Direct Synthesis of Tungsten Carbide by Solid-State Carbothermic Reduction of Tungsten Trioxide

Key parameters (milling time, temperature, time, and reduction atmosphere) on the preparation of tungsten carbide by carbothermic reduction of WO3 were investigated. SEM, XRD, TG/DTA, and hardness tests were used for characterizations. TG/DTA showed that the endothermic reactions related to the 10 h milled WO3 reduction and its conversion to tungsten and tungsten sub-oxides occur between 700 and 826 & DEG;C. Subsequently, the formation of tungsten carbide occurs in the temperature range of 1000-1287 & DEG;C. The amount of tungsten carbide increases, and the uniformity of the structure improves with an increment in the reduction temperature. The tungsten carbide formation became complete with increasing process time, and the WO3 was converted to tungsten carbide in 6 h. The reduction process can almost be completed in the hydrogen atmosphere. Moreover, results showed that increasing the milling time up to 30 h improves the tungsten carbide formation leading to an improvement in structural homogeneity and an increase in hardness.