MAO-derived hydroxyapatite–TiO2 nanostructured bio-ceramic films on titanium

Micro Arc Oxidation (MAO) process was utilized to fabricate nano bioceramic TiO2–hydroxyapatite coatings on titanium substrates. Samples were produced in electrolytes contained 1 g/l β-glycerophosphate and 5, 10 and 15 g/l calcium acetate for 3, 6 and 10 min at 350 V. The techniques including XRD, XPS, SEM, FESEM and EDX were employed to study the effect of processing parameters. Hydroxyapatite, anatase, α-tri calcium phosphate and calcium titanate phases as well as 30–60 nm-size crystals were detected in the coating layer. It was also observed that the pore volume would increase by increasing the electrolyte concentration. The growth time was also found to influence the total pore volume. Furthermore, the individual pore sizes would also be increased as the arcing time increased. By increasing the electrolyte concentration and growth time, the rougher surface layers were obtained. Depending on the growth time and electrolyte concentration, pore size and density were measured 0.303–1.77 μm and 10.7–17.3%, respectively.

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► HAp–TiO2 nanostructured layers were derived by MAO technique.
► The relation between electrolyte concentration and growth time was studied.
► The volume fraction of HAp phase was increased by raising these two parameters.
► Crystalline coatings were fabricated via MAO process and without any heat treatment.