Al_2O_3涂层的真空吸附研究

Adsorption of Al_2O_3 Coating

合肥光源的脉冲切割磁铁表面用等离子体喷涂了一层Al2 O3 ,发现这种涂层表面出气率较小 ,这种特性对于维持注入段的系统真空度 ,提高束流寿命很有好处。本文的工作是制备了涂层样品 ,进行了真空环境下的吸附实验 ,同时使用了SEM、XRD、ASAP、XPS等测试手段分析涂层的微观特性与吸附成因。结果表明涂层具有多孔表面特性 ,晶相结构、比表面积和孔径分布都发生了变化 ,得到了 2 5 0℃烤 2 4h处理后在室温条件下涂层吸附能力的定量结果 ,对气体分子的吸附形态做了初步探讨。

The exposed surfaces of the PULSE SEPTUM magnet (used in the Light Source of Hefei National Synchrotron Radiation Laboratory) were coated with Al 2O 3 films by plasma spraying for the purposes of maintaning base pressure of high vacuum system and long lifetime of electron beams.Surface adsorption of Al 2O 3 films was experimentally studied with surface probes,including scanning electron microscopy (SEM),X ray diffraction (XRD),X ray photoelectron spectroscopy (XPS) and ASAP to correlate the adsorption mechanisms with surface structure and surface electronic properties.The results show that the Al 2O 3 coating is capable of adsorbing about 3 68×10 -4 Pa·L/s·cm 2 residual gas after 24 hours′ baking at 250 ℃.As compared with Al 2O 3 raw powder,considerable changes occur to the surface morphology,porosity,and specific area of the Al 2O 3 coating.Adsorption of polar molecules on Al 2O 3 film surfaces,such as H 2O,CO and CO 2 was also discussed.