Violet tungsten oxide (VTO), that is, γ-tungsten oxide, has a chemical formula of WO2.72 and is in the form of purple or blue-purple finely divided crystalline powder. Violet tungsten oxide has a unique fine needle-like structure. Compared with blue tungsten and yellow tungsten, Violet tungsten has a special surface and the highest chemical activity. Therefore, violet tungsten is most suitable for the production of ultrafine particle tungsten powder. Purple tungsten oxide is obtained by calcining ammonium paratungstate (APT) under certain conditions and reducing it. Of course, the same is true for yellow tungsten and blue tungsten. So how can we get purple tungsten oxide powder? This is the knowledge in the process of tungsten smelting. Violet tungsten is jointly developed by my country’s Zhuzhou Cemented Carbide Factory and Central South University. It is an authentic Chinese original product, and its main production parameter is temperature.
The preparation process of purple tungsten oxide mainly includes APT wet hydrogen direct reduction method, hydrogen tungstate reduction method, APT ammonia gas mild reduction method, etc. No matter which method is used, it must be carried out in a hydrogen return furnace. The process parameters that affect the production of violet tungsten in the APT preparation method mainly include temperature, feed rate, furnace tube rotation speed and hydrogen (or liquid ammonia) flow rate. The most important ones are the reduction temperature and the inert gas flow rate. Some scholars have obtained the best plan when studying the APT ammonia mild reduction method to produce purple tungsten oxide. In the tubular hydrogen reduction furnace, the temperature in the first zone is 790 ℃, The temperature is 805 ℃, the feed rate is 0.55 kg/min, the furnace tube speed is 2.0 r/min, and the NH3 flow rate is 0.7 m3/h, which can convert APT into single-phase violet tungsten (W18O49), and realize continuous industrial production.
Violet tungsten oxide is mainly used to produce ultra-fine or nano-scale metal tungsten powder and tungsten carbide. It is well known that the crystal integrity, uniformity, surface morphology, particle size and particle size distribution of tungsten carbide powder will have a great impact on the properties of the alloy, and the characteristics of these particles depend on the properties of tungsten oxide. The tungsten carbide powder prepared by purple tungsten has fine and uniform particle size, narrow particle size distribution, and no structural agglomeration. And violet tungsten is a single phase (W18O49), through reduction can get nano-scale ultra-fine tungsten powder with uniform performance , the production cost is lower than that of yellow tungsten and blue tungsten.
More details of violet tungsten oxide product, please visit website: violet-tungsten-oxide.com
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