Mechanical, Electrical and Thermal Properties of α/β SiAlON-SiC Composites Fabricated by Gas Pressure Sintering Method

α/β SiAlON-SiC composites were produced by coating SiAlON based spray dried granules with varying amounts of SiC (0-10 vol % SiC) following gas pressure sintering technique. A two step sintering schedule between 1940-1990°C under 10 MPa N₂ gas pressure was designed in order to achieve high densification rate. All the composites and the reference SiAlON material were densified up to 99 %. α/β SiAlON - 10 vol. % SiC composite had the highest hardness value (Hv₁₀: 16.33 GPa) due to the formation of α-SiAlON phases promoted with the increasing SiC content. No significant changes in the fracture toughness values of composites were observed. 3D segregated network of SiC particles along granules to establish electrical and thermal conductivity in the composites was successfully achieved with incorporation of 10 vol. % SiC. α/β SiAlON - 10 vol. % SiC composite exhibited the semiconductor characteristic and high thermal conductivity with the electrical resistivity of 10² Ω.m and thermal diffusivity of ~11 mm²/s measured at room temperature.