Electrochemical Noise in Crevice Corrosion of Aluminum and Possibility for Its Monitoring

摘要

Possibility of the application of the electrochemical noise analysis to aluminum crevice corrosion was studied. Anodic polarization curves with various scanning rates of potential were measured for the aluminum electrode in the artificial crevice. Current noises were measured for the aluminum artificial crevice electrode at various anodic potentials. On the other hand, current noises were measured for the platinum artificial crevice electrode at various cathodic potentials. The short-circuited current noise and the potential noise of the aluminum artifical crevice electrode coupled with an external aluminum electrode were measured. Any current noises were not observed in the region of the potential less noble than crevice potential (E_c), above which the noises were generated due to the hydrogen evolution. This was verifyed by the fact for the hydrogen evolution on the platinum crevice electrode. Notable noises of synchronized short-circuited current and potential appeared after 50 minutes of immersion being due to the hydrogen evolution. Thus, the natural crevice corrosion was simulated with this short-circuited coupling cell. The potential noise will be considered as an easy monitoring tool for these crevice corrosion detection, because the potential noise was changed with the current noise in the same period.