Anti-Corrosion Properties of Nitrogen and Oxygen Plasma-Implanted Nickel-Titanium Shape Memory Alloy

Nickel-titanium shape memory alloys (NiTi) have potential applications as orthopedic implants but out-diffusion of harmful Ni from the NiTi substrate during prolonged use inside a human body is a serious issue and the problem must be solved before the materials can be more widely used in orthopedics. In this work, we produce TiN and TiOx barrier layers by plasma immersion ion implantation (PIII) and study the effects of different working voltages (20kV, 30kV, and 40kV). The corrosion resistance of the plasma-treated materials is found to be much improved and the optimal processing windows are described in this paper.