METAL DISSOLUTION KINETICS IN ALUMINUM ETCH TUNNELS

摘要

The potential dependence of the metal dissolution current density of aluminum in etch tunnels was measured, using pulsed increases of current during galvanostatic etching experiments. Etching was carried out in 1 N HC1 solution at 65℃, and was accompanied by analysis of the topographic development of the dissolving surfaces using scanning electron microscopy. By manipulation of the current waveform, the dissolving area and the applied current were varied independently. After correction of the potential for solution phase potential drops, the current was found to obey an exponential Tafel dependence on potential. Measurements of the patch depth vs. time show that the rate of cathodic hydrogen evolution is significantly increased during the anodic pulse, by comparison with that at the more cathodic potentials during constant current etching. Good agreement of the present current - potential relation was obtained with that derived from the measurements of pit currents in thin films by Frankel et al. (1).