The phase transformation behaviors of plasma sprayed partially stabilized ZrO 2 (PSZ) coatings were studied under the different thermal cycles. Both ZrO2-8Y2O3 and ZrO2-25CeO2-2.5Y2O3 were isothermally heat treated at 1300oC and 1500oC for 100 hr and were cooled through four different cooling rate methods, such as water quenching, air-cooling, open furnace cooling (the furnace door was open during cooling stage) and furnace cooling. It was observed that the martensitic phase transformation from tetragonal to monoclinic was affected by the thermal cycle and stabilizer. The amount of oxygen vacancy which acts cubic as stabilizer was found to be the main factor of the phase transformation behaviors, and was strongly related to the cooling rates.

Keywords: Thermal barrier coating, Partially stabilized zirconia, Martensitic, Cooling rate, Oxygen vacancy