Evaluation of metal cation effects on galvanic corrosion behavior of the A5052 aluminum alloy in low chloride ion containing solutions by electrochemical noise impedance

摘要

The effects of metal cations on the galvanic corrosion behavior of the A5052 aluminum alloy in low chloride ion containing solutions (tap water) were examined by electrochemical noise impedance. The electrochemical noise impedance and conductance were calculated by the power spectral density (PSD) of the galvanic current and potential. The oscillations in the galvanic current correlate well with the oscillations in the potential. The total charge (summation of galvanic current) during galvanic corrosion tests was suppressed by the addition of Ca~(2+), while it was increased with Mg~(2+) addition. Only a small effect on mean impedance and conductance was observed in solutions with Cu~(2+) and Mg~(2+), while addition of Ca~(2+) strongly influences both the mean impedance and conductance. These results may be explained by the passive film structure changes due to the metal cations. The results obtained in this study indicate that metal cations play a very important role in the corrosion behavior of A5052 aluminum alloys in tap water.