Corrosion protection of epoxy coating with pH sensitive microcapsules encapsulating cerium nitrate

The ability of an epoxy coating with pH sensitive microcapsules (pH-MC) to protect AA2024-T3 aluminum alloy from corrosion in a NaCl solution was investigated. Immersion of the noncoated alloy in the solution revealed that addition of cerium nitrate to the solution led to a decrease in the cathode area or cathodic reactivity to form cerium oxides on copper-enriched sites. Application of the pH-MC containing cerium nitrate to the coated alloy resulted in an increase in the charge transfer resistance with time. Encapsulation of cerium ions in the pH-MC was beneficial for preventing excess elution of cerium ions and self-healing ability.