Electrochemical impedance spectroscopy as a monitoring tool for passivation and localized Corrosion of aluminum alloys

Abstract

Abstract Pitting and crevice corrosion of Al alloys and Al‐based metal matrix composites can be detected by characteristic changes of the impedance spectra in the low frequency region. A pitting model has been developed which is in agreement with the experimental data. A fitting procedure has been used to analyze a large number of data which have been obtained for as‐received samples and samples which had been passivated in CeCl 3 solutions. This chemical passivation process produces surfaces which are very resistant to localized corrosion. Al 6061, Al/SiC and Al/graphite which had been passivated in CeCl 3 for one week did not pit in 0.5 N NaCl for at least one month. Electrochemical impedance spectroscopy (EIS) is a convenient tool for monitoring of the passivation and the corrosion processes.