An engineering model for solid-liquid phase change within sprayed ceramic coatings of nonuniform thickness

The heat transfer within coatings and substrate materials during plasma deposition of ceramic particles has been modeled numerically using an enthalpy-based finite volume method. The particle distribution within the spray is described by a Gaussian function, while the effects of heat transfer to the substrate from the plasma torch are included using empirical correlations. Using the model, the temperature evolution in the substrate as well as in the coating is predicted in a parametric study involving the plasma torch traversing velocity, the thermal contact resistance between splats, the material deposition rate, as well as the substrate cooling mechanism and plasma jet characteristics. The possibility of melting and subsequent resolidification of material in the substrate as well as in the coating under certain conditions is illustrated.