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1201 |
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Monday, June 02, 2008, Room 08 4:20 PM Plasma Spraying and Plasma Transferred Arc 2 New trends and modified plasma processes for the application of ceramic-based coatings |
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Effective parameters in axial injection suspension plasma spray process of alumina-zirconia ceramics |
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Fariba Tarasi* / Concordia University, Canada Mamoun Medraj/ Concordia University Canada , Canada Ali Dolatabadi/ Concordia University Canada , Canada Jorg Oberste Berghaus/ NRC-IMI Boucherville Canada , Canada Christian Moreau/ NRC-IMI Boucherville Canada , Canada |
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Suspension Plasma Spray (SPS) is a novel process for producing nano-structured coatings with metastable phases from extra small particles (nano and or submicron range). In suspension spraying the particles are created by atomization, solvent evaporation and melt consolidation in the spray process, which can add substantial complexity to the system, as compared to conventional thermal spraying. Using feedstock mixtures, such as alumina and zirconia, the intricacy of the system is even more. There is consequently a need to more understand the relationship between plasma spray conditions and resulting microstructure and coating integrity. In axial injection plasma spray system, the effect of the principal deposition parameters on the microstructural features (microcracks, porosities and deposition rate) of alumina-zirconia composite coatings are evaluated using Taguchi design of experiment (DOE). For better understanding the role of the spray parameters, in-flight particle characteristics (temperature, velocity) were also measured. The effect of substrate preheating was evaluated and it was shown that up to 150 ºC preheating temperature does not significantly affect the microstructure. The role of the porosity in this multi-component structure is studied as well. The results indicate that thermal diffusivity of the coatings, an important property for potential thermal barrier applications, is more controlled by horizontal microcracks rather than by the coating porosity. |