Effect of Milling on the Carbothermal Reduction of Oxide Mixture for (Ti,W)C-Ni

Abstract

The effect of high-energy milling on the phase transformation and carbothermal reduction was examined using an oxide mixture, TiO₂-WO₃-NiO-C, with a process to synthesize (Ti,W)C cermets. Due to the high energy involved in the mill raw, anatase TiO₂ transformed first to TiO₂-II and then to rutile, while WO₃ transformed to a high-pressure WO₃-HP and hexagonal WO₃ phase. The co-existence of WO₃ and TiO₂ enhanced the formation of a nano-crystalline or amorphous phase. The (Ti,W)C phase was formed mainly at 1150°C from TiC and WC formed in the early stages. These results were further examined using XRD, the Rietveld method and mass spectroscopy.