Ti-6Al-4V alloy has wide applications in the medical industry due to its unique mechanical properties and biocompatibility. However, in the long-term use of these alloys, the release of aluminum and vanadium can result in serious illnesses. For solving these problems, the implant surface modification can be done to improve the corrosion and biocompatibility properties. In this study, TiN coating was applied by Plasma-Assisted Chemical Vapour Deposition (PACVD) method along with hydroxyapatite coating (HA) by sol-gel method on Ti-6Al-4V substrate surface. Afterwards, X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Atomic Force Microscopy (AFM) and potentiodynamic polarization and electrochemical impedance tests were used for evaluating the phase, morphology, chemical composition, surface roughness, and corrosion behavior in the simulated body fluid (SBF), respectively. Results showed that the surface roughness of HA/TiN, HA, TiN and substrate specimens were the highest to minimum values with roughness of 30.86±0.5, 25.1±0.42, 20.43±0.14 and 15.1±0.02 nm, respectively, and the HA-TiN composite coating had the lowest corrosion current density, highest polarization resistance and corrosion potential. Results of cell viability and proliferation demonstrated that the HA/TiN nanocomposite coating is a good choice for dental and orthopedic implants due to its corrosion resistance and biocompatibility.
