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1-20 of 32
Nitride ceramics
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Proceedings Papers
Enhanced Coating Deposition by Development of Oxide Shelled Aluminium Nitride
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ITSC2024, Thermal Spray 2024: Proceedings from the International Thermal Spray Conference, 197-203, April 29–May 1, 2024,
Abstract
View Papertitled, Enhanced Coating Deposition by Development of Oxide Shelled Aluminium Nitride
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for content titled, Enhanced Coating Deposition by Development of Oxide Shelled Aluminium Nitride
The need for effective electrical insulation coupled with good thermal conductivity in power electronics has led to an exploration of suitable solutions for components like Insulated-Gate Bipolar Transistors (IGBTs). Considering its material properties, AlN emerges as a promising candidate for this application due to its high thermal conductivity, good electrical insulation and ample dielectric strength. However, aluminium nitride (AlN) has a low deposition efficiency when applied by atmospheric plasma spraying (APS). In contrast to AlN, alumina has a very good deposition efficiency during thermal spraying. Feedstock development was conducted to enhance the coating deposition for AlN. Therefore, a parameter study was carried out with AlN feedstock material to form a protective alumina shell around the AlN particles. Subsequently, the heat-treated powder was applied on an aluminium substrate by APS. X-ray diffraction (XRD) analysis displayed that, the heat-treated feedstock material contained AlN and α-Al 2 O 3 phases. It was observed from scanning electron microscopy (SEM) analysis that the AlN particles formed an oxide shell which led to an enhanced deposition efficiency with a high amount of AlN in the coating. The coatings were also investigated by XRD and SEM to prove the presence of AlN and alumina. For the first time, oxide shelled AlN was successfully applied by thermal spraying with sufficient coating deposition and enhanced AlN-content in the coating.
Proceedings Papers
On Parametric Analysis of Cold Spray of Metallic Coating Onto Ceramic Substrates Using Ceramic Damage Evolution Approach
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ITSC 2019, Thermal Spray 2019: Proceedings from the International Thermal Spray Conference, 816-823, May 26–29, 2019,
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View Papertitled, On Parametric Analysis of Cold Spray of Metallic Coating Onto Ceramic Substrates Using Ceramic Damage Evolution Approach
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for content titled, On Parametric Analysis of Cold Spray of Metallic Coating Onto Ceramic Substrates Using Ceramic Damage Evolution Approach
In this work, a fine copper layer was deposited on an aluminum nitride substrate via cold spraying. Parametric modeling was used to develop a parameter selection map that helped guide preliminary experiments to validate the model for different substrate surfaces, nozzle geometries, gas dynamics, standoff distances, and deposition angles. Further modifications were then made to include failure prediction based on particle impact, leading to the deposition of well-adhered cold-sprayed copper on a ceramic surface.
Proceedings Papers
Characterizations and Properties of Titanium Nitride Composited Coatings Deposited by Very Low Pressure Reactive Plasma-Spraying
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ITSC 2018, Thermal Spray 2018: Proceedings from the International Thermal Spray Conference, 787-791, May 7–10, 2018,
Abstract
View Papertitled, Characterizations and Properties of Titanium Nitride Composited Coatings Deposited by Very Low Pressure Reactive Plasma-Spraying
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for content titled, Characterizations and Properties of Titanium Nitride Composited Coatings Deposited by Very Low Pressure Reactive Plasma-Spraying
The objective of this work is to investigate the microstructure, composition and hardness of reactive titanium nitride coatings manufactured by Reactive Very Low Pressure Plasma Spraying (R-VLPPS) process. Pure titanium powder is injected into the plasma and a reactive gas is added to generate a reaction with the molten particles /vapors. Firstly the plasma-jet properties were analyzed by means of optical emission spectroscopy (OES). Then titanium nitride coatings were manufactured with a F4-VB low-power plasma gun under a working pressure of 150Pa. Investigations show that according to the radial position of the substrates compared to the plasma jet axis, the resulting coatings microstructures are different (mix of semi-molten particles, liquid spat, clusters and vapors). In addition, the coatings composition is modified with an evolution of TiN 0.3 and TiN phase crystalline phases. Finally, the hardness of the coatings is examined.
