Nanometer violet tungsten oxide may be applied for manufacturing transparent thermal insulation nanopowder. It should be noted that the obtained powder is not really transparent, but the thermal insulation film made therewith is transparent. The violet tungsten oxide, instead of the tungsten salt, can also be used in the preparation of WC-Co composite powder by violet tungsten oxide spray drying-calcination-carbonization method.
The morphology of the precursor powder prepared by spray drying in the preparation process was investigated. The structure of violet tungsten oxide is a loose particle group composed of needle-like or rod-like crystal grains. The columnar crystal diameter is less than 100nm and the length is of 1~2μm, as shown in (a) of the following image. Violet tungsten oxide is insoluble in water and slightly soluble in acid. At the same time, the water-soluble cobalt acetate is used as a deep red monoclinic prism crystal, as shown in (b). During the ball milling process, the violet tungsten oxide particles and the carbon source are crushed and mixed with water-soluble cobalt acetate to form slurry.
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