Abstract
D.C. plasma spraying process leads to coatings with high level properties. The control of these properties implies to overcome well the process and in particular the interactions between the particles and the plasma plume. This latter shows high fluctuations outside the torch due to arc root movements on the anode wall inside the torch. These movements are responsible of less or more weak plasma flow stretching outside the torch and of air engulfment. From a simple numerical model based on the gas heating by JOULE effect in the anode, the realistic flow behavior is reproduced, in particular, the mechanisms of air engulfment into the plasma plume, such as it was described by PFENDER and al. Moreover, the centerline velocities and temperatures of the gas are compared with experimental values: the comparison shows good agreement. From this realistic flow, zirconia particle treatment modeling is carried on. Depending on the plasma plume stretching outside the torch and on particle granulometry, the particle trajectories and also velocities and temperatures present high variations, leading to particle thermocinetic states at impact quite different from one particle to the other.