Proceedings Papers
Reactive Plasma Sprayed Nitride Coatings with Improved Conductivity
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ITSC 2017, Thermal Spray 2017: Proceedings from the International Thermal Spray Conference, 934-940, June 7–9, 2017,
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View Papertitled, Reactive Plasma Sprayed Nitride Coatings with Improved Conductivity
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for content titled, Reactive Plasma Sprayed Nitride Coatings with Improved Conductivity
Decomposition of the nitride ceramic particles like aluminium nitride (AlN) during conventional thermal spray process prevents their deposition on the substrate. Reactive plasma spraying (RPS) is a promising solution to fabricate AlN coatings. It is based on reaction and deposition of molten particles in active nitrogen ambient to form the AlN phase. Several thick AlN based coatings were fabricate successfully by reactive plasma spraying of aluminium and/or alumina particles. This study shows our recent achievements of fabrication of AlN coatings with improved conductivity. It was possible to fabricate AlN based coatings through reactive spraying of fine alumina particles mixed with fine AlN additives. Using small particle size powders improved the particles melting, surface area, therefore nitriding conversion and the AlN content. The fabricated AlN based coating contains several of oxide phases, with low density and high porosity, therefore its thermal conductivity was very low (about 2.6 W/m.K). To fabricate AlN coatings with high thermal conductivity, a liquid phase promoting additive (yttria) was added to the feedstock powder. It assists the formation of the yttrium aluminate (Y-Al-O) phase and therefore the sintering of the coatings during heat treatment. Finally, AlN coating with improved thermal conductivity (above 90 W/m.K) was developed.
Proceedings Papers
Spraying of Aluminum Nitride-Alumina-Yttria Mixtures in Nitrogen
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ITSC2016, Thermal Spray 2016: Proceedings from the International Thermal Spray Conference, 1156-1161, May 10–12, 2016,
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View Papertitled, Spraying of Aluminum Nitride-Alumina-Yttria Mixtures in Nitrogen
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for content titled, Spraying of Aluminum Nitride-Alumina-Yttria Mixtures in Nitrogen
This study investigates the feasibility of spraying aluminum nitride-alumina-yttria mixtures in a nitrogen plasma ambient. Coatings consisting of h-AlN, c-AlN, Al 5 O 6 N, and γ-Al 2 O 3 with small amounts of α-Al 2 O 3 and aluminum-yttrium oxide phases were produced. Although using the Y 2 O 3 additives significantly affected the process and microstructure, it did not achieve the high thermal conductivity desired in as-sprayed coatings. However, a high thermal conductivity (>90 W/m·K) AlN coating was fabricated by increasing the AlN content and enhancing sintering during heat treatment.
Proceedings Papers
Particle Diagnostics and Coating Properties in Reactive Plasma Spray Process
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ITSC2016, Thermal Spray 2016: Proceedings from the International Thermal Spray Conference, 1162-1167, May 10–12, 2016,
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View Papertitled, Particle Diagnostics and Coating Properties in Reactive Plasma Spray Process
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for content titled, Particle Diagnostics and Coating Properties in Reactive Plasma Spray Process
This study investigates the influence of particle temperature and velocity during reactive plasma spraying and the effect of plasma gases on coating properties. Using hydrogen gas with low flow rate was found to be better for reactive plasma spraying of fine Al 2 O 3 -AlN mixtures. The H 2 gas increased in-flight particle temperature, affecting in-flight vaporization, AlN content, phase transformation, deposition efficiency, and coating thickness. N 2 gas, on the other hand, increased particle velocity, thereby reducing particle residence time in the plasma, which affects melting, nitride conversion, and phase transformation.
