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