Ion Release and Surface Characterization of Nanostructured Nitinol during Long-Term Testing
Elena O. Nasakina,
Maria A. Sudarchikova,
Konstantin V. Sergienko,
Sergey V. Konushkin,
Mikhail A. Sevost’yanov
Affiliations
Elena O. Nasakina
Laboratory of Durability and Plasticity of Metal and Composite Materials and Nanomaterials, Institution of Russian Academy of Sciences, A.A. Baikov Institute of Metallurgy and Material Science RAS (IMET RAS), Leninsky Prospect, 49, 119991 Moscow, Russia
Maria A. Sudarchikova
Laboratory of Durability and Plasticity of Metal and Composite Materials and Nanomaterials, Institution of Russian Academy of Sciences, A.A. Baikov Institute of Metallurgy and Material Science RAS (IMET RAS), Leninsky Prospect, 49, 119991 Moscow, Russia
Konstantin V. Sergienko
Laboratory of Durability and Plasticity of Metal and Composite Materials and Nanomaterials, Institution of Russian Academy of Sciences, A.A. Baikov Institute of Metallurgy and Material Science RAS (IMET RAS), Leninsky Prospect, 49, 119991 Moscow, Russia
Sergey V. Konushkin
Laboratory of Durability and Plasticity of Metal and Composite Materials and Nanomaterials, Institution of Russian Academy of Sciences, A.A. Baikov Institute of Metallurgy and Material Science RAS (IMET RAS), Leninsky Prospect, 49, 119991 Moscow, Russia
Mikhail A. Sevost’yanov
Laboratory of Durability and Plasticity of Metal and Composite Materials and Nanomaterials, Institution of Russian Academy of Sciences, A.A. Baikov Institute of Metallurgy and Material Science RAS (IMET RAS), Leninsky Prospect, 49, 119991 Moscow, Russia
The corrosion resistance of nanostructured nitinol (NiTi) was investigated using long-term tests in solutions simulating physiological fluids at static conditions, reflecting the material structure and metal concentration in the solutions. Mechanical polishing reduced the ion release by a factor of two to three, whereas annealing deteriorated the corrosion resistance. The depassivation and repassivation of nitinol surfaces were considered. We found that nanostructured nitinol might increase the corrosion leaching of titanium into solutions, although the nickel release decreased. Metal dissolution did not occur in the alkaline environment or artificial plasma. A Ni-free surface with a protective 25 nm-thick titanium oxide film resulted from soaking mechanically treated samples of the NiTi wire in a saline solution for two years under static conditions. Hence, the medical application of nanostructured NiTi, such as for the production of medical devices and implants such as stents, shows potential compared with microstructured NiTi.