Proceedings Papers
Ti x Al y N Coating Manufacturing by Reactive Very Low Pressure Plasma Spraying (R-VLPPS)
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ITSC 2015, Thermal Spray 2015: Proceedings from the International Thermal Spray Conference, 746-752, May 11–14, 2015,
Abstract
View Papertitled, Ti x Al y N Coating Manufacturing by Reactive Very Low Pressure Plasma Spraying (R-VLPPS)
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for content titled, Ti x Al y N Coating Manufacturing by Reactive Very Low Pressure Plasma Spraying (R-VLPPS)
Very low pressure plasma spraying (VLPPS) is an emerging process allowing manufacturing oxide and metallic coatings by condensation of vapors generated by feedstock powder vaporization. This process operates at unusually low pressures, typically between 100 and 1000 Pa. This paper aims at presenting recent developments for manufacturing Ti,Al,N coatings via a reactive mode. At first, nitrogen was used as the primary plasma forming gas to enrich spraying surrounding with nitriding species. Plasma jet mass enthalpy and substrate surface temperature were varied to evidence nitride phase formation during spraying. Then, a secondary nitrogen injection was implemented and located close to the surface to be covered in view of creating a continuous nitrogen supply to promote the nitriding mechanisms on the surface. SEM, XRD, GDOES and NHT were implemented to characterize coatings structure. This study highlights the nitrides formation versus spray operating conditions. The microstructural and mechanical features as well as the chemical composition are presented.
Proceedings Papers
High Thermal Conductivity Plasma Sprayed AlN Coating
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ITSC 2015, Thermal Spray 2015: Proceedings from the International Thermal Spray Conference, 811-817, May 11–14, 2015,
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View Papertitled, High Thermal Conductivity Plasma Sprayed AlN Coating
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for content titled, High Thermal Conductivity Plasma Sprayed AlN Coating
Aluminum nitride (AlN) ceramics is characterized with its high thermal conductivity and chemical stability. However, it was impossible to fabricate AlN coatings by conventional thermal spray processes directly from AlN feedstock powder due to thermal decomposition of AlN during spraying. In the last decade we were apple to fabricate the AlN coatings through the reactive plasma spraying process (RPS) in the atmospheric ambient. This study describes the way to fabricate high thermal conductivity plasma sprayed AlN coatings. The thermal conductivity of the AlN coatings was investigated by laser flash method. The as sprayed coating had very low thermal conductivity (2.43 W/m.K), compared to the AlN value. It is attributed to presences of high oxide content (Al 5 O 6 N, γ-Al 2 O 3 and α-Al 2 O 3 phases), low density (2.32 g/cm 3 ) and high porosity in the plasma sprayed coating (about 22%). Besides that, although the N 2 gas flow improved the nitride content, the thermal conductivity decreased gradually. It is related to the further increase of the coating porosity and decreasing its density with the N 2 gas. The influence of the process parameters on the thermal conductivity was investigated and to fabricate high thermal conductivity AlN coating adjusting the oxide content, the coating porosity and microstructure are the main factors. Very high thermal conductivity (about 95 W/m.K) atmospheric plasma sprayed AlN coating was fabricated. The coating consists of mainly AlN phase (more than 95% AlN), very small amount of oxide phases, low porosity (about 3%) with a sintered microstructure (nicked-shape sintered particles).
