How to Make Tungsten Powder?
How to make tungsten powder?
Tungsten powder is a kind of metal tungsten in powder form, which is the main raw material for processing tungsten products and tungsten alloys. Pure tungsten powder can be made into wire, rod, tube, plate and other processing materials and certain shape products. Tungsten powder can be mixed with other metal powder to make various tungsten alloys, such as tungsten molybdenum alloy, tungsten rhenium alloy, tungsten copper alloy and high density tungsten alloy. Tungsten powder can also be made into tungsten carbide powder, and then hard alloy tools, such as turning tools, milling cutters, drills and molds, etc.
So, how to make tungsten powder?
1.Hydrogen reduction tungsten trioxide method
The process of preparing tungsten powder by hydrogen reduction is generally divided into two stages: the first stage is to reduce tungsten trioxide to tungsten dioxide at 500-700 ℃, and the second stage is to reduce tungsten dioxide to tungsten powder at 700-900 ℃. The reduction reaction is usually carried out in tubular electric furnace or rotary furnace.
The properties of reduced tungsten powder (such as purity, particle size, particle size composition, etc.) mainly depend on the reduction process. When the tungsten powder is reduced in a tubular furnace, the main process parameters affecting the reduction speed include reduction temperature, tungsten oxide loading in the boat, boat moving speed, hydrogen flow rate and moisture content in hydrogen. With the increase of reduction temperature, the particle size of tungsten powder becomes coarser.
2.Tungsten oxide carbon reduction method
This method requires reduction temperature higher than 1050 ℃. But the purity of tungsten powder obtained by this method is low. In addition, the reduction of tungsten oxide by aluminum, calcium and zinc is also in progress.
3.Hydrogen reduction of tungsten chloride
If we need high-purity and ultra-fine-grained tungsten powder, we can adopt the method of hydrogen reduction of tungsten chloride, and the particle size of tungsten powder can be less than 0.05 μ M.
Industrial production can be made by reducing tungsten trioxide with hydrogen; or ammonium paratungstate can be treated with acid, and then decomposed to get tungsten trioxide, which can be made by reducing with hydrogen.
1)Hydrogen reduction tungsten trioxide method:
In the first stage, tungsten trioxide is heated to 550-800 ℃, and in the second stage, it is reduced to 650-850 ℃.
2)Ammonium paratungstate treatment method:
Firstly, ammonium paratungstate is reduced to blue tungsten oxide (blue tungsten) by hydrogen or hydrogen free, and then to tungsten powder by hydrogen reduction. The particle size and composition of tungsten powder are important quality indexes of tungsten powder. Reduction is carried out in a tubular or rotary furnace.
