Electrodeposition of sustainable fluoridated hydroxyapatite coatings on 316L stainless steel for application in bone implant

Abstract

Fluoridated hydroxyapatite (FHAp) coatings were deposited on 316L stainless steel (316LSS) substrate by the electrodeposition method. Different concentrations of F- ion were incorporated into the apatite structure by adding NaF into the electrolyte solution. The coating was uniform and dense, with thickness of 9.6 μm, and F- ions were doped on HAp with mass percentage of 1.7%; F- concentration was 0.002 M. Results of IR, energy-dispersive X-ray (EDX), X-ray and scanning electron microscopy (SEM) analysis showed that the obtained coatings were single phase crystals of HAp, of a cylinder shape with average size of about 100 nm×30 nm, and characterized for the molecular structure FHAp. The in vitro test of 316LSS, HAp/316LSS and FHAp/316LSS materials in simulated body fluid (SBF) solution was realized with different immersion times. After 21 immersion days in SBF solution, the apatite crystals have a cactus-like shape, and they grow to form a thick block on the surface of FHAp/316LSS leading to the decrease of the corrosion current density during the immersion process in the SBF solution.