Proceedings Papers
Wear Behaviour of Conventional and Nanostructured Thin Films of Titanium Aluminium Nitride
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ITSC 2015, Thermal Spray 2015: Proceedings from the International Thermal Spray Conference, 1199-1207, May 11–14, 2015,
Abstract
View Papertitled, Wear Behaviour of Conventional and Nanostructured Thin Films of Titanium Aluminium Nitride
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for content titled, Wear Behaviour of Conventional and Nanostructured Thin Films of Titanium Aluminium Nitride
Titanium aluminium based nitride (Ti, Al)N coatings possess excellent tribological behaviour with respect to metal cutting and polymer forming contacts. In the present work TiAlN coatings were deposited by plasma spray process. Three coatings of TiAlN were deposited on AISI-347 grade boiler steel substrate out of which two were thin nano coatings deposited at different temperatures of 500°C and 200°C and one conventional coating was deposited by plasma spraying. The as sprayed coatings were characterized with relative to coating thickness, microhardness, porosity and microstructure. The optical microscopy (OM), the XRD analysis and field mission scanning electron microscope (FESEM with EDAX attachment) techniques have been used to identify various phases formed after coating deposited on the surface of the substrate. Subsequently the sliding wear behaviour of uncoated, PVD sprayed nanostructured thin TiAlN coatings deposited at 500°C and 200°C and plasma sprayed conventional coated AISI-347 grade boiler steel were investigated according to ASTM standard G99-03 using pin on disk wear test rig. Cumulative wear volume loss and coefficient of friction, μ were calculated for the coated as well as uncoated specimens for 10, 15 and 20 N normal loads at a constant sliding velocity of 1 m/sec. The worn out samples were analysed with SEM/EDAX. Wear rates in terms of volumetric loss (mm³/g) for uncoated and coated alloys were compared. The nanostructured TiAlN coatings deposited at 500°C and 200°C has shown minimum wear rate as compared to conventional TiAlN coating and uncoated AISI-347 grade boiler steel. Nanostructured TiAlN coatings were found to be successful in retaining surface contact with the substrate after the wear tests.
Proceedings Papers
Development of Thermal Spray Coating Solution for Ceramic Substrates
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ITSC 2013, Thermal Spray 2013: Proceedings from the International Thermal Spray Conference, 79-84, May 13–15, 2013,
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View Papertitled, Development of Thermal Spray Coating Solution for Ceramic Substrates
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for content titled, Development of Thermal Spray Coating Solution for Ceramic Substrates
This work assesses the challenges of preparing dense technical ceramic substrates for thermal spraying and evaluates the capabilities of laser ablation in comparison with sandblasting. Sintered Si3N4 and AlN substrates were prepared by both methods and surface roughness was measured before and after treatment. Alumina coatings were deposited by suspension-HVOF and atmospheric plasma spraying, and coating cross-sections were analyzed by optical microscopy and SEM. Sandblasting had little or no effect on surface roughness and cracks were observed in coating cross-sections at the near-surface region of the substrate. Laser ablation, on the other hand, significantly increased surface roughness for both ceramics, producing hole patterns that are shown to vary with laser power and pulse timing. In the case of plasma spraying, the best coatings were achieved when the holes in the substrate were less than 100 µm in depth. With suspension sprayed coatings, the best results were obtained on substrates with deeper (> 100 µm) holes.
Proceedings Papers
Deposition Behavior and Microstructural Features of Vacuum Kinetic Sprayed AlN
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ITSC2012, Thermal Spray 2012: Proceedings from the International Thermal Spray Conference, 340-344, May 21–24, 2012,
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View Papertitled, Deposition Behavior and Microstructural Features of Vacuum Kinetic Sprayed AlN
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for content titled, Deposition Behavior and Microstructural Features of Vacuum Kinetic Sprayed AlN
Vacuum kinetic spray (VKS) technology was employed to fabricate AlN films. In order to investigate the relationship between the deposition behavior with change of the size and microstructure of feedstock, AlN powders were pre-treated through ball-milling and heat-treatment. It is observed that the particle size decreased and defect density increased after the ball-milling. After the heat-treatment of the ball-milled powder, on the other hand, the particle size was not changed significantly, while the defect density was reduced by recovery. The coatings of ball-milled and heat-treated powder were obviously thicker than that of only ball-milled powder. It is inferred that, during the heat-treatment, although the defects were reduced by recovery, the dislocations were aligned, through which the cracks were able to propagate more easily. By the combined effects of ball-milling and heat-treatment, more fragmentations with new surfaces of the particles were generated during VKS, which would improve the deposition efficiency. Therefore, in VKS process, the deposition behavior is shown to be affected by not only particle size, but also the defect density and microstructure of the feedstock powder.
