Ultra-fine particle tungsten powder is black, fine particle tungsten powder is dark gray, and coarse particle tungsten powder is light gray with metallic luster. Metal tungsten powder can be produced by reducing tungsten oxide. The main reduction methods are hydrogen reduction and carbon reduction. At present, the hydrogen reduction method is usually used. The affinity of hydrogen and oxygen at high temperatures is greater than the affinity of tungsten and oxygen. Therefore, tungsten trioxide begins to be reduced by hydrogen at 380~400°C. Hydrogen can reduce tungsten dioxide into tungsten powder above 630°C.
.The tungsten powder produced by the hydrogen reduction method has high purity and is easy to control the particle size of the powder. In the absence of hydrogen, the carbon reduction method is also available. The advantage of dry grass is that carbon black is cheap and easy to obtain, but the particle size of the powder is difficult to control. There is a one-time reduction method for reducing tungsten oxide with hydrogen to prepare tungsten powder, and there is also a multi-stage reduction method that first reduces WO3 to WO2, and then reduces oxalic acid first to form w powder. In the current production process, tungsten powder is usually produced by a one-stage direct reduction method.
In addition, there is also the method of directly reducing ammonium paratungstate into tungsten powder. Some special-purpose tungsten is also prepared by halide reduction method.
There is also the aluminothermic method to reduce ore powder and prepare it. Since 2000, the process of preparing ultrafine tungsten powder by hydrogen reduction of violet tungsten has been widely promoted.
Post time: Jan-03-2024
