Interfacial fracture mechanism associated with mixed oxides growth in thermal barrier coating system

The interfacial failure mechanism of the thermal barrier coating system (TBCs) was numerically investigated by considering the role of mixed oxides (MO), which was induced by the discontinuous α -Al₂O₃ at the interface between top and bond coatings. It is shown that MO has a significant effect on the interface integrity. High growth rate of MO will induce the initiation and propagation of interface cracks and eventually results in the debonding of ceramic coating. The high coverage ratio of MO at the interface will accelerate the propagation of an interface crack. Therefore, suppressing the formation of MO can effectively improve the durability and performance of TBCs. The results obtained herein can well explain some previous observations in the thermal shock experiments of TBCs and could offer the potential for improving the durability of TBCs.