Nano blue tungsten oxide may be used as a raw material for preparing thermal insulating glass material. And it can also be applied to produce ultra-fine tungsten powder by hydrogen reduction method. Some researchers have conducted research on the effect of reducing process conditions on the particle size of tungsten powder. The reduction process conditions include reduction temperature, hydrogen flow rate, layer thickness, push speed, and the like. The following mainly focuses on the effect of reduction temperature on the particle size of tungsten powder.
From the experimental results, if the reduction temperature is low, and the obtained tungsten powder has a fine particle size. This is because when blue tungsten oxide is reduced in hydrogen atmosphere at a lower temperature, most of blue tungsten oxide directly obtains fine tungsten powder through the reaction pathway --- WO2.9→α-W, and some of the blue tungsten oxide passes through the reaction pathway --- WO2.9→WO2→α-W. They also find that if the intermediate product WO2 has a fine particle size, highly dispersed, and the finally obtained tungsten powder is also fine. If the reduction temperature is high and the heating rate is fast, resulting in a large amount of water generated in the reaction, so that WO2 is easily sintered and recrystallized, and the obtained tungsten powder has a coarse particle size. The particle size of tungsten obtained by reduction at 650°C is half of the particle size of the obtained tungsten particles at 750°C, as in other conditions being the same.
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