Effect of Electrolyte Composition on Photocatalytic Activity and Corrosion Resistance of Micro-Arc Oxidation Coating on Pure Titanium

Micro-arc oxidation(MAO) coatings on pure titanium were prepared in sodium phosphate electrolyte, in sodium silicate electrolyte, in sodium aluminate electrolyte and in composite electrolyte (Na3PO4+Na2SiO3+NaAlO2 electrolyte), respectively. The surface morphologies and the phase composition of coatings were analyzed by means of SEM, XRD. A kind of typical textile industry pollutant (methylene blue) was used to evaluate the photo-catalytic activity of the films. The results show that MAO coatings prepared in the four electrolytes are rough and microporous, but the pores on the surface of the coating prepared in the sodium phosphate and composite electrolyte are smaller and more homogeneous than others.This surface may attract more reactants in photocatalytic degradation, The result of absorbance test shows that the photocatalytic activity of the coating formed in composite electrolyte is higher than that of the coating formed in the sodium silicate electrolyte and sodium aluminate electrolyte.in addition, The corrosion potential is also differents along with electrolyte solution change. The corrosion potential of the coating formed in composite electrolyte was improved greatly reach to –0.580 V, which provides a good protection method for the pure titanium.