Enhanced aluminium activation induced by gallium. Part I.

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

Rio de Janeiro

Congreso; 2nd Mercosur Congress on Chemical Engineering, 4th Mercosur Congress on Process System Engineering.; 2005

ENPROMER

The electrochemical behaviour of pure Al in the presence of Ga3+ or when a particle of Ga was mechanically attached to Al, in chloride and acetic acid solutions and distilled water is reported. The significative enhancement of Al activity is described and discussed. Two active regions were observed, one at approximately ? 1.5 V and the second at near ? 1.1 V. To explain these findings, two activation mechanisms are proposed: (i) When a critical surface concentrations of Ga in liquid state are achieved, a Ga-Al amalgam is responsible for the activation process (? 1.5 V) and a quasi uniform attack given by smooth wide cavities is observed. This process is favoured by the exothermic Al ion hydrolysis reaction and unfavoured by Ga losses at the active interface. ii) At higher anodic potentials (near ? 1.1 V), and in aggressive media, the presence of solid Ga (saturated amalgam) at the interface facilitates a chloride adsorption process which depolarised the anodic reaction, and gives a more localised attack.3+ or when a particle of Ga was mechanically attached to Al, in chloride and acetic acid solutions and distilled water is reported. The significative enhancement of Al activity is described and discussed. Two active regions were observed, one at approximately ? 1.5 V and the second at near ? 1.1 V. To explain these findings, two activation mechanisms are proposed: (i) When a critical surface concentrations of Ga in liquid state are achieved, a Ga-Al amalgam is responsible for the activation process (? 1.5 V) and a quasi uniform attack given by smooth wide cavities is observed. This process is favoured by the exothermic Al ion hydrolysis reaction and unfavoured by Ga losses at the active interface. ii) At higher anodic potentials (near ? 1.1 V), and in aggressive media, the presence of solid Ga (saturated amalgam) at the interface facilitates a chloride adsorption process which depolarised the anodic reaction, and gives a more localised attack.