Tungsten carbide is a compound composed of tungsten and carbon, with a molecular formula of WC and a molecular weight of 195.85.
It is a black hexagonal crystal with metallic luster and hardness similar to that of diamond. It is a good conductor of electricity and heat. Tungsten carbide is insoluble in water, hydrochloric acid and sulfuric acid, but easily soluble in a mixed acid of nitric acid and hydrofluoric acid. Pure tungsten carbide is fragile, 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. Tungsten carbide powder is used in cemented carbide production materials.
Using metal tungsten and carbon as raw materials, tungsten powder with an average particle size of 3 to 5 μm and carbon black of the same amount are dry mixed with a ball mill, fully mixed, press molded, and placed into a graphite plate, and then placed in a graphite resistance furnace Or it can be heated to 1400～1700℃ in an induction furnace, preferably 1550～1650℃. In the hydrogen stream, W2C is initially produced, and continues to react at high temperature to produce WC. Or firstly, tungsten hexacarbonyl is thermally decomposed in a CO atmosphere at 650-1000°C to obtain tungsten powder, and then reacted with carbon monoxide at 1150°C to obtain WC. Temperatures higher than this temperature can generate W2C.
The total carbon of WC used in alloys with different application ranges, different cobalt contents and different grain sizes can be adjusted slightly. Low-cobalt alloys can choose tungsten carbide with higher total carbon, and high-cobalt alloys can choose tungsten carbide with lower total carbon. In short, the specific requirements of cemented carbide have different requirements on the particle size of tungsten carbide.
It is widely used as high-speed cutting tools, kiln structure materials, jet engine parts, cermet materials, resistance heating elements, etc.
Used to manufacture cutting tools, wear-resistant parts, melting crucibles for metals such as copper, cobalt, and bismuth, and wear-resistant semiconductor films.
Used as super-hard tool material and wear-resistant material. It can form a solid solution with many carbides. WC-TiC-Co cemented carbide tools have been widely used. It can also be used as a modified additive of NbC-C and TaC-C ternary system carbides, which can reduce the sintering temperature and maintain excellent performance. It can be used as aerospace materials.
Tungsten carbide (WC) powder is synthesized by using tungsten anhydride (WO3) and graphite in a reducing atmosphere at a high temperature of 1400～1600℃. Dense ceramic products can be obtained by hot pressing sintering or hot isostatic pressing sintering.
