抄録
Attempts to cement the (Ti W) (C N) carbonitride with binder-metals to form hard alloys have been successful and promising as cutting tool applications. The (Ti W) (C N) solid solutions have ordinarily been prepared by mixing nitrides and carbides intimately and heating them together under vacuum until homogeneity is obtained.
Because of non-affinity between W and N, this solid solution tends to be decomposed at high temperatures. Thus during the sintering procedure of these carbonitrides, nitrogen pressure has to be adjusted within a certain limit to the composition of the carbonitrides.
This study has investigated the processes to prepare directly the (Ti W) (C N) solid solutions by carbothermic reduction of mixed constituent metal oxides at 2273 K and subsequent annealing under fixed nitrogen pressure at 1773 K, and has succeeded in synthesizing homogeneous and stoichiometry-controlled (Ti W) (C N) carbonitrides.
The evaluation of the stability of the carbonitrides against nitrogen has been carried out by measuring the ralationship between nitrogen pressure and composition of the carbonitrides doped with Hf, Zr, Ta, Nb and Mo as the third metallic constituent, and it was found that the carbonitride can effectively be stabilized by adding these elements in this order.
