Microstructure and Mechanical Properties of α-Silicon Carbide Sintered with Yttrium-Aluminum Garnet and Silica

Abstract

The effect of glassy-phase chemistry, using Y3Al5O12 (YAG) and SiO2 as sintering additives, on the microstructure and mechanical properties of liquid-phase-sintered, and subsequently annealed, α-SiC materials was investigated. The microstructural development of annealed materials was insensitive to changes in glass chemistry. The mechanical properties vs SiO2/YAG ratio curve had a maximum; i.e., there was a small glass composition range at which optimum mechanical properties were realized. The best results were obtained when the ratio was ∼0.5. The flexural strength and fracture toughness of the material were >450 MPa and >6 MPa·m1/2, respectively.