Finite Element Analysis of Residual Stresses in Zirconia Thermal Barrier Coatings on Superalloy

Abstract

Finite element method was used to simulate the thermal and stress fields in zirconia thermal barrier coatings on superalloy during the cooling process. The correlations of cooling rate, thermal gradient, crack, sintering and stress were studied. The calculated results show that there is a large thermal gradient in the ceramic layer during initial cooling period. The thermal gradient increases with the increasing of cooling rate. The gradient results in delaminating stress at the edge of the sample with thermal barrier coating (TBC). The results show that cooling rate, sintering of zirconia and preexisted crack length impact the crack propagation during thermal cycles. In the case of thermal cycles, cooling rate is crucial to lifetime of TBCs.