Enhancing the corrosion behavior of Ti–6Al–4V and Nitinol alloys by simple chemical oxidation in H2O2

Abstract

This study investigated the effect of hydrogen peroxide treatment on the corrosion behavior of two Ti biomaterial alloys (Ti–6Al–4V and Nitinol (NiTi)). The obtained oxides were characterized by a scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Even though both oxidized alloys are constituted mostly by TiO2 oxide on their surfaces, different topographies were obtained: a non-porous film with mud-cracked structure type was formed on Ti–6Al–4V while some micropores were observed on the NiTi surface. Oxidized NiTi samples also exhibited Ni species present as oxides and hydroxides in the form of Ni2+ and Ni3+. The ICP-AES analysis demonstrated that the presence of the oxides reduced the amount of alloying ions released to the simulated physiological environment after the electrochemical tests. The results show that this simple technique without the need for thermal post-treatment is enough to reduce the corrosion current density (icorr) and shift the corrosion potential (Ecorr) to more noble values enhancing the anticorrosive properties of both Ti-based alloys in Ringer solution. Moreover, the hydrophilicity of the surfaces was increased after the treatment.