A recent study reported on the synthesis of calcium tannate, its characterisation, and use in an epoxy coating as an inhibitive pigment.
Electrochemical Impedance Spectroscopy (EIS) was used to monitor the anti-corrosive performance of the coating formulated with the as-prepared pigment after exposure in a salt spray chamber. Reference coatings with a commercial calcium phosphate pigment and an unpigmented coating were also evaluated for comparison.
EIS results showed that epoxy coating pigmented with calcium tannate had higher coating impedance after 21 days of exposure compared with reference coatings, either unpigmented, or calcium phosphate pigmented coatings. XPS analysis was also used to give a deeper understanding of the inhibitive action of calcium tannate for corrosion protection, and verified the incorporation of tannate molecules in the protective film formed on the steel substrate under the coating.
The study was published in Progress in Organic Coatings, Volume 167, June 2022.