Hydrothermal synthesis of a nanocrystalline anatase layer on Ti6A4V implants

In the present work we propose a simple, one-step hydrothermal process for the direct crystallisation of an anatase layer, up to 2 μm thick, and with high bonding strength, on a Ti6Al4V alloy without any surface pretreatment. The samples were processed at different pH values with or without the addition of TiO2 or Ti(OH)4, resulting in different morphologies of anatase crystals and different thicknesses of the oxide layer. The thickest, uniform, well-bonded nanocrystalline anatase layer was obtained with a hydrothermal treatment in a TiO2 suspension, whereas treating the samples in an aqueous solution led to the formation of a thin layer of {001}-oriented anatase crystallites. The layers were characterised using the SEM, TEM, XRD and XPS techniques to study their crystallinity and composition. Aluminium was absent from all the layers, while a low, equilibrium amount of vanadium remained incorporated in the anatase structure after the hydrothermal treatment with the addition of Ti4+ ions.