A finite difference model for the thermal analysis of the dynamic stochastic multiple particle deposition process of thermal spray was developed in this paper. Contrary to the traditional layer by layer deposition model, the thermal contribution of individual particles randomly distributed around the spray jet center was taken into account so as to simulate coating formation process. New material was dynamically added onto coating/substrate surface with prescribed gun movement. Latent heat effect was introduced by defining the enthalpy of the material as a function of temperature in order to take into account solidification induced phase change. Real thermal spray process can be simulated with adjustable particle size, spray deposition rate, velocity of gun movement, etc.

The crystal structure of the coating depends on the splashing and solidification of the sprayed particles. The splashing of the particles is simulated by commercial software taking temperature dependent parameters like melt viscosity and surface tension into account. This article provides the theoretical background and the experimental verification. The steps of simulation solidification, splashing, and heat and momentum transfer help to develop novel coating systems with defined microstructure and shorten the time to market. Experimental investigations were carried out using Ni and Ni/Cr 80/20 spray powders with a mean particle diameter of about 15 μm. The theoretical investigations to describe the flattening process of a droplet show the influence of particle velocity and temperature. It was shown that different material parameters, as latent heat or surface energy, have a significant influence on the simulation results.