Corrosion and wear resistance of TiN and Ti-O/TiN films deposited on Ti-6Al-4V using plasma implantation and deposition

Summary form only given. Titanium and its alloys are good biomaterials because of their comparatively high corrosion resistance and good biocompatibility. It has been suggested that the native surface oxide layer with good physiochemical and dielectric properties is responsible for its good properties. However, this native layer is usually too thin to prevent dissolution of metal in a biological environment. There is increasing evidence that titanium ions can be released extensively in vivo, and under certain conditions, accumulated in adjacent tissues. Various modification methods can enhance the corrosion and wear resistance of the materials and plasma immersion ion implantation & deposition (PHI-D) developed in the last decade is regarded as one of the best techniques due to the nonline of sight advantage and high efficiency. In this work, titanium nitride (TiN) films were deposited on Ti-6Al-4V alloy using PIII-D, followed by oxidation to form Ti-O/TiN films. The corrosion and wear resistance of the films were investigated in phosphate buffered solution (PBS). The open-circuit potential versus exposure time (I-t), polarization curves (E-I) and electrochemical impedance spectra (EIS) were obtained. Our results show enhancement of the corrosion resistance. The I-t as well as E-I curves show that the both the TiN and Ti-O/TiN films have lower dissolution currents than the untreated Ti-6Al4V alloy, and EIS analysis indicates that TiN films have higher corrosion resistance due to the dense barrier layer slowing the mass transport process between the films and substrate. The corrosion resistance of the Ti-O/TiN film is higher on account of the higher corrosion potential (E/sub corr/) compared to the substrate. However, although the Ti-O/TiN film exhibits higher E/sub corr/ than the TiN film, the former has slightly lower corrosion resistance because of the porous outer layer. Tribological investigation in PBS indicates that TiN and Ti-O/TiN films both possess higher wear resistance than Ti-6Al-4V, and TiN has the highest wear resistance probably because of its better mechanical behaviors.