Modeling of the residual stresses in plasma-spraying functionally graded ZrO2/NiCoCrAlY coatings using finite element method

The thermo-mechanical behaviors and the distribution of residual stresses in functionally graded ZrO2/NiCoCrAlY coatings due to thermal spraying were analyzed by thermo-mechanical finite element analysis (FEA). To different coatings, they each have a remarkable stress concentration at the edge of the interfaces. The effects of ZrO2 topcoat to substrate thickness ratio and cooling rate on the residual stresses distribution were obtained by ZrO2/NiCoCrAlY two-layer duplex coating systems. Moreover, the effects of 50%ZrO2 + 50%NiCoCrAlY interlayer and its thickness on the residual stresses in the functionally graded ZrO2/NiCoCrAlY coatings were also discussed. Modeling results showed that the level of residual stresses at the critical interface regions (i.e., coating/substrate interface, coating surface etc.) is obviously influenced by coating to substrate thickness ratio, the presence of interlayer and cooling rate. Furthermore, the residual stress-induced failure model of coatings is also discussed. These studies can be used to optimize the design and processing of some plasma-spraying coating.