Effect of Y2O3 contents on microstructural, mechanical, and antioxidative characteristics of Al2O3-ZrO2-Y2O3 coatings

The Al2O3-ZrO2-Y2O3 ternary ceramic coatings (AZY-TCC) with different Y2O3 contents were successfully prepared by thermal explosion spraying assisted rapid solidification. The microstructural, mechanical, and anti oxidative characteristics of different solidification morphologies for AZY-TCC were tested and analyzed. The results show that, along the solidification direction, AZY-TCC mainly contained nanocrystalline, nano-eutectic, submicro-eutectic and micro-eutectic regions. According to the growth rate of these areas, the solidification morphology mapping of AZY-TCC with different Y2O3 contents was drawn. As the Y2O3 contents increased from 1.5 mol% to 16 mol%, ZrO2 gradually changed from m-phase to t-phase, and finally stabilized to c-phase. When the Y2O3 content was up to 12 mol%, the excess Y2O3 and Al2O3 formed a small amount of Y3Al5O12 (YAG) phase, and a typical Al2O3-ZrO2-YAG ternary eutectic structure appeared with 16 mol% Y2O3. The hardness and fracture toughness of AZY-TCC with different Y2O3 contents reached up to 23.57 +/- 0.66 GPa and 5.35 +/- 0.38 MPa.m(1/2), which were much higher than those of other ceramic coatings with the same composition, and AZYTCC with 3 mol% Y2O3 had excellent friction and wear resistance and oxidation resistance. Consequently, the high-performance AZY-TCC provides theoretical guidance for its microstructural evolution under rapid solidification.