Electrochemical evaluations of zinc-rich epoxy primers modified with polyaniline and exfoliated polyaniline graphite nanocomposite

Polyaniline (Pani) and exfoliated polyaniline graphite (EPaniG) nanocomposites were used to modify the protective properties of an epoxy zinc-rich primer (ZRP). The corrosion resistance properties of primers were evaluated in 3.5% sodium chloride solution for a period of 120 days via electrochemical noise (EN) and electrochemical impedance spectroscopy (EIS). EN data were analysed via Wavelet and Hilbert spectra analysis to evaluate the protection mechanism of different ZRP coatings during immersion. Coating resistance and charge transfer resistance of the primers were evaluated by EIS measurements. Results showed good compatibility between |Z|(0.01Hz) from EIS measurements and mean noise resistance which results from EN data and these evaluations allowed the examination of coating performances during immersion. Free corrosion potential (E-corr) measurements and salt spray test revealed that both the cathodic protection and barrier properties of the ZRP primer were improved after addition of EPaniG nanocomposite to the ZRP sample.