Mechanical properties of silicon carbide—in situ zirconium carbonitride composites

SiC–Zr 2 CN composites were fabricated by conventional hot pressing from β‐SiC and ZrN powders with 2 vol% equimolar Y 2 O 3 –Sc 2 O 3 as a sintering additive. The effects of the ZrN addition on the room‐temperature (RT) mechanical properties and high‐temperature flexural strength of the SiC–Zr 2 CN composites were investigated. The fracture toughness gradually increased from 4.2 ± 0.3 MPa·m 1/2 for monolithic SiC to 6.3 ± 0.2 MPa·m 1/2 for a SiC–20 vol% ZrN composite, whereas the RT flexural strength (546 ± 32 MPa for the monolithic SiC) reached its maximum of 644 ± 87 MPa for the SiC–10 vol% ZrN composite. The monolithic SiC had improved strength at 1200°C, whereas the SiC–Zr 2 CN composites could not retain their RT strengths at 1200°C. The typical flexural strength values of the SiC–0, 10, and 20 vol% ZrN composites at 1200°C were 650 ± 53, 448 ± 31, and 386 ± 19 MPa, whereas their RT strength values were 546 ± 32, 644 ± 87, and 528 ± 117 MPa, respectively.