Microstructure and High-Temperature Mechanical Properties of ZrO₂-Al₂O₃-SiC Ceramics

In the present work, ZrO₂-Al₂O₃ ceramics incorporated with and without β-SiC were prepared by hot pressing. ZrO₂-Al₂O₃ ceramic powder used in this study is a mixture of 71 vol.% YSZ (3 mol.% Y₂O₃ partially stabilized zirconia) and 29 vol.% α-Al₂O₃. β-SiC powders with different volume fractions are added into the ZrO₂-Al₂O₃ powder to form the composite powder. The microstructure and high-temperature mechanical properties of ZrO₂-Al₂O₃-SiC ceramics were investigated by tailoring the compositions and sintering parameters to optimize the strengthening mechanisms. For a comparative study, the TZ3Y20A powder was also hot-pressed under identical sintering condition to form dense bulk ceramic. ZrO₂-Al₂O₃-SiC ceramics consist mainly of t-ZrO₂, α-Al₂O₃, and β-SiC phases. SiC particles in the ZrO₂-Al₂O₃ ceramic restrain the grain growth of the oxide matrix. The incorporation of SiC into ZrO₂-Al₂O₃ ceramic enhances high-temperature flexural strength at 1273 K. ZrO₂-Al₂O₃ ceramic incorporated with 15 vol.% SiC has a flexural strength of 518 MPa at 1273 K, much higher than that (201 MPa) of unmodified ZrO₂-Al₂O₃ ceramic.