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 antioxidative 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 AZY-TCC 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.