Blue nano tungsten oxide is not only a type of material that may be applied for preparing thermal insulating glass material, but a kind of the most widely used raw material for producing tungsten powder. When it comes to the preparation of tungsten powder, what are the main factors that affect the particle size change of tungsten powder? The change of particle size of tungsten powder is mainly related to factors such as reduction temperature, reduction time, loading amount, hydrogen flow rate, dryness and humidity of furnace atmosphere.
Through chemical equilibrium studies on tungsten reduction, it was found that hydrogen reduction of blue tungsten oxide generally undergoes the following changes: WO2.9→WO2.72→WO2→W. However, practice shows that the reaction mechanism of the process is very complicated due to the control conditions, which is mainly affected by factors such as reduction temperature and hydrogen humidity. Since the process of hydrogen reduction of tungsten oxide belongs to the gas-solid heterogeneous reaction type, WO2 and H2O can form unstable oxygen-tungsten hydroxide during the reduction, and then tungsten crystal grains grow by chemical vapor transport.
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