Basic concept and characteristics of PVD coating

PVD is the abbreviation of "Physical Vapor Deposition", which means physical vapor deposition. We now generally refer to vacuum evaporation, sputtering, ion plating, etc. as physical vapor deposition.

The more mature PVD methods mainly include multi arc plating and magnetron sputtering plating. Multi arc plating equipment is simple in structure and easy to operate. Its ion evaporation source depends on the power supply of the electric welding machine.

Electricity can work, and the arc striking process is similar to that of electric welding. Specifically, under a certain process pressure, the arc striking needle briefly contacts and disconnects with the evaporation ion source to discharge the gas. Because the cause of multi arc plating is mainly to continuously form a molten pool on the surface of the evaporation source by virtue of the constantly moving arc spot, so that the metal evaporates and is deposited on the substrate to obtain a film layer, compared with magnetron sputtering, it not only has the advantages of high target utilization, but also has the advantages of high metal ion ionization rate and strong adhesion between the film and the substrate. In addition, the color of multi arc plating coating is relatively stable, especially when making TiN coating, each batch is easy to get the same stable golden yellow, which makes the magnetron sputtering method out of reach. The disadvantage of multi arc plating is that when the coating thickness reaches 0.3 under the condition of low temperature coating with traditional DC power supply μ M, the deposition rate is close to the reflectivity, and the film formation becomes very difficult. Moreover, the film surface began to become hazy. Another disadvantage of multi arc plating is that the metal is evaporated after melting, so the deposition particles are large, the density is low, and the wear resistance is worse than that of the film formed by magnetron sputtering. It can be seen that multi arc coating and magnetron sputtering coating have their own advantages and disadvantages. In order to maximize their respective advantages and achieve complementarity, a coating machine combining multi arc technology and magnetron technology came into being. In the process, there is a new method of multi arc plating for priming, using magnetron sputtering to thicken the coating, and then using multi arc plating to achieve a stable surface coating color. About the middle and late 1980s, hot cathode electron gun evaporation ion plating and hot cathode arc magnetron plasma plating machines appeared, with good application effects, making TiN coated tools quickly popularized. The hot cathode electron gun is used to evaporate ion plating, the copper crucible is used to heat and melt the plated metal materials, the tantalum filament is used to heat and degas the workpiece, and the electron gun is used to enhance the ionization rate, which can not only obtain a thickness of 3-5 μ TiN coating of m, and its adhesion and wear resistance are excellent, even it is difficult to remove by grinding. But these devices are only suitable for TiN coating or pure metal film. As for multi-component coating or composite coating, it is hard to meet the requirements of high-speed cutting of high hardness materials and diversity of die applications.