Electrochemical study of the corrosion inhibition ability of “smart” coatings applied on AA2024
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Smart epoxy coatings modified with different additives were applied on AA2024. The following three different systems were studied: a reference consisting of an epoxy coating containing chromate active pigments and two “smart” coatings modified with containers loaded with corrosion inhibitor—layered double hydroxides filled with mercaptobenzothiazole and tubular halloysites (HS) filled with 8-hydroxyquinoline. The thickness of the coatings was determined by scanning electron microscopy. The barrier properties and the average corrosion resistance were assessed by electrochemical impedance spectroscopy (EIS). The long-term corrosion repair ability of the various coatings was confirmed by EIS measurements carried for a period of 3 weeks in scratched samples. The ability of the smart additives to inhibit corrosion over defects with different sizes and geometry was studied at the microscale by using localized impedance spectroscopy (LEIS) and the scanning vibrating electrode technique. The results demonstrate that the additives provide effective corrosion inhibition on defects of various sizes. Moreover, the LEIS measurements give some important highlights concerning the mechanisms and kinetics of inhibition of each system.
KeywordsCorrosion protection AA2024 “Smart” coatings LEIS EIS SVET
The authors acknowledge the MUST (NMP3-LA-2008-214261) project, funded by the FP7 program and all the partners that provided contributions to this work: production of coatings and coated panels Mankiewicz and EADS, with a special mention to Diana Becker, Sonja Nixon, and T. Hack and his co-workers for their support, suggestions, and motivating discussions during the preparation of this work; production of inhibitor filled LDH particles, Dr. Zheludkevich and Dr. João Tedim and co-workers from the University of Aveiro; and production of HS particles, Prof. Shchukin and co-workers from the Max Planck Institute.
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