Since 1940s, tungsten powder manufacture changed greatly in the choose of tungsten oxide raw material. Beforehand, tungsten powder production mainly uses tungstic acid or yellow tungsten oxide as raw material. Until 1960s, in the USA, France, Netherlands, Britain, they used violet tungsten oxide as raw material to produce tungsten powder.
In recent years, there are more and more reports about good property of fine crystalline tungsten carbide. So people again concentrated on the production of super fine tungsten powder. In the past ten years, consumption of submicron tungsten powder（< 1um）is increasing, which reflects the enlargement of tungsten carbide market.
Violet Tungsten Oxide Hydrogen Reduction Producing Super Fine Tungsten Powder
Use four tube reduction furnace, propane hydrogen boat under rate 2 boat/30min, hydrogen flow is 30m3/h. Use two band cooling-side, temperature of the three field is 650℃, 750℃, 800℃. Let tungsten oxide stay for 1h in these temperature zones, all the raw materials are reduced in the same furnace to ensure the same reduction condition. Weigh each raw material for 20g to ensure the same material thickness. Use 80x50x20 ceramic boat, every boat for inputting raw material are located in a big boat, then put into the reduction furnace to ensure the consistent reduction. Equation is WO3-x → W.