Effect of nitrogen ion implantation on in vitro corrosion behaviour of NiTi

Abstract

In the last decade, different surface modifications have been developed to enhance the biocompatibility of NiTi shape memory alloys. The present paper deals with the influence of nitrogen ion implantation on corrosion behavior of NiTi in Hank's solution. Nitrogen implantation at 150 keV with nominal doses ranged from 0.5×1017 to 8×1017 ion cm -2 were used. Mechanical surface characterization was carried out by nanohanrdness, corrosion mechanism evaluation by electrochemical polarization and impedance spectroscopy (EIS) tests and surface composition by XPS spectra. The results point out the benefit of the N-implanted for corrosion resistance at a suitable dose 2×1017 ion cm-2 and an increase of the mechanical properties with the doses.