SILICON-CARBIDE PLATELET-REINFORCED SILICON-NITRIDE COMPOSITES

Different grades of high aspect ratio SiC platelets were used to reinforce Si3N4. Dispersion of additives (4 wt % Y2O3 and 3 wt % Al2O3)was achieved by ball milling in ethanol using alumina balls, while dispersion of platelets was done by ball milling using plastic balls. Consolidation of the composites was carried out by uniaxial hot pressing. A slight decrease in flexural strength was measured, while significant increases in elastic properties, fracture toughness and Weibull modulus were noted. Microstructure and crack-propagation studies as well as reinforcement mechanisms are presented.