Proceedings Papers
Effect of Powder Structure on the Adhesion and Electrical Properties of TiN Coatings Deposited by Vacuum Cold Spray
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ITSC2012, Thermal Spray 2012: Proceedings from the International Thermal Spray Conference, 689-693, May 21–24, 2012,
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View Papertitled, Effect of Powder Structure on the Adhesion and Electrical Properties of TiN Coatings Deposited by Vacuum Cold Spray
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for content titled, Effect of Powder Structure on the Adhesion and Electrical Properties of TiN Coatings Deposited by Vacuum Cold Spray
Sub-micro-structured titanium nitrides (TiN) coatings on Al 2 O 3 substrates were fabricated by vacuum cold spray (VCS) process using ceramic powders, which were ball-milled at room temperature. The microstructure features and crystal structures of the VCS TiN coatings were analyzed by scanning electron microscopy and X-ray diffraction. The adhesion between the coating and the substrate was evaluated with a scratch tester. The sheet resistance of the VCS TiN coatings was measured by using a four-point probe method. The effects of nozzle traverse speed on the microstructure, adhesion to substrate and electrical properties of the coatings were investigated. It was found that the adhesion improves greatly with the nozzle traverse speed increasing from 5 to 15mm/s, and the electrical resistivity levels of the coatings is decreased significantly. The resistivity of sub-micron-structured TiN coatings is substantially lower than those of nano-structured ones fabricated by the same VCS process. And a minimum resistivity of 1.16×10 -4 Ω·m is achieved.
Proceedings Papers
Effect of Processing Parameters on the Deposition Characteristics and Microstructure of Vacuum Kinetic Sprayed TiN Layer
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ITSC2012, Thermal Spray 2012: Proceedings from the International Thermal Spray Conference, 694-698, May 21–24, 2012,
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View Papertitled, Effect of Processing Parameters on the Deposition Characteristics and Microstructure of Vacuum Kinetic Sprayed TiN Layer
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for content titled, Effect of Processing Parameters on the Deposition Characteristics and Microstructure of Vacuum Kinetic Sprayed TiN Layer
Vacuum kinetic spray (VKS) is a relatively new coating process by which dense, low porosity nanostructured ceramic coatings can be produced. Titanium nitride films with thickness of 0.5-5 µm on glass were fabricated by VKS method for a mechanism and microstructure study. Deposition behavior and structure with different gas consumption and gun traverse speed were studied based on X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM). The as-deposited titanium nitride film consisted of ~20 nm grains is well condensed and expected to have excellent mechanical properties.
Proceedings Papers
Aluminum Nitride Coating Fabricated by Reactive Plasma Spraying of Al 2 O 3
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ITSC2012, Thermal Spray 2012: Proceedings from the International Thermal Spray Conference, 873-879, May 21–24, 2012,
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View Papertitled, Aluminum Nitride Coating Fabricated by Reactive Plasma Spraying of Al 2 O 3
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for content titled, Aluminum Nitride Coating Fabricated by Reactive Plasma Spraying of Al 2 O 3
Reactive plasma spraying (RPS) has been considered as a promising technique for in situ formation of aluminum nitride (AlN) based thick coatings. This study investigated the reactive plasma spraying of AlN coating with using Al 2 O 3 powder and N 2 /H 2 plasma. It was possible to fabricate a cubic- AlN (c-AlN) based coating. The phase composition of the coating consists of c-AlN, α-Al 2 O 3 , Al 5 O 6 N and γ-Al 2 O 3 . Understanding the nitriding process during coating deposition is essential to control the process and improve the coating quality. The nitriding process was performed by spraying, collecting the particles into a water bath (to maintain its particle features) and observing their microstructures and cross sections. During the coating process, the sprayed particles were melted, spheroidized and nitrided in the N 2 /H 2 plasma to form the cubic aluminum oxynitride (Al 5 O 6 N). The particles collided, flattened, and rapidly solidified on the substrate surface. The Al 5 O 6 N is easily transformed to c-AlN phase (same cubic symmetry) by continuous reaction through plasma environment. Improving the specific surface area by using smaller particle sizes enhances the surface nitriding reaction and improves the nitriding conversion. Furthermore, using AlN additives enhances the nitride content in the coatings. It was possible to fabricate thick and uniform coatings with high AlN content by spraying fine Al 2 O 3 /AlN mixture. Furthermore, the N 2 gas flow rate improved the nitriding conversion and the coating thickness.
