Nanometer violet tungsten oxide may be applied for producing near infrared shielding material, such as office heat insulation film, sun room heat insulation film, and automotive heat insulation film, etc. Violet tungsten oxide can also be used in the preparation of nanometer WC-Co composite powder by violet tungsten oxide spray drying-direct carbonization. Some scholars have observed the mechanism of reduction carbonization reaction and found that:
In the low temperature region, violet tungsten oxide and cobalt acetate are reduced to W and Co. And the carbon source is cleaved at low temperature to form elemental carbon, the hydrogen reacts with the cracked carbon in the charge to form hydrocarbon gas such as methane (CH4). These gases are extremely unstable under certain circumstances and decompose into carbon and hydrogen. The dissociated carbon has high activity, which deposits on the tungsten powder, and diffuses into the interior of the tungsten powder particles, so that the entire particle is gradually carbonized from the outside to the inside. The decomposed hydrogen in turn reacts with the carbon black in the charge to form hydrocarbon. In this cycle, the carbon in the charge is continuously reduced, and the tungsten carbide is continuously formed.
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