HA coating on titanium with nanotubular anodized TiO2 intermediate layer via electrochemical deposition
(College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics,Nanjing 210016, China)
Abstract: Hydroxyapatite(HA) coating has been prepared on titanium substrate through an electrochemical deposition approach. In order to improve the bonding strength between HA coating and Ti substrate, a well oriented and uniform titanium oxide nanotube array on the surface of titanium substrate was applied by means of anodic oxidation pre-treatment. Then the calcium hydrogen phosphate(CaHPO4∙2H2O, DCPD) coating, as the precursor of hydroxyapatite coating, was electrodeposited on the anodized Ti. At the initial stage of electro-deposition, the DCPD crystals, in nanometer precipitates, are anchored in and between the tubes. With increasing the deposition time, the nanometer DCPD crystals are connected together to form a continuous coating on titanium oxide nanotube array. Finally, the DCPD coating is converted into hydroxyapatite one simply by being immersed in alkaline solution.
Key words: anodic oxidation; nanotubes; hydroxyapatite; electrochemical deposition