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

氮化硼覆盖层的表面对化学吸附是惰性的，因此被认为是极高真空用途的候选材料之一。本项目旨在寻找最合适的表面处理方法，以获得不锈钢表面极低的放气。研究了奥氏体不锈钢表面处理与六方氮化硼（h-BN）析出的关系。表面处理，如抛光抛光（BP），电抛光（EP），电化学抛光（ECB）和浮子抛光（FP）。实验结果如下：1。用扫描电镜观察了不同方法抛光表面BN的析出情况。结果表明，在FP和EP处理的表面附近，电子通道图没有显示出修饰层形成的证据。在这些表面上，BN几乎均匀地沉淀并覆盖整个表面。随着氮化硼层厚度的增加，在FP表面形成了强取向的三角形氮化硼晶体。热解吸测试表明，表面覆盖强取向h-BN晶体对气体的吸附是惰性的。FP可能是一种最合适的BN沉淀表面处理方法。对钛表面不同处理的热脱附光谱进行了比较，结果表明，脱附光谱的峰高与不锈钢表面的不同也有相似的关系。

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.