Effect of the addition of chloride on the anodic dissolution of aluminium through barrier films

Abstract

Barrier oxide layers of defined thickness were made on aluminium by constant current anodization in borate solutions. The aluminium electrode potential was a criterion for the film thickness. Once the defined thickness was achieved, the Al electrode potential decay and the establishment of the steady-state potential were followed after the addition of NaCl solutions of different concentrations. It was found that the addition of chloride causes a sudden potential decay of several hundreds of volts, while the time constant of the decay and the steady-state potential achieved depend on the NaCI concentration.