Hot-pressed ceramic SiC–YAG materials

Abstract

Dense SiC-based ceramic materials containing yttrium aluminum garnet (YAG) as an oxide sintering aid have been prepared by hot pressing in the temperature range 1750–1850°C. As a result of melting, the oxides fill spaces between the SiC particles, contributing to the densification of the material and mass transport during the hot pressing process. The present results demonstrate that relatively small amounts of the oxides (≤5 wt %) are needed to ensure a high degree of densification of the SiC–YAG materials. The best physicomechanical properties are offered by the SiC + 3 wt % YAG material sintered at a temperature of 1850°C: ρ = 3.24 ± 0.01 g/cm3, П = 1.1 ± 0.1%, σb = 640 ± 10 MPa; KIc = 6.4 ± 0.2 MPa m1/2, Еel = 410 ± 20 GPa, and HV = 26.0 ± 0.2 GPa. This material experiences predominantly intercrystalline fracture.