Microstructure and mechanical properties of hot-pressed Al2O3-mullite-ZrO2-SiC composites

In this study, the effects of SiC content, sintering temperature and Al2O3/SiO2 ratio on the microstructure and mechanical properties of hot-pressed alumina mullite zirconia silicon carbide (Al2O3 mullite ZrO2 SiC) composite ceramics were investigated systematically. The research results indicate that the composite ceramics have excellent combined properties when SiC content is 20 vol% and sintering temperature is 1530 degrees C, with Vickers hardness, fracture toughness and flexural strength of 17.5 GPa, 12.3 MPa M-1/2 and 970 MPa, respectively. The fracture toughness and flexural strength are higher than those of monolithic Al2O3 ceramics and Al2O3-based composites, which are fairly attributed to the refined microstructures of composites and the synergistic effects of crack deflection, pull-out, branching, and phase transformation toughening mechanisms induced by short columnar Al2O3 grains and SIC platelets formed in the ceramics, as well as the ZrO2 particles existed in the ceramics.