Modeling of oxidation of molybdenum particles during plasma spray deposition

An oxidation model for molybdenum particles during the plasma spray deposit ion process is presented. Based on a well-verified model for plasma chemist ry and the heating and phase change of particles in a plasma plume, this mo del accounts for the oxidant diffusion around the surface of particles or s plats, oxidation on the surface, as well as oxygen diffusion in molten moly bdenum. Calculations are performed for a single molybdenum particle sprayed under Metco-9MB spraying conditions. The oxidation features of particles d uring the flight are compared with those during the deposition. The result shows the dominance of oxidation of a molybdenum particle during the flight , as well as during deposition when the substrate temperature is high (abov e 400 degreesC).