Corrosion, wear, and cell culture studies of oxygen ion implanted Ni–Ti alloy

To increase the biocompatibility of nickel–titanium (Ni–Ti) alloy substrates, oxygen ions have been implanted by the plasma immersion ion implantation (PIII–O) technique at low temperature without affecting the substrate properties. The implanted Ni–Ti surface is characterized for microhardness and composition. Energy‐dispersive spectroscopy and X‐ray photoelectron spectroscopy investigations show the replacement of native oxide on the alloy by a compact oxide during the implantation process. The corrosion behaviors of untreated substrate and PIII–O samples are investigated using potentiodynamic polarization and electrochemical impedance spectroscopy in simulated body fluid (Hanks' solution). Polarization and electrochemical impedance spectroscopy studies reveal nearly ideal capacitor behavior with better passivation characteristics for the oxygen‐implanted substrate. Sliding wear studies reveal lower friction of coefficient for the implanted layers as compared with the substrate. The bare and surface modified Ni–Ti alloy samples are evaluated for biocompatibility using osteoblast‐like cells (MG‐63). Cellular behavior in terms of cell morphology along with the viability and proliferations is evaluated by using scanning electron microscopy and in vitro cell culture assay, respectively. The results clearly show that oxygen implantation by PIII–O provides a better compatible surface for cell attachment and growth. The modified surface exhibits a higher percentage of cell viability demonstrating the enhanced biocompatibility of the oxygen‐implanted surface compared with bare Ni–Ti alloy.