2002 Volume 51 Issue 8 Pages 343-349
The corrosion of Al (99.99% in mass) in deaerated methanol with and without H2O, 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 H2O 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% H2O. When 0.1% NaCl was added to methanol containing 0.1-30% H2O, the corrosion occurred only at 0.1% H2O. The EIS measurement endorsed that corrosion resistance of Al was higher in methanol containing 30% H2O than that in methanol containing 0.1% H2O. In case that 0.1% HCOOH was added, the corrosion occurred only at 30% H2O. Potentiodynamic polarization curves obtained in deaerated methanol with 0.01-0.1% NaCl showed that pitting potential increased with increasing H2O content. In this case, the passive region became obvious with increasing H2O content. The passive films composed of Al2O3 and Al(OH)3 were identified by XPS.
