Superfine crystal tungsten carbide has many characteristics, such as high hardness, high bending strength, and so on, which is widely used in industrial field. Ultrafine tungsten carbide powder is needed as raw material for the preparation of superfine crystal tungsten carbide. And the ultrafine tungsten carbide powder is carbonized by ultrafine tungsten powder.

 

Therefore, the biggest problem is the manufacture of ultrafine tungsten powder. At present, the preparation of ultrafine tungsten powder mainly includes the direct carbonization process, the sol-gel method, the UV - tungsten in situ reduction method and so on.

 

 

1, High-Energy Ball Milling

This method is to use the mechanical ball milling process to grind the powder into submicron or nanoscale ultrafine powders. Ball milling often takes dozens of hours or longer. With the prolongation of ball milling time, the cost of energy consumption and other costs increased, and the production capacity of the mill decreased.

 

In the ball milling process, it is easy to lead to impurity entrainment and influence the purity of the powder. And the obtained powder is easy to be reunion and not easy to disperse. There are four kinds of mechanical pulverizing equipment used in industrial production of micro powder or superfine powder: high speed rotary mill, ball mill, mixing ball mill and air jet mill.

 

2, Hydrogen Reduction Method of Tungsten Halide

Generally, the process of producing ultrafine tungsten powder by hydrogen reduction of tungsten oxide takes a lot of hydrogen, of which the production cost is high. Therefore, much attention has been paid to the extraction of ultrafine tungsten powder by hydrogen reduction by tungsten halide, and a lot of research has been made.

 

3, Spray Drying-Fluidized Bed Method

After the spray drying process and calcination, the tungsten powder is prepared by reduction in the atmosphere of hydrogen. The principle of the spray drying fluidized bed technology is to atomization of the original mixed solution through gas pressure to produce fine droplets. 

 

With the rapid evaporation of solvents and rapid solute deposition, the precursor powder with homogeneous chemical composition and no phase separation can be crystallized from the complex original solution. Then the powder is reduced to prepare tungsten powder.

 

4, Drying Atmosphere Reduction Method

One of the key measures for the preparation of fine tungsten powder is the water vapor produced by the rapid reduction of the reduction reaction from the reaction space and the inner layer of the material. Because the growth of tungsten powder in the hydrogen reduction process is mainly influenced by the mechanism of gas migration. The content of water vapor in the reaction zone can be controlled by the low temperature and the thickness of the material layer.