With modern machinery industry are developing towards high-precision, high-speed cutting, grinding, low cost, and environmental protection and other directions, tungsten carbide cutting tool has higher requirement on the properties. Theoretically, the efficiency of cutting process, the precision and the surface quality depend on the hardness and the strength of the cutting tool. But it is difficult to balance the relationship between the hardness and the strength. In general, the strength of the material with higher hardness is relatively lower, and the increase of the strength is also base on the decrease of the hardness frequently. Therefore, in order to reconcile this contradiction and further improve the wear resistance of tungsten carbide cutting tools, the relevant researchers develop tungsten carbide coating layer. It deposits a tungsten carbide layer on the base and forms a chemical barrier and a thermal barrier, which effectively reduce the wear of the cutting tools. Furthermore, coating layer with higher coefficient of friction can remarkably improve the service life of the cutting tools.Generally, the requirements of tungsten carbide cutting tool coating layer as follow:
1. High hardness and excellent wear resistance;
2. The coating film has a little effect on the toughness of the base material;
3. Reduce the friction coefficient of the cutting tool and the workpiece;
4. Longer service life.

At present, the most used tungsten carbide coating technologies include CVD (Chemical Vapor Deposition), PVD (Physical Vapor Deposition), MTVD (Medium Temperature Vapor Deposition), PCVD (Plasma Chemical Vapor Deposition) and so on. Wherein the chemical vapor deposition is the most widely used one. The principle is that a mixed gas of the coating material in cemented carbide surface interaction at Steel Inserts high temperatures, the mixed gas of some component decomposed and carbide surface coating metals or compounds formed. It should be noticed that deposition reaction must be carried out under certain conditions activation energy. In addition, high-temperature CVD has many advantages, such as:
1. Relatively easy source of coating material;
2. Can obtain TiC, TiN, TiCN, TiB, Al2O3 and other single or multiple composite coating layers;
3. High bonding strength between the base and the coating layer, excellent wear resistance.