Microstructure and Mechanical Properties of alpha‐Silicon Carbide Sintered with Yttrium‐Aluminum Garnet and Silica

Abstract

The effect of glassy‐phase chemistry, using Y 3 Al 5 O 12 (YAG) and SiO 2 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 SiO 2 /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·m 1/2 , respectively.