Influence of material parameters on the interfacial crack growth in thermal barrier coating system

Surface crack failure and interfacial crack failure are typical failure modes in thermal barrier coating (TBC) system. The most common failure form is the peeling of top coat (TC) caused by interfacial crack. In this study, the influence of material parameter on the energy release rate of interfacial crack in TBC system was studied by extended finite element method. The influence of the elastic modulus of TC and the elastic modulus of bond coat (BC) was considered, and the effect of the crack position and length was also taken into account. The results show that the value of the energy release rate at TC/thermally grown oxide (TGO) and TGO/BC interfaces increases with the increase of the elastic modulus of TC, and the increase rate increases with the increase of crack length. With the increase of crack length, the value of the energy release rate and the increase rate increase. With the increase of the elastic modulus of BC, the influence of the shorter cracks at TC/TGO interface decreases, while for the longer cracks, the value of the energy release rate decreases with the increase of the elastic modulus of BC, and the decrease rate of the energy release rate decreases with the elastic modulus of BC increasing. For TGO/BC interface crack, the value of the energy release rate gradually decreases with the increase of the elastic modulus of BC, and the longer the crack length is, the more obvious the influence is. Both the elastic moduli of TC and BC have more influence on TC/TGO interfacial cracks than on TGO/BC interfacial cracks.