Violet tungsten oxide powder may be used for preparing thermal insulation dispersion liquid. And violet tungsten oxide can be produced by hydrogen reduction using APT as a raw material under wet hydrogen conditions. Some scholars have studied the preparation process and found that the main factors affecting the particle size of violet tungsten oxide include the particle size of APT, the thickness of the layer, and the partial pressure ratio of water vapor to hydrogen. The specific impacts are shown in the following:
1. Effect of APT particle size on the particle size of violet tungsten oxide. As can be seen from the image below, the smaller the particle size of APT is the smaller the particle size of the obtained violet tungsten oxide is, and vice versa.
2. Effect of layer thickness on the particle size of violet tungsten oxide. As can be seen from the image below, the thinner the layer is, the smaller the particle size of the product is. Conversely, the thicker the layer is, the larger the particle size of the product is. It is mainly due to the large partial pressure of water vapor in the thick layer, which is beneficial to the formation of volatile hydration tungsten oxide.
3. The effect of water vapor to hydrogen partial pressure ratio on the particle size of violet tungsten oxide. As seen from the image below, the larger the partial pressure ratio of water vapor to hydrogen is, that is, the greater the humidity of hydrogen is, the larger the particle size of the product is. This is because wet hydrogen facilitates the formation of volatile aqueous tungsten oxide, which can be coated on finer particles to increase particle size.
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