The cleaning treatment in vacuum technology generally refers to the cleaning treatment of the structural materials, filling materials and vacuum zero parts of the vacuum device. In all kinds of vacuum process production, such as electric vacuum process, vacuum coating process, vacuum welding process, all attach great importance to vacuum health. In the electric vacuum process, the parts assembled to the high vacuum environment are required to be carefully cleaned in advance, otherwise various pollutants can become the source of a large number of gases and vapors, which will greatly prolong the exhaust time of vacuum devices, and it is not easy to obtain high vacuum. The removal or reduction of contaminants will benefit from a good vacuum, increased connection strength and airtightness, and improved product life and reliability.
Common types of pollutants:
(1) grease: lubricant and vacuum grease contaminated during processing, installation and operation;
(2) water droplets: operation of the hand sweat, blowing glass saliva, etc.;
(3) surface oxide: oxidizable material long-term base dew or placed in the moist atmosphere formed by the surface oxide;
(4) acid, alkali, salt substances: wash residual substances, hand sweat, minerals in tap water;
5. Dust and other organic matter in the air.
Cleaning treatment:
First, solvent cleaning
Solvent cleaning is the most common method in vacuum system cleaning. Common cleaning solvents include organic solvents, water containing detergent, dilute acid, alkali, petroleum fractionates, various metal cleaning agents and so on. Depending on the contaminant, different solvents should be used for cleaning. Such as mineral oils need to use organic solvents, corrosion needs to use acid metal cleaning agent.
Second, ultrasonic cleaning
Ultrasonic cleaning is to use ultrasonic gap to clean the target, can achieve a strong physical cleaning effect, remove strong adhesion pollutants. Ultrasonic cleaning can enter into the complex profiled channels, which can not be realized by many cleaning methods. Ultrasonic cleaning in the application, according to the different pollutants, with a variety of cleaning solvents.
Steam degreasing cleaning
Steam degreasing cleaning is suitable for cleaning grease film and lipid film on the surface. After scrubbing or ultrasonic cleaning, steam degreasing cleaning can achieve a good cleaning effect. It is often used in the last step of cleaning glass objects.
Electrolytic erosion cleaning
Electrochemical erosion cleaning is similar to electropolishing, which refers to the use of electrolysis in the solvent to remove the thin rust or oxidation film on the surface of metal parts and other pollutants, mainly used for alloy parts with high chemical stability, such as stainless steel, heat resistant steel, nickel-based alloy and so on.
Heating and irradiation cleaning
Heating cleaning is mainly to heat the parts under normal pressure or vacuum, so that the surface of volatile pollutants volatilize to achieve the purpose of cleaning. Irradiation cleaning is the decomposition of hydrocarbons on the surface of components by ultraviolet irradiation.
Discharge cleaning
Discharge cleaning is generally used in high vacuum and ultra-high vacuum system cleaning. The use of electrons to bombard the gas results in desorption and the removal of certain hydrocarbons. The effect of discharge cleaning depends on the material, geometry and its relation to the surface.
Nitrogen cleaning
Nitrogen cleaning mainly takes advantage of the small adsorption heat, short retention time of nitrogen on the material surface and its characteristics of easy extraction. Nitrogen is used to flush the polluted vacuum system and squeeze the adhesion space of water and other gas molecules to shorten the extraction time of the vacuum system.
A good vacuum environment will have a good effect on the vacuum device itself and vacuum process, we should pay attention to it.
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