Role of chloride ions in relation to copper corrosion and inhibition

Corrosion rates of copper single crystal faces are determined in stirred 0·1N sulphuric acid with various chloride ion concentrations. A mechanism is proposed to explain the variation of corrosion rate with Cl^? ion concentration. Up to 7·5 × 10^?3 M Cl^? ions, the stabilities of the crystal faces are in the order (111)>(100)>(110) but this order is changed to (110)>(100)>(111) in presence of 10^?2 M Cl^? ions. The corrosion potentials of the crystal faces are less noble at all concentrations of Cl^? ions and Cl^? ion acts as a cathodic inhibitor. There is no significant orientation effect on the kinetics of dissolution of copper.