Arc evaporation is a way of physical vapor deposition. The application of PVD in hard coating starts from the arc technology. The arc technology originated from electric welding. The evaporated solid metal (target) is placed in the vacuum chamber to generate glow discharge, and then it runs on the target surface. The target evaporates in a very small range, about several microns in size. The arc motion is controlled by the magnetic field. The plasma formed by the evaporated metal ions will be deposited on the surface of the workpiece. These workpieces rotate in the vacuum cavity. The coating prepared by the arc is usually used for the surface coating of tools and parts, such as tin, AlTiN, AlCrN, TiSiN, TiCN, crcn and CrN. The evaporated metal is ionized and accelerated into the electric field at the same time. In the arc process, the evaporated material is highly ionized, and the deposited coating has excellent adhesion.

Advantages of arc technology:
+High deposition rate (~ 1-3 μ M / h)
+High dissociation rate, good adhesion and compact coating
+When the target is cooled, the coated workpiece is heated less, so that it can be deposited below 100 ° C
+Metals with multiple components can be evaporated, and the remaining solid target components remain unchanged
+The cathode can be placed in any position (horizontal, vertical, upper and lower), and the equipment design is flexible

Main disadvantages of arc technology:
-Limited target material
-Only metals (excluding oxides) can be used, so that the evaporation temperature will not be low
-Due to the high current density, some target materials are splashed out by evaporation in the form of small droplets

Vacuum evaporation coating is a kind of vacuum coating method in which the evaporated material is heated by evaporator under vacuum condition to sublimate it. The evaporated particles flow directly onto the substrate and deposit on the substrate to form a solid film, or to heat the evaporation coating material.

The physical process is that the material is evaporated and transported to the substrate and deposited into film. The physical process is as follows: the material is converted into heat energy by several energy sources, and then evaporated or sublimated by heating the plating material to form gaseous particles (atoms, molecules or atomic clusters) with certain energy (0.1 ~ 0.3ev); After leaving the surface of the plating material, the gaseous particles with considerable motion velocity are transported to the substrate surface in a straight line basically without collision; the gaseous particles arriving at the substrate surface agglomerate and nucleate and grow into solid films; the atoms of the film are rearranged or chemically bonded.

In order to escape atoms or molecules from the surface of liquid or solid plating materials, enough heat energy and enough thermal movement must be obtained. When the kinetic energy of the velocity component of the vertical surface is enough to overcome the energy of mutual attraction between atoms or molecules, it can escape from the surface and complete evaporation or sublimation. The higher the heating temperature is, the greater the molecular kinetic energy is, and the more particles are evaporated or sublimated. Evaporation process continuously consumes the internal energy of the plating material. In order to maintain evaporation, it is necessary to continuously replenish the heat energy of the plating material. Obviously, the evaporation amount (expressed as the vapor pressure above the plating material) is closely related to the heating (temperature rise) of the plating material. Therefore, the growth rate of the coating is closely related to the evaporation rate of the plating material.

Some of the evaporated particles are reversed and the other part is adsorbed. The adsorbed atoms diffuse on the surface of the substrate, resulting in two-dimensional collision between the deposited atoms, forming clusters, some of which stay on the surface for a period of time and then evaporate. Clusters collide with diffusion atoms, or adsorb or release single atoms, which is repeated. When the number of atoms exceeds a certain critical value, it becomes a stable nucleus, and then continuously adsorbs other and compound atoms and gradually grows up. Finally, it merges with the adjacent stable nuclei and becomes a continuous membrane.

Sputtering is another way of physical vapor deposition technology. The sputtering process is the technology that the target material is bombarded out by ion bombardment. Inert gas, such as argon, is charged into the vacuum cavity. By using high voltage, glow discharge is generated to accelerate the ion to the target surface. Argon ion bombards (sputters) the target material from the surface and deposits it on the workpiece in front of the target. Other gas bodies, such as nitrogen and acetylene, are usually used to react with the target material sputtered out to form a thin compound Membrane. Sputtering technology can prepare many kinds of coatings, and has many advantages in decorative coatings (such as Ti, Cr, Zr and carbonitride). Because of its very smooth coating, sputtering technology is also widely used in the field of Tribology in the automobile market (for example, CrN, Cr2N and many kinds of diamond (DLC) coatings). High energy ions bombard the target, extract atoms and transform them into gas state. A large number of materials can be sputtered by magnetron sputtering technology.

Advantages of sputtering technology:
+Target material adopts water cooling to reduce thermal radiation
+Almost any metal material can be sputtered as a target without decomposition
+Insulating materials can also be sputtered by RF or if power supply
+It is possible to prepare oxide (reactive sputtering)
+Good coating uniformity
+The coating is very smooth (without droplets)
+The cathode (up to 2m long) can be placed at any position, which improves the flexibility of equipment design

Disadvantages of sputtering technology:
-Lower deposition rate compared with arc technology
-Compared with the arc, the plasma density is lower (~ 5%), the coating adhesion and the coating density are lower

There are many forms of sputtering technology. Here we will explain some of them. These sputtering technologies can be realized on the vacuum coating equipment of vacuum production.
+Magnetron sputtering uses a magnetic field to maintain the plasma in front of the target, strengthen the ion bombardment and improve the plasma density.
+UBM sputtering is the abbreviation of unbalanced magnetron sputtering. The enhanced magnetic field coil is used to enhance the plasma density near the workpiece. A more compact coating can be obtained. Higher energy is used in the UBM process, so the temperature will rise accordingly.
+The closed field sputtering uses the magnetic field distribution to confine the plasma in the closed field. The loss of the target material to the vacuum chamber is reduced and the plasma is closer to the workpiece. A compact coating can be obtained and the vacuum chamber can be kept relatively clean.
+Twin target sputtering (DMS) is a technique for the deposition of insulator coatings. Alternating current (AC) acts on two cathodes instead of using direct current (DC) between the cathodes and the vacuum chamber. This enables the target to have a self-cleaning function. Twin target magnetron sputtering is used for high-speed deposition such as oxide coating.
+Hipims + (high power pulsed magnetron sputtering) uses high pulse power supply to improve the ionization rate of sputtering materials. The coatings prepared by hipims + have the advantages of arc technology and sputtering technology. Hipims + is a compact coating with good adhesion, and it is also a smooth and defect free coating at the atomic level.

PVD is the abbreviation of physical vapor deposition. PVD is the technology of material evaporation deposition in vacuum state. Vacuum chamber is the necessary condition to avoid the reaction of evaporated material and air. PVD coating is used to prepare new products with additional value and characteristics, such as brilliant color, wear resistance and friction reduction. The PVD process is used to form the coating by condensing most of the metal materials and combining them with gases, such as nitrogen. The matrix material is transformed from solid state to gas state, and is ionized by heat energy as received in the arc process, or by kinetic energy as in the sputtering process. PVD technology is environmentally friendly and pollution-free. In general, Huicheng vacuum focuses on PVD coating.