MgF2/MgO composite coating on porous magnesium surface and its biocorrosion resistance

Abstract

MgF2/MgO composite coatings were prepared on the surface of porous magnesium by chemical vapor deposition (CVD) techniques in a mixed atmosphere of argon and 1,1,1,2‐tetrafluoroethane (HFC‐134a). The morphology, elemental composition and phase composition of the composite coatings were characterized by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X‐ray photoelectron spectroscopy (XPS) and X‐ray diffraction (XRD), and the biocorrosion resistance of the coatings in simulated body fluid (SBF) was investigated by immersion and electrochemical tests. The characterization analysis showed that a dense MgF2/MgO composite coating with some small pores was formed. The content of MgF2 in the coating increased with the increase of HFC‐134a concentration in the mixed atmosphere, reaction time and temperature. The content of MgO decreased with the increase of the concentration of HFC‐134a and reaction time. Immersion tests indicated that MgF2/MgO composite coatings obviously reduced the degradation rate of porous magnesium in simulated body fluid, and the higher the fluorine content in the coating, the smaller the degradation rate of porous magnesium. Electrochemical test demonstrated that MgO/MgF2 coated porous magnesium exhibited a higher biocorrosion resistance than porous magnesium. These results suggest that the MgF2/MgO coated porous magnesium possesses suitable corrosion behavior for the application as biodegradable implant material.