced with the High Velocity Oxygen Fuel Thermal Spray Method HVOF and a Substrate Surface of a Worn C45 Steel Shaft." Key Engineering Materials 854 (July 2020): 117–25. http://dx.doi.org/10.4028/www.scientific.net/kem.854.117.
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Nowadays, thermal spray coatings are used to enhance mechanical properties of the material. One of the technologies used to produce thermal spray coating is HVOF spray technology. This is the most advanced and modern technology which has been widely used in the industry due to its flexibility and ability to create coatings with better adhesion in comparison with other thermal spray methods. This article presents some empirical findings from applying the 67Ni18Cr5Si4B alloy powder coating onto C 45 steel shaft by HVOF spray technology. It also analyzes the influence of some technological parameters on the adhesion of the coating. As a result, the parameters of HVOF spray technology are obtained suitable for recovering worn axis-sized workpieces.
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Naidu, S. V., Carlos Green, Christopher Maxie, James D. Garber, and Gary A. Glass. "Surface Analysis of Shear Strength Tested Tungsten Carbide Thermal Spray Coatings+." Microscopy and Microanalysis 3, S2 (August 1997): 791–92. http://dx.doi.org/10.1017/s1431927600010849.
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Thermal spray processing has become an important powder-consolidation technique to yield new materials for extremes of temperature, radiation, wear, corrosion and mechanical stresses. High Velocity Oxy-Fuel (HVOF) spray coating process gives higher deposition densities and coating hardness; lower oxide content and porosity. The adhesive strength of thermal spray coatings is greatly effected by the interfacial impurities. The ring shear test method shown in Fig. 1 appears to give the most accurate results on shear adhesive strength. A typical ring shear test result of 88WC12Co 1/4" ring HVOF thermal spray coating on 4140 steel rod using a Jet kote thermal spray gun is shown in Fig. 2. Repeated ring shear tests on similar samples prepared under same spray and test conditions resulted in different shear bond strength and coating ring displacement before break off. We examined the ring shear tested coatings using a Zeiss DMS942 Scanning Electron Microscope (SEM) and Kevex Energy Dispersive X-ray Spectrometer (EDXS) with LPX1 Quantum Si(Li) Detector.
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Yang, Mu Ye, Kazuyoshi Muto, Shigenobu Kainuma, Jin Xuan Du, and Hirokazu Miyata. "Deterioration Characteristics of Overlapping Layers between Al-5Mg Thermal Spray Coating and Heavy-Duty Paint Coating." Materials Science Forum 972 (October 2019): 235–40. http://dx.doi.org/10.4028/www.scientific.net/msf.972.235.
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In recent years, Al-5Mg alloy thermal spray coatings have been used as an anti-corrosion coating applied for various components of steel structures, in some cases it was covered by the conventional heavy-duty coating. However, the deterioration characteristics of overlapping layers between thermal spray layer and heavy-duty paint coating still not clear. In this study, to compare the anti-corrosion characteristics of the single thermal spray coating and overlapping layers, the accelerated cyclic exposure tests were carried out on specimens with three types of coating layers. To clarify the deterioration characteristics, the cross-cut defect were introduced into specimens, and the EIS measurements, glossiness test, EPMA elemental analyses were conducted on test specimens. The test results indicated that the deterioration of the overlapping layer at the steel base-exposed portion occurs earlier than the case of Al-5Mg thermal spray coating. In addition, the deterioration of thermal spray coating was accelerated by the sealing treatment in specimen with overlapping layers.
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Krishna, L. Rama, D. Sen, Y. Srinivasa Rao, G. V. Narasimha Rao, and G. Sundararajan. "Thermal spray coating of aluminum nitride utilizing the detonation spray technique." Journal of Materials Research 17, no. 10 (October 2002): 2514–23. http://dx.doi.org/10.1557/jmr.2002.0366.
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The main objective of this work is to examine the feasibility of depositing aluminum nitride (AlN) powders, synthesized using self-propagating high-temperature synthesis, on a mild steel substrate using the detonation spray coating technique. Thick coatings produced by utilizing the AlN powder were obtained at four different oxygen–acetylene ratios and analyzed for microstructure, microhardness, porosity, indentation fracture toughness, and phase distribution. The AlN powder particles were found to be undergoing oxidation during the deposition process. The interrelationship between the spray parameters and the extent of oxidation of AlN during the coating process was investigated. Tribological performance of the coatings was evaluated using a dry sand abrasion test and a pin-on-disc sliding wear test. The mechanical and tribological properties of the above four coatings were compared with pure alumina (Al2O3) coatings. The correlation between the structure of the coatings and their tribological performance was also established.
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Faisal, N. H., R. Ahmed, A. K. Prathuru, A. Paradowska, and T. L. Lee. "Measuring Residual Strain and Stress in Thermal Spray Coatings Using Neutron Diffractometers." Experimental Mechanics 62, no. 3 (November 10, 2021): 369–92. http://dx.doi.org/10.1007/s11340-021-00803-9.
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Abstract Background During thermal spray coating, residual strain is formed within the coating and substrates due to thermo-mechanical processes and microstructural phase changes. Objective This paper provides a comprehensive guide to researchers planning to use neutron diffraction technique for thermal spray coatings, and reviews some of these studies. Methods ENGIN-X at the ISIS spallation source is a neutron diffractometer (time-of-flight) dedicated to materials science and engineering with high resolution testing. The focus is on the procedure of using ENGIN-X diffractometer for thermal spray coatings with a view that it can potentially be translated to other diffractometers. Results Number of studies involving neutron diffraction analysis in thermal spray coatings remain limited, partly due to limited number of such strain measurement facilities globally, and partly due to difficulty is applying neutron diffraction analysis to measure residual strain in the thermal spray coating microstructure. Conclusions This technique can provide a non-destructive through-thickness residual strain analysis in thermally sprayed components with a level of detail not normally achievable by other techniques. Neutron sources have been used to measure strains in thermal spray coatings, and here, we present examples where such coatings have been characterised at various neutron sources worldwide, to study residual strains and microstructures. Graphic Abstract
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KIM, SEONG-JONG, and YONG-BIN WOO. "COATING LAYER AND CORROSION PROTECTION CHARACTERISTICS IN SEA WATER WITH VARIOUS THERMAL SPRAY COATING MATERIALS FOR STS304." Surface Review and Letters 17, no. 03 (June 2010): 299–305. http://dx.doi.org/10.1142/s0218625x10013783.
