Chemical-Hydrothermal Synthesis of Bioinert Oxide Films on Ti Substrates

摘要

Titanium and its alloys have been employed in bone plates+screws,and these are normally designed to be removed after the patient has recovered. However, bone can sometimes attach to the surface of implanted materials that remain in the body for long periods of time. This can lead to re-iracture of newly repaired bone during operations to remove the implants. The purpose of the present study was to synthesise bioinert films, including ZrO2 on pure Ti surfaces and to study apatite (HAp) formation on the synthesized oxide films in Hanks' solution. Commercial purity Ti disks were chemically treated with H2O2/HNO3 aqueous solutions at 353 K for 20 min. The disks were hydrothermally treated with ZrOCl2/ NH3/QH8O7(citric acid) aqueous solutions in a Teflonlined autoclave at 453 K for 12 h. The specimens were immersed in Hanks' solution, which was maintained at 310 K. After being soaked for different periods of time, the surfaces were observed by SEM. In the hydrothermal treatment with ZrOCl2/NH3 aqueous solution,the surface product was anatase-type TiO2. On the other hand, when citric acid was added the surface of Ti was covered homogeneously with a ZrO2TiO2 composite film. Some of the Zr(OH)4 sol in the solution is thought to have dissolved into the solution by coordinate bonding with citric acid carboxyl groups,leading to precipitation of ZrO2 in the TiO2 or on its surface. The ZrO2-TiO2 film suppressed the precipitation of HAp on the surface in the SBF soaking. A bioinert ZrO2-TiO2 composite film could be synthesised on Ti surfaces by a combined chemical-hydrothermal treatment. This method offers excellent potential for inhibiting direct bonding to living bone, and can be applied to assist the remove of implants made from existing Ti alloys.