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

Modeling the Formation of Coatings on Substrates with Arbitrary Shapes B. Haghighi+, M. Passandideh-Fard+, J. Mostaghimi* +Department of Mechanical Engineering, Ferdowsi, Mashhad, Iran *Centre for Advanced Coating Technologies, University of Toronto, Toronto, Canada The formation of nickel coatings on stainless steel substrate and Zirconia on NiCrAlY in the Atmospheric Plasma Spray (APS) process is investigated. Coating formation over several substrate geometries is considered, e.g., an inclined step, The topography of the coatings, as well as their microstructure, e.g., porosity, average thickness, and average roughness, are evaluated. A numerical program is used, which is based on the Monte-Carlo stochastic model. A large difference between the coating temperature and that of the substrate leads to the formation of residual thermal stresses. These stresses are analyzed using an Object Oriented Finite-element code (OOF) developed by the National Institute of Standards and Technology (NIST). An image of the cross-section of the coating is imported into the code, which utilizes an adaptive meshing technique and Finite-Element Method to calculate residual thermal stresses. The results indicate that the maximum stress in all shapes of substrates appears at the coating interface with the substrate. The coatings' topography and microstructure are compared with those of the experiments.