The behavior of aluminum in alkaline media

Polarization and impedance measurements were performed on aluminum in 0.1, 1 and 3 mol/l NaOH, The frequency range studied was 1 x 10(-2)-1 x 10(4) Hz in the potential range -2 to -1 V vs. SCE. In polarization experiments the potential was extended up to 0 V vs. SCE. The behavior of the system was characterized by a high frequency capacitive loop related to the charge transfer due to dissolution of the metal, an inductive loop at medium frequency which we have attributed to surface roughening and a second capacitive loop obtained at low frequency which has been ascribed to the adjustment of the surface film to the change in potential resulting in higher charge transfer resistance. (C) 2000 Published by Elsevier Science Ltd.