An advanced model for plasma spraying of functionally graded materials

A comprehensive model for the simulation of the plasma spraying of functionally graded materials (FGMs) is developed based on the recently modified CFD code, LAVA-P, that incorporates a well-verified model for plasma gas flow and chemistry. The particle movement and its trajectory are described within a Lagrangian framework by considering the drag as the major driving force. Melting and evaporation of particles are considered using a recently developed model for particle-flame interaction that also accounts for the non-continuum and variable property effects of high temperature plasma on particle momentum and heat transfer. Calculations are performed for NiCrAlY (alloy) and Y ₂ O ₃ stabilized ZrO ₂ powders with a wide range of size distribution. The influence of the power levels and flow rate of H ₂ on the plasma flow field, and hence, on the particle velocity and temperature are investigated numerically. The predicted velocity and temperature fields agree well with the measurements performed under similar spraying conditions. Segregation is investigated for two powder injection configurations. The model presented here can be used successfully for FGM deposition uniformity.