Tannin-based inhibitive pigment for sustainable epoxy coatings formulation
By Lamprakou, Zoi; Bi, Huichao; Weinell, Claus Erik; Dam-Johansen, Kim
Published in Progress in Organic Coatings
2022
Abstract
Calcium tannate was synthesized, characterized, and dispersed into an epoxy coating as an inhibitive pigment. Electrochemical Impedance Spectroscopy (EIS) was employed to monitor the anti-corrosive performance of the coating formulated with the as-prepared pigment after exposure to the salt spray chamber. Reference coatings with the commercial calcium phosphate pigment and unpigmented coating were also evaluated for comparison reasons. EIS results showed that epoxy coating pigmented with calcium tannate has higher coating impedance after 21 days of exposure compared with reference coatings, either unpigmented or calcium phosphate pigmented coatings. XPS analysis was employed for a deeper understanding of the inhibitive action of calcium tannate towards corrosion protection and verified the incorporation of tannate molecules in the protective film formed on the steel substrate under the calcium tannate pigmented coating.