Effect of polyaniline-based plate on the anticorrosion performance of epoxy coating

Herein, the effects of the addition of polyaniline-based plate (PANP) on the anticorrosive properties of epoxy coatings on Q235 mild steel were investigated. PANP was synthesized by a chemical oxidation method, and the barrier effect of the epoxy coatings containing PANPs were characterized by water absorption and oxygen permeability tests. Electrochemical impedance spectroscopy and scanning vibrating electrode technique were utilized for studying the anticorrosion performance and self-healing ability of different coatings. The corrosion product beneath the coatings was characterize by scanning electron microscopy and X-ray powder diffraction. Thanks to the strong barrier effect caused by the well-dispersed PANPs and self-healing behavior derived from the electroactivity of PANPs. The epoxy coating containing 1.0 wt% PANPs has improved corrosion protective performances such as water absorption (2.23 % after 40-day immersion), and O2 shielding effect (7.92 × 10–15 cm3 cm cm–2 s–1 Pa–1). Also, the impedance modulus of this coating still reached 1.94 × 109 Ω cm2 after 40 days of immersion in a 3.5 wt% NaCl solution.