Electrochemical behaviour of EPD synthesized graphene coating on titanium alloys for orthopedic implant application

摘要

Titanium based alloys are one of the most popular biomedical materials and widely utilized as metallic implants; however, they often encounter failures resulted by the combined effects of wear and corrosion. Graphene, a single layer of carbon atoms arranged in an aromatic hexagonal lattice, is regarded as a potential promising coating material to settle this issue due to its impermeability, thermodynamic stability, transparency and flexibility. In this study, a layer of continuous graphene film is deposited on the surface of TC4 substrate by the electrophoretic deposition (EPD) method. The surface morphology and microstructure of the deposited graphene coatings are characterized by scanning electron microscopy and Raman spectroscopy; the corrosion behaviors of the fabricated graphene coated TC4, as well as the bare TC4 in 1.0 wt.% NaCl solution are investigated using an electrochemical workstation. The anti-corrosion properties were proven by potentiodynamic polarization curves (Tafel polarization curves). The open circuit potential (OCP) value of graphene coated TC4 is -0.01 V, compared with that of the bare TC4, which is measured as around -0.33 V; moreover, its corrosion current density dramatically reduces to the 40% of that of bare TC4. Further studies show that increasing the applied voltage or the deposition duration of the EPD process would weaken the corrosion resistance of the deposited graphene coating, indicating that the protective nature of the coating would be impaired by intercrystallite pores and microdefects.