Proceedings Papers
Synthesis of Porous Super-Capacitor Electrodes using the SPPS Deposition Technique
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ITSC 2011, Thermal Spray 2011: Proceedings from the International Thermal Spray Conference, 869-873, September 27–29, 2011,
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View Papertitled, Synthesis of Porous Super-Capacitor Electrodes using the SPPS Deposition Technique
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for content titled, Synthesis of Porous Super-Capacitor Electrodes using the SPPS Deposition Technique
Electrical double-layer capacitors (EDLCs) owe their large capacitance to high specific surface area carbon-based electrode materials adhered to a current collector via an adhesive. However, recent studies attribute greater electrical energy storage capacity to transition metal oxides/nitrides: a new generation of electrode materials for use in super-capacitors with mixed double-layer and pseudo-capacitive properties. Solution Precursor Plasma Spray (SPPS) deposition is a technique that allows coatings to be fabricated with fine grain sizes, high porosity levels, and high surface area; characteristics ideal for application as transition metal oxide super-capacitor electrodes. A liquid injection apparatus was designed to inject the liquid into the DC-arc plasma and to investigate the effects of various operating parameters such as spray distance, solution concentration and solution flow rate on the chemistry and surface topography of the deposits. Understanding and controlling the evolution of the precursor solution in the DC-arc plasma jet is crucial in producing coatings of the desired structures. DTA/TGA, SEM, XRD, and electrochemical analyses performed to characterize the coatings will be discussed, and the potential of the deposits for use in super-capacitors will be assessed.
Proceedings Papers
Influence of Deposition Conditions and Heat Treatment on Tensile Strength of Cold Spray Aluminium Coatings on Al 2 O 3 and AlN Substrates
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ITSC 2011, Thermal Spray 2011: Proceedings from the International Thermal Spray Conference, 1130-1135, September 27–29, 2011,
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View Papertitled, Influence of Deposition Conditions and Heat Treatment on Tensile Strength of Cold Spray Aluminium Coatings on Al 2 O 3 and AlN Substrates
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for content titled, Influence of Deposition Conditions and Heat Treatment on Tensile Strength of Cold Spray Aluminium Coatings on Al 2 O 3 and AlN Substrates
A novel process to produce dense, well adherent aluminium coatings on ceramic materials is cold gas spraying (CGS). The mechanical, physical and chemical processes leading to the bonding of cold-sprayed coatings on ceramic substrates have only been described rudimentarily. A survey of the literature on adhesion mechanisms of cold spray coatings is given, where influences on bond strength are discussed and parameters identified. Using the example of coating Al 2 O 3 and AlN substrates with pure aluminium via cold gas spraying, a process and substrate parameter variation is presented. A significant raise in tensile coating strength was seen at elevated substrate temperatures and after subsequent annealing. Tensile strength also depended on chemical composition and roughness of the substrate. The results allow the discussion of the bonding mechanisms of cold spray aluminium on ceramic substrates as a function of deposition and annealing parameters.
Proceedings Papers
Influence of Feedstock Powder for Fabrication of Aluminum Nitride in Reactive Atmospheric Plasma Spray Process
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ITSC 2010, Thermal Spray 2010: Proceedings from the International Thermal Spray Conference, 213-218, May 3–5, 2010,
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View Papertitled, Influence of Feedstock Powder for Fabrication of Aluminum Nitride in Reactive Atmospheric Plasma Spray Process
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for content titled, Influence of Feedstock Powder for Fabrication of Aluminum Nitride in Reactive Atmospheric Plasma Spray Process
It was possible to fabricate cubic-AlN (c-AlN) based coating through the reaction between Al powder and the N 2 /H 2 plasma in APS system. The fabricated coating was about 100 μm with hardness about 540 Hv, which is much higher than the hardness of Al. The formation of the cubic phase in APS is directly related to the rapid solidification phenomena of plasma spraying process. The sprayed powder particles show rapid cooling rates upon impact with the substrate, which prevent its complete crystal growth. The nitride content increased with the spray distance due to increase the flight time of Al particles in the N 2 plasma. Using smaller particle size improved the nitriding reaction at short spray distance due to increasing the particle temperature. However increasing the particle temperature leads to excessive vaporization of Al particles and completing nitriding reaction during flight, therefore suppressing the coatings thickness. The nitriding reaction of the larger particle size Al powders can be enhanced through NH4Cl powders addition. That NH4Cl addition changed the reaction pass way from liquid-gas to vapor-phase intermediate mechanism.
