Formation of titania photocatalyst films by microarc oxidation of Ti and Ti-6Al-4V alloys

Microarc oxidation (MAO) was performed for pure Ti and Ti-6Al-4V alloys, respectively to evolve porous titanium oxide (TiO₂:titania) films at their surfaces. X-ray diffraction (XRD) analysis results reveal that TiO ₂ films formed on pure Ti and Ti-6Al-4V alloys have high content of anatase with small content of rutile phases, which would be ideal for high-performance photocatalytic properties. The rutile content was gradually increasing with MAO time period for Ti alloys, while that was almost constant value of 10 vol% for pure Ti. Scanning electron microscopy (SEM) images of the films show uniformly distributed pores for both pure Ti and Ti-6Al-4V alloys. The pore density was higher for pure Ti from 10 min MAO and the pore size became larger for Ti-6Al-4V alloys after 40 min MAO. Microarc oxidized pure Ti showed relatively higher photodecomposition efficiency compared to Ti-6Al-4V alloys, possibly due to the large surface area coming from high porosity and optimum composition of anatase and rutile phases.