Measuring Substrate Temperature Variation During Application of Plasma-Sprayed Zirconia Coatings

Salimijazi, Hamidreza; Pershin, Larry; Coyle, Thomas W.; Mostaghimi, J.; Chandra, Sanjeev; Lau, Yuk-Chiu; Rosenzweig, L.; Moran, Eric

doi:10.1007/s11666-007-9050-7

Cited by 27 publications

(10 citation statements)

References 14 publications

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“…As it is well known in plasma spraying process, the powder particles are quickly melt in the plasma stream and accelerated to the substrate where they spread upon impact and rapidly solidify. 27,28) The formation process of meta-stable c-AlN is strongly related to the rapid solidification. During the nitriding of the Al 2 O 3 particles, the aluminum oxynitride phase (Al 5 O 6 N) was formed and it is easy convert to c-AlN phase through continuous nitriding.…”

Section: Formation Process Of Cubic Aln Coatingmentioning

confidence: 99%

Synthesis of Cubic Aluminum Nitride Coating from Al2O3 Powder in Reactive Plasma Spray Process

et al. 2013

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Plasma spraying is a versatile technique for producing abradable and protective ceramic coatings. However, it was difficult to fabricate aluminium nitride (AlN) coating by conventional plasma spray processes. It is due to the thermal decomposition of the feedstock AlN powder during spraying without a stable melting phase. Reactive plasma spraying (RPS) has been considered as a promising technology for in-situ formation of AlN thermally sprayed coatings. This study investigated the feasibility of reactive plasma spraying of Al 2 O 3 powder in N 2 /H 2 plasma upon fabrication of AlN coating. It was possible to fabricate a cubic-AlN (c-AlN)/Al 2 O 3 composite coating and the fabricated coating consists of c-AlN, ¡-Al 2 O 3 , Al 5 O 6 N and £-Al 2 O 3 . Furthermore, the AlN content was improved with increasing the flight time (spray distance), due to increasing the reaction time between the Al 2 O 3 particles and the surrounding N 2 /H 2 plasma. It was possible to fabricate coating contains about 97% of c-AlN. However, it was difficult to clarify the in-flight reaction during the coating process, due to losing the particles shape and features after colliding and flattening on the substrate surface. The sprayed particles were collected into a water bath to maintain its particle features in order to investigate the in-flight reaction. It was clear from the microstructure and the cross section observation of the collected particles that, the nitriding reaction started from the surface. During the coating process, the sprayed particles were melted, spheroidized and reacted in the high temperature N 2 /H 2 plasma and formed aluminum oxynitride (Al 5 O 6 N) which have cubic structure. The particles collided, flattened, and rapidly solidified on a substrate surface. The Al 5 O 6 N is easily converted to c-AlN phase via continuous nitriding (both have the same cubic symmetry: cubic and closely packed) during the rapid solidification and plasma irradiation on the substrate. The high quenching rate of the plasma flame prevents the AlN crystal growth to form the hexagonal phase. Therefore, it was possible to fabricate c-AlN/Al 2 O 3 composite coatings through reactive plasma nitriding of Al 2 O 3 powder and the nitriding process of the Al 2 O 3 particle as well as the formation process of cAlN phase were investigated.

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Section: Formation Process Of Cubic Aln Coatingmentioning

confidence: 99%

Synthesis of Cubic Aluminum Nitride Coating from Al2O3 Powder in Reactive Plasma Spray Process

et al. 2013

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“…Embedded and fast response micro-thermocouples in metallic substrate (Ref 121,122) with the still unresolved problem of the lack of good contact between substrate and coating, especially for low conductivity sprayed materials.…”

Section: Ir Thermography (Ref 118-120)mentioning

confidence: 99%

Sensors in Spray Processes

Fauchais

Vardelle

2010

J Therm Spray Tech

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This paper presents what is our actual knowledge about sensors, used in the harsh environment of spray booths, to improve the reproducibility and reliability of coatings sprayed with hot or cold gases. First are described, with their limitations and precisions, the different sensors following the in-flight hot particle parameters (trajectories, temperatures, velocities, sizes, and shapes). A few comments are also made about techniques, still under developments in laboratories, to improve our understanding of coating formation such as plasma jet temperature measurements in non-symmetrical conditions, hot gases heat flux, particles flattening and splats formation, particles evaporation. Then are described the illumination techniques by laser flash of either cold particles (those injected in hot gases, or in cold spray gun) or liquid injected into hot gases (suspensions or solutions). The possibilities they open to determine the flux and velocities of cold particles or visualize liquid penetration in the core of hot gases are discussed. Afterwards are presented sensors to follow, when spraying hot particles, substrate and coating temperature evolution, and the stress development within coatings during the spray process as well as the coating thickness. The different uses of these sensors are then described with successively: (i) Measurements limited to particle trajectories, velocities, temperatures, and sizes in different spray conditions: plasma (including transient conditions due to arc root fluctuations in d.c. plasma jets), HVOF, wire arc, cold spray. Afterwards are discussed how such sensor data can be used to achieve a better understanding of the different spray processes, compare experiments to calculations and improve the reproducibility and reliability of the spray conditions. (ii) Coatings monitoring through in-flight measurements coupled with those devoted to coatings formation. This is achieved by either maintaining at their set point both in-flight and certain spray parameters (spray pattern, coating temperature…), or defining a good working area through factorial design, or using artificial intelligence based on artificial neural network (ANN) to predict particle in-flight characteristics and coating structural attributes from the knowledge of processing parameters.

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“…Thus, the microstructure and properties of a TBC coating, as characterized by grain morphology, grain size, and microsegregation, are directly related to individual splat morphology and crystal structure, and the adhesion between the TBC and substrate as well as between individual splats. A variety of factors affect the solidification behavior of a splat: in-flight particle characteristics such as temperature and velocity, the substrate material and its surface properties (including temperature and roughness), and the thermal contact resistance caused by gases and solid impurities trapped at the splat-substrate interface [4,[6][7][8]. For an overview of thermal spray splat formation, see the review by Chandra and Fauchais [9].…”

Section: Introductionmentioning

confidence: 99%

“…[6][7][8]) have examined the microstructure of an APS deposit, focusing on the final morphology of solidified splats and the associated solidification behavior, to gain a better understanding of the fundamental mechanisms of rapid solidification and microstructure formation during plasma spraying. In this study we examine YSZ single splat solidification, both experimentally and numerically, to visualize how rapid solidification influences grain formation in the microstructure.…”

Section: Introductionmentioning

confidence: 99%

Experiments and modeling of rapid solidification of plasma-sprayed yttria-stabilized zirconia

et al. 2009

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Measuring Substrate Temperature Variation During Application of Plasma-Sprayed Zirconia Coatings

Cited by 27 publications

References 14 publications

Synthesis of Cubic Aluminum Nitride Coating from Al<sub>2</sub>O<sub>3</sub> Powder in Reactive Plasma Spray Process

Synthesis of Cubic Aluminum Nitride Coating from Al<sub>2</sub>O<sub>3</sub> Powder in Reactive Plasma Spray Process

Sensors in Spray Processes

Experiments and modeling of rapid solidification of plasma-sprayed yttria-stabilized zirconia

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