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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 Cu2S/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 pre-requisite 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. This paper is part of a supplement on the 6th International Workshop on Long-Term Prediction of Corrosion Damage in Nuclear Waste Systems. [ABSTRACT FROM AUTHOR]

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 Na2S solutions containing chloride concentrations in a range from 0.1 to 5 mol L−1. Chloride was found to (i) inhibit Cu2S 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). This paper is part of a supplement on the 6th International Workshop on Long-Term Prediction of Corrosion Damage in Nuclear Waste Systems. [ABSTRACT FROM AUTHOR]

The influence of anions (Cl−, SO 4 2−, HCO 3 −) on the anodic formation of Cu 2 S films on Cu was investigated using cyclic voltammetry at rotating disk electrodes. At low ionic strengths, film growth was partially or completely controlled by ionic migration within pores in the growing film depending on the sulphide concentration. At low sulphide concentrations and high ionic strengths, film growth was controlled by the rate of anodic formation of CuI (as adsorbed Cu(SH) ads) at the base of pores in the Cu 2 S film. The ability of anions to suppress this reaction was in the order SO 4 2− > HCO 3 − > Cl−. At higher sulphide concentrations, the film porosity was significantly reduced and film growth controlled by the properties of the compact Cu 2 S film with ionic migration rate-controlling even at high ionic strength. [ABSTRACT FROM AUTHOR]