Durability Evaluation of Thermal Barrier Coating (TBC) at High Temperature

Thermal barrier coating (TBC) which protects the gas turbine from high temperature is damaged by repeated thermal fatigue [1,2]. Generally, damage of top coating of thermal barrier coating is resulted in damage to the entire gas turbine. Thus, the durability of the thermal barrier coating should be evaluated to protect the gas turbine from damage. In general, the major cause of delamination in the top coating is the thermal stress at its interface according to the change in temperature [3]. In this research, parallel stress at the top coating interface (S11) was verified as the major cause of delamination by finite element analysis. In order to evaluate the durability of the TBC, we need information about the parallel strength at the interface, but it is difficult to measure. Furthermore, we verified the relationship between the stress perpendicular to the interface (S22) and the stress parallel to the interface (S11) by finite element analysis. The durability of the thermal barrier coating was evaluated by comparison of the results of the bond strength test of Kim et al. with the results of the finite element analysis of this research.