Evaluating sol-gel ceramic thin films for metal implant applications. I. Processing and structure of zirconia films on Ti-6Al-4V

Thin ceramic films or coatings over metallic bone-interfacing implant surfaces have the potential to improve implant performance with respect to implant fixation, wear, or corrosion. In this study, zirconia (ZrO₂) thin films formed on Ti-6Al-4V using a polymeric alkoxide-based sol-gel process were investigated. ZrO₂ films of uniform thickness on the order of 100 nm were obtained by dip coating Ti-6Al-4V samples into a zirconium propoxide containing solution using a substrate withdrawal speed ranging from 2 to 8 cm/min and a sol of nominal viscosity ≃ 6 cps. These films were essentially free of surface macrodefects but had random submicron 'pinholes.' X-ray diffraction studies suggested that the films were at least partially crystalline, with some 'metastable' cubic and/or tetragonal phases after annealing for 1 h at 500 °C. The demonstrated reproducibility of this approach for producing good quality ZrO₂ films on Ti-6Al-4V warrants further studies to optimize processing conditions for implant applications.