Study on thermal shock behavior of YSZ abradable sealing coating prepared by mixed solution precursor plasma spraying

In this study, a yttria-stabilized zirconia (YSZ) ceramic matrix abradable sealing coating named 8YSZ-5 was successfully prepared by mixed solution precursor plasma spraying, and its thermal shock behavior was studied in detail. During the thermal shock cycles, the microstructure, residual stress and phase stability of the 8YSZ-5 coating were examined by using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) technique. The results show that the 8YSZ-5 coating has excellent thermal shock resistance through a 200-cycle thermal shock test at 1150 °C. During the thermal shock cycles, the spallation only existed in a small scale in the edge of the 8YSZ-5 coating, and the coating always maintains a stable phase composition of tetragonal structure. The residual stress study shows that the in-plane residual stress of the 8YSZ-5 coating is detected to be compressive stress, which increases with increasing the thermal shock cycles. The microstructure analysis shows that as the thermal shock test progresses, the number of the pores in the coating gradually decreases due to their spontaneous closure and the average size of the grains gradually increases. The mechanical properties investigation shows that the hardness and surface friction coefficient of the 8YSZ-5 abradable sealing coating increase gradually, while the bond strength of the coating decreases by 50% after 200 thermal shock cycles. The implications of this study are important for the design of advanced abradable sealing coatings prepared by the mixed solution precursor plasma spraying technology.