Direct Reduction of Spherical Tungsten Powder with Old Routines

Spherical tungsten powder is widely used in powder metallurgy processes such as preparation of porous materials, thermal spraying and injection moulding. Porous tungsten prepared with spherical tungsten powder has more uniform pore, so it is gradually replacing conventional tungsten powder to make porous tungsten components, such as cathode of high power pulse microwave tube, barium tungsten cathode of electron tube, sweating material of rocket, carrier of catalyst or catalyst, etc.

Tungsten powder commonly used in industry is obtained by hydrogen reduction of tungsten oxide. The existing technology of preparing spherical tungsten powder needs to use the tungsten powder prepared by conventional reduction method as raw material, and then be treated to obtain spherical tungsten powder, which makes the cost of spherical tungsten powder higher, and after high temperature plasma treatment, tungsten powder particles become significantly coarser. Therefore, researchers have proposed a way to reduce the cost of preparing spherical tungsten powder.

The preparation process of spherical tungsten powder is characterized by using concentrated sulfuric acid as precipitator and dispersant of ammonium tungstate to obtain tungsten acid precipitation, and then drying and hydrogen reduction of the precipitate to obtain spherical tungsten powder.

First, the saturated ammonium tungstate solution and the dispersing agent are uniformly stirred by ultrasonic stirring. The dispersing agent is selected from BYK-154, BYK-163, sodium lauryl sulfate or sodium dodecyl sulfate, and the dispersing agent is added in an amount of 1-2%. (Based on ammonium tungstate solution, the dispersant is a liquid, the amount added is a volume percentage, the dispersant is a solid, and the amount added is a weight percentage); The volume ratio of concentrated sulfuric acid to ammonium tungstate solution is (15-20):100 by adding concentrated sulfuric acid under ultrasonic stirring. During the stirring process, precipitation is formed and filtered out. After drying and crushing, the precipitation is reduced in a hydrogen reduction furnace. The reduction temperature is 680-720 ℃, and the fine spherical tungsten powder with a particle size of 1.2-2.8 micron is obtained.

The above-mentioned methods still follow the traditional routine, but new changes have taken place. The spherical tungsten powder obtained by direct reduction method can not only obtain better spherical tungsten powder, but also greatly simplify the production process and reduce the production cost of spherical tungsten powder.

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