Synthesis of Ultra Fine Titanium-Tungsten Carbide Powder from Titanium Dioxide and Ammonium Metatungstate

Abstract

In the present study, the focus is on the synthesis of ultra fine titanium-tungsten carbide powder by the carbothermal reduction process. The starting powder was prepared by the combination of drying and calcination methods using titanium dioxide powder and an aqueous solution of ammonium metatungstate to obtain a target composition of 60 mass%TiC-40 mass%WC, i.e., (Ti 0.83 W 0.17 )C. The synthesized oxide powder was mixed with carbon black, and this mixture was then heat-treated under a flowing argon atmosphere. The changes in the phase structure, thermal gravity and particle size of the mixture during heat treatment were analyzed using XRD, TG-DTA and SEM. The synthesized oxide powder has a mixed phase structure of anatase-TiO 2 and WO 3 phases. This composite oxide powder was carbothermally reduced to titanium-tungsten carbide by solid carbon through three steps with increasing temperature; the reduction of WO 3 , the reduction of TiO 2 and formation of tungsten carbides, and the formation of titanium-tungsten carbide. The synthesized (Ti 1-x W x )C y powder at 1673 K for 10.8 ks has an average particle size of about 200 nm.