The synergistic effect of cerium acetate and sodium sulphate on corrosion inhibition of AA2024-T3 at various temperatures

Abstract

Abstract The present work examines the corrosion inhibition of aluminium alloy 2024-T3 immersed in NaCl+Ce(OAc)3 and NaCl+Ce(OAc)3+Na2SO4 solutions to evaluate the synergetic effect between cerium and sulphate ions at various temperatures (5\xa0°C, 25\xa0°C and 50\xa0°C). The electrochemical properties were studied using short-term potentiodynamic measurements and long-term electrochemical impedance measurements. The surface topography, morphology and composition of cerium deposits formed on the alloy surface after two days of immersion were evaluated using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The results revealed an efficient long-term (up to 8 weeks) corrosion inhibition in NaCl+Ce(OAc)3 that was superior in the NaCl+Ce(OAc)3+Na2SO4 solution, especially at lower temperatures (5\xa0°C > 25\xa0°C > 50\xa0°C). The composition of the Ce-based film varied with the temperature and the presence of Na2SO4, resulting in different mixtures of Ce(III) and Ce(IV) species. The synergistic effect of cerium and sulphate ions on corrosion inhibition was reflected by a higher degree of cerium oxidation from Ce3+ to Ce4+ at a low temperature and the incorporation of sulphates into the formed film, which protected the surface from the corrosion medium more efficiently.