Views:7 Author:Site Editor Publish Time: 2017-09-06 Origin:Site
Tungsten powder is made from tungsten oxide in the four-tube muffle furnace or multi-tube furnace with hydrogen reduction with particle size from 0.6-30 microns. Mainly has coarse, medium and fine granularity, silver gray powder, impurity content based on national standards.
Tungsten powder can made by hydrogen reduction of tungsten trioxide or ammonium paratungstate. The process of preparing tungsten powder by hydrogen reduction method is generally divided into two stages: the first stage is reduced to tungsten oxide at the temperature of 500 ~ 700oC; the second stage is at the temperature of 700 ~ 900oC, Into tungsten powder. The reduction reaction is often carried out in a tubular electric furnace or a rotary kiln.
The performance of the reduced tungsten powder (such as purity, particle size, particle size composition, etc.) depends mainly on the reduction process. When the tungsten powder is reduced in the tube furnace, the main technological parameters that affect the reduction rate are the reduction temperature, the loading of tungsten oxide in the boat, the moving speed of the boat, the flow rate of hydrogen and the moisture content in the hydrogen. With the increase of the reduction temperature, the grain size of the tungsten powder becomes thicker.
Preparation of tungsten powder In addition to hydrogen reduction method, there are early use of tungsten oxide carbon reduction method, the reduction temperature is higher than 1050oC. The purity of the tungsten powder obtained by this method is low. In addition, metal aluminum, calcium, zinc and other reduction of tungsten oxide process research work is also ongoing. For the special application of high purity, ultrafine grain size of the tungsten powder, the development of tungsten chloride hydrogen reduction method, the tungsten powder particle size can be less than 0.05μm.