Electrochemical behaviour of NiTi alloy coated with TiN using DPF

Abstract

Dense plasma focus (DPF) nitriding method was used to coat titanium nitride (TiN) on NiTi alloys as bone implant. These coatings were developed to modify the surface properties, such as corrosion resistance and biocompatibility. This method was done with a pressure of 2 mbar and voltage of 8 kV under pure nitrogen gas and mixed gas of nitrogen and argon separately. The electrochemical behaviour of the uncoated and coated samples was assessed by open circuit testing, potentiodynamic scanning and the electrochemical impedance spectroscopy in Ringer's solution at 37°C. Ni concentration in the Ringer's solution at 37°C was measured via the atomic absorption spectrometry. The TiN-modified surface of the sample with a distance of 7 cm from anode under 100% nitrogen gas during DPF nitriding demonstrates good corrosion resistance and low nickel ion release that could lead to a better biocompatibility.