Surface precipitation of graphite layers on carbon‐doped nickel and their stabilization effect against chemisorption and initial oxidation

Abstract

AbstractA new method for coating the inner surface of ultrahigh‐vacuum (UHV) vessels with an inert material is proposed, namely coating with highly oriented graphite layers which precipitate on the surface of a carbon‐doped nickel substrate. By using various surface analytical methods, characterization of the precipitated graphite has been performed. AES measurements at elevated temperatures clarified the surface precipitation process on polycrystalline Ni–C. Low‐energy electron diffraction studies on Ni(111) showed that the surface‐precipitated graphite grew epitaxially with the substrate and its structure was found to agree with that of highly oriented pyrolytic graphite. Reflection high‐energy electron diffraction studies revealed that the basal planes (0001) of precipitated graphite preferentially cover the surface even in the case of polycrystalline Ni–C. AES measurements in an O2 atmosphere showed that the graphite‐covered surface was hardly oxidized by prolonged oxygen exposure. Thermal desorption spectroscopy measurements suggested that the desorption of CO after O2 dosing was much smaller from the graphite‐precipitated surface than from a stainless steel surface. From the standpoint of applications to problems in engineering, graphite precipitation on metals is found to be a promising method for making an inert and low‐outgassing surface for UHV use.