Integrated self-healing coating system for outstanding corrosion protection of AA2024

This work reports the preparation of an integrated self-healing system that combines the anodization of Al-substrates with the deposition of environmentally friendly coatings prepared by sol-gel for obtaining an active corrosion protection of aluminum alloys AA2024. The system consists on a first step of forming appropriate anodized layers by controlling the potential and anodizing time. The second step is the infiltration of a cerium sol-gel sol and deposition of a Ce-glass like film, followed by a final hybrid silica sol-gel coating, creating an adherent, stable and active corrosion protective system. SEM, electrochemical techniques (potentiodynamic and EIS tests) as well as an accelerated corrosion test are used to analyze the structure of the coatings and to study the corrosion behavior of the different coatings on AA2024. The results of potentiodynamic measurements showed the excellent corrosion properties and EIS measurements confirmed the self-healing behavior by blocking the pitting defects. The outstanding self-healing corrosion protecting behavior provided by this integrated self-healing coating system offers an efficient chromium-free system for substituting chromium CCC and CCA coatings.