Model and powder particle heating, melting, resolidification, and evaporation in plasma spraying processes

A comprehensive model is developed to study the heating, melting, evaporati on, and resolidification of powder particles in plasma flames. The well-est ablished LAVA code for plasma flame simulation is used to predict the plasm a gas field under given power conditions, and provide inputs to the particl e model. The particle is assumed to be a spherical and one-dimensional heat conduction equation with phase change within the particle is solved numeri cally using an appropriate coordinate transformation and finite difference method. Melting, vaporization, and resolidification interfaces are tracked and the particle vaporization is accounted for by the mass diffusion of vap or through the boundary layer around the particle. he effect of mass transf er on convective hear transfer is also included Calculations have been carr ied out for a single particle injected into an Ar-H, plasma jet, Zirconia a nd nickel are selected as solid particles because of their widespread indus trial applications as well as significant differences in their thermal prop erties. Numerical results show strong nonisothermal effect of heating, espe cially for materials with low thermal conductivity, such as zirconia. The m odel also predicts strong evaporation of the material at high temperatures.