Corrosion inhibition of Q215 steel by epoxy coatings using poly (1,1′-ferrocenediacyl anilide-co-aniline) as conductivity modifier

In this study, the ferrocene modified polyaniline [P(FcA- co -ANI)] with tunable electrical conductivity was prepared by introducing ferrocene groups into the main chain of polyaniline (PANI) with a hydrochloric acid dopant . The 1 H NMR, SEM, XRD and FT-IR results proved the successful preparation of the copolymers P(FcA-co-ANI). The corrosion resistance of the coatings on Q215 steel was investigated by EIS . The results showed that the P(FcA-co-ANI)/EP coatings and PANI/EP coatings all improved the long-term corrosion resistance by more than 2 orders of magnitude with comparison of EP coatings. Both coatings showed excellent corrosion inhibition . Furthermore, the |Z| 0.01 Hz values of the P(FcA-co-ANI)/EP coating started to recover in a shorter period of time and returned to higher values compared to the PANI/EP coating, and did not drop as sharply as the PANI/EP coating in the later stages of immersion. Besides, the results of R c and R ct values also show that the P(FcA-co-ANI)/EP coatings provide faster and better corrosion inhibition. This is due to the greater conductivity P(FcA-co-ANI) being more sensitive to the electrons generated by metal corrosion and so generating the passivation layer faster. The impact and peel tests show excellent mechanical properties and adhesion of the coating. This work offers some theoretical help for understanding the anticorrosion mechanism of PANI.