Avaliação de aço ABNT 1020 em meio salino utilizando inibidor natural de corrosão

Abstract

Pipelines and their accessories, equipments, such as centrifugal pumps, among other types of devices that carry multiphase fluids (oil, water, gas and solid particulates) can suffer mechanical and corrosive damage. To monitor and prevent against these types of damage corrosion coupons and inhibitors are widely used in various industry sectors. In this sense it is proposed a scientific investigation that consolidates a thesis focused on the development of new corrosion inhibitors and on a new method to investigate the tribocorrosive wear of a mild steel in saline aqueous medium. Thus, a corrosive cell was used for gravimetric measurements, evaluation of the tribocorrosive wear of ABNT 1020 steel coupons, and to study the efficiency of natural corrosion inhibitors, which were also characterized by physicochemical and electrochemical techniques. The mechanisms of damage to the surface and subsurface of the corrosion coupons due to corrosion and corrosion-erosion synergism were investigated, mapped and characterized. By analyzing the polarization curves for the 0.4 ppm concentration of the inhibitors, the following inhibition efficiencies were obtained: microemulsion system saline (87.06%), hydroalcoholic extract of Bixa Orellana L. (67.79%), and the microemulsion system with the solubilized extract (78.25%). In the wettability of the ABNT 1020 carbon steel surface when in contact with the saline solution (1% NaCl), and with the inhibitors in various concentrations, varying the time, they had contact angles of less than 90°. The comparison with 95% of statistical certainty, using the Fisher LSD method, showed that a cylindrical body submitted in the conditions of the proposed tests presented differentiated superficial and subsurface damages and that such damages could be perceived through microhardness, roughness and waviness.