Bioactive plasma electrolytic oxidation coatings on Mg-Ca alloy to control degradation behaviour

Abstract

The present work reports on PEO coatings which can be potentially used for degradation control of Mg-based implant materials. Three coatings were developed on Mg-0.8wt%Ca alloy: two in an electrolyte with fluoride species using different treatment times and one in a fluoride-free electrolyte. Uncoated and coated materials were examined in terms of structure and morphology using TEM, SEM and XRD. The corrosion investigations on fluoride-containing samples were performed using DC potentiodynamic curves, EIS and hydrogen evolution measurements. Both PEO coatings improved the corrosion resistance compared to the bulk material and the best behaviour was found for the thinnest PEO coating (PEO1-F). The amount of released F− ions was also measured with the aim of underpinning the effect of coatings and presence of fluorides species on the cell response. The bulk material and the coated alloy were studied using live/dead cell test, with the best results obtained for thinner fluoride containing coatings.