Modeling the formation of thermal spray coatings on a rough substrate

Thermal spray coatings are done on grit blasted, rough surfaces. Coating formation models typically assume a smooth substrate. One method to simulate formation of coating on a rough substrate is to use two-layer coating, as the first layer of coating may be considered as a rough surface. This is the approach that we will employ in this paper. In this research, the formation of Nickel coating on a rough stainless-steel substrate in an Atmospheric Plasma Spray (APS) process is investigated. The topography of the coating, as well as its microstructure, e.g., porosity, average thickness, and average roughness, is evaluated. The numerical model of simulation is based on the Monte-Carlo stochastic algorithm. The significant difference between the coating temperature and that of the substrate leads to the formation of residual thermal stresses. These stresses are analyzed using Object Oriented Finite-element software (OOF) developed by the National Institute of Standards and Technology (NIST). The results showed that the roughness of substrate, will intensify the roughness of the coating. Additionally, maximum stress occurs at the coating-substrate interface, but the roughness leads to non-uniform stress distribution, causing stress concentrations at specific points.