The Inhibition of Sodium Oleate for Pitting Corrosion of Aluminum Alloy 2024 in 0.1 mol L-1 NaCl Solution

The inhibition mechanism of sodium oleate (C17H33COONa) for pitting corrosion of aluminum alloy (AA) 2024 in 0.1 mol L-1 NaCl solution was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy with energy dispersive spectrometer (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). C17H33COONa showed good inhibition effect on uniform corrosion of AA2024 in 0.1 mol L-1 NaCl solution by promoting surface passivity of aluminum alloy. But in NaCl solution with high concentration (3.5 wt.% NaCl), C17H33COONa could not promote passivity of aluminum alloy. C17H33COONa also suppressed the tendency of pitting initiation and reduced the pitting corrosion sensitivity of aluminum alloy. The addition of 0.1 g L-1 C17H33COONa showed good inhibition performance but further concentration increase had little effect on the inhibition efficiency. The C17H33COO- groups adsorbed on the surface of aluminum alloy by chemical adsorption effect, which promoted oxidation of the aluminum alloy surface.