Fabrication of a Conductive Additive for the Anticorrosion Enhancement of Zinc-Rich Epoxy Coatings

In the study, a conductive polypyrrole (PPy) is deposited on the lamellar sericite powder (SCP) surfaces by an in situ oxidization growth method and the prepared PPy/SCP conductive additive is successfully applied on the zinc-rich primer (ZRP) coating. The equal mass substitution and the equal volume substitution methods of the conductive additives to zinc dusts are discussed, as well as the optimal replacing ratio to achieve the best corrosion protection effect of the ZRP coatings. The results indicate that the equal volume substitution method is in favor of corrosion resistance of coating film. The salt spray test and the electrochemical impedance spectroscopy (EIS) and polarization curves show that the prepared ZRP coating with a 66% zinc content and replacing ratio of 1:3 possesses the best corrosion-resistant performance and an optimal adhesion strength. The replacement of PPy/SCP particles to zinc dusts using the equal volume substitution method is feasible to achieve the improvement in anticorrosion ability through a synergic function of the cathodic protection effect and barrier effect.