Tungsten Product Produced by WO3
Tungsten trioxide(WO3) is an important intermediate product in producing tungsten. Usually use WO3 as raw material, hydrogen, carbon monoxide or carbon as reductant can produce tungsten powder. Tungsten powder has grain size varies from coarse, middle and fine grade, it appears as silver grey powder, the impurities content is subject to national standard.
Producing tungsten powder mainly uses tungsten trioxide hydrogen reducing method. The process is firstly reducing tungsten trioxide to tungsten dioxide under 500~700℃. Secondly, reducing tungsten dioxide to tungsten powder under 700~900℃. The reducing equipments can be electric tube furnace or rotary furnace. Reducing process directly determines the property of tungsten powder.
In early days, WO3 carbon reducing method for producing tungsten powder was used. The reacting temperature is 1050℃ and the obtained purity of products if lower. Using aluminum, zinc and calcium to reduce WO3 is also the methods which are under research. Tungsten powder for special application which requires high purity and super fine grain size, tungsten chloride hydrogen reduction method is used, the obtained grain size can be less than 0.05um.