Effect of carbon source on the carbothermal reduction nitridation for synthesis of (Ti, W, Mo, V)(C, N) nanocrystalline powders

The effect of carbon source on the carbothermal reduction-nitridation during synthesizing (Ti, W, Mo, V)(C, N) nanocrystalline powders was investigated. For a systematic comparison, activated carbon, graphite and two kinds of carbon black powder were used as reducing agents in this study. Ultrafine (Ti, W, Mo, V)(C, N) powders with a particle size of ~ 200-500 nm have been produced at 1450 °C for 2 h by using nanosized carbon black source with small particle size. The presence of phases in the reaction products was characterized with X-ray diffraction (XRD) and the microstructure of carbon source powders and final products was studied by scanning electron microscopy (SEM). The results show that the formation of the Ti(C, N) phase is strongly dependent on the particle size of carbon source powders, and the synthesizing temperature of the Ti(C, N) phase decreases significantly from 1750 °C to 1300 °C by using nanosized carbon black, as compared with micron graphite. In addition, activated carbon with a particle size of 5-50 μm does not favor the dissolution of tungsten or molybdenum carbides into Ti(C, N) despite its large specific surface area.