Vacuum angle valve of vacuum coating machine
It is used as a supporting element for the backing pump in low, high and ultra-high vacuum systems. Stainless steel is used as the valve body, and the bellows seal is used as the valve transmission seal, which solves the problem of air leakage in the movement of the transmission rod.
The material must be cleaned before it is coated by the vacuum coating machine, which is the vacuum cleaning process that everyone is currently talking about. The vacuum cleaning of the vacuum coating machine is generally defined as cleaning the workpiece or the surface of the system material before the vacuum process. The desired material process. It is necessary to clean the surface of vacuum parts, because the gas and vapor sources caused by pollutants will make the vacuum system unable to obtain the required vacuum. In addition, due to the presence of contaminants, the strength and sealing performance of the joints of the vacuum components will also be affected.
1. Vacuum heating cleaning
Place the workpiece under normal pressure or vacuum to heat. Promote the evaporation of volatile impurities on the surface to achieve the purpose of cleaning. The cleaning effect of this method is related to the environmental pressure of the workpiece, the length of the retention time in the vacuum, the heating temperature, the type of contaminants and the material of the workpiece. The principle is to heat the workpiece. Promote the desorption of water molecules and various hydrocarbon molecules adsorbed on its surface. The degree of desorption enhancement is related to temperature. Under ultra-high vacuum, in order to obtain an atomic level clean surface, the heating temperature must be higher than 450 degrees. The heating cleaning method is particularly effective. But sometimes, this treatment method can also produce side effects. As a result of heating, some hydrocarbons may polymerize into larger agglomerates and decompose into carbon residue at the same time
2. Ultraviolet radiation cleaning
Using ultraviolet radiation to decompose hydrocarbons on the surface. For example, exposure to air for 15 hours can produce a clean glass surface. If you put a properly pre-cleaned surface in a UV source that produces ozone. It takes a few minutes to form a clean surface (process cleaning). This indicates that the presence of ozone increases the cleaning rate. The cleaning mechanism is: under ultraviolet irradiation, dirt molecules are excited and dissociated, and the generation and existence of ozone produces highly reactive atomic oxygen. The excited dirt molecules and free radicals produced by the dissociation of dirt interact with atomic oxygen. The formation of relatively simple and volatile molecules. Such as H203, CO2 and N2. The reaction rate increases with increasing temperature.
Three, discharge cleaning
This cleaning method is widely used in the cleaning and degassing of high vacuum and ultra-high vacuum systems. Especially used most in vacuum coating machines. Use hot wires or electrodes as electron sources. Applying a negative bias relative to the surface to be cleaned can achieve ion bombardment gas desorption and removal of certain hydrocarbons. The cleaning effect depends on the electrode material, geometry and its relationship with the surface. That is, it depends on the number of ions per unit surface area and ion energy. It depends on the effective electrical power. Fill the vacuum chamber with an inert gas (typically Ar gas) with an appropriate partial pressure. The purpose of cleaning can be achieved by the ion bombardment generated by the glow discharge at low pressure between two appropriate electrodes. The method. The inert gas is ionized and bombarded the inner wall of the vacuum chamber, other structural parts in the vacuum chamber, and the substrate to be plated, which can prevent certain vacuum systems from being baked at high temperatures. If oxygen is added to the charged gas, a better cleaning effect can be obtained for certain hydrocarbons. Because oxygen can oxidize certain hydrocarbons to produce volatile gases, which are easily eliminated by the vacuum system. The main components of impurities on the surface of stainless steel high vacuum and ultra-high vacuum vessels are carbon and hydrocarbons. Under normal circumstances, the carbon cannot be volatilized alone. After chemical cleaning, Ar or Ar+O2 mixed gas needs to be introduced for glow discharge cleaning, so that impurities on the surface and gas bound on the surface due to chemical action are removed. In the glow discharge cleaning. The most important parameters are the type of applied voltage (AC or DC), the size of the discharge voltage, the current density, the type of gas charged and the pressure. The duration of the bombardment. The shape of the electrode and the material and location of the parts to be cleaned.
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