SILICON-CARBIDE PLATELET SILICON-CARBIDE COMPOSITES

alpha-silicon carbide platelet/beta-silicon carbide composites have been produced in which the individual platelets were coated with an aluminum oxide layer. Hot-pressed composites showed a fracture toughness as high as 7.2 MPa.m(1/2). The experiments indicated that the significant increase in fracture toughness is mainly the result of crack deflection and accompanying platelet pullout. The coating on the platelets also served to prevent the platelets from acting as nucleation sites for the alpha- to beta-phase transformation, so that the advantageous microstructure remains preserved during high-temperature processing.