Effect of Electrodeposition Parameters on the Morphology, Topography and Corrosion Resistance of Epoxy Resin/Zinc Hybrid Coatings

The paper presents the morphology, topography and corrosion behavior of epoxy resin/zinc hybrid coatings obtained by electrodeposition from zinc sulphate electrolyte. The effect of current density and mean diameter size of polymer particles used for electrodeposition of the epoxy resin/zinc coatings on the morphology, topography and roughness of the surfaces were investigated by Scanning Electron Microscopy and Atomic Force Microscopy. The corrosion behavior of the hybrid coatings in 0.5 M sodium chloride solution was evaluated using electrochemical methods. For microbiological corrosion, the effect of sulphate reducing bacteria (SRB) on the surfaces was evaluated using epifluorescence microscopy. The surface roughness before and after bacteria attachment was evaluated using Atomic force microscopy. Polymer particles provide an influence in restricting the growth of zinc crystals as well as a catalytic role in nucleation sites increase. The results of electrochemical tests indicate a very good corrosion resistance of hybrid coatings comparing with zinc coatings. Epifluorescence images demonstrate that hybrid coating surfaces are slightly attacked by sulphate reducing bacteria