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

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.