Outgassing rate of vacuum material

    Materials can absorb and dissolve gases in the atmosphere. Therefore, the materials stored in the atmosphere will gradually release the gas adsorbed on the surface of the material and the gas dissolved in the material under vacuum conditions. This phenomenon is called outgassing of the material. The air output per unit time and unit area is called the air output rate.

    Different materials have different outgassing rates. Even the same material will affect the outgassing rate of the material due to differences in smelting conditions, storage conditions, processing techniques, surface roughness, corrosion, and pretreatment before putting it into the vacuum chamber. The reasons for the different outgassing rates measured by the author.

    When selecting the outgassing rate of the material, these conditions must be considered, and the data close to the test conditions should be selected as much as possible, and the outgassing rate of the material can be rechecked if necessary.

    The outgassing rate of a material is a function of temperature and a slow changing function of outgassing time. Usually, the venting time is extended by an order of magnitude, and the venting rate is only reduced by 0.5 to 1 order of magnitude. The material that has been vacuum degassed will be re-inhaled and restored to its original condition after being exposed to the atmosphere for a long time. For a frequently-operated vacuum system, exposure to the atmosphere for a short period of time (within 1h) between two operations can be equivalent to the material having experienced 10h of outgassing time in a vacuum; for a frequently-operated system, keep a low vacuum after stopping the operation. Without exposure to the atmosphere, it can be equivalent to an outgassing time of 100h.

(huiputech)