Corrosion and electrochemical evaluation of an Al-Si-Cu aluminum alloy in ethanol solutions

The corrosion of aluminum alloy AlSi8Cu3Fe(Zn) in ethanol and ethanol solutions containing 10 vol.% water and 10 vol.% acetic acid, respectively, was investigated by means of electrochemical impedance spectroscopy (EIS), polarization curve, immersion, optical microscopy, scanning electron microscopy and element mapping. The Al alloy in the ethanol and its solutions exhibited a capacitive loop in the measured Nyquist EIS spectra at high frequencies, which can be attributed to the ethanol's dielectric response. Addition of 10 vol.% acetic acid increased the ethanol corrosivity more significantly than the same amount of water addition. The Al-Si-Cu-Mg precipitated zones in the alloy were susceptible to corrosion attack due to the micro-galvanic effect by the Cu-containing precipitates. (C) 2013 Elsevier Ltd. All rights reserved.