Corrosion behavior of brass alloys in aqueous solutions of different pH

Corrosion and passivation behaviors of three brass alloys, including select ive leaching of the alloys in acidic, neutral, and basic solutions, were in vestigated in aqueous solutions of different prl, Open-circuit potential me asurements, 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-circ uit potential behavior, were compared to those of the pure alloy constituen ts (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 (O-2) or oxidizers such as dichromate (Cr2O72-) in the solution or the increased ratio of active component in the alloy enhanced the dispropor tionation reactions, which led to breakdown of the passive film. X-ray phot oelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were us ed to explain and to confirm polarization and EIS results. A mechanism for the reactions taking place at the electrode/electrolyte interface was sugge sted.