Low temperature sintering of sub-micrometer scale SiC using spark plasma sintering

抄録

Dense SiC was obtained at 1525°C under 40 MPa pressure after sintering a sub-micrometer scale SiC powder for 3 h using Al₈B₄C₇ and carbon additive. Densification was also accomplished within 1 min by increasing sintering temperature and pressure to 1575°C and 120 MPa. The average grain size could be maintained to 0.71 µm when using SiC powder having 0.55 µm in size by decreasing sintering temperature and time. Viscous flow and grain boundary sliding initiated sintering and liquid phase sintering occurred at the final stage. The formation of a core–rim structure within SiC grains indicated that liquid phase sintering occurred during densification. The sintering behavior of sub-micrometer scale SiC powder is similar with that of nano-SiC powder when using Al₈B₄C₇ additive. The sintered SiC had high Young’s modulus (368 GPa) and fracture toughness (4.7 MPa·m^1/2) after sintering at 1575°C for 1 min.