Nano violet tungsten oxide may be used for producing thermal insulation dispersion liquid, which has good properties such as high transparency, weather resistance and stability. The glass film made of this kind of dispersion liquid does not exhibit a halo effect, and can prevent interference with the user, especially in the dark environment. Therefore, such film has a good effect for applying in the automobile film.
The same batch of APT was used to calcine in air to obtain yellow tungsten oxide; pre-reduction was carried out at different temperatures and H2 atmosphere, and blue tungsten oxide and violet tungsten oxide of ammonium tungsten bronze were respectively obtained. Then, using these three kinds of tungsten oxides to prepare tungsten powder under the same hydrogen reduction process, and verifying in an industrial hydrogen reduction furnace. It can be found that:
1. The hydrogen reduction of violet tungsten oxide starts not only from the active center of the W18O49 polymer surface, but also from the inside of the W18O49 polymer; its chemical activity is good, the hydrogen reduction rate is fast, the crystal nucleus is formed with fine crystal grains.
2. W18O49 has a low bulk density, and its polymer is like a loose sponge. When W18O49 is reduced by hydrogen, it is beneficial to the infiltration of hydrogen and the escape of water vapor.
3. Although the BET specific surface of W18O49 is small, its chemical activity is large and the hydrogen reduction rate is fast. The chemical activity of tungsten oxide, in addition to its specific surface and particle size, is also closely related to the crystal structure, morphology and crystal defects of tungsten oxide.
4. The tungsten powder obtained by hydrogen reduction of violet tungsten oxide is the finest and the specific surface is the largest, which indicates that several different kinds of tungsten oxides produced by the same batch of APT can produce tungsten powder of different particle sizes under the same hydrogen reduction process conditions.
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