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We investigated the optimal method of application and the anticorrosive abilities of Zn , Al , and Zn + 15%Al spray coatings in protecting stainless steel 304 (STS304) in sea water. If a defect such as porosity or an oxide layer, causes STS304 to be exposed to sea water, and the thermal spray coating material will act as the cathode and anode, respectively. The Tafel experiments revealed that Al -coated specimens among applied coating methods had the lowest corrosion current densities. As the corrosion potential decreases with increasing corrosion current density, we estimated the characteristics and lifetime of the protective thermal spray coating layer in the galvanic cell formed by the thermal spray coating layer and STS304.
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Rafiq, Nafisah Mohd, and Shijie Wang. "Thermal Barrier Coatings: An Insight into Conventional Plasma Spray and Water-Stabilized Plasma Spray." Coatings 12, no. 12 (December 7, 2022): 1916. http://dx.doi.org/10.3390/coatings12121916.
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Thermal barrier coating (TBC) systems have presented an ongoing design issue in bids to improve the lifespan of coatings. A TBC can support an extended lifespan by repairing cracks between interfacial layers during high thermal exposure while at the same time increasing coating thickness. Two deposition techniques, atmospheric plasma spray and water-stabilized plasma spray (WSP), have been distinguished to understand mechanical and thermal performance based on their contrasting torch systems and microstructural characterization. This insight paper will underline the superiority of WSP coating and the need to leverage existing technology by optimizing better deposition parameters for future fatigue-resistant TBC production.
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Chen, Wen Long, Min Liu, Xiao Ling Xiao, and Xin Zhang. "Effect of Spray Distance on the Microstructure and High Temperature Oxidation Resistance of Plasma Spray-Physical Vapor Deposition 7YSZ Thermal Barrier Coating." Materials Science Forum 1035 (June 22, 2021): 511–20. http://dx.doi.org/10.4028/www.scientific.net/msf.1035.511.
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In order to study the effect of spray distance on the structure and high temperature oxidation resistance of feather-columnar thermal barrier coatings, the feather-columnar ZrO2-7wt. % Y2O3 (7YSZ) thermal barrier coatings were prepared at spray distances of 650 mm, 950 mm, 1100 mm, 1250 mm, and 1400 mm by plasma spray-physical vapor deposition (PS-PVD) technology. The surface roughness, micro morphology, and porosity of the sprayed 7YSZ coating were analyzed by 3D surface profiler, SEM, XRD, etc., and the impedance spectrum characteristics of the 7YSZ coating were characterized by electrochemical alternating current (AC) impedance technology. In addition, the high temperature oxidation resistance test of 7YSZ coating under different spray distances was carried out at a temperature of 1000 °C to study the influence of spray distance on the high temperature oxidation resistance of 7YSZ coating. The research results show that the surface roughness and porosity of feather-columnar 7YSZ coating increased sequentially with the increase of spray distance. At the same time, The YSZ grain boundary resistance value increased exponentially as the porosity of the coating increases. Where the spray distance was in the range of 650 mm and 1250 mm, the high temperature oxidation rate constant of the coating increased with the spray distance. However, the spray distance was greater than 1250 mm, and the spray distance had no significant effect on the high temperature oxidation resistance of the coating.
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Curry, Nicholas, Matthias Leitner, and Karl Körner. "High-Porosity Thermal Barrier Coatings from High-Power Plasma Spray Equipment—Processing, Performance and Economics." Coatings 10, no. 10 (October 4, 2020): 957. http://dx.doi.org/10.3390/coatings10100957.
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High-porosity thermal barrier coatings are utilized on gas turbine components where maximizing the coating thermal insulation capability is the primary design criteria. Though such coatings have been in industrial use for some time, manufacturing high-porosity coatings quickly and efficiently has proven challenging. With the industry demand to increase productivity and reduce waste generation, there is a drive to look at improved coating manufacturing methods. This article looks at high-porosity coatings manufactured using a high-power plasma system in comparison with a current industrial coating. A commercial spray powder is compared with an experimental Low-Density powder developed to maximize coating porosity without sacrificing coating deposition efficiency. The resultant coatings have been assessed for their microstructure, adhesion strength, furnace cyclic lifetime, thermal conductivity and sintering behavior. Finally, the impact of spray processing on coating economics is discussed. The use of a Low-Density powder with a high-power plasma system allows a high-porosity coating to be manufactured more efficiently and more cost effectively than with conventional powder feedstock. The improvement in thermal properties for the experimental coating demonstrates there is scope to improve industrial coatings by designing with specific thermal resistance rather than thickness and porosity as coating requirements.
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Knudsen, Ole Øystein, Håkon Matre, Cato Dørum, and Martin Gagné. "Experiences with Thermal Spray Zinc Duplex Coatings on Road Bridges." Coatings 9, no. 6 (June 8, 2019): 371. http://dx.doi.org/10.3390/coatings9060371.
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Road bridges are typically designed with a 100-year lifetime, so protective coatings with very long durability are desired. Thermal spray zinc (TSZ) duplex coatings have proven to be very durable. The Norwegian Public Roads Administration (NPRA) has specified TSZ duplex coatings for protection of steel bridges since 1965. In this study, the performance of TSZ duplex coatings on 61 steel bridges has been analyzed. Based on corrosivity measurements on five bridges, a corrosivity category was estimated for each bridge in the study. Coating performance was evaluated from pictures taken by the NPRA during routine inspections of the bridges. The results show that very long lifetimes can be achieved with TSZ duplex coatings. There are examples of 50-year old bridges with duplex coatings in good condition. Even in very corrosive environments, more than 40-year old coatings are still in good condition. While there are a few bridges in this study where the coating failed after only about 20 years, the typical coating failures are due to application errors, low paint film thickness and saponification of the paint. Modern bridge designs and improved coating systems are assumed to increase the duplex coating lifetime on bridges even further.
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Cao, Peng, Brian Gabbitas, Asma Salman, De Liang Zhang, and Z. H. Han. "Consolidation of TiAl Powder by Thermal Spray Processes." Advanced Materials Research 29-30 (November 2007): 159–62. http://dx.doi.org/10.4028/www.scientific.net/amr.29-30.159.
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Thermal spray deposition has been widely used as a coating process for applying thin protective layers to the need-to-protect materials, or substrates. Recent technological developments in thermal spray processing, particularly cold gas spraying (CGS) and supersonic plasma spraying (S-PS), have enabled some emerging applications for making structural components. This paper reports on the results of our recent attempts to obtain thick TiAl coatings using three coating techniques: atmospheric plasma spraying (APS), S-PS and CGS. We successfully achieved a 3 mm thick coating using both APS and S-PS techniques, but failed in cold spray. A significant phase change was observed of the powder particles experienced during both APS and S-PS processes. Nevertheless, a considerable quantity of titanium oxides was observed in the APS coating.
