TiO2Thick Films by Anodic Oxidation
by H.Z. Abdullah(1,2), and C.C. Sorrell(1)
(1)School of Materials Science and Engineering
University of New South Wales, NSW 2052, Australia
(2)Faculty of Mechanical and Manufacturing Engineering
Universiti Tun Hussein Onn Malaysia (UTHM), 86400 Parit Raja, Batu Pahat, Johor, Malaysia
Abstract Anodic oxidation is an electrochemical method for the production of an oxide film on a metallic substrate. It involves the application of an electrical bias at relatively low currents while the substrate is immersed in an acid bath. The films can be very dense and stable, with a variety of microstructural characteristics.
In the present work, thick films of the anatase polymorph of TiO2 were formed on high-purity Ti foil (50 ¦Ìm thickness) using the following solutions: S1 (1.5 M H2SO4), S2 (1.5 M H2SO4 + 0.3 M H2O2), S3 (1.5 M H2SO4 + 0.3 M H3PO4), and S4 (1.5 M H2SO4 + 0.3 M H2O2 + 0.3 M H3PO4). The conditions of deposition consisted of potentials of 90 V, 120 V, 150 V, and 180 V for times in the range 1-50 min at room temperature. The microstructures and thicknesses of the films were characterised using X-ray diffraction (XRD), Raman microspectroscopy, and field emission scanning electron microscopy (FESEM).
The phase formation, thickness, and pore size of the films depended strongly on the applied voltage and anodising time. The role of the solution composition was not clear, although the presence of hydrogen peroxide (H2O2) may have been detrimental to the development of the film. Strongly adhered anatase was observed to form in as short a time as 3 min. The film thicknesses were limited to ¡Ü3 ¦Ìm owing to the time and voltage constraints of the process.
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