Improving the performance of zinc-rich coatings using conductive pigments and silane

By analysing the results of corrosion potential, EIS, SEM and XRD test of zinc-rich coatings (ZRCs) in 3.5wt-% NaCl solution, it was found that conductive pigment (di-iron phosphide, Fe2P) can accelerate the activation and corrosion rate of zinc powders in ZRCs, but too fast corrosion rate can reduce the cathodic protection and shielding of ZRCs. Silane improves the mechanical properties and shielding effect of coatings, but reduces the activation and corrosion rate of zinc powders. The synergy effect of the two strengthens both the cathodic protection and the shielding effect. Finally, the synergy mechanism of Fe2P and silane to improve the performance of ZRCs is proposed. These mechanisms provide references for solving the galvanic corrosion of conductive fillers (Fe2P, graphite, carbon black, carbon nanotubes, graphene, etc.) in ZRCs.