Bioactive titania-gel layers formed by chemical treatment of Ti substrate with a H2O2/HCl solution.

An amorphous titania gel layer was formed on the titanium surface after the titanium specimen was treated with a H2O2/0.1 M HCl solution at 80 degrees C. The thickness of the gel layer increased almost linearly with the period of the treatment. A subsequent heat treatment above 300 degrees C transformed gradually the amorphous gel to the anatase crystal structure and the rutile started to appear after heat treatment at 600 degrees C. Meanwhile, the densification of the gel occurred significantly after heat treatment above 700 degrees C. Similar to the sol-gel derived titania gel coatings. titania gel layers obtained in the present study exhibited in vitro apatite deposition ability after the gel layers exceeded a minimum thickness (0.2 microm) and was subsequently heated in a proper temperature range (400-600 degrees C).