Ammonium Paratungstate Advanced Ultrafine Tungsten Powder

With the development of China's manufacturing industry, the thirst for ultrafine tungsten powder has been greatly stimulated. Ultrafine tungsten powder is the main raw material for the direct production of ultrafine tungsten carbide powder. In the existing market, the price of high performance ultrafine tungsten carbide powder is about 1 to 2 times that of ordinary micron scale tungsten carbide powder, and the cost of production is basically the same. Therefore, the production of ultrafine tungsten carbide powder is an effective way to improve the added value of tungsten raw materials.

Using ammonium paratungstate 5(NH₄)₂O•12WO₃•5H₂O as the raw material, ammonium paratungstate was fed into a well-sealed container, the container was heated, the heating temperature was set at 400 ℃, ammonium paratungstate was heated and decomposed into tungsten trioxide WO₃, ammonia NH₃ And water vapor H₂O.

The tungsten trioxide WO₃ was reduced to the blue tungsten oxide WO2.9 by setting the reaction temperature at 550℃ and the pressure of the furnace gas at 0.2 mbar using the hydrogen gas H₂ decomposed as described above. Then by further adjusting the reaction temperature and adjusting the pressure of the furnace gas, the temperature was set at 750 ℃, the pressure of the furnace gas was adjusted at 0.3 mbar, and the inclination angle of the rotary furnace tube was set at 2 to 6°. The rotation speed of the furnace tube for 3 ~ 8 rev / min, the above-mentioned blue tungsten oxide is further reduced to active purple tungsten oxide WO_2.72, and then prepared to prepare ultrafine tungsten powder.

A blue tungsten oxide WO_2.9 containing a certain amount of violet tungsten WO_2.72 is added to high purity hydrogen H₂, high purity hydrogen H₂ dew point is -60 ℃, and at low temperature, tungsten oxide WO_X is reduced to tungsten powder under the action of high purity hydrogen H₂.

The obtained tungsten powder is dehumidified and cooled, dehumidified and cooled is dehumidified and cooled by an air conditioner, the relative humidity set is below 60% and the temperature is below 25 ℃; and a protective gas such as carbon dioxide CO₂ is passivated, ultrafine tungsten powder can be obtained, and the particle size of tungsten powder is between 50 nanometers and 0.5 microns.

The tungsten powder is obtained by using air conditioning dehumidification and cooling, the relative humidity below 60%, temperature at 25 ℃; and under the protection of gases such as carbon dioxide CO₂ passivation; As just produced ultrafine metal tungsten powder, its surface energy is very high, prone to spontaneous combustion, it must be cooling treatment and pass protective gas passivation.

At this point, the process of ammonium paratungstate advanced to ultrafine tungsten powder is completed. The tungsten powder obtained from the finished product has high purity and fine particle size; thus, ultrafine tungsten carbide powder is further prepared, and the added value of the product is greatly increased.

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