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Bartuli, C., T. Valente, F. Casadei, and M. Tului. "Advanced thermal spray coatings for tribological applications." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 221, no. 3 (July 1, 2007): 175–85. http://dx.doi.org/10.1243/14644207jmda135.
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Thermal spray coating is one of the most common procedures to improve the tribological properties of materials. Ceramic and cermet coatings, especially those based on oxides (alumina, chromium oxide, etc.) and carbides, are widely used for wear protection. Improvements under investigations are related to the possible use of nanostructured coatings and to the potential application of hybrid techniques. As a possible alternative, solid lubrication is proposed as integration or replacement of the traditional liquid lubrication in the case of severe operative conditions when there is the possibility of a lack of lubricant or when environmental problems can arise from waste disposal. In the present paper, results from experimental activities on different types of abrasion-resistant thermal spray coatings are presented: graded coating systems, specifically designed for titanium-based alloys, obtained by reactive plasma spraying and physical vapour deposition of titanium nitrides; nanostructured WC-Co coatings deposited by high velocity oxy-fuel; plasma-sprayed ceramic coatings based on oxides containing nanophases either from nanostructured precursors or postprecipitated by purposely designed thermal treatments; self-lubricant coatings deposited by plasma spray with the inclusion of graphite.
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Killinger, Andreas, and Rainer Gadow. "Thermally Sprayed Coating Composites for Film Heating Devices." Advances in Science and Technology 45 (October 2006): 1230–39. http://dx.doi.org/10.4028/www.scientific.net/ast.45.1230.
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Direct heated systems in white goods for medium temperature applications (approx. 250° -350° C) can be applied onto glass, glass ceramic and metal substrates by means of thermal spray techniques. Essentially, such a system requires at least two functional layers to work properly: (1) The metal coating that works as the heating element and (2) an insulator coating that electrically separates the substrate from the film heater. Therefore, the heating device combines three materials (substrate, insulator and film heater) with rather different thermophysical properties. An optimized spray deposition process with proper guidance of the heat flow is required to produce coatings that can operate under cyclic thermal load conditions. The paper discusses the influence of thermal spray process parameters as well as the applied spray powders on the electrical properties of the achieved layer structures of the respective insulator and film heater coatings.
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Kriba, Ilhem, and A. Djebaili. "The Interaction between Particles and a Plasma Beam in the Thermal Projection Process." Advanced Materials Research 83-86 (December 2009): 801–9. http://dx.doi.org/10.4028/www.scientific.net/amr.83-86.801.
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Plasma spray processes have been widely used to produce high performance coatings of a wide range of Materials (metallic, non-metallic, ceramics), offering protection from, eg. wear, extreme temperature, chemical attack and environmental corrosion. To obtain good quality coatings, spray parameters must be carefully selected. Due to the large variety in process parameters, it is difficult to optimize the process for each specific coating and substrate combinations. Furthermore modelling the spray process allows a better understanding of the process sequences during thermal spraying. Good agreement of the virtual spraying process with the real coating formation is achieved by modelling the particular process steps. The simulation of coating formation to estimate the process parameters is an important tool to develop new coating structures with defined properties. In this work, the process of plasma sprayed coating has been analyzed by numerical simulation. Commercial code is used to predict the plasma jet characteristics, plasma –particle interaction, and coating formation. Using this model we can obtain coating microstructure and characteristics which form a foundation for further improvement of an advanced ceramic coating build up model.
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Nurisna, Zuhri, Sotya Anggoro, and Hidayat Nur Mujtahid. "Physical and Mechanical Properties of Twin-Wire Arc Spray and Wire Flame Spray Coating on Carbon Steel Surface." Materials Science Forum 1057 (March 31, 2022): 235–39. http://dx.doi.org/10.4028/p-z698i0.
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Thermal Spray Coating is a material surface engineering process, where the coating material is heated until it melts then the melt is pushed with high-pressure air as individual particles or droplets to a surface. This study compares two thermal spray coating methods, twin-wire arc spray and wire flame spray to measure the level of hardness, coating strength and good quality of the coating and porosity. This study used medium carbon steel AISI 1045 as substrate and coating material with FeCrMnNiCSiSP alloy elements (AISI 420). Testing mechanical properties were undergone by hardness testing and pull-off test to determine the coating's adhesive strength. The microstructures were observed using a microscope to test the physical properties. After analyzing the research results, it can be concluded that the twin-wire arc spray coating process produces an adequate level of hardness and coating strength. Twin-wire arc spray can increase the percentage value of substrate surface hardness by 50,56 % and the average coating strength of 21,345 MPa. The microstructure observation results on the coating show that the coating results from twin-wire arc spray have good coating quality with the bonds between the elements contained in the FeCrMnNiCSiSP wire which are bonded to each other and form layered layers and minimal porosity in the coating.
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Wang, Jiang Ting, Peter D. Hodgson, Jing De Zhang, and Chun Hui Yang. "Residual Thermal Stresses in a Fe3Al/Al2O3 Gradient Coating System." Advanced Materials Research 32 (February 2008): 71–74. http://dx.doi.org/10.4028/www.scientific.net/amr.32.71.
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To combine the merits of both metals and ceramics into one material, many researchers have been studying the deposition of alumina coating using plasma spray on metal substrates. However, as the coatings are deposited at a high temperature, residual thermal stresses develop due to the mismatch of thermal expansion coefficients of the coating and substrate and these are responsible for the initiation and expansion of cracks, which induce the possible failure of the entire material. In this paper, the residual thermal-structural analysis of a Fe3Al/Al2O3 gradient coating on carbon steel substrate is performed using finite element modelling to simulate the plasma spray. The residual thermal stress fields are obtained and analyzed on the basis of temperature fields in gradient coatings during fabrication. The distribution of residual thermal stresses including radial, axial and shear stresses shows stress concentration at the interface between the coatings and substrate. The mismatch between steel substrate and composite coating is still the dominant factor for the residual stresses.
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Shibe, Vineet, and Vikas Chawla. "Combating Wear of ASTM A36 Steel by Surface Modification Using Thermally Sprayed Cermet Coatings." Advances in Materials Science and Engineering 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/3894145.
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Thermal spray coatings can be applied economically on machine parts to enhance their requisite surface properties like wear, corrosion, erosion resistance, and so forth. Detonation gun (D-Gun) thermal spray coatings can be applied on the surface of carbon steels to improve their wear resistance. In the present study, alloy powder cermet coatings WC-12% Co and Cr3C2-25% NiCr have been deposited on ASTM A36 steel with D-Gun thermal spray technique. Sliding wear behavior of uncoated ASTM A36 steel and D-Gun sprayed WC-12% Co and Cr3C2-25% NiCr coatings on base material is observed on a Pin-On-Disc Wear Tester. Sliding wear performance of WC-12% Co coating is found to be better than the Cr3C2-25% NiCr coating. Wear performance of both these cermet coatings is found to be better than uncoated ASTM A36 steel. Thermally sprayed WC-12% Co and Cr3C2-25% NiCr cermet coatings using D-Gun thermal spray technique is found to be very useful in improving the sliding wear resistance of ASTM A36 steel.
