Development of a New Surface Treatment of constructional Material for Extreme-high Vacuum Systems

覆盖有氮化硼覆盖层的表面对化学吸附是如此惰性，以至于它被认为是极高真空用途的候选者之一。本计画旨在寻求最适当的表面处理方法，以获得极低的不锈钢覆层表面出气量。采用抛光（BP）、电解抛光（EP）、电化学抛光（ECB）和浮法抛光（FP）等表面处理方法，研究了奥氏体不锈钢表面六方氮化硼（h-BN）析出形态与表面处理的关系。主要研究结果如下：1.用扫描电镜观察了BN在不同抛光方法抛光表面上的析出情况。结果表明，FP和EP处理的电子沟道图案均未显示出在表面附近形成改性层的证据。在这些表面上，BN几乎均匀地沉淀并覆盖整个表面。随着BN层厚度的增加，在FP表面形成了强取向的三角形BN晶体。2.热脱附测试表明，强取向的h-BN晶体覆盖的表面对气体吸附是惰性的。3.对钛表面不同处理方法的热脱附性能进行了比较，发现脱附谱的峰高与改性表面的关系与不锈钢相似。

The surface covered with boron nitride overlayr is so inert to chemisorption that it has been considered as one of the candidates for extreme high vacuum uses. This project aims at finding the most proper surface treatment method in order to obtain the extreme low outgassing from stainless steelsurface with the overlayr. A correlation between surface treatments and the precipitation aspects of hexagonal boron nitride (h-BN) on an austenitic stainless steel was studied.Surface treatment, such as buff polishing (BP), electro-polishing (EP), electro-chemical buffing (ECB) and float polishing (FP) were employed. Results obtained are as follows :1.Precipitation aspects of BN on a polished surface with different methods were observed using scanning electron microscopy. It was found that electron channeling pattern showed no evidence of formation of the modified layr near the surface of both FP and EP treatments. On these surfaces, BN was precipitated almost uniformly and covered the whole surfaces. As the thickness of the BN layr increased, strong oriented triangular crystalline BN was observed on FP surface.2.Thermal desorption measurements showed that the surface covered with the strong oriented crystalline h-BN was inert to the gas adsorption. The FP may be a candidate of the most proper surface treatment for BN precipitation.3.A comparison of thermal desorption aspects in correlating with the different treatments of titanium surface shows that a peak height of the desorption spectra depends similarly on the modified surface as of the stainless steel.