Several tungsten carbide coating systems

       Abstract: Tungsten carbide coating has good wear resistance and high yield strength, and tungsten carbide coating has better deformability. Tungsten carbide coating has good thermal conductivity, low coefficient of thermal expansion, good corrosion and oxidation resistance at room temperature, good electrical resistance, and high bending strength. These excellent properties of tungsten carbide meet the basic requirements of tungsten carbide coating matrix with it as the main component.

Tungsten carbide coating mainly includes the following systems:

① WC-Co series;

②WC-Tic-Co series;

③WC-TiC- -TaC(NbC)-Co series;

④WC- TiC- -TaC(NbC)-Ti(c,n) -Co series;

⑤Tic(N)-based cemented carbide.

1 WC-Co series

The WC-Co series alloy is composed of WC and Co. The hard phase of the matrix is WC, and the bonding phase is Co. Its code name is YG. It is equivalent to the K category of the ISO standard, and the basic characteristics of the alloy are shown in Table 3-2.

WC-Co tungsten carbide has high bending strength and impact toughness, which can reduce chipping during cutting. It is mainly used for processing cast iron, non-ferrous metals and non-metal materials. When processing brittle materials, the chips are broken and broken, which can withstand the impact on the tool, and the cutting force and cutting heat are concentrated near the tool tip. The alloy has good thermal conductivity, which is conducive to the dissipation of cutting heat from the tool tip, thereby reducing the cutting temperature and avoiding overheating and softening of the tool tip. Although the heat resistance of WC-Co alloys is poor, the cutting temperature when cutting cast iron is much lower than when processing steel, which is lower than the temperature at which significant diffusion occurs, and cast iron can be processed. In addition, WC-Co alloys have good grinding workability and can grind sharp cutting edges, which are suitable for processing non-ferrous metal materials.

When WC-Co tungsten carbide contains more cobalt, its flexural strength and impact toughness are better, especially the fatigue strength is improved, and it is suitable for rough machining under shock and vibration conditions. When the cobalt content is less, the hardness of the alloy is higher, and its wear resistance and heat resistance are higher, and it is suitable for continuous cutting finishing.

The tungsten carbide coating can be well combined with the substrate to form a tungsten carbide coating. It is a high-hardness coating that can be applied in a large number of wear areas.