News List

News

Products

Elementary

Boride powder

Fluoride

Alloy powder

Laurate series

Oleate series

Acetylacetone salt series

Rear Earth Carbonate

Rear Earth Sulfate

Oxide powder

Sulfide powder

Hydride powder

Carbide powder

Silicide powder

Nitride powder

Selenide powder

Telluride

Magnetic Material

Environmental material

Company News

Home > News >

An irreplaceable material in modern industry society

2019-08-27
Tungsten carbide powder (WC) is the main raw material for the production of cemented carbide. The annual production of tungsten carbide powder is mainly for domestic use, and some are exported to Japan, the United States, Germany, Italy, France, Sweden and other countries. Tungsten carbide is a black hexagonal crystal with a metallic luster and a hardness similar to that of diamond. It is a good conductor for electricity and heat. The melting point is 2870°C, the boiling point is 6000°C, and the relative density is 15.63 (18°C). Tungsten carbide is insoluble in water, hydrochloric acid and sulfuric acid, and is easily soluble in a mixed acid of nitric acid-hydrofluoric acid. Pure tungsten carbide is brittle, and if a small amount of metal such as titanium or diamond is incorporated, brittleness can be reduced. Tungsten carbide used as a steel cutting tool is often added with titanium carbide, tantalum carbide or a mixture thereof to improve the antiknock ability. The chemical properties of tungsten carbide are stable.
 
Tungsten carbide can be used to produce various alloys
1. It is widely used as a high-speed cutting tool, kiln structural materials, jet engine parts, cermet materials, and resistance heating elements.
2. Used in the manufacture of cutting tools, wear parts, smelting crucibles of metals such as copper, drills, bismuth, and wear-resistant semiconductor films.
3. Used in the manufacture of cutting tools, wear parts, smelting crucibles of metals such as copper, cobalt and bismuth, and wear-resistant semiconductor films.
 
At present, the production methods of coarse-grained tungsten carbide mainly include:
1. High temperature carbonization of tungsten powder
High temperature and long-term carbonization can minimize the lattice defects of C, minimize the microscopic strain, and improve the plasticity of WC. The temperature of carbonization should not exceed 1800-1900°C. When the temperature exceeds 1800°C, grain boundary fusion occurs easily between WC grains, resulting in uneven WC particle size distribution. Some studies have shown that reducing the particle size of the raw material tungsten, increasing the carbonization temperature, and lowering the carbonization time can improve the WC quality obtained.

2. Medium temperature reduction and high temperature carbonization of tungsten oxide doped lithium salt
The principle of the method is: by adding additives, the volatilization deposition rate in the reduction process of WO3 is accelerated, so that the particle size of the tungsten powder is grown at a lower temperature, and the additive for the growth of the tungsten powder is a lithium salt, and the method is mainly used for Preparation of mining alloys and cold micro-mold alloys.

3. Add cobalt and nickel to high temperature carbonization
Adding a small amount of cobalt, nickel or their oxides when tungsten powder is mixed with carbon can change the carbonization mechanism and increase the speed of carbonization. The grain size of coarse crystal C produced by this method is greatly affected by the amount of diamonds. The larger the WC, the thicker the resulting WC.
4. Add sodium salt method
The sodium salt is added to the APT, and then reduced at a relatively high temperature to obtain a coarse tungsten powder having a particle size of more than 10μm, and then carbonized at a high temperature to obtain a coarse particle WC powder. The law is still in the process of research and some technologies are still immature.

5. APT rapid calcination rapid reduction method
The essence of this method is that the APT is rapidly heated and calcined in an oxidizing atmosphere at 850-1000℃, and then rapidly heated in a hydrogen furnace to a temperature of 1100-1300℃. In this way, tungsten having a particle size of 25-36μm can be prepared.

6. Halogen boiling layer hydrogen reduction method
The chloride or fluoride of tungsten is reduced in the boiling layer with H2. First, H2 and raw tungsten powder are fed into the bottom of the reactor to form a tungsten boiling layer, and the halide vapor is introduced into the reactor from the upper part of the reactor, reduced to tungsten powder by H2 at a given optimum temperature, and deposited. On the original tungsten powder, the original tungsten powder is gradually roughened, and the tungsten powder is periodically discharged from the inside of the reactor. The tungsten powder prepared by this method has a particle size of more than 40 
μm.

7.coarse crystal aluminum thermal process
The WC is produced directly from the tungsten concentrate by a high endothermic reaction, which produces high purity, coarse particle, bulk, single phase WC grains.

8. tungsten concentrate molten salt carbonization method (gas injection method)
First, the tungsten concentrate is decomposed with Na2SiO3-NaC molten salt at a high temperature of 1050-1100℃, and the resulting Na2WO4-NaCI molten salt is separated from the silicate phase containing Fe, Mn, Ca, and then sprayed into the molten salt phase with methane. Medium coarse WC is generated. The advantage of this method is low, about 60%, and the disadvantage is that the impurities (Mo, Cr, Fe, Ni, Si) are high in content and require long-term chemical treatment.