Abstract
Studies were made on the synthesis of transition metal nitrides (TiN, ZrN, HfN, NbN and TaN) by the combustion reaction of metal powder compacts under 0.1-25MPa nitrogen pressures. Under low nitrogen pressures (≅0.1MPa), stoichiometric nitrides were not obtained in all cases due to incomplete supply of nitrogen gas into the powder compacts. Under high nitrogen pressures (≅10MPa), it was found that the nitriding ratio of product depends on the adiabatic combustion temperature and melting point of nitrides. In the cases of Ti, Zr, Hf and Nb, which have quite high adiabatic temperatures compared with the melting points of the corresponding nitrides, the nitriding ratio was low (<80%) because of coalescing of metal particles by melting. On the other hand, in the cases of Ta and other metals with their nitride additions (0.5Ti+0.5TiN, 0.5Zr+0.5ZrN and 0.7Nb+0.3NbN), which have the adiabatic temperatures close to the melting points of the corresponding nitrides, the stoichiometric nitrides were produced.
