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.