Chemical Precipitation of Nano Tungsten Oxide

Tungsten metal has high melting point, high hardness, wear resistance, good conductivity and thermal conductivity. It is widely used in the fields of mine, metallurgy, electronics and machinery, and it is also an important raw material for the preparation of hard alloy materials. The rapid development of modern industry has put forward higher requirements for today's cemented carbide materials, and it is necessary to develop hard alloy materials with high hardness, high strength and high wear resistance.

In order to improve the comprehensive mechanical properties of the traditional cemented carbide, one of the effective ways is to reduce the grain size of the tungsten powder of the raw material and obtain high performance ultrafine powder or even nanometer powder.

There are many methods for the production of nano tungsten powder, such as high energy ball milling, gas evaporation, plasma and tungsten oxide reduction. In this way, many technical branches can be derived. Scholars have continuously improved and solved problems in practice, making the main methods form a more complete system.

Some scholars take the soluble tungstic acid as the main raw material and add thioacetamide as the inducer. Through the acidification of the liquid phase precipitation reaction, the tungsten oxide nano powder is synthesized easily and efficiently. After calcining, the tungsten nano powder can be obtained after the calcining reduction. The specific content of the process is as follows:

1 sodium tungstate and 50 inducers were dissolved in 4500 water, heated above the above solution, then heated at 100 ℃, and treated with 2000 pH = 4 acid solution, followed by precipitation reaction. After the reaction is completed, the tungsten oxide Nanopowders are obtained through filtration, washing and drying. The tungsten oxide were calcined for 20 minutes in H₂ atmosphere for 1200 minutes to obtain nano tungsten powders.

The main principle of the process is that thioacetamide is used as an inducer to dissolve tungstate and inducer in proper amount of water. At suitable temperature, thioacetamide is hydrolyzed uniformly in the acid solution, and can release hydrogen sulfide gas evenly. It can not only maintain the pH value in the solution, but also provide a large number of nucleation and induce the formation of tungsten oxide nano powder. The synthesis process is simple, the reaction is fast and can be produced in large quantities. It can not only obtain nanometer tungsten oxide powder, but also can further obtain nano tungsten tungsten powder after calcining reduction.

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