A 3D computational model of fluid flow and heat transfer including solidification was developed. The model is an extension of the Bussmann et al. model. The model was used to simulate the impact of two droplets on a stainless steel substrate in conditions typical of thermal plasma spray processes. Two spraying conditions with two materials, alumina and nickel, were considered. After a completely solidified splat was made from the first droplet impact, the second droplet was introduced. Droplets had different center of impacts. Liquid breakup and splashing occurred with the impact of the second droplet. Void spaces were made between the splats and substrate at the location of the second droplet breakup. These spaces remained void until the end of the process. This may explain one cause of porosity formation in thermal spray coatings.

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