The transition from used fuel container corrosion under oxic conditions to corrosion in an anoxic environment

Abstract

The conversion of copper oxide films on copper to copper sulfide has been investigated in sulfide‐containing chloride solutions. Single‐phase Cu2O films and duplex films consisting of Cu2O and CuO, and possibly Cu(OH)2, were prepared electrochemically on copper specimens at various applied potentials and characterized using Raman spectroscopy, scanning electron microscopy, and energy dispersive X‐ray analyses. The surface condition of the specimens subsequently exposed to a solution containing sulfide was monitored by measuring the corrosion potential (Ecorr) for various exposure periods, then cathodic stripping voltammetry was performed. Cuprite (Cu2O) was observed to be converted to Cu2S by chemical reaction with sulfide, while the conversion mechanism for the mixed deposit could comprise a galvanic process involving CuII reduction coupled to the formation of Cu2S by the reaction of sulfide with copper within pores in the Cu2O/CuO surface film and a chemical conversion of Cu2O to Cu2S. Cupric hydroxide was not converted to Cu2S on the time scale (24 h) of these experiments.