Solvothermal fabrication of TiO2 nanosheet films on degradable Mg-Zn alloys

摘要

Anatase TiO2 nanosheet films were fabricated on Mg-Zn alloy substrates through a special solvothermal method, aiming to improve the corrosion resistance of degradable Mg-Zn alloy stents. In this novel synthesis process, absolute alcohol was used as solvent, and small amounts of hydrofluoric acid and NH4F aqueous solution were used to adjust the hydrolysis rate of titanium precursors and the crystal morphology of anatase TiO2, respectively. The NH4F played a key role in the growth of TiO2 nanosheets by supplying fluorine ions (F-). The anatase TiO2 films had a compact surface consisting of interleaving nanosheets with thickness of about 50 nm. In simulated body fluids, the corrosion current density (I-corr) of Mg-Zn alloy substrates decreased from 789.5 to 24.4 mu A cm(-2), after being coated with the TiO2 nanosheet films.