Surface Analysis and Electrochemical Studies of Sulfur Enhanced Corrosion of Nickel

摘要

A combined surface analysis and electrochemical study of sulfur implanted nickel has examined the lifetime of sulfur on the surface and the mobility of sulfur on the surface and in an acid solution. XPS and AES have been used to examine the chemistry, location and amount of sulfur on the surface and in films formed on the implanted nickel in a 0.5 normal nitric acid solution at various electrochemical potentials. Specimens were prepared in a low oxygen partial pressure glove box and transferred to the spectrometer in an anaerobic transfer vessel. Although most sulfur is removed from the implanted nickel during rapid dissolution, a submonolayer of sulfur remains on the surface in ''sulfide'' form in the active region. Upon exposure to higher oxidizing potentials, some of the sulfur is oxidized and both sulfate and sulfide are found in the film. Recycling the film back to the active region removed some of the oxidized sulfur, but much of the sulfur remains on the surface. Sulfur transfers through the solution to nearby materials where it appears on the surface in both ''sulfide'' and sulfate states. Current studies suggest only a very slow oxidation of sulfur on the surface or in solution. 13 refs., 4 figs. (ERA citation 12:011869)