Re Exploration of the Preparation of Nano Tungsten Powder

Tungsten oxide is a very important intermediate product in tungsten industry. In recent years, blue tungsten oxide has gradually replaced yellow tungsten oxide because of its advantages of easy doping and better physical and chemical properties.

In the process of making tungsten powder, the size of the tungsten powder is greatly influenced by the tungsten oxide in the upstream products, that is, the finer the size of tungsten oxide is, the finer the grain size of the tungsten powder is obtained by the reduction of hydrogen. Practice has proved that nano tungsten powder can greatly improve the properties of tungsten wire and enhance the hardness, strength and toughness of tungsten based fine grain cemented carbide.

At present, the main raw material for the industrial production of tungsten oxide is APT (ammonium para tungstate), and the evaporation crystallization process is the most important method to produce APT. However, the evaporation crystallization process is difficult to control the grain size of the product, and it is difficult to produce the fine grain APT. Therefore, it is difficult to produce fine particles of tungsten oxide. The preparation system and preparation method of fine particle blue tungsten are provided. By improving the grain size of tungsten oxide, fine tungsten powder is prepared, and the hardness, strength and toughness of tungsten based fine grain hard alloy can be enhanced.

The preparation system of nanometer blue tungsten consists of raw material feeding device, pretreatment furnace, ammonium tungsten compound bin, first vibrating screen machine, ammonia tungsten compound feeding device, calciner, blue tungsten hopper and second vibrating screen machine. The feeding port of the raw material feeding device is connected with pretreatment furnace, ammonium tungsten compound bin and first vibrating screen in turn. The machine and the ammonium tungsten compound feeding device are designed by numerical control temperature.

The preparation of nano blue tungsten using the system includes the following steps:

(1)The raw material of APT is sent from the raw material feeding device to the preprocessing furnace; (2) The pretreatment furnace dissociates the raw material in the oxidizing atmosphere; (3) the dissociated materials enter the ammonium tungsten compound bin, and the ammonium tungsten compound is obtained by the cooling through the sieve; (4) The ammonium tungsten compound after the screening is sent to the calciner from the ammonium tungsten compound feeding device. (5) The ammonium tungsten compounds were calcined in the calciner of the reduction atmosphere at 500 C -800 ℃; (6) The calcined materials entered the blue tungsten hopper, and the fine particles of blue tungsten were obtained by the cooling.

The fine tungsten blue tungsten is prepared by preprocessing the raw material APT. Compared with the direct calcined APT, the tungsten blue tungsten is finer. The fine tungsten blue tungsten is beneficial to the preparation of nanometer tungsten powder, thus strengthening the hardness, strength and toughness of tungsten based fine grain hard alloy.

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