Tungsten carbide

       Tungsten carbide powder (WC) is the main raw material for the production of cemented carbide, chemical formula WC. The full name is Wolfram Carbide, also translated as tungsten carbide, which is a black hexagonal crystal with metallic luster and a hardness similar to that of diamond. It is a good conductor of 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, but is easily soluble in the mixed acid of nitric acid and hydrofluoric acid. Pure tungsten carbide is brittle, and if a small amount of titanium, cobalt and other metals are added, the brittleness can be reduced. Tungsten carbide used as a steel cutting tool is often added with titanium carbide, tantalum carbide or their mixture to improve the anti-knock ability. Tungsten carbide is chemically stable.



Place of Origin The main domestic production enterprises are Zhuzhou, Zigong, Nanchang, Tungsten Border. Chengdu Jiupinweik Cemented Carbide Factory. The tungsten carbide powder produced every year is mainly for domestic use, and some are exported to Japan, the United States, Germany, Italy, France, Sweden and other countries.



 

nature

 



Tungsten carbide powder is dark gray powder, which can be dissolved in various carbides, especially in titanium carbide, which has a high solubility, forming a TiC-WC solid solution. Another compound of tungsten and carbon is ditungsten carbide, the chemical formula is W2C, the melting point is 2860°C, the boiling point is 6000°C, and the relative density is 17.15. Its properties, preparation methods and uses are the same as those of tungsten carbide.



 

use

Tungsten carbide powder is mainly used in the production of cemented carbide. In tungsten carbide, carbon atoms are embedded in the interstitial spaces of the tungsten metal lattice, without destroying the original metal lattice, forming interstitial solid solutions, so it is also called interstitial (or insertion) compounds. Tungsten carbide can be made from a mixture of tungsten and carbon



It is prepared by heating at high temperature, and the presence of hydrogen or hydrocarbons can accelerate the reaction. If prepared with oxygenated compounds of tungsten, the final product must be vacuum treated at 1500°C to remove carbon oxides. Tungsten carbide is suitable for machining at high temperature, and can be used to make cutting tools, structural materials of kilns, jet engines, gas turbines, nozzles, etc.



 

production system

Metal tungsten powder and carbon black are used as raw materials, and a mixture is prepared according to a certain proportion. The mixture is put into a graphite boat, placed in a carbon tube furnace or a medium and high frequency induction furnace, and carbonized at a certain temperature. Ball milling and sieving to obtain tungsten carbide powder.



 

quality specification

The technical conditions of tungsten carbide powder are GB/T4295-93, and the internal control standards of enterprises are generally implemented. The technical conditions of some enterprises are shown in Table 6-6-42 and Table 6-6-43.



Table 6-6-42 Quality specifications of tungsten carbide powder



 

Category Fisher Average Particle Size (μ) Total Carbon (%) Free Carbon (%)



 

WC-1 ≤1.0 6.08～6.18 ≤0.08



 

WC-2 1～1.99 6.08～6.18 ≤0.08



 

WC-3 2～3.99 6.08～6.18 ≤0.08



 

WC-4 4～5.99 6.08～6.18 ≤0.08



 

WC-5 6～7.99 6.08～6.18 ≤0.08



 

WC-6 8～11.99 6.08～6.18 ≤0.08



 

WC-7 12～15.99 6.08～6.18 ≤0.08



 

WC-8 ≥16 6.08～7.18 ≤0.08



 

Table 6-6-43 Chemical composition index of tungsten carbide powder



 

Grade\Content% WC Fe Mo Al Si Ca Mn Mg Ni Na



 

FWC-1 ≥99.8 ≤0.04 ≤0.010 ≤0.001 ≤0.01 ≤0.005 ≤0.002 ≤0.002 ≤0.005 ≤0.003



 

FWC-2 ≥99.7 ≤0.06 ≤0.015 ≤0.002 ≤0.01 ≤0.008 ≤0.002 ≤0.004 ≤0.008 ≤0.005



 

Note: Customers have special requirements for the above specifications, which can be negotiated specifically.



 

Package

Generally, the inner plastic bag is used for sealing, and the outer iron drum is used for packaging, and the net weight of each drum does not exceed 50kg.



 

Inspection standards

The chemical composition analysis method of the exported tungsten carbide powder is carried out according to GB4324-84, the Fischer average particle size is carried out according to GB3249-82, the sampling method is carried out according to GB5314-85, and the main content (WC) is calculated by the subtraction method.