Study of the synergistic effect of cerium acetate and sodium sulphate on the corrosion inhibition of AA2024-T3

This study presents a detailed characterisation of the AA2024-T3 immersed in NaCl + Ce(OAc)₃ solutions without and with added Na₂SO₄ at various concentrations aimed to understand the synergistic effect of cerium and sulphate ions on corrosion inhibition. The corrosion process was evaluated using micro- and macro-scale electrochemical techniques performing anodic polarisation and electrochemical impedance spectroscopy measurements. The cerium species on alloy surface were analysed using a scanning electron microscope coupled with energy dispersive X-ray spectroscopy as well as atomic force and scanning Kelvin probe force microscopy. The results show a corrosion inhibition of AA2024-T3 immersed in NaCl + Ce(OAc)₃, which becomes more effective in the presence of Na₂SO₄ due to a synergistic effect between ions involved in the inhibition process. The local techniques confirm the formation of insoluble cerium species on intermetallics and on aluminium matrix. The synergistic effect results in the formation of more compact and more durable film, which significantly retards the corrosion process.