Electrical and mechanical properties of pressureless sintered SiC-Ti2CN composites

Highly conductive SiC-Ti2CN composites were fabricated from beta-SiC and TiN powders with 10 vol% Y2O3-AlN additives via pressureless sintering. The effect of initial TiN content on the microstructure, and electrical and mechanical properties of the SiC-Ti2CN composites was investigated. It was found that all specimens could be sintered to >= 98% of the theoretical density. The electrical resistivity of the SiC-Ti2CN composites decreased with increasing initial TiN content. The SiC-Ti2CN composites prepared from 25 vol% TiN showed the highest electrical conductivity (similar to 1163(Omega cm)(-1)) for any pressureless sintered SiC ceramics thus far. The high electrical conductivity of the composites was attributed to the in situ-synthesis of an electrically conductive Ti2CN phase and the growth of N-doped SiC grains during pressureless sintering. The flexural strength, fracture toughness, and Vickers hardness of the composite fabricated with 25 vol% TiN were 430 MPa, 4.9 MPa m(1/2), and 23.1 GPa, respectively, at room temperature.