Structural parameter study on stress intensity factors of interfacial crack in thermal barrier coatings

Abstract Cracks on the wave-shaped interface between the top coating (TC) layer and the bonding coating (BC) layer of thermal barrier coatings (TBCs) are unavoidable during manufacture and operation, which may reduce the strength of the TBCs under thermal shock. A model with curved crack on the wave-shaped interface is established, and the influences of structural parameters, including the porosity, the distribution of pores and thickness of the TC layer, the interface roughness and position of crack tip on the wave-shaped interface, on the stress intensity factors (SIFs) of the cracks during thermal shock are numerically studied with the finite element method (FEM). According to the microstructure of the TBCs, the shape of a pore is assumed to be elliptical, and the pores are randomly distributed in the TC layer. A program is developed to automatically generate the distribution of pores. The variation laws of the stress intensity factors (SIFs), KI and KII, of the curved interfacial crack under various structural parameters are obtained and analyzed, which may provide an instruction for the design of the TBCs.