Simulation of thermally sprayed coating properties considering the splat boundaries

Abstract

The properties of thermally sprayed coatings depend heavily on the solidification process during the impact on the substrate. The simulation of the coating build-up is of essential importance in order to understand the processes behind it. The main objective of his study is the development of a coating build-up model to predict the properties e.g. thermal conductivity of plasma sprayed coatings. Therefore, a CFD simulation based on a VOF approach coupled with the momentum source method is applied. 3D-simuations of the impact of multiple alumina particles are performed to observe the coating build-up. Subsequently, the result is transferred to another model to calculate the coatings thermal conductivity. Since the resolution of the mesh does not allow a proper representation of the air gap at the splat boundaries between two solidified particles, a new function is developed to cover such phenomena. This function enables a broader representation of the splat boundaries and an adjustment of the coating properties in these areas. To validate this function, multiple simulations with different particle temperatures and velocities are calculated. Likewise, different assumptions for the thermal conductivity values in the gap are investigated. The results of the calculated properties correspond with experimental values.