The microstructure model on the residual stress distribution of metal-ceramic coating

This paper deals with the thermal residual stress of plasma spraying of functionally graded 8 wt.% Y2O3-ZrO2 (8YSZ)/NiCoCrAlY/5A06 alloy system, arising from the different coefficients of thermal expansion (CTEs) by reason of the temperature difference during processing. A theoretical model based on force and moment balances and a thermo-mechanical finite element analysis (FEA) are applied to estimate the distributions of residual stresses. In the analytical model, the effect of thickness is discussed. It has been found that the residual stress almost increases linearly with increasing thickness. Furthermore, FEA model with micro-structure is modeled to observe internal thermal residual stress visually and compared that with macro-structure as well. A submodel with FEA under both biaxial and uniaxial loads is established on the basis. The result reveals that the uniaxial way bears larger stress than biaxial one.