Electrochemical behaviour of Al-In alloys in chloride solutions

The work is concerned with the study of the activation mechanism of aluminum in alloys produced by indium. The electrochemical behaviour of Al in NaCl solutions containing In exp 3+ ions and the dissolution of Al-In and In-Al alloys were studied using potentiostatic, galvanostatic and potentiodynamic techniques, complemented by SEM. It was concluded that the Al activation is obtained only when In comes into a true metallic contact with Al within an active pit and in the presence of chloride ions. Polarization curves for dissolution of Al-In and In-Al alloys were compared. The results suggest that the initial step in the dissolution mechanism of the Al-In alloy can be interpreted through chloride ion adsorption on a surface In-Al alloy. This adsorption occurs at more electronegative potentials than that of pure Al, thus avoiding repassivation.