Fabrication of highly ordered nanotube layer on Zr-based bulk metallic glass for biomedical uses

Anodization was adopted on a biomedical Zr-based Zr₅₆Al₁₆Co₂₈ bulk metallic glass (BMG). A highly ordered nanotube layer was fabricated on the surface of Zr₅₆Al₁₆Co₂₈ BMG. The highly ordered nanotubes formed at 20 V in glycerol electrolyte with 0.5 M NH₄F and 10 vol.% H₂O are amorphous with a diameter of ∼20 nm, a wall thickness of ∼5 nm and a length of ∼620 nm. Compared with the original composition, cobalt was excessively dissolved after anodization. The nanotube layer treated by alternative immersion method (AIM) can facilitate the formation of hydroxyapatite (HAp). Bioactivity experiments showed that a thick hydroxyapatite (HAp) layer can form on the treated nanotube layer after immersed in simulated body fluid (SBF) for 7 days.