Micro arc oxidation of S-containing TiO2 films by sulfur bearing electrolytes

Porous S-containing titania (TiO2) films were fabricated by micro arc oxidation (MAO) in sulfur bearing electrolytes. Two kinds of electrolytes, Na2SO3 solution and Na2S2O3 solution, were used in the experiment. The influence of electrolyte and applied voltage on the structure and surface morphology of prepared TiO2 films has been evaluated. The critical voltage for film generation is 150 V in Na2SO3 solution and 100 V in Na2S2O3 solution. Under applied voltage of 250 V, the thickness of the TiO2 film is 15 μm for Na2SO3 electrolyte and 25 μm for Na2S2O3 electrolyte, respectively. The films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) later. Two main phases, anatase and rutile, are contained in the porous film. Detailed reaction mechanism of MAO process was discussed later, and it is concluded that TiO2 films are more easily prepared in Na2S2O3 solution due to sulfur deposition.