Desenvolvimento de revestimentos de óxidos mistos nanoestruturados de TiO2/Al2O3 em substratos metálicos de aço AISI 1020 e estudo das propriedades anticorrosivas

Abstract

Precursors lyophilized sols Al2O3/TiO2were prepared by sol-gel technology, with different percentages of titanium oxide (5%, 10%, 15%, 20%, mass). The lyophilized sols were characterized through several analyzes in order to obtain information about the thermal behavior, phases present, size particle composition and samples uniformity. The results indicate that the sols presents boehmite and anatase phases, nanometric particle size, very similar compositions when analysed in distinguish/distinct points, dispersed atoms and equally distributed. After this stage, AISI 1020 samples were covered with these sols through dip coating method. The corrosive behavior was studied by electrochemical tests and the morphology of the layers analyzed at the microscopy. It was observed that the layers were uniform and covered completely all the samples surface, the electrochemical polarization tests showed improvements of the electrochemical potential for the coated samples when compared to the uncoated steel samples. The monitoring of the open circuit showed good adjustments, indicating the layer s good behaviour. It was noted through microscopy the presence of corrosion points in some samples before the trials, which leads the suspicion that the results would be better, if there was a greater control of the coating process.