Fabrication of Ni-Ti-O nanoporous film on NiTi alloy in ethylene glycol containing NaCl

Ni-Ti-O nanoporous film with pore diameters of 60–75 nm are produced anodically on NiTi in ethylene glycol containing 5–10 vol% H₂O and 0.15–0.3 M NaCl at 10–20 V. The film fabricated in the NaCl-containing electrolyte are much thinner than those prepared in the HCl-containing electrolyte under similar experimental conditions, implying proper amount of H⁺ in the electrolyte accelerates formation of the nanopores. Moreover, the experimental conditions to grow Ni-Ti-O nanoporous film on NiTi are not proper for pure Ti and Ni. The film of 1.9 μm in thickness exhibits good cytocompatibility thus is suitable for biomedical applications.