Synthesis and properties of hydroxyapatite-containing porous titania coating on ultrafine-grained titanium by micro-arc oxidation

• Published in: Acta biomaterialia 2010-07, Vol.6 (7), p.2816-2825
• Main Authors: Yao, Z.Q., Ivanisenko, Yu, Diemant, T., Caron, A., Chuvilin, A., Jiang, J.Z., Valiev, R.Z., Qi, M., Fecht, H.-J.
• Format: Article
• Language: English
• Subjects: Coating; Crystallization; Durapatite - chemical synthesis; Durapatite - chemistry; Equal channel angular pressing; Micro-arc oxidation; Microscopy, Electron, Scanning; Molecular Structure; Nanocrystalline hydroxyapatite; Oxidation-Reduction; Spectrum Analysis - methods; Surface Properties; Titanium - chemistry; Ultrafine-grained titanium; X-Ray Diffraction; X-Rays
• ISSN: 1742-7061; 1878-7568
• DOI: 10.1016/j.actbio.2009.12.053

Equal channel angular pressing results in ultrafine-grained (∼200–500 nm) Ti with superior mechanical properties without harmful alloying elements, which benefits medical implants. To further improve the bioactivity of Ti surfaces, Ca/P-containing porous titania coatings were prepared on ultrafine-grained and coarse-grained Ti by micro-arc oxidation (MAO). The phase identification, composition, morphology and microstructure of the coatings and the thermal stability of ultrafine-grained Ti during MAO were investigated subsequently. The amounts of Ca, P and the Ca/P ratio of the coatings formed on ultrafine-grained Ti were greater than those on coarse-grained Ti. Nanocrystalline hydroxyapatite and α-Ca 3(PO 4) 2 phases appeared in the MAO coating formed on ultrafine-grained Ti for 20 min (E20). Incubated in a simulated body fluid, bone-like apatite was completely formed on the surface of E20 after 2 days, thus evidencing preferable bioactivity. Compared with initial ultrafine-grained Ti, the microhardness of the E20 substrate was reduced by 8% to 2.9 GPa, which is considerably more than that of coarse-grained Ti (∼1.5 GPa).