Proceedings Papers
Effect of Nitrogen Flow Rate on the Microstructure and Transformation Rate of TiN Coatings in Reactive Plasma Spraying
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ITSC 2010, Thermal Spray 2010: Proceedings from the International Thermal Spray Conference, 812-815, May 3–5, 2010,
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View Papertitled, Effect of Nitrogen Flow Rate on the Microstructure and Transformation Rate of TiN Coatings in Reactive Plasma Spraying
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for content titled, Effect of Nitrogen Flow Rate on the Microstructure and Transformation Rate of TiN Coatings in Reactive Plasma Spraying
TiN coatings and some particle of TiN were prepared by reactive plasma spraying, in which titanium powder react with nitrogen under different flow rate, at the same time keeping all other parameters invariableness. The microstructure of the TiN coatings and particles were analyzed by means of SEM and the rate of TiN coating was tested by XRD. The results show that the microstructure and transformation rate of TiN coatings are greatly affected by nitrogen flow rate. The microstructure and transformation rate of TiN coatings were the best when the nitrogen flow rate was 1500 L/h.
Proceedings Papers
Preparation and Characterization of Nickel Clad h-BN Composite Powders for Abradable Sealing Coating
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ITSC 2008, Thermal Spray 2008: Proceedings from the International Thermal Spray Conference, 1120-1122, June 2–4, 2008,
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View Papertitled, Preparation and Characterization of Nickel Clad h-BN Composite Powders for Abradable Sealing Coating
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for content titled, Preparation and Characterization of Nickel Clad h-BN Composite Powders for Abradable Sealing Coating
Nickel clad hexagonal boron nitride (h-BN) powders were prepared by reducing nickel ions from a solution under hydrogen pressure in the presence of ammonia as a complexing agent, and plasma spraying was carried out to deposit the corresponding coating. The microstructure, morphology and phase composition of the powders and the coating were characterized by optical microscope (OM), Scanning Electronic Microscope (SEM) and X-ray Diffraction (XRD), respectively. The results show that alkali solution pretreatment and activation procession are necessary for acquiring a dense and uniform nickel coating on the surface of the h-BN particles, and the h-BN particles are distributed well throughout the coating with the porosity of about 26%, which indicate that the coating was potential for abradable sealing application.
Proceedings Papers
Reactive Plasma Spraying of Fine Feedstock Powders for Fabrication of Nitride Ceramic Coatings
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ITSC 2007, Thermal Spray 2007: Proceedings from the International Thermal Spray Conference, 694-698, May 14–16, 2007,
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View Papertitled, Reactive Plasma Spraying of Fine Feedstock Powders for Fabrication of Nitride Ceramic Coatings
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for content titled, Reactive Plasma Spraying of Fine Feedstock Powders for Fabrication of Nitride Ceramic Coatings
Aluminum nitride (AlN) and iron nitride (Fe 4 N) coatings were fabricated by reactive plasma spraying using fine feedstock powders. Reactive plasma spraying, in which element particles react with surrounding active species in the plasma, enables to fabricate nitride ceramics which decompose without stable melting phase. However, it is difficult to fabricate the coatings which include higher concentration of nitride phase by reactive plasma spraying using conventional particle size of feedstock powders. Therefore, fine feedstock powders were used in order to enhance the nitriding reaction during spraying. Aluminum or iron particles were injected into Ar/N 2 plasma and were deposited onto graphite substrates. It was possible not only to increase the nitride phase content in the coatings but also to densify the microstructure in both materials. Thus, it became clear that using fine feedstock powders are useful for fabrication of nitride ceramic coatings by reactive plasma spraying.
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