Production and EDM of Si3N4-TiB2 ceramic composites

Ceramic matrix composites TiB2 as a particulate phase have been produced by not pressing. The problems of the reactivity of TiB2 with the Si3N4 matrix and with the sintering environment have been successfully addressed. A nov el dual atmosphere sintering profile combined with low temperature hot pres sing has been used to successfully produce fully dense materials. The effec t of TiB2 addition on mechanical properties has been investigated. Composit es containing TiB2 show significant improvements in hardness and fracture t oughness. The addition of TiB2 at a level of 40 vol.-% raises the conductiv ity of the composite to a level where electro-discharge machining (EDM) is possible. A comprehensive study of the application of EDM has been carried out and the optimum machining conditions Si3N4-TiB2 composites have been sh aped with relative ease and proved to be 'robust' materials under EDM.