Estudo de inibidores comerciais e corrosão para o aumento da vida útil de materiais metálicos

Abstract

Corrosion is a spontaneous process resulting from the interaction of the medium with the metal surface that can sometimes cause equipment deterioration, thus reducing the life of these materials and generating extra costs of maintenance and repairs. Thus, the present work evaluated the performance of the commercial inhibitor AZ 8101® from GE Water & Process Technologies, which is used to combat the corrosion of copper and its alloys. Some techniques were used to evaluate the corrosion rate: weight loss, linear polarization and electrochemical impedance. In order to simulate cooling water, water from the supply network was added with addition of sodium chloride at concentrations of 250 and 500 ppm in addition to concentrations of 5, 10 and 25 ppm of inhibitor. The results were satisfactory for all concentrations evaluated, reaching inhibition efficiencies above 90% for the two media evaluated, both in the polarization assays and in the impedance assays. Weight loss tests for the medium of 250 ppm of Cl- had duration of 28 days, however, only the samples immersed in the medium without inhibitor showed mass variation. For the medium of 500ppm Cl- were performed for 15 days, but no significant mass variation was found in any of the media evaluated. As for the analysis of the adsorption mechanism, the best approximation was for the Langmuir isotherm. In addition, the best performance sample for the 500 ppm NaCl medium, with a concentration of 5 ppm of inhibitor, was submitted to Scanning Electron Microscopy (SEM) and Dispersive Energy Spectroscopy (EDS) in order to evaluate the microstructural characteristics and the composition of the corrosion products, the result was consistent with the other tests presented, showing that the medium without inhibitor showed evident signs of corrosion with the formation of CuCl, CuO and Cu2O.