Ammonium Paratungstate Advanced Ultrafine Tungsten Powder

In the existing market, the price of high-performance ultra-fine tungsten carbide powder is about one to two times that of ordinary micron-sized tungsten carbide powder, and the production costs of both are basically the same. Therefore, the production of ultra-fine tungsten carbide powder is a effective way for tungsten upgrading.

(1) Using ammonium paratungstate 5(NH₄)₂O•12WO₃•5H₂O as raw material, ammonium paratungstate is fed into a well-sealed container, the container is heated, the heating temperature is set to 400°C, and the ammonium paratungstate is thermally decomposed into tungsten trioxide WO₃, ammonia NH₃ And H₂O.

(2) With the reaction temperature set at 550°C and the pressure of the furnace gas at 0.2 mbar, the decomposed hydrogen H₂ can reduce tungsten trioxide WO₃ to blue tungsten oxide WO_2.9. Adjust the reaction temperature and adjust the pressure of the furnace gas. The temperature is set at 750°C. The pressure of the furnace gas is adjusted to 0.3 mbar. The tilt angle of the rotary furnace tube is 2 to 6°, and the rotation speed of the furnace tube is 3 to 8 rpm. In part, the blue tungsten oxide is reduced to the active violet tungsten oxide WO_2.72 and then prepared to produce ultra-fine tungsten powder.

(3) The blue tungsten oxide WO_2.9 containing a certain amount of violet tungsten WO_2.72 is passed with high-purity hydrogen H₂, and the dew point of H₂ is −60° C, at a lower temperature, tungsten oxide WO_X is reduced to tungsten powder under the action of H₂.

(4) Using air conditioning to dehumidify and cool the tungsten powder, set the relative humidity below 60%, and the temperature is below 25°C. Pass the protective gas carbon dioxide CO₂ for passivation to obtain ultrafine tungsten powder, the particle size of the tungsten powder is between 50 nm~0.5 microns.

At this point, the process of progressing from ammonium paratungstate to ultrafine tungsten powder is completed.

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