Thermomechanical fatigue behavior of an air plasma sprayed thermal barrier coating system

Failure behavior of an air plasma sprayed thermal barrier coating (TBC) system was investigated under in-phase (IP) and out-of-phase (OP) thermomechanical fatigue (TMF) tests. All the TMF tests were performed in the temperature range of 450–850 °C with a given period of 300 s under mechanical strain control. Both the bond coat NiCrAlY and the top coat 7%Y2O3–ZrO2 were fabricated by air plasma spraying (APS). Results revealed that the IP TMF lifetime was longer than that of the OP TMF under the same mechanical strain amplitude. Morphology observations of the failed specimens showed that the coating cracking and spallation processes were different in the two phase conditions.