Surface modification of titanium by hydrothermal treatment

The chemical-hydrothermal combined synthesis of TiO 2 and CaTiO 3 films on pure Ti substrates was examined with a focus on crystallinity and surface morphology of the films. Pure Ti disks were chemically treated with H 2 O 2 /HNO 3 solu-tions at 353K for 5–60min in order to introduce a TiO 2 layer with low crystallinity on the surface. The samples were then hydrothermally treated in an autoclave at 453K for 12h. Anatase-type TiO 2 and perovskite-type CaTiO 3 films with high crystallinity were obtained upon treatment with distilled water and an aqueous solution of Ca （ OH ） 2 , respectively. Cracks in the TiO 2 precursor films disappeared after hydrothermal treatment. Uniform and crack-free films could be obtained by the present process. In addition, in vitro formation of hydroxyapatite （ HAp ） on the films was investigated. Obtained samples were immersed in SBF （ Simulated Body Fluid ） , adjusted to 310K. A light HAp precipitate could be observed on non-surface modified Ti after six days of immersion. In contrast, precipitate formed after only two days on the present oxide film. The present surface modification was confirmed to drastically promote deposition of HAp on the surface of Ti.

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