Aluminium activation produced by gallium

FLAMINI D.O.; SAIDMAN S.B.; BESSONE J.B:

CORROSION SCIENCE

Elsevier

Lugar: Cambridge, UK; Año: 2006 vol. 48 p. 1413 - 1425

0010-938X

The electrochemical behaviour of pure aluminium in the presence of gallium ions or indirect contact with gallium, in chloride, acetic acid solutions or distilled water is reported.The enhance activity of aluminium is described and discussed. Two active regions wereobserved, one at approximately 1.5 V and the second at near 1.1 V.Two activation mechanisms are proposed. One where a critical surface concentration ofliquid gallium is achieved, a Ga–Al amalgam is responsible for the activation process(1.5 V) and a uniform attack morphology is observed. This process is favoured by the exothermic Al ion hydrolysis reaction and hindered by Ga losses at the active interface. And asecond at higher anodic potentials (near 1.1 V), and in chloride containing media, wherethe presence of solid Ga (saturated amalgam) at the interface facilitates a chloride adsorptionprocess which depolarised the anodic reaction, and produced localised attack.