To obtain good quality coatings, spray parameters must be carefully selected. Due to the large variety in process parameters, it is difficult to optimize the process for each specific coating and substrate combination. In this paper, the process of particle in-flight, coating growth and pore formation has been analyzed by numerical simulation. Three sub-models, plasma-particle, splat formation and coating buildup, have been developed. A comprehensive three-dimensional computational code (LAVA3D-P) is used to predict the plasma flame formation, flame-particle interaction, and particle state and trajectory. Assuming each splat is disk-like shape and the flattening ratio, a ratio between the splat diameter and droplet diameter, can be calculated based on the interplay among particle kinetic energy, dissipation energy and solidification. A set of rules of coating buildup are proposed to predict the coating deposition and pore formation, considering the influences of particle size, velocity, temperature and location related to the substrate. Using this model we can obtain the porosity, surface roughness and thickness of the coating considering splat adhesion and quenching stresses. Although the current model has severe restrictions which attributes to many assumptions, it however, forms a foundation for further improvement of an advanced ceramic coating buildup model.

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