High Purity Ammonium Tungstate Obtained Nano Tungsten Powder

Nanocrystalline cemented carbide has excellent properties such as high strength, high toughness, high hardness, good wear resistance and heat resistance, which is difficult to be produced by conventional materials. Nano tungsten powder is the key raw material to prepare nano cemented carbide.

The improvement of the pyrolysis process can be more beneficial to the preparation of nano tungsten powder. First, select the high purity pure ammonium paratungstate with the granularity of about 5 um and the purity of more than 99.9% as the reaction raw material, add distilled water into the reaction vessel, stir with a magnetic stirrer, the stirring speed is 180-200r / min, and add the citric acid solution; Ammonium paratungstate (APT) and citric acid molar ratio is calculated as 1-3;

Second, wait for the citric acid solution to be completely dissolved and mixed uniformly, and add the high-purity ammonium paratungstate (APT) to the reaction vessel while stirring;

Third, ammonia water is added after the high purity APT is added, and the ammonia concentration is 30%; the reaction solution is obtained by stirring uniformly;

Fourth, the reaction solution is placed in an evaporation container for concentration, and the concentrated concentrate obtained is dried in a drying apparatus at 150-160 °C to obtain a precursor;

Fifth, the precursor is pulverized in a grinding apparatus, and then placed in a crucible with oxygen for heat treatment to finally obtain a tungsten oxide (WO₃) nanopowder;

Sixth, the tungsten oxide (WO₃) nanopowder is reduced in hydrogen atmosphere, the flow rate of oxygen is calculated as 50-60ml / min per g precursor, the temperature is 500-520 ° C, the time is 1.2-1.5h; the temperature of reduction 600 ℃, the reduction time of 1.5h, resulting in tungsten nano powder;

After optimizing the raw material composition and the corresponding ratio and optimization of preparation parameters associated with the system, the uniform distribution of particle size of tungsten oxide (WO₃) nano powder, and then restore the excellent performance of the prepared nano tungsten powder, this method can not only meet the needs of large-scale production, but also save the cost.

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