Synthesis of Ti(Cx, N1-x) powders under different carbothermal reduction-nitridation temperatures and N2 partial pressures

Abstract

Ti(C_x, N_1-x) powders were synthesized through a combined approach of carbothermal reduction-nitridation (CRN) and the subsequent Ca treatment. The carbon black and TiO₂ were reacted at high temperatures in a N₂ atmosphere at a molar ratio of 3:1, followed by the removal of residual carbon using molten Ca. The influences of temperature and N₂ partial pressure during the CRN process on the C/N ratio, microstructure, and grain size of the final Ti(C_x, N_1-x) were systematically investigated. The prepared Ti(C_x, N_1-x) powders exhibited high purity, fine grain size, uniform morphology, good crystallinity, and excellent dispersibility. As the CRN temperature increased, the residual oxygen content gradually decreased, the grain size enlarged, and the C/N ratio increased. A lower N₂ partial pressure during the CRN process led to increases in grain size and C/N ratio, and the morphology became closer to spherical. The smallest average grain size of 538 nm was achieved for Ti(C_0.31, N_0.69) powder synthesized under conditions of 1 atm N₂ pressure at 1400 °C.