Modeling of the residual stresses in plasma-sprayin functionally graded ZrO_2/MCoCrAlY coatings using finite element method

摘要

The thermo-mechanical behaviors and the distribution of residual stresses in functionally graded ZrO_2/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 ZrO_2 topcoat to substrate thickness ratio and cooling rate on the residual stresses distribution were obtained by Zr0_2/NiCoCrAlY two-layer duplex coating systems. Moreover, the effects of 50 percent ZrO_2 + 50 percent NiCoCrAlY interlayer and its thickness on the residual stresses in the functionally graded ZrOVNiCoCrAlY 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.