Tailoring the composition of fluoride conversion coatings to achieve better corrosion protection of magnesium for biomedical applications

Abstract

The methodology of deposition of fluoride conversion coatings is modified with the use of galvanic coupling, agitation of the electrolyte solution, and addition of K₂CO₃, which helps to provide a better understanding of the mechanism and new avenues to tailor the composition of the coating. A very good correlation exists between the F/O ratio of the coatings prepared under varying experimental conditions and their i_corr, |Z| and phase angle maximum; the higher the F/O ratio, the better the corrosion protective ability of the coatings in Hank's balanced salt solution. The corrosion behaviour of the coatings of the present study suggests that fluoride conversion coatings show much promise for their use for biomedical applications, as long as their uniformity is improved and the composition is tailored to enrich the MgF₂ phase, encompassing a higher F/O ratio.