Modeling of the plasma spray process : From powder injection to coating formation

This paper presents a numerical simulation of the plasma-spraying of alumina particles. The first section deals with the coating formation. The latter is governed by various time-scales ranging between microseconds (splat flattening and solidification) and seconds (time between two passes). This large range makes the deposit process difficult to simulate. However, such simulations would help to have a better understanding of coating building and, therefore, a better control of coating quality. The second section addresses the modeling of the plasma jet and particle treatment using a three-dimensional commercial fluid dynamics code ESTET 3.4 The effect of (i) turbulence model and turbulence radial profiles at the torch exit on plasma flow and particle behavior, (ii) particle injection conditions on particle trajectories and heating and (iii) plasma jet fluctuations on temperature and velocity flow fields is investigated. The comparison of predictions with experimental measurements of gas and particle velocity and temperature, makes it possible to determine the influential parameters and set them to pertinent values.