Thermal fatigue in thermal barrier coating

This paper presents an experimental investigation on the thermal fatigue failure in thermal barrier coating (TBC) system at high temperature. The thermal fatigue failure was induced by temperature gradient along TBC system thickness direction and oxidation between TBC and bond coat. Laser heating method was employed to simulate the operating state of TBC system. The non-destructive evaluation methods such as acoustic emission (AE) and impedance spectroscopy (IS) were used to examine the evolution of TBC system damage. Both micro-observation and acoustic emission (AE) detection revealed that the fatigue damage consisted of vertical crack in the top coat layer and interface delamination between the top and bond coat. The life of thermal fatigue was shown to be reduced by the formation of alumina at interface. It was also found that the temperature gradient between the inner and outer surface of specimen accelerated the growth of alumina layer.