In order to overcome the problems of highly interconnected pores and insufficient long-term corrosion resistance in micro-arc oxidation (MAO) coatings this study integrated softened spark MAO (S-MAO) with a Sr2+/Zn2+ complexation regulation strategy to fabricate composite MAO coatings on Ti6Al4V implant surfaces. The S-MAO treatment transformed coating architecture from a bilayer into a three-layer gradient structure (barrier layer/softened-spark layer/porous layer). This significantly diminished the interconnectedness of interior pores. Electrochemical tests showed that the way S-MAO coatings corrode changed from diffusion control to the interfacial charge transfer process being the most important. This indicates that the coatings' electrochemically protective qualities are more stable. The Z1S3MAO coating, with a Sr/Zn ratio of 3 : 1, demonstrated elevated interfacial charge transfer resistance (443.6 Ω cm2) and enhanced impedance responsiveness. The examination of the elemental distribution showed that Sr was spread out evenly throughout the coating thickness. However, Zn had a localized enrichment zone at the interface between the softened-spark layer and the porous outer layer. The spatial distribution is determined by the varying stability of ion complexation. The Z1S3MAO coating exhibited superior performance regarding wettability and cytocompatibility associated with osteogenesis.
Hao et al. (Thu,) studied this question.