Mechanical properties and tribology of Si3N4-TiB2 ceramic composites produced by hot pressing and hot isostatic pressing

Ceramic matrix composites containing TiB2 as a particulate phase were produced by hot pressing and hot isostatic pressing. The problems of the reactivity of TiB2 with the Si3N4 matrix and with the sintering environment were successfully addressed. A novel dual atmosphere sintering profile combined with low temperature hot pressing was used to successfully produce fully dense materials. The effect of TiB2 addition on mechanical properties was investigated and the tribological behaviour of optimized compositions was examined using a ball-on-disc apparatus. Wear coefficients and friction coefficients for Si3N4-TiB2 composites were measured and compared to monolithic Si3N4 materials. Composites containing TiB2 show significant improvements in hardness, fracture toughness and wear whilst also exhibiting electrical conductivity. 27 refs.