Microstructure, formation mechanism and antifouling property of multi-layered Cu-incorporated Al2O3 coating fabricated through plasma electrolytic oxidation

Abstract In this work, a Cu-incorporated Al2O3 coating has been successfully produced through the one-step plasma electrolytic oxidation (PEO) method. Unexpectedly, the resultant Cu-incorporated Al2O3 coating displays a multi-layered structure, which exhibits significant variations in morphology, composition and crystallinity. Compared to the compact outer layer of the PEO coating, both medium and inner layers are highly porous even the average pore size of the medium layer is obviously higher than that of the inner layer. The medium layer has a higher Cu content in comparison to both outer and inner layers. And the outer layer mainly consists of crystalline γ-Al2O3 phase whereas both medium and inner layers are in amorphous states. Further, it was found that Cu specie could exist as Cu2O and CuO in the Cu-incorporated PEO coating. Finally, it was revealed that the incorporation of Cu into the porous PEO coating significantly improves the antifouling property of Al metallic substrate against SRB, which successfully prevents the formation of SRB biofilm. Hence, PEO method is a promising surface modification technique for the fabrication of antifouling coating.