Characterization of bioactive ceramic coatings synthesized by plasma electrolyte oxidation on AZ31 magnesium alloy having different Na2SiO3•9H2O concentrations

Surface modification of magnesium alloys by Plasma Electrolytic Oxidation (PEO) method can be a great help for the development of degradable implants in clinical applications. In this study, the aim was to investigate the effect of changing Na2SiO3 center dot 9H(2)O concentration (5, 10, and 15 g L-1) in a bath containing Ca2H4P2O4, Na3PO4 center dot 12H(2)O, NaF, and KOH compounds at pH = 12 and a conductivity of 20 mS/cm. Coating characterization was performed by Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray Spectroscopy (EDX), X-ray Diffraction (XRD), nanoindentation, Electrochemical Impedance Spectroscopy (EIS), Fourier Transform-Infrared Spectroscopy (FTIR), and immersion in Simulated Body Fluid (SBF). The formed bioactive ceramic coating contains bioelements from the electrolyte, including Ca, P, Si, F, and Na. And, as Na2SiO3 center dot 9H(2)O concentration increases, it also silicon, sodium, and oxygen values in the coating, and reduces magnesium and phosphor values. Pore density decreases in the coatings by an increase in Na2SiO3 center dot 9H(2)O concentration. The optimum bioactive ceramic coating considering hardness and corrosion resistance contains 10 g L-1 of Na2SiO3 center dot 9H(2)O. The optimized bioactive ceramic coating has the ability to form carbonate hydroxyapatite after immersion in SBF at 37 degrees C for one and four days.