No abstract

The formation of copper sulphide films on copper in aqueous sulphide solutions has been investigated under both natural corrosion and electrochemical conditions. Film growth occurs at the Cu 2 S/ electrolyte interface and involves Cu + transport through a generally porous film. Both corrosion and anodic film growth are suppressed by high chloride concentrations. Passivity, a prerequisite for pitting, is achievable only at high sulphide concentrations and transport fluxes, conditions not expected under most geologic repository conditions since both sulphide groundwater concentrations and diffusive transport rates are expected to be low.

The effect of chloride on copper corrosion in anaerobic aqueous sulphide solutions has been investigated using corrosion potential measurements, electrochemical impedance spectroscopy, scanning electron microscopy, focused ion beam and inductively coupled plasma atomic emission spectroscopy. Long-term exposure experiments were performed in 10 −3 mol L −1 Na 2 S solutions containing chloride concentrations in a range from 0.1 to 5 mol L −1. Chloride was found to (i) inhibit Cu 2 S film growth by displacing adsorbed sulphide from the Cu surface; (ii) induce film porosity; (iii) facilitate transport of Cu + to the solution (at very high chloride concentrations).

No abstract

No abstract