Tungsten powder processing is the main raw material of powder metallurgy tungsten and tungsten products. Pure tungsten powder can be made into silk, rods, tubes, plates and other processing of material and shape of a certain products. When tungsten powder mixed with other metal powder, it can be made into all kinds of tungsten alloy, such as tungsten molybdenum alloy, tungsten rhenium tungsten alloy, copper alloy and high density tungsten alloy, etc. Another important application for tungsten powder is that can be made into tungsten carbide powder and the preparation of cemented carbide tools, such as turning tool, milling cutter, drill bits and mould, etc.
The purity of conventional tungsten powder is 99.95%, residual impurity elements in tungsten powder impact on product processing and using performance, the Ca/Mg/P/As/Si/S/Fe/Ni/Cu/Al/Mo in which will reduce the strength of the tungsten alloy; K/Na will promote the tungsten carbide particles to grow up; V and Cr has been experiencing grew up.
According to the average particle size, tungsten powder can be divided into ultrafine tungsten powder, general tungsten powder and coarse tungsten powder.
Metal tungsten powder preparation methods mainly include: hydrogen reduction of halide and tungsten trioxide, hydrogen reduction of tungsten oxide or carbon reduction of tungstate, metal hot reduction of tungsten oxide or tungstate, and hydroxyl compound thermal dissociation. The first one approaches to the most mature technology and the most widely industrial application. During the preparation process, the reduction temperature, tungsten oxide loading capacity, burning speed boat, hydrogen flow rate and moisture content in the hydrogen will affect the final powder particle size.
In addition to the particle size, other important parameters including particle shape, specific surface area and apparent density, mobility, compressibility, etc. If the shape of the particles is irregular or dendritic, the compact strength will increase due to mechanical engagement between particles.