Fig xA SEM images of

Thermal cycling test was performed in a gas burner test facility operating with propane and oxygen. The temperatures of the substrate back surface and YSZ surface during thermal cycling test RN 1 shown in Fig. 2. YSZ surface was heated to the peak temperature in 70 s, then kept for a dwell time of 50 s at the peak temperature and cooled down to 100 °C in 120 s. Different temperature gradients through YSZ were designed by changing the temperature of YSZ surface, while the temperature at the bond coat surface was kept at a constant temperature of 1000 °C. The peak temperatures of YSZ surfaces were controlled to be 1150 °C, 1200 °C and 1250 °C, respectively. The YSZ/bond coat interface temperature has been confirmed to be ~1000 °C by the same method in our previous study [5]. Two surface temperatures of the samples were measured with non-contact infrared thermometers. The detailed parameters settings can be referred in our previous study [5]. The measured temperature gradients across YSZ coating, well agreeing with the designed values, are aneuploidy shown in Fig. 2. Thermal cycling test was terminated when clearly visible spallation of the YSZ coating was observed. The lifetime of TBCs was the average of three specimens.