Copper corrosion in bentonite/saline groundwater solution: Effects of solution and bentonite chemistry

Copper corrosion has been studied in simulated groundwater with and without added bentonite clay using different electrochemical techniques. The corroded surfaces were characterised by SEM/EDS, Raman spectroscopy and Auger depth profiling. In both environments small amounts of sulphide (0.005 mM) control the early corrosion behaviour. Under aerated conditions an initially formed Cu2S film is rapidly converted to a non-protective layer of cuprite and corrosion proceeds with the deposition of an outer layer of atacamite. In the presence of bentonite corrosion proceeds slowly under O2 transport control. No atacamite is observed and the Cu surface appears slightly pitted.