Epoxy-ester coating reinforced with cerium (III)-tannic acid-based hybrid pigment for effective mild-steel substrate corrosion protection

Epoxy ester coating with dual active inhibition and passive barrier anti-corrosion properties was constructed using a novel hybrid pigment based on the cerium nitrate and tannic acid (Ce-TAA). At first, the inorganic organic pigment was synthesized and then characterized by FTIR, TGA, and Raman methods. Electrochemical measurements evidenced an inhibition degree of 81% for the metal sample exposed to the saline solution containing the Ce-TAA pigment extract. The polarization test showed significant corrosion current density reduction via a mixed corrosion retardation mechanism. According to the UV-visible and ICP analyses outcomes, the solubility of the hydrophilic tannic acid and cerium nitrate decreased in the cerium-tannate complex. EIS results evidenced that the vertical bar Z vertical bar(at10) (mHz) and R-ct values of the Ce-TAA containing coating with defect increased over time. Besides, up to 21 days of immersion, the circle minus values near to - 90 degrees and the |Z|(10) (mHz) > 10(7) Omega.cm(2) were recorded for the intact coating containing Ce-TAA pigment. Via FE-SEM/EDS analyses the released inhibitive species were detected on the scratched areas of the coating.

Automated summary

A novel epoxy ester coating with dual active inhibition and passive barrier anti-corrosion properties was constructed using a hybrid pigment based on cerium nitrate and tannic acid (Ce-TAA). The coating showed high inhibition efficiency and stability, as evidenced by electrochemical measurements and other analysis methods. Additionally, released inhibitive species were detected on the scratched areas of the coating through FE-SEM/EDS analyses.