Epoxy-silica anticorrosive coatings modified with Ce(III) and Ce(IV) ions with self-healing properties

Coatings that provide effective anti-corrosion barriers are essential for protecting metal surfaces. However, over time, the coated substrate can become susceptible to localized corrosion, while physical damage, such as cracks and scratches, reduces the effectiveness of the protective coating. In this work, intelligent systems based on epoxy-silica coatings were developed to confer long-term protection against corrosion of the AA7075 aluminum alloy, using a strategy combining a dense and effective passive barrier against the permeation of oxidizing species, and active protection by incorporation of the inhibitors Ce(IV) and Ce(III). Different characterization techniques were used to identify structural changes in the modified epoxy-silica nanocomposites. Excellent long-term corrosion protection performance was obtained in 0.6 mol L −1 NaCl solution, with electrochemical impedance spectroscopy analysis showing that impedance modulus on the order of 10 MΩ cm 2 was maintained over a period of 400 days. Detailed investigation of the modified coatings revealed their self-healing ability after film corrosion damage and exposure of artificially scratched coatings to accelerated corrosion and salt spray testing, confirming the effectiveness of the Ce(III) and Ce(IV) agents for the long-term protection of epoxy-silica coatings.