Double-doped zeolites for corrosion protection of aluminium alloys

• A new concept of double doping zeolite carrier with corrosion inhibitors is proposed.
• Double doped zeolite provides immediate and sustained corrosion protection.
• The release mechanism explains improved corrosion protection.
• Corrosion inhibitors deposit on surface with preference to Cu-intermetallics.
• Distinctive release events are revealed from the coatings with doped zeolites.

This work has introduced a new doping concept to develop self-healing anticorrosive coatings by synergistic and controlled release of corrosion inhibitors. NaY zeolites were double doped in a two-step process with cerium and diethyldithiocarbamate (DEDTC) as these are known efficient corrosion inhibitors for AA2024-T3. The corrosion efficiency and mechanisms were evaluated by a combination of optical, analytical and electrochemical techniques. It was observed that the inhibitors deposit on the metallic surface with preference for intermetallic particles. Current density measurements of the samples revealed that the double doped NaY zeolite was able to provide both immediate and sustained corrosion protection for the alloy substrate. Moreover, impedance analysis of hybrid sol–gel coatings with 10% wt. of the most relevant doped zeolites revealed distinctive release events from the coatings containing the doped zeolites. The results confirm the potential of this double doping concept which can be extrapolated to other carriers and inhibitors for an effective environmentally friendly active corrosion protection. It is believed that the double doping concept can be extrapolated to fields other than corrosion protection.

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