To study the mechanism of formation and inhibition of Ce conversion films on Al 2024-T3 alloy, scanning microreference electrode technique (SMRE) is used to probe the potential map on Al 2024-T3 in CeCl 3 solution, the localized corrosion of Al alloy decreases with immersion time and disappears finally, which results from the competition of Cl - aggression and Ce 3+ inhibition on alloy surface. The results of X-ray photoelectron spectroscopy (XPS) indicate that the Ce conversion films consist of Al 2O 3, CeO 2 and Ce 2O 3(Ce(OH) 3), and CeO 2/Ce 2O 3 ratio decreases with the immersion time. When a critical pH for Ce(OH) 3 formation was reached, Ce(OH) 3 will precipitate on the micro cathodic area on alloy surface. Consequently, H 2O 2, the product of the catholic reaction will oxidize a part of Ce(OH) 3 to CeO 2, which appears a better corrosion resistance for Al alloys.
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