Microstructure and mechanical properties of ZrB2–SiC composites prepared by gelcasting and pressureless sintering

ZrB 2 –SiC ceramic composites were prepared through water-based gelcasting and pressureless sintering. Effects of the pressureless sintering temperature (1500–2000   °C), heating rate (5–15   °C/min) and soaking time (0.5–2   h) on the relative density, microstructure and mechanical properties of the ZrB 2 –SiC composites were investigated in detail. A sintering temperature of 2000   °C, a heating rate of 5   °C/min and a soaking time of 2   h were found to be the optimal pressureless sintering procedure. The relative density, flexural strength and fracture toughness of the ZrB 2 –SiC composite prepared under the optimum condition were 97.8%, 403.1   ±   27.8   MPa and 4.05   ±   0.42   MPa·m 1/2 , respectively.