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Srinivasan, Dheepa. "Cold Spray: Advanced Characterization Methods—Transmission Electron Microscopy." AM&P Technical Articles 175, no. 5 (July 1, 2017): 59–62. http://dx.doi.org/10.31399/asm.amp.2017-05.p059.
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Abstract This article series explores the indispensable role of characterization in the development of cold spray coatings. Transmission electron microscopy is used to understand powder characteristics, cold spray coating deformation behavior both within splats as well as near the coating-substrate interface, phase transformations in the as-sprayed and heat treated conditions, phase equilibria of the coating under the operating conditions pertaining to the application of the coating, the coating recovery mechanism, and the thermal stability of the coating.
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Tahari, M., B. Luo, J. Geng, D. Jing, and M. Hatami. "Optimization of Thermal Spray Parameters of NiAl/Cr2C3 Coating by Taguchi Method." Solid State Phenomena 295 (August 2019): 9–14. http://dx.doi.org/10.4028/www.scientific.net/ssp.295.9.
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In this study the effect of thermal spray process on wear resistance of NiAl/Cr2C3 thermal spray coating has been investigated. For this purpose the NiAl power mixed with 10 %wt. Cr2C3 powder and milled for 1 hrs at argon atmosphere. The APS parameters such as voltage (V), current (A), spray distance (mm), powder feed rate (gr/min), were optimize using a response surface methodology. For investigation effect of spray parameters on quality of coatings, the porosity and wear resistance of coatings analyzed with SEM and pin on disk wear test. Results show that increase of voltage and current are more effective other parameters. Increasing of powder feed rate and spray distance raised porosity of coatings intensively.
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Fu, Gaosheng, Lei Zuo, Jon Longtin, Yikai Chen, and Sanjay Sampath. "Progress on Searching Optimal Thermal Spray Parameters for Magnesium Silicide." MRS Proceedings 1490 (2013): 173–77. http://dx.doi.org/10.1557/opl.2013.27.
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ABSTRACTThe thermoelectric properties of Mg2Si coatings prepared by Atmospheric Plasma Spray (APS), and Vacuum Plasma Spray (VPS) are presented. Seebeck coefficient results of both APS and VPS have been reported. XRD and SEM analysis of the samples are also presented to understand how microstructure influences the coating thermoelectric properties. The results suggest significant improvements can be made on the reduction of impurity including oxidation and pure silicon by using proper spray method and parameters. Thermal spray has been demonstrated before to be effective way to reduce thermal conductivity which may due to the coating microstructure. VPS result shows higher Seebeck coefficient than APS which may due to lower level of oxidization.
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Szczucka-Lasota, B., and J. Piwnik. "New Technological Concept for Thermal Spray Protective Coatings." Archives of Metallurgy and Materials 62, no. 3 (September 26, 2017): 1499–504. http://dx.doi.org/10.1515/amm-2017-0232.
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Abstract Thermally spraying with micro-jet cooling is an innovate technology. It is possible to get fine dispersive structure of coatings during the shorter time in comparable to the classical high velocity oxygen fuel process (HVOF). It corresponds with good corrosion-erosion properties of structure. In the paper the parameters of the spraying with micro-jet cooling process are presented. The selected properties of coatings obtained by hybrid method are presented. The results of wear tests for hybrid and HVOF coating are compared. Results of investigation are very optimistic. The presented technology should be adapted to the actual production of protective coating for machines and construction working in wear conditions.
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Shafigullin, Lenar N., A. R. Ibragimov, and A. I. Saifutdinov. "Investigation into the Effects of High Temperature on Mechanical Properties of Thermal Spray Coatings Applied by Plasma Spraying." Solid State Phenomena 284 (October 2018): 1151–56. http://dx.doi.org/10.4028/www.scientific.net/ssp.284.1151.
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C. C. Berndt advanced investigations of mechanical properties of thermal spray coatings under 4-point bending. He found that this investigation method is sensitive to the mechanical properties of thermal spray coatings.This paper contains the detailed investigation results for thermal spray coatings of zirconium dioxide under 4-point bending, i.e. tests of the specimens subjected to spraying at varying conditions and pre-test soaking with the various duration at 1100 °С.It was established how the mechanical properties of thermal spray coatings changed depending on the spraying mode and high temperature soaking. The test results show that the double heat treatment of coatings is more preferable than one-time heat treatment as it make the properties change linearly. It is more easily controllable during operation of the components with thermal spray coating.
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TROMPETTER, W., A. MARKWITZ, and M. HYLAND. "USE OF IBA TECHNIQUES TO CHARACTERIZE HIGH VELOCITY THERMAL SPRAY COATINGS." Modern Physics Letters B 15, no. 28n29 (December 20, 2001): 1428–36. http://dx.doi.org/10.1142/s0217984901003354.
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Spray coatings are being used in an increasingly wide range of industries to improve the abrasive, erosive and sliding wear of machine components. Over the past decade industries have moved to the application of supersonic high velocity thermal spray techniques. These coating techniques produce superior coating quality in comparison to other traditional techniques such as plasma spraying. To date the knowledge of the bonding processes and the structure of the particles within thermal spray coatings is very subjective. The aim of this research is to improve our understanding of these materials through the use of IBA techniques in conjunction with other materials analysis techniques. Samples were prepared by spraying a widely used commercial NiCr powder onto substrates using a HVAF (high velocity air fuel) thermal spraying technique. Detailed analysis of the composition and structure of the power particles revealed two distinct types of particles. The majority was NiCr particles with a significant minority of particles composing of SiO 2/ CrO 3. When the particles were investigated both as raw powder and in the sprayed coating, it was surprising to find that the composition of the coating meterial remained unchanged during the coating process despite the high velocity application.
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Jech, David, Ladislav Čelko, Lenka Klakurková, Karel Slámečka, Miroslava Horynová, and Jiří Švejcar. "Formation of Thermally Sprayed Coatings on Grid-Like Structure Substrate." Solid State Phenomena 258 (December 2016): 387–90. http://dx.doi.org/10.4028/www.scientific.net/ssp.258.387.
