High temperature oxidation behavior of a EBPVD thermal barrier coating

A Y2O3 partially stabilized ZrO2 ceramic top coating was deposited on a NiCrAlY bond coating by electron beam physical vapor deposition (EB-PVD). Isothermal oxidation was performed at 900 degreesC, 1000 degreesC, and 1100 degreesC for 100 h, and thermal cyclic oxidation at 1050 degreesC. All the specimens were characterized by scanning electron microscopy (SEM), energy dispersion X-ray spectroscopy (EDS) and X-ray diffraction (XRD). It is shown that among the three isothermal oxidation conditions, the weight gain of the specimen at 1100 degreesC is the smallest in the initial 20 h. The thermal stress resulted from the thermal cycle and the growth stress of the oxide cause cracks at the interface between the Ni-Cr-Al-Y bond coating and its oxide, leading to failure of the EB-PVD thermal barrier coating.