Corrosion protection by epoxy/poly(aniline-co-pyrrole)/ZnO nanocomposite coating

Anticorrosion behavior of epoxy/poly(aniline-co-pyrrole)/ZnO (EPAPZ) coating on stainless steel 304 alloys is investigated using the electrochemical impedance spectroscopy (EIS) method, and the coating is compared with epoxy/polyaniline/ZnO (EPAZ) and pure epoxy (EP) coatings. Scanning electron microscopy images are used for structural characterization and to compare the particle size of nanoparticles. EIS result showed that coating resistance for EPAPZ, EPAZ, and EP coatings after 90 days of immersion in 3.5% NaCl was 1.18 × 10⁷, 1.08 × 10⁶, and 4.28 × 10⁴ Ω cm⁻², respectively. In addition, the volume percentage of water absorbed by the coating, which could be obtained by coating capacitance, is 2.81, 4.21, and 9.11, respectively. Immersion tests showed 0.063, 0.194, and 0.752% of weight loss in the metals under EPAPZ, EPAZ, and EP coatings, respectively. These results show that the EPAPZ coating has superior anticorrosive performance compared with EPAZ and EP coatings. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48265.