Desenvolvimento de filmes finos de TiO2, TiO2/RGO e TiO2/RGO/Nb2O5 depositados em aço AISI 304 para aplicação como revestimentos anticorrosivos

Abstract

Promising strategies in the search for adequacy of methods to mitigate corrosion may involve physical barrier protection, using coatings and paints, and electrochemical protection, through cathodic or anodic protection, however, it is still necessary to develop methods with low cost and environmental impact. Photocathodic protection presents itself as a hybrid method of physical barrier and cathodic protection, as it uses coatings formed by semiconductors that can absorb light and polarizing the surface, and these coatings also become a physical barrier of protection. In this work, thin films of titanium dioxide (TiO2) were prepared and combined with reduced graphene oxide (RGO) and niobium pentoxide (Nb2O5) to produce anticorrosive coatings for AISI 304 steel. composition, structure, morphology by X-ray diffraction (XRD), transmission electron microscopy (TEM and HRTEM), atomic force microscopy (AFM) and electrochemical properties were analyzed by open circuit potential (OCP), Tafel extrapolation and electrochemical impedance spectroscopy (EIS). In an attempt to change the radiation absorption region of TiO2 to low wavelengths, thin films of TiO2 with GO were prepared, in which the samples coated with thin film TiO2/GO calcined at 400ºC with 3 layers, showed a significant increase in roughness, a uniform deposition along the surface and greater resistance to corrosion compared to AISI 304 steel. As for the samples containing Nb2O5, it showed an increase in the value of corrosion resistance, but not significantly. However, this study was carried out in order to evaluate the use of thin films as photocathodes. It was observed that all films showed resistance to corrosion even under visible light, and that the compositions, structural, morphological and electrochemical properties were different, depending on the number of deposited layers, amount of different phases present and the intrinsic properties of TiO2, GO and Nb2O5.