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The main goal of this contribution is to investigate the influence of the substrate morphology on the resulting thermally sprayed coatings microstructure. Therefore, three different representative coating systems and/or thermal spray techniques were utilized to produce the coatings on grid-like structure substrates: (i) CoNiCrAlY bond coat (BC) sprayed by high velocity oxygen fuel (HVOF) technique and yttria stabilized zirconia (YSZ) top coat (TC) sprayed by means of atmospheric plasma spray (APS) technique, (ii) YSZ coating sprayed by means of APS and (iii) YSZ coating sprayed by means of nanoparticle colloid suspension plasma spraying (SPS). The shadowing effect of thermal spray coatings in relation with the grid-like substrate structure was investigated in detail. Resulting microstructure of sprayed samples was studied utilizing light microscopy, digital image analysis, scanning electron microscopy, energy-dispersive spectrometer and X-ray diffraction techniques.
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Tailor, S., RM Mohanty, and PR Soni. "A Review on Plasma Sprayed Al-SiC Composite Coatings." Journal of Materials Science and Surface Engineering 1, no. 1 (2013): 15–22. http://dx.doi.org/10.52687/2348-8956/115.
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This review is done essentially to study results in the field of synthesis and characterization of SiC reinforced Al-SiC composite coatings using thermal spray process. SiC reinforced composite coatings produced by thermal spray process are being developed for a wide variety of applications, e.g. aerospace, automotive, structural and industrial. It is anticipated that, if properly deposited, Al-ceramic coatings could also provide improved properties like wear resistance and thermal barrier coatings. These results clearly demonstrate that the significant improvement in coating performance can be achieved by utilizing proper thermal spray conditions and SiC % in composite coatings. This paper presents a critical review on SiC reinforced Al-SiC composite coatings using thermal spray by various researchers in past years. The researcher’s findings with necessary parameters for achieve good Al-SiC composite coatings are given.
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Tharajak, Jirasak, and Noppakun Sanpo. "The Study on High Temperature Stability Test of Ni/Cr Cold Spray Coating." Applied Mechanics and Materials 901 (August 2020): 43–48. http://dx.doi.org/10.4028/www.scientific.net/amm.901.43.
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Recently cold spray coating technology was used for many applications in petrochemical business especially for high temperature required section. For this reason, the applied coating must be able to withstand at least 800 °C. The developed Ni/Cr cold spray coating was studied mainly on high temperature resistant property. Ni/Cr with the ratio of 80/20 feedstock powders revealed the highest deposition efficiency and it was selected to use as optimum feedstock powder compositions for the less of experimental study. Finally, it was found that Ni/Cr cold spray coatings reveal excellent thermal stability performance after completed both corrosion and thermal shock tests.
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Bobzin, Kirsten, Wolfgang Wietheger, and Martin Andreas Knoch. "Development of Thermal Spray Processes for Depositing Coatings on Thermoplastics." Journal of Thermal Spray Technology 30, no. 1-2 (January 2021): 157–67. http://dx.doi.org/10.1007/s11666-020-01147-x.
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AbstractThermoplastics combine high freedom of design with economical mass production. Metallic coatings on thermoplastics enable power and signal transmission, shield sensitive parts inside of housings and can reduce the temperature in critical areas by functioning as a heat sink. The most used technical thermoplastics are polyamides (PA), while the described use cases are often realized using Cu. Consequently, several studies tried to apply copper coatings on PA substrates via thermal spraying; so far, this combination is only feasible using an interlayer. In this study, a new approach to metallize thermoplastics via thermal spraying based on validated state-of-the-art predictions of the thermoplastics’ material response at relevant temperatures and strain rates is presented. Using these predictions, high velocity wire-arc spraying was selected as coating process. Furthermore, the process parameters were adapted to realize a continuous coating while also roughening the substrate during coating deposition. The resulting Cu coating on PA6 had a sufficiently high coating adhesion for post-treatment by grinding. The adhesion is achieved by in situ roughening during the coating application. The results indicate that different process parameters for initial layer deposition and further coating buildup are required due to the low thermal stability of PA6.
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Gadow, Rainer, Andreas Killinger, Andreas Rempp, and Andrei Manzat. "Advanced Ceramic Tribological Layers by Thermal Spray Routes." Advances in Science and Technology 66 (October 2010): 106–19. http://dx.doi.org/10.4028/www.scientific.net/ast.66.106.
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Protective and functional coatings featuring outstanding tribological performance are of general interest for all kinds of industrial applications i.e for high performance automotive and mechanical applications. Thermal spray coating technologies play a key role in fabricating hard layers based on ceramic, metal - ceramic and further multiphase materials. Additional functionality can be achieved by combining these coatings with polymer based top coats with low friction coefficient or anti adhesive behaviour. Combined coatings feature also designed thermophysical and electrophysical properties. Several case studies will be discussed, ranging from automotive applications to paper and printing industry. Thermally sprayed coatings were applied using APS, HVOF and the newly developed HVSFS processes (High Velocity Suspension Spraying) with a special focus on nanoceramic feedstocks. In some applications polymer top coats with dispersed solid phases are applied to enhance functional properties. Special aspects in manufacturing engineering are addressed with particular importance not only of the influence of spray process parameters on coating properties but also of spray torch kinematic and robot trajectories on hardness, residual stress distributions, dimensional tolerances and porosity distributions will be discussed.
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Fauchais, Pierre, and Ghislain Montavon. "Thermal and Cold Spray: Recent Developments." Key Engineering Materials 384 (June 2008): 1–59. http://dx.doi.org/10.4028/www.scientific.net/kem.384.1.
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Thermal spraying consists in a technology aiming at producing coatings whose thicknesses range from 10 μm to a few millimeters onto mechanical components to confer them specific and unique functional properties, such as wear and corrosion resistances, friction coefficient adaptation, thermal and electrical insulation, biocompatibility, repair, etc., among the principals. Thermal spraying consists in injecting in a viscous enthalpic jet (animated by a momentum) powder with particles which average size ranges from 0.01 to 100 μm. These particles are melted and simultaneously accelerated towards the surface of the part to be covered. They form, after impact, spreading and solidification, near-circular lamellae the stacking of which form the coating. Due to the versatility of the available processes exhibiting a wide range of enthalpic and momentum contents, virtually any kind of material exhibiting congruent melting behavior can be processed, from alloys and ceramics to polymers, ever since its melting temperature differs from its vaporization or decomposition temperature by at least 300 K and that it can be processed previously under the form of powder particles or wires. Thermal spray techniques offer the unique capability to manufacture a large variety of coatings on components of a large variety and geometry. However, thermal spraying constitutes a special process for which the coating service properties derive mostly from the structure and indirectly from the selection of the operating parameters. Very significant improvements over the past years permitted to diagnose the in-flight particle characteristics, mostly in terms of velocity and temperature. Recently, these new capabilities have made possible the development of on-line process controls. This should participate to a drastic increase in coating reliability. In convetntional thermal spraying processes, a pulverulent feedstock (i.e., powder particles) is injected within the plasma jet via a carrier gas. This approach does not permit to process small diameter particles; i.e., nano-sized particles, which could permit to form finely grained coatings. Replacing gas by liquid to carry particles offer the unique possibility to process nano-sized particles. Cold gas spraying may appear as an alternative process to reach the same goal. Indeed, thermal spray processes experienced very significant developments over the past years, opening new doors to manufacture coatings with a high reliability and superior properties. This papepr indend at presenting some of those developments.
