Abstract: The thermal fatigue behaviour of an air plasma sprayed thermal barrier coating was investigated. And also the interfacial strengths of thermal barrier coated specimens subjected to thermal fatigue, as well as a retired TBC vane were also evaluated by means of an instrumented indentation machine. The results indicated that, (1) the TGO grew at the interface during thermal fatigue cycle as a function of the exposure time at elevated temperature; (2) the microcracks were initiated in the top coating and at the interface after thermal cycle tests; (3) the interfacial strength of TBC, which was evaluated by the indentation method, increased with the thermal cycles; (4) the interfacial strength of the retired TBC vane was almost equal with that of the as-sprayed TBC specimen.

Key words: Thermal barrier coating, Interfacial fracture toughness, Indentation method