Corrosion Behavior of Brass Alloys in Aqueous Solutions of Different pH

Abstract Corrosion and passivation behaviors of three brass alloys, including selective leaching of the alloys in acidic, neutral, and basic solutions, were investigated in aqueous solutions of different pH. Open-circuit potential measurements, polarization data, and electrochemical impedance spectroscopy (EIS) were used to obtain the corrosion current density, corrosion potential, and corrosion resistance of each alloy. Results, especially for open-circuit potential behavior, were compared to those of the pure alloy constituents (i.e., copper, lead, and zinc). In aqueous solutions, the alloy surface was covered by a passive Cu(I) film, which was responsible for the passive behavior of the surface. The stability of such a passive film was dependent upon the solution pH and was affected by alloy composition. The presence of oxygen (O2) or oxidizers such as dichromate (Cr2O72−) in the solution or the increased ratio of active component in the alloy enhanced the disproportionation reactions, which led to bre...