Effects of Vickers Cracks on the Mechanical Properties of Solid-phase-sintered Silicon Carbide Ceramics

In order to study the effects of Vickers cracks on the mechanical properties of solid-phase-sintered silicon carbide (SSiC for short) ceramics, the indentation cracks and the crack profiles were observed after loading 0.1–100 N loads on the SSiC samples by SEM. The critical indentation load for Vickers crack initiation in SSiC ceramics lies between 0.1 N and 0.2 N. Indentations by loads lower than 0.5 N have limited influence on bending strength. And if the indentation loads is higher than 10 N, the obtained hardness floats around 24.2 GPa and the cracks are half-coin type. The proper Vickers indentation load range for SSiC ceramic hardness and toughness tests are determined to be 10 N or above.