Nano grain size cemented tungsten carbide has potential to exhibit superior properties of hardness and toughness resulting in improved performance and life of cutting tools, drill bits etc. Nano size tungsten carbide powder is the critical starting material to manufacture nano size cemented tungsten carbide. A study was carried out to evaluate thermal plasma technology as a potential route to manufacture nano size tungsten carbide powders starting from a mixture of tungsten oxide and carbon. The effect of hydrogen flow and power on the progress of reduction and carburization was studied. The plasma reduction of tungsten oxide with carbon resulted in partial reduction of the oxide and carburization of the formed W to W_2C. As the oxide powder is exposed to the plasma for a very short time, complete carburization did not occur and only W_2C was formed. The amount of residual W present in the powder produced increased with increase in hydrogen flow rate and power. The crystallite size of the reduced W and the resulting W_2C was under 70 nm. The free carbon, total carbon and surface area of the powders decreased with increase in hydrogen flow rate and powder. The results from the study highlight the challenges involved in obtaining successful reduction and carburization of the tungsten oxide in a one step process.
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