PREPARATION OF SIC-ALN COMPOSITES BY LIQUID-PHASE SINTERING AND THEIR MICROSTRUCTURE

Monolithic SiC and SiC-AlN composites were prepared by liquid-phase sintering, Polytypes of SiC, transformation of its polytypes and microstructure of the sintered materials were investigated. The SiC-AlN composites were composed of the 2H phase with dispersed SiC grains, The microstructure of sintered monolithic SiC varied depending on the polytypes of the starting SiC powders, alpha and beta, as well as on the sintering conditions, The SiC-AlN composites showed the same microstructure irrespective of the initial phase of SiC. The 2H phase was a SiC-AlN solid solution and had a spherical grain shape, and the 4H-SiC had a platelike shape.