A modified Laval-like-contour for a convergent-divergent nozzle is presented for the Atmospheric Plasma Spraying (APS). The influence of the nozzle design on the thermal and deposition efficiency as well as on the arc voltage fluctuations and the sound level of the plasma torch are investigated and compared with former investigations. The improvements of the quality of DC-Plasma sprayed Al2O3 coatings by the nozzle design is shown by the coating porosity, adhesive and breakdown strength. A 2D-model presents the gas dynamics inside the nozzle. The intention of this study is to promote the industrial application of convergent-divergent nozzles for the APS in conjunction with the optimisation of the plasma gas dynamics.

adhesive strength, aluminum oxide coatings, atmospheric plasma spraying, plasma torches, porosity, spray nozzles
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Copyright © 2003 ASM International. All rights reserved.
2003
ASM International
Topics
Thermal spray equipment Alumina ceramics Plasma spray coating Bonding strength Porosity
Issue Section:
Equipment and Processes
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