Characterization of corrosion products formed from the exposure of cold sprayed copper to anoxic gaseous hydrogen sulfide

The corrosion of cold-sprayed copper was investigated in a gaseous mixture of 100 ppm H2S in dry N2. Both pristine and thermally pre-oxidized samples were exposed, and the resulting sulfide films were characterized using x-ray photoelectron spectroscopy and scanning electron microscopy. The films were all identified as copper(I) sulfide. No traces of oxide from the thermal pre-oxidation process were detectable through the film. Samples exposed for six-months exhibited surface platelets with altered chemistry; however, these features were attributed to post-exposure storage and are not representative of the as-formed corrosion products. The chemical conversion of oxide to sulfide on pre-oxidized samples was observed to be slower than sulfide formation on pristine surfaces. This behavior contrasts with the kinetics reported for similar oxide-sulfide interactions in equivalent aqueous environments and is likely due to differences in oxide-sulfide conversion mechanisms under gaseous conditions. These results advance the understanding of copper corrosion processes relevant to used fuel containers proposed for the long-term management of used nuclear fuel.