Corrosion and antifouling properties of copper-containing PEO coatings produced on steels

In this work, antifouling copper-containing PEO coatings were produced on zinc-aluminized steels and their antifouling properties in circulating seawater were tested at the Hydrobiological Station Umberto D'Ancona located in Chioggia (Venice, Italy). The effect of the presence of the copper particles on the localized corrosion properties of the PEO coatings was also investigated in depth. In detail, the PEO-coated samples were produced and characterized in terms of microstructure and phase composition through SEM and XRD analysis. The antifouling properties of the samples were evaluated through stereo-microscope and SEM observations after up to 28 days of immersion and the corrosion properties were analyzed with EIS and SVET tests. The results, besides the successful incorporation of the copper particles into the coatings, evidenced the remarkable antifouling effect of the copper particles which also produced a clear selection in the type of algae that can colonize the samples. Considering the corrosion properties, the copper particles were found to be detrimental, due to the galvanic coupling with the substrate. Considering both results, the copper-containing PEO coating can be suggested only in combination with a topcoat which further increases the corrosion performance.