CORROSION OF COMMERCIALLY PURE AL-99.5 IN CHLORIDE SOLUTIONS CONTAINING CARBON-DIOXIDE, BICARBONATE, AND COPPER IONS

The corrosion behavior of aluminum in solutions containing chloride (C l-), carbon dioxide (CO2), bicarbonate (HCO3-), and copper ions (Cu2+) at various concentrations and temperatures has been of frequent inter est in connection with applications in direct contact with a corrosive aqueous phase, such as in natural waters and produced brines. Availab le information about the combined effects of these species on aluminum is conflicting. A more systematic study uas undertaken using commerci ally pure aluminum (DIN Al 99.5 [AA 1050A]) as the test material. Corr osion tests performed in Cl- solutions containing these species indica ted that dissolved CO2-HCO3- combinations giving a neutral solution pN resulted in low corrosion rates for aluminum me added presence of sma ll Cu2+ concentrations could have been detrimental but did not produce a synergistic effect. High temperatures in general caused increased c orrosion rates, except near pH 9, where the cathodic intermetallic pha ses passivated. The observed corrosion behavior was explained in terms of cathodic polarization data for the aluminum matrