Modeling the Formation of Thermal Spray Coatings on Substrates with Arbitrary Shapes

The main focus of this study is on simulation of coating formation on substrates with arbitrary shapes. For this purpose, several substrate geometries shaped as inclined step, cylinder and sphere are considered. The stress analysis for these complex coating geometries is also performed. The formation of Nickel coatings on various shapes of stainless-steel substrates and Yttria-Stabilized Zirconia (YSZ) on NiCrAlY in the atmospheric plasma spray (APS) process is investigated. The topography of the coatings, as well as their microstructure, e.g., porosity, average thickness and average roughness, are evaluated. An algorithm, which is based on the Monte-Carlo stochastic model, is employed in this work. The parameters of the droplets impacting the surface, including their velocity, temperature and size, are predicted through the use of this stochastic model. Simulation results show that on the inclined part of the step or peripheral parts of the cylinder/sphere, the coating porosity is considerably lower than the flat parts, while the roughness is remarkably higher. A significant difference between the coating temperature and that of the substrate leads to the formation of residual thermal stresses. These stresses are analyzed using the object oriented finite-element (OOF) software, which utilizes an adaptive meshing technique and finite-element method to calculate residual thermal stresses. The maximum stress in the coatings occurs at the interface between the coating and the substrate. The coatings’ topography and microstructure are compared with those of the experiments.

Link to publication

Originally published at Journal of Thermal Spray Technology (04 December 2023, Volume 33, pages 551–571, 2024)
By Behrouz Haghighi, Mohammad Passandideh-Fard, and Javad Mostaghimi