Investigation of the conditions required for the formation of V(C,N) during carburization of vanadium or carbothermal reduction of V2O5 under nitrogen

Phase stability diagrams of V-C-N and V-O-C-N systems were constructed as a function of carbon activity, nitrogen partial pressure, oxygen partial pressure, and solution formation characteristics to determine the conditions for the formation of V(C,N) via the carburization of vanadium or carbothermal reduction of V2O5 under nitrogen. The diagram showed that only V, V2C, and V(C,N) phases would be stable in the V-C-N system. From the diagram, it was also observed that only V(C,N) exists after the carburization of vanadium under nitrogen atmosphere more than 10−5 atm. The diagram of V-O-C-N system suggests that V2O5 can be reduced to V(C,N) without forming VO, owing to the high stability of the V(C,N) phase. Using these stability diagrams, the conditions for preparing V(C,N) from vanadium or V2O5 were deduced and the validity of the diagrams was verified using the experimental results.