Effect of interfacial defect on surface crack behavior of an air plasma sprayed thermal barrier coating

Multiple surface cracking has significant effect on the failure of thermal barrier coating system (TBCs). The surface cracking is influenced by interface defects. It is of significance to study the relationship between the interface defect and the surface crack. In present work, the effect of interface defect on the surface crack behavior of TBCs has been investigated by using finite element method. The strain energy release rate (SERR) of the surface vertical crack is obtained as functions of the interfacial defect length and location. The results show that both the defect location and the defect length have a significant influence on the driving force of surface crack. It is concluded that the interface defect under the surface crack may induce a more intense facilitation on the surface cracking behavior than the remote defect. Moreover, a large scale interface defect may also induce a larger SERR of the surface crack which may promote its propagation.