INVESTIGATION OF THERMAL FATIGUE LIFE PREDICTION OF THERMAL BARRIER COATING

Thermal barrier coating is applied to some airplane engine parts to improve engine performance and increase durability at high temperature. These parts are thermally cycled during the operation of the engine. Thus, it is desired to develop thermal fatigue life prediction methodology of the thermal barrier coating for design. Thermal barrier coatings are used as a coating system with an environment barrier coating to increase the oxidation resistant of the substrate. The coating durability is still an issue because delamination near the interface of the environment barrier coating is observed during thermal cycles. It is presumed that failure resulted from the growth of a thermal growth oxidation (IGO) layer along the interface. This paper examines the growth law of the IGO layer and the resulting stremes in thermal barrier coating near the interface for three kinds of interface shapes using the finite element method. It was found that the IGO growth rate increases with increasing temperature but not with the thermal barrier coating thickness. The stresses in the thermal barrier coating increases with increasing the amplitude of the waviness of the interface resulting in reduced the thermal barrier coating life. This paper was investigated about the effects of coating thickness and interface waviness.