Finite element analysis of residual stress in plasma-sprayed ceramic coatings

A numerical study was carried out by finite element analysis (FEA) for the calculation of absolute values and through-thickness variation of residual stress originating in thermal spray coatings. The investigated deposit was an air plasma sprayed alumina coating sprayed on a carbon steel substrate previously coated with Ni20Al bond coat. Results show compressive residual in-plane stresses with linear through-thickness variation and tensile normal and shear stresses having a peak at the coating-substrate interface. The influence of deposition temperature on residual stress was also investigated. The experimental validation of the FEA model was carried out using a high-speed hole drilling technique, suitably adapted for the analysis of a multimaterial structure through FEA calculation of the required calibration coefficients. A very good agreement between simulated and measured stresses was obtained, inspire of the adopted simplification hypothesis.