Resistência à corrosão em meio aquoso ácido da liga de elemento multiprincipal Cr40Co30Ni30

Abstract

In this study, the corrosion resistance of the Cr40Co30Ni30 multi-principal element alloy was evaluated using electrochemical tests in aqueous solutions of 0.1 mol/L hydrochloric acid, 0.1 mol/L sulfuric acid, and a third aqueous solution of 0.1 mol/L lactic acid, aiming to simulate an acidic environment, in both as-cast and homogenized conditions (at 1100 ºC for 2 hours air-cooled). All homogenized samples exhibited a decrease in polarization resistance compared to the as-cast condition in their respective environments. The homogenized sample in sulfuric acid solution showed the lowest polarization resistance value, while the as-cast sample in lactic acid solution presented the highest polarization resistance value. The alloy demonstrated greater corrosion resistance in the lactic acid aqueous solution. Both as-cast and homogenized microstructures exhibited the same transpassivation potential in each medium; however, the passive current densities were lower for the as-cast microstructure, indicating higher corrosion resistance. The potentiodynamic polarization test results align with those of electrochemical impedance spectroscopy, as the as-cast samples showed higher polarization resistance values and lower corrosion current values, indicating greater corrosion resistance compared to the homogenized samples in each studied medium.