DLC films fabricated by plasma immersion ion implantation and deposition on the NiTi alloys for improving their corrosion resistance and biocompatibility

Diamond-like carbon films with different bias voltages were deposited on polished NiTi alloys by plasma immersion ion implantation and deposition (PIIID) using acetylene as precursor. The chemical structure of the DLC films was characterized by Raman scattering spectroscopy. The electrochemical behavior and blood compatibility of the DLC coated and uncoated NiTi alloys were investigated by means of potentiodynamic polarization tests, clotting time measurement, and platelets adhesion.The results show the corrosion resistance and blood compatibility of the NiTi alloys is improved due to the DLC films, and the sp3/sp2 ratio and the corrosion resistance of the DLC films on the NiTi alloys first increases and then decreases with the increase of the bias voltage. Thus, it can be inferred that the corrosion resistance of the DLC films is influenced by the sp3/sp2 ratio.