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Barradas, Sophie, Michel Jeandin, Régine Molins, F. Borit, L. Berthe, C. Bolis, M. Boustie, M. Arrigoni, and M. Ducos. "Local Approach to Thermally-Sprayed Coating/Substrate Adhesion through LASAT (Laser Shock Adhesion Test)." Materials Science Forum 539-543 (March 2007): 1067–73. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.1067.
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Three interface factors may influence thermally-sprayed coatings adhesion: interface morphology (as usual), thermal and chemical features. It was shown that these three aspects of adhesion mechanisms are shown to be dependent and very local. It is especially true for cold spray which is one of the most promising spray processes. As this spraying technique is based on rapid deformation, cold spray coating/substrate interfaces show local morphological, thermal and chemical features, in a way that none of them can be neglected. LASAT is particularly suitable for testing these coatings because it can be applied to small areas (~1 mm²). From this, it has the outstanding advantage to be sensitive to fine-scaled phenomena responsible for coating adhesion.
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Jayanth, P., and E. Sangeeth Kumar. "Investigation and Analysis of Wear Reduction in Piston Rings through Coating." Applied Mechanics and Materials 813-814 (November 2015): 874–79. http://dx.doi.org/10.4028/www.scientific.net/amm.813-814.874.
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In this study, the surface of a Piston Ring in the engine is coated with multilayered coating powder using plasma-spray technique, and its surface behavior is subsequently analyzed. The purpose of this study is to analyze the mechanical and thermal effects of surface coating for a Piston Ring during friction. Here specimens with and without coatings were prepared and then microstructure, hardness and corrosion tests were carried out. From the experimental results and Ansys results, it has been found that the coated specimen has improved the properties in improving the diesel engine performance. The results show less deformation and fewer scratches due to wear on the multilayer coated Piston Ring as compared to the uncoated one. The surfaces topography and the structure of the plasma spray coatings is observed on the scanning Electron microscope. The evaluation of the adhesion of coatings is made using the hardness test and also compared using the thermal barrier properties. Taking into account the results of measurements, one can state that the lowest wear and thermal resistance on piston rings by plasma spray coating.
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Goral, Marek, Slawomir Kotowski, and Jan Sieniawski. "The Technology of Plasma Spray Physical Vapour Deposition." High Temperature Materials and Processes 32, no. 1 (February 22, 2013): 33–39. http://dx.doi.org/10.1515/htmp-2012-0051.
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AbstractThe article presents a new technology of thermal barrier coating deposition called Plasma Spray – Physical Vapour Deposition (PS-PVD). The key feature of the process is the option of evaporating ceramic powder, which enables the deposition of a columnar ceramic coating. The essential properties of the PS-PVD process have been outlined, as well as recent literature references. In addition, the influence of a set of process conditions on the properties of the deposited coatings has been described. The new plasma-spraying PS-PVD method is a promising technology for the deposition of modern thermal barrier coatings on aircraft engine turbine blades.
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Powell, Tommy, Ryan O’Donnell, Mark Hoffman, Zoran Filipi, Eric H. Jordan, Rishi Kumar, and Nick J. Killingsworth. "Experimental investigation of the relationship between thermal barrier coating structured porosity and homogeneous charge compression ignition engine combustion." International Journal of Engine Research 22, no. 1 (July 29, 2019): 88–108. http://dx.doi.org/10.1177/1468087419843752.
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Heat transfer has a profound influence on homogeneous charge compression ignition combustion. When a thermal barrier coating is applied to the combustion chamber, the insulating effect magnifies the wall temperature swing, decreasing heat transfer during combustion. This enables improvements in both thermal and combustion efficiency without the detrimental impacts of intake charge heating. Increasing the temperature swing requires coatings with lower thermal conductivity and heat capacity. A promising avenue for simultaneously decreasing both thermal conductivity and capacity is to increase the porosity fraction. A proprietary solution precursor plasma spray process enables discrete organization of the porosity structure, called inter-pass boundaries, which in turn produces a step-reduction in thermal conductivity for a given porosity level. In this investigation, yttria-stabilized zirconia is used to create four different thermal barrier coatings to study the potential of structured porosity as means of improving the “temperature swing” behavior in a homogeneous charge compression ignition engine. The baseline coating is “dense YSZ,” applied using a standard air-plasma spray process. Next, significant reductions of the thermal conductivity are achieved by utilizing the solution precursor plasma spray process to create inter-pass boundaries with a moderate overall porosity. Performance, efficiency, and emissions are compared against both a baseline configuration with a metal piston and an air-plasma spray “dense YSZ” coating. Experiments are carried out in a single-cylinder gasoline homogeneous charge compression ignition engine with exhaust re-induction. Experiments indicate that incorporating structured porosity into thermal barrier coatings produces tangible gains in combustion and thermal efficiencies. However, there is an upper limit to porosity levels acceptable for homogeneous charge compression ignition engine application because an elevated porosity fraction leads to excessive surface roughness and undesirable fuel interactions. Comparison of the coatings showed the best results with coating thickness of up to 150 µm. Thicker coatings led to slower surface temperature response and attenuated swing temperature magnitude.
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Riyanto, Edy, and Budi Prawara. "Mikrostruktur dan Karakterisasi Sifat Mekanik Lapisan Cr3C2-NiAl-Al2O3 Hasil Deposisi Dengan Menggunakan High Velocity Oxygen Fuel Thermal Spray Coating." Journal of Mechatronics, Electrical Power, and Vehicular Technology 1, no. 1 (March 9, 2012): 1–4. http://dx.doi.org/10.14203/j.mev.2010.v1.1-4.
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Surface coating processing of industrial component with thermal spray coatings have been applied in many industrial fields. Ceramic matrix composite coating which consists of Cr3C2-Al2O3-NiAl had been carried out to obtain layers of material that has superior mechanical properties to enhance component performance. Deposition of CMC with High Velocity Oxygen Fuel (HVOF) thermal spray coating has been employed. This study aims to determine the effect of powder particle size on the microstructure, surface roughness and hardness of the layer, by varying the NiAl powder particle size. Test results show NiAl powder particle size has an influence on the mechanical properties of CMC coating. Hardness of coating increases and surface roughness values of coating decrease with smaller NiAl particle size.
