Violet Tungsten Oxide - An Ideal Raw Material for Preparing Tungsten Powder

With high chemical activity and unique needle structure, violet tungsten oxide is an ideal raw material for preparing ultrafine tungsten powder. When applied in the production of tungsten powder, it can effectively improve the quality and performance of tungsten powder products.

In general, tungsten powder is prepared from tungsten oxide in presence of hydrogen. There are two quality parameters of tungsten powder: size and purity. The quality of tungsten powder is affected by many factors, including raw materials, hydrogen flow and process conditions.

Raw Materials

During the preparation of tungsten powder, the selection of raw materials has a great influence on the quality of tungsten powder products. Violet tungsten oxide is considered as an ideal raw material for preparing ultrafine tungsten powder. It has an absolute advantage over other oxides of tungsten in productivity. Violet tungsten oxide has special pore structure and good permeability. It can quickly remove water vapor from reducing atmosphere, so as to produce ultrafine tungsten powder. In addition, violet tungsten oxide can be reduced in dry hydrogen without passing through the intermediate phase of tungsten dioxide. During the reduction process, the process conditions should be controlled strictly to avoid the formation of tungsten dioxide aggregates.

Hydrogen Flow

The particle size of reduced tungsten powder is affected by three factors: hydrogen flow rate, hydrogen flow direction and hydrogen humidity.

The higher hydrogen humidity and the smaller hydrogen flow rate leads to the finer tungsten powder. Generally, the flow direction of hydrogen in production is opposite to that of materials.

Process Conditions

There are three main process conditions affecting the particle size of tungsten powder: reduction temperature, boat handler speed and material thickness.

1. If the temperature is too low, the reduction will be insufficient. If the temperature is too high, the size of tungsten powder particles will increase.

2. If the boat handler is pushed too fast, the raw materials will be pushed into the high temperature zone and then be reduced in the low temperature zone, which will make the particle size of tungsten powder increases. And the oxygen content may be increased as well.

3. The thinner the materials in the container are, the finer tungsten powder is prepared. However, the output will decrease.

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