The corrosion of Al (99.99% in mass) in deaerated methanol with and without H
2O, NaCl, and HCOOH as contaminants was investigated using immersion corrosion tests, potentiodynamic polarization tests, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). The content of H
2O in deaerated methanol was changed from 0.1% to 30%, that of NaCl from 0% to 0.1%, and that of HCOOH from 0% to 0.1%. The immersion corrosion tests showed that Al did not suffer from corrosion in deaerated methanol containing 0.1-30% H
2O. When 0.1% NaCl was added to methanol containing 0.1-30% H
2O, the corrosion occurred only at 0.1% H
2O. The EIS measurement endorsed that corrosion resistance of Al was higher in methanol containing 30% H
2O than that in methanol containing 0.1% H
2O. In case that 0.1% HCOOH was added, the corrosion occurred only at 30% H
2O. Potentiodynamic polarization curves obtained in deaerated methanol with 0.01-0.1% NaCl showed that pitting potential increased with increasing H
2O content. In this case, the passive region became obvious with increasing H
2O content. The passive films composed of Al
2O
3 and Al(OH)
3 were identified by XPS.
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