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Vaz, Rodolpho F., Alessio Silvello, Javier Sanchez, Vicente Albaladejo, and Irene García Cano. "The Influence of the Powder Characteristics on 316L Stainless Steel Coatings Sprayed by Cold Gas Spray." Coatings 11, no. 2 (January 31, 2021): 168. http://dx.doi.org/10.3390/coatings11020168.
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Thermally sprayed 316L stainless steel coatings are commonly used on metallic structures due to their corrosion and wear resistance when compared to carbon steel. Cold Gas Spray (CGS) is a convenient thermal spray process to deposit 316L coatings, producing thick and very dense coatings, with almost no deleterious changes on the feedstock properties to the coating condition. The powder characteristics have influence on the microstructure of the coating, such as porosity and oxide contents, which alter its corrosion and wear behavior. CGS is an efficient technique to reduce the problems associated with material melting commonly found in other conventional thermal spray methods. In this work, different 316L powders, produced by different manufacturers, were deposited by CGS, applying the same equipment and parameters, with the objective to evaluate the relation between the powders’ characteristics and coating properties. Their microstructure, adherence, hardness, as well as the performance on corrosion and wear testing were evaluated. The water atomized powders presented in general better results than gas atomized powders.
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Sadeghi, Esmaeil, Nicolaie Markocsan, and Shrikant Joshi. "Advances in Corrosion-Resistant Thermal Spray Coatings for Renewable Energy Power Plants. Part I: Effect of Composition and Microstructure." Journal of Thermal Spray Technology 28, no. 8 (November 7, 2019): 1749–88. http://dx.doi.org/10.1007/s11666-019-00938-1.
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Abstract Power generation from renewable resources has attracted increasing attention in recent years owing to the global implementation of clean energy policies. However, such power plants suffer from severe high-temperature corrosion of critical components such as water walls and superheater tubes. The corrosion is mainly triggered by aggressive gases like HCl, H2O, etc., often in combination with alkali and metal chlorides that are produced during fuel combustion. Employment of a dense defect-free adherent coating through thermal spray techniques is a promising approach to improving the performances of components as well as their lifetimes and, thus, significantly increasing the thermal/electrical efficiency of power plants. Notwithstanding the already widespread deployment of thermal spray coatings, a few intrinsic limitations, including the presence of pores and relatively weak intersplat bonding that lead to increased corrosion susceptibility, have restricted the benefits that can be derived from these coatings. Nonetheless, the field of thermal spraying has been continuously evolving, and concomitant advances have led to progressive improvements in coating quality; hence, a periodic critical assessment of our understanding of the efficacy of coatings in mitigating corrosion damage can be highly educative. The present paper seeks to comprehensively document the current state of the art, elaborating on the recent progress in thermal spray coatings for high-temperature corrosion applications, including the alloying effects, and the role of microstructural characteristics for understanding the behavior of corrosion-resistant coatings. In particular, this review comprises a substantive discussion on high-temperature corrosion mechanisms, novel coating compositions, and a succinct comparison of the corrosion-resistant coatings produced by diverse thermal spray techniques.
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Mifune, Noriyuki, and Yoshio Harada. "2CaO･SiO2-CaO･ZrO2 Thermal Barrier Coating Formed by Plasma Spray Process." Materials Science Forum 522-523 (August 2006): 239–46. http://dx.doi.org/10.4028/www.scientific.net/msf.522-523.239.
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The applicability of 2CaO·SiO2-CaO·ZrO2 ceramic coatings as thermal barrier coatings (TBCs) was investigated. Coatings consisting of various ratios of 2CaO·SiO2-CaO·ZrO2 bond-coated with NiCrAlY were prepared using the plasma spray process. The structure of the coatings was characterized by scanning electron microscopy and X-ray diffraction analysis. The resistance of the coatings to thermal shock was evaluated with acoustic emission techniques under a thermal cycle from 1273 K to room temperature, and the hot corrosion resistance of the coatings was investigated with V2O5 and Na2SO4 at 1273 K for 3 h. The 2CaO·SiO2-10~30mass%CaO·ZrO2 coatings had excellent thermal shock resistance, because the coatings contained a vertical micro-crack in a single flattened ceramic particle. These coatings possessed excellent corrosion protection preventing direct contact between the corrosive ashes and a NiCrAlY bond coating. The CaO in the coating reacted with vanadium compounds and inhibited the penetration of corrosive ashes to the bond coating. The developed 2CaO·SiO2-20mass%CaO·ZrO2 thermal barrier coating on stationary vanes was evaluated in an actual gas turbine. The ceramic coating did not separate from the bond coating and reacted with SOx in combustion gas to produce a stable sulfate (CaSO4), which fixed in the coating. The TBC effectively protected the metal substrate of the vanes in practical operating condition for 25,000 h.
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Naidu, Seetala V., James D. Garber, and Gary A. Glassc. "Impurity Effects on Shear Adhesive Strength of Tungsten Carbide Thermal Spray Coatings on Steel." Microscopy and Microanalysis 7, S2 (August 2001): 328–29. http://dx.doi.org/10.1017/s1431927600027719.
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We have used High Velocity Oxy-Fuel (HVOF) thermal spray coating process to obtain tungsten carbide coatings on steel. It is important to control the powder quality and surface roughness of the substrate in the thermal spray coating process to obtain good adherence. The adhesive strength is greatly effected by the interfacial impurities. Most commonly used in the thermal spray industry is Al2O3 grit abrasive for good surface roughness of steel substrate to produce anchor patterns for the coating. The previous studies indicated that some fine Al2O3 particles are trapped in the rough surface grooves during this process. The ring shear test method, described previously, appears to give the most accurate results on shear adhesive strength. The ring shear strength test was comprised of a 0.02” thick and 0.25” wide ring coating on a 1” diameter cylindrical substrate rod. This rod is placed in a disk with a cylindrical hole of the rod size and an incremental pressure is applied on the rod.
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Yang, De Ming, and Bo Han Tian. "Microstructure and Mechanical Properties of FeAl Coating Deposited by Low Pressure Plasma Spray." Applied Mechanics and Materials 333-335 (July 2013): 1916–20. http://dx.doi.org/10.4028/www.scientific.net/amm.333-335.1916.
