Porous films on surface of titanium prepared by low voltage micro arc oxidation

Abstract

Porous TiO₂ films were prepared by using micro arc oxidation (MAO) in an electrolytic solution of Na₃PO₄ with a voltage of 200 V. Three different concentrations of Na₃PO₄ electrolyte were used, i.e. 10, 15 and 20 g L⁻¹. The oxidation time ranged from 5 to 15 min. The oxide films were characterised by scanning electron microscopy, energy dispersive X-ray spectrometer and X-ray diffraction. Scanning electron microscopy analysis shows that the oxide films had numerous pores with dimensions between 0·5 and 2·5 μm. The phosphorous concentrations on the surfaces of the oxide films were found to be between 4·73 and 5·73%. The anatase TiO₂ phase was determined in all the films, and no rutile phase was detected. The titanium phosphate phase was only found in the oxide films prepared with 20 g L⁻¹ of concentration of Na₃PO₄ electrolyte. The experimental results suggest that the low voltage MAO method is an effective way to prepare porous TiO₂ film containing a high concentration of phosphorous.