Corrosion protection properties of anodized AA2024T3 alloy sealing with organic-based species

The present study investigates the effect of EDTA disodium salt and Monosodium citrate treatments to improve the corrosion resistance of anodized aluminum alloys coated with sol-gel. The anticorrosive properties were studied by Electrochemical Impedance Spectroscopy (EIS) technique. The chemical and morphological characterization were carried out by Focus Ion Beam (FIB), Field Emission Scanning Microscopy (FESEM) and Fourier Transform Infrared Spectroscopy (FTIR) techniques. The results suggests that the addition of any of these salts in the sol-gel film improves the corrosion resistance of the anodized aluminum alloy. Very stable and high impedance values are obtained after a long period of immersion in 0.1 M NaCl solution. The best results are obtained with the addition of 0.5 g L-1 EDTA disodium salt and 1 g L-1 monosodium citrate. The improvement of the corrosion properties is attributed to the changes in sol-gel formation that produce a more compact protective barrier with the COO - groups, which can prevent the entry of aggressive electrolyte by repulsion of charges.