Pressureless sintering of ZrB2–SiC ceramics: the effect of B4C content

Systematic studies were carried out on the sintering of ZrB2–SiC ceramics without any external pressure being applied. The densities, mechanical properties and microstructures with different contents of B4C were investigated. The results showed that B4C additions were beneficial not only for the sintering process but also for the oxidation resistance. The sintered ZrB2–SiC ceramics with 0.4 wt.% B4C addition had an average strength of 382 ± 24 MPa and a modulus of 405 ± 34 GPa. The hardness and toughness were 13.4 ± 0.4 GPa and 3.7 ± 0.2 MPa m1/2, respectively. The effect of B4C addition on the oxidation resistance of ZrB2–SiC was studied by observing the mass changes and the residual strengths of samples after oxidized treatments.