Electrodeposition of gallium and zinc onto aluminium. Influence of the electrodeposited metals on the activation process

The electrodeposition of gallium and/or zinc on aluminium, aluminium–zinc alloy and vitreous carbon electrodes in chloride solutions is analysed. The electrodissolution of the formed interfaces is also described and discussed. For this purpose, potentiodynamic and potentiostatic techniques and open circuit potential measurements were employed and surface characterisation was performed by scanning electron microscopy and energy dispersive X-ray analysis. The presence of zinc, electrodeposited from the solution or as an alloying component, facilitates gallium enrichment at the interface and improves the wetting on the aluminium oxide. These conditions ensure the formation of a surface Ga–Al amalgam. As a result, the dissolution process occurs at potentials which are more active than those observed for aluminium or aluminium–zinc alloy in halide solutions.