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The FeAl intermetallic compound coatings were deposited by low pressure plasma spray, air plasma spray and high velocity oxy-fuel spray. The influence of three kinds of thermal spraying processes on the microstructure, microhardness, elastic modulus and fracture toughness of coatings was investigated. The results show that the FeAl coating deposited by low pressure plasma spray presents special mechanical properties such as higher microhardness and elastic modulus as well as lower fracture toughness, when compared with those by atmospheric plasma spray or high velocity oxy-fuel spray.
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Spencer, Kevin, and Ming Xing Zhang. "The Emergence of Cold Spray as a Tool for Surface Modification." Key Engineering Materials 384 (June 2008): 61–74. http://dx.doi.org/10.4028/www.scientific.net/kem.384.61.
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Cold spray is an emerging coating technology that allows hardness, corrosion and wear resistance, as well as thermal and electrical properties of surfaces to be optimised. The advantages of cold spray over thermal spray are discussed, with emphasis on a new cold spray variant called Kinetic Metallization. The influence of gas dynamics on surface adhesion are examined. Examples from the literature and from the present work of corrosion and wear resistance, bond strength and cohesive strength of cold spray coatings are reviewed.
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SHAHIEN, MOHAMMED, MOTOHIRO YAMADA, TOSHIAKI YASUI, and MASAHIRO FUKUMOTO. "REACTIVE PLASMA NITRIDING OF AL2O3 POWDER IN THERMAL SPRAY." International Journal of Modern Physics: Conference Series 06 (January 2012): 546–51. http://dx.doi.org/10.1142/s2010194512003753.
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Among advanced ceramics, aluminum nitride ( AlN ) had attracted much attention in the field of electrical and structural applications due to its outstanding properties. However, it is difficult to fabricate AlN coating by conventional thermal spray processes directly. Due to the thermal decomposition of feedstock AlN powder during spraying without a stable melting phase (which is required for deposition in thermal spray). Reactive plasma spraying (RPS) has been considered as a promising technology for in-situ formation of AlN thermally sprayed coatings. In this study the possibility of fabrication of AlN coating by reactive plasma nitriding of alumina ( Al 2 O 3) powder using N 2/ H 2 plasma was investigated. It was possible to fabricate a cubic- AlN (c- AlN ) based coating and the fabricated coating consists of c- AlN , α- Al 2 O 3, Al 5 O 6 N and γ- Al 2 O 3. It was difficult to understand the nitriding process from the fabricated coatings. Therefore, the Al 2 O 3 powders were sprayed and collected in water. The microstructure observation of the collected powder and its cross section indicate that the reaction started from the surface. Thus, the sprayed particles were melted and reacted in high temperature reactive plasma and formed aluminum oxynitride which has cubic structure and easily nitride to c- AlN . During the coatings process the particles collide, flatten, and rapidly solidified on a substrate surface. The rapid solidification on the substrate surface due to the high quenching rate of the plasma flame prevents AlN crystal growth to form the hexagonal phase. Therefore, it was possible to fabricate c- AlN / Al 2 O 3 based coatings through reactive plasma nitriding reaction of Al 2 O 3 powder in thermal spray.
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Naidu, S. V., Carlos Green, Christopher Maxie, James D. Garber, and Gary A. Glass. "Interfacial Elemental Distribution In Tungsten Carbide Coated Steel." Microscopy and Microanalysis 5, S2 (August 1999): 838–39. http://dx.doi.org/10.1017/s1431927600017517.
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Thermal spray of carbide coatings with high hardness and corrosion resistance onto steel substrates has technological importance. The adhesive strength is greatly effected by the interfacial impurities. Low porous and good quality 200 μm thick 86WC10Co4Cr coatings on 4140 steel are obtained by thermal spray methods using SC-HVOF gun at Cooper Oil Tools, Houston, TX. A Carl Zeiss DSM942 SEM with 3.5 nm resolution at 30 keV and Kevex LPX1 Super Dry Quantum Si(Li) Detector with < 145 eV resolution for Energy Dispersive X-ray Spectroscopy (EDXS) were used to study the elemental distribution across the interface. Fig. 1 shows the SEM micrographs of the interface between 86WC10Co4Cr thermal spray coating and 4140 steel substrate. The anchor patterns seen at the interface are believed to improve the adhesive qualities between the coating and the substrate.
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Gan, Jo Ann, and Christopher C. Berndt. "Nanocomposite Thermal Spray Review." AM&P Technical Articles 173, no. 5 (May 1, 2015): 40–43. http://dx.doi.org/10.31399/asm.amp.2015-05.p040.
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Obelode, Esther, and Jens Gibmeier. "Influence of the Interfacial Roughness on Residual Stress Analysis of Thick Film Systems by Incremental Hole Drilling." Materials Science Forum 768-769 (September 2013): 136–43. http://dx.doi.org/10.4028/www.scientific.net/msf.768-769.136.
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Thick film systems with coating thicknesses between 50 and 1000 µm are often fabricated by thermal spray processes. During the deposition and due to the substrate pre-treatment residual stresses, which influence the coating properties, develop. Due to the substrate preconditioning thermal spray coatings exhibit a large interfacial roughness. This study investigates the application of the incremental hole-drilling method on thermal spray coatings. The focus is on the influence of the interfacial roughness on the residual stress evaluation. A systematic FE-study was carried out in order to minimize the final error for the residual stress evaluation. The simulation results are transferred to experimental hole-drilling results of a thermally sprayed model thick film system. Finally, the hole-drilling results are compared to the residual stress depth profile that was determined by X-ray diffraction in combination with successive electrochemical layer removal. The results clearly show that the effect of the interfacial roughness can be neglected for residual stress calculation if the mean coating thickness is properly considered for calculation of the calibration function / parameters.
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Kainuma, Shigenobu, Jin Xuan Du, Mu Ye Yang, Kazuyoshi Muto, and Hirokazu Miyata. "Deterioration Behaviors of Overlapping Layers between Al-5Mg Alloy Thermal Spray Coating and Heavy-Duty Paint Coating." Key Engineering Materials 754 (September 2017): 55–58. http://dx.doi.org/10.4028/www.scientific.net/kem.754.55.
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The objective of this study is to clarify the deterioration behaviors of overlapping layers between Al-5Mg alloy thermal spray coating and heavy-duty paint coating. Combined cyclic corrosion tests were carried out on common carbon steel plates with overlapping layers. To evaluate the effective area of the sacrificial anode reaction caused by the thermal spray coating, machined straight-line defects with widths of 0.2, 6 and 12 mm were introduced in the overlapping layer. The experimental results indicated that the layers began to deteriorate from the lower part of the thermal spray coating along the defects. The deterioration of the thermal spray coating was accelerated by the sealing treatment. The blister area and height at the overlapping layer were significantly different depending on the sealing treatment.