Electrochemically-coated hydroxyapatite films on nanotubular TiNb alloys prepared in solutions containing Ca, P, and Zn ions

Electrochemically-coated hydroxyapatite films on nanotubular TiNb alloys prepared in solutions containing Ca, P, and Zn ions were explored for dental applications using various experimental methods. Ti-xNb binary alloys were used in this study. Homogenization treatment of samples was carried out at 1000 °C for 2 h, followed by quenching in 0 °C water. Self-organized nanotubular TiO2 was prepared by electrochemical oxidation of the samples in 1.0 M H3PO4 + 0.8 wt.% NaF electrolyte at anodization potential of 30 V, for 1 h. Electrochemical deposition of pure HA and Zn-doped HA on the alloys was conducted at 85 °C in electrolytes containing Zn ions. The Zn-HA films, along with the nanotubes, were characterized via X-ray diffraction, field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDS). The Ti-xNb alloys underwent structural transformation from the α″ + β phases to β phase with a large grain size as the Nb content increased. The nanotubular structure of Ti30Nb and Ti50Nb alloys had highly ordered diameter distributions consisting of two distinct diameters. The nanotubular surface was covered with precipitated HA and Zn-HA, and the plates of HA became increasingly larger with smaller particles surrounding the pores as the Nb content of the alloy increased, leading to eventual loss of the nanotube pores. In the case of the Zn-HA coating, the entire surface showed a uniform distribution of elements on the nanotube surface.