Violet Tungsten Oxide Ultrafine Tungsten Powder Reduction Advantages

The preparation methods of violet tungsten are hydrogen reduction, reverse hydrogen reduction, and liquid ammonia reduction, and the most commonly used methods are hydrogen reduction and reverse hydrogen reduction. Take the reverse hydrogen reduction as the main method, this paper aims to investigate the advantages of tungsten reduction of ultrafine tungsten powder.

The use of ammonium paratungstate in a single-tube reduction furnace was charged with hydrogen (reverse hydrogen), loading boat 180/180 ± 10g, pushing boat speed 37 min ± 2/2 boat, a hydrogen flow of 3. 6 ± 0. 1 m³ / h, hydrogen (dew point <- 40 ℃), the reduction temperature is 850 ~ 900 ℃.

After the reduction of the purple tungsten product SEM scan shows that visible purple tungsten appearance to maintain the appearance of the raw material characteristics of APT, violet tungsten micro-morphology is different from other tungsten oxide, small acicular or rod-shaped crystals, the formation of arch bridge between each other, the particle distribution is more loose, the appearance is purple, which is more typical purple crystal phase. The best form of purple tungsten oxide is a fine needle, which is conducive to the formation of water and hydrogen into the crystal particles inside the discharge. Therefore, at the beginning of the reduction, not only the reduction reaction on the surface of tungsten oxide, but also the reduction reaction inside it.

Tungsten powder particle morphology changes occur mainly in the tungsten dioxide generation before. This shows that the reduction process of tungsten dioxide to tungsten powder is not the key process to control the morphology of tungsten powder particles. If the process conditions of reducing tungsten powder are well controlled, for example, the temperature can not rise too fast, the hydrogen dew point is low, the flow rate is large, etc., violet tungsten will easily bypass the tungsten dioxide stage, the direct generation of ultrafine tungsten powder. This is the inherent advantage of producing ultrafine tungsten powder from purple tungsten oxide over blue tungsten oxide and tungsten trioxide.

• < Prev
• Next >