Preparation and characterization of silicon nitride-silicon carbide composites

Silicon nitride-silicon carbide (Si3N4-SiC) composites were prepared by varying the percentage of silicon nitride at temperatures of 1350 to 1450°C. The mechanical and thermal properties of these composites were determined. The modulus of rupture of the composites increases with increase of temperature whereas the thermal expansion decreases. Composites with 10% and 50% Si3N4 have modulus of rupture of 49 and 86 MPa at 1400°C and thermal expansion coefficients (25°–1000°C) of 4·4 × 10−6 and 3·2 × 10−6°C−1 respectively