Porous titanium dioxide coatings obtained by anodic oxidation for photocatalytic applications

H.D. TRAID; M.L. VERA; A.E. ARES; M.I. LITTER

Congreso; 15º Congreso Internacional de Metalurgia y Materiales, CONAMET-SAM-2015; 2015

The aim of this work is to obtain porous titanium dioxide with good efficiency for photocatalytic environmental applications.TiO2 coatings were obtained by anodic spark deposition, at constant applied potential (150 V), using a platinum cathode and0.5 M sulfuric acid as electrolyte. Samples of titanium Grade 2 were used as substrate, metallographically prepared until 1 μmdiamond surface finishing. The variables of the process were temperature (25 and 40 °C) and anodization time (5 and 10 min).Samples obtained at 40 °C showed a higher current density than those obtained at 25 °C and the potential reached by thesesamples was lower than those obtained at 25 °C. These results are attributed to an increased electrolyte conductivity. Opticalmicroscopy images of the oxides obtained at 40 ºC showed heterogeneity in color, indicating a non-uniform oxide thickness. Thiscoincides with the images obtained by scanning electron microscopy that revealed "valleys" where the material did not presentporosity. On the other hand, the oxides obtained at 25 °C showed a complete homogeneous porous structure. The average porediameter was reduced with the increased oxidation time and temperature of the electrolyte. An increase of the crystalline anatasephase was observed with an increase of the anodization time; besides, rutile formation was observed, probably due to the finalpotential achieved by the samples