Tungsten carbide is important tool and structural material, it has wide application in many fields, its hardness and strength are determined by crystal size of tungsten carbide. Tungsten powder as main raw material for tungsten carbide, its grain size and distribution uniformity has become the key points for producing tungsten carbide. As a result, production of fine, nano grade tungsten powder is important, it then has strict requirement for tungsten oxide raw material.
Study shows that violet tungsten oxide is the most suitable raw material for producing tungsten powder with uniform grain size, super fine nano crystalline. Since violet tungsten oxide is elongated columnar micro crystals with ammonium paratungstate fake crystalline accumulated. Its sharp split shape forms good permeability can realize the fast recovery of dry hydrogen, avoid it generatesβ-W andα-W in WO2 period.
Violet Tungsten Oxide Producing Nano Tungsten Powder
The dry ammonium paratungstate is first quantitated by a screw conveyor into an industrial rotary tube furnace and calcined under certain conditions. As the thermal decomposition of APT with NH3 generated at high temperatures will be re-decomposed into H2, the generating WO3 reduces to WO2.72, which is self-reduction of violet tungsten oxide. The prepared violet tungsten oxide is fed into a 15-tube reduction furnace at proper intervals. The three-furnace chamber is preheated from the low-temperature zone and sent to the high-temperature zone to carry out high-flow dry hydrogen-controlled gas phase migration. Inverse reduction of hydrogen to prepare nano tungsten powder with different grain size. Cooling down for 30 min, then baking, sifting, detecting.