Numerical Design of an Adaptive-pressure Plasma Coating Process

Thermal barrier coatings (TBC) are mainly produced by EB-PVD or atmospheric plasma spray depending on their thermomechanical loading. This study deals with the numerical design of a two-step thermal plasma-aided physical vapor deposition process making it possible i) to efficiently evaporate the material and ii) to get a resilient-coating microstructure from vapor phase condensation. This microstructure can also be varied by modifying the deposition pressure (50-1000 Pa) to achieve coatings built from vapor condensation and/or already-vapor-formed clusters and so to allow other applications than TBC (e.g. photocatalytic doped titania coatings). In this work, the effect of the process geometry and operating conditions on the gas flow fields, powder vaporization efficiency and nucleation/growth phenomena in the gas phase will be discussed.