The virtues of the silicon nitride ceramic tools reinforced by transition metal nitride particles are compared with those of the carbides. It is found that the nitrides have better compatibility than the carbides when they are introduced into silicon nitride. Furthermore, because nitride particles can dissolve small amounts of carbon and oxygen, the carbonization of the silicon nitride matrix decreases, and hot pressing without an inert atmosphere is possible. In addition, electrical discharge machining and wear resistance are improved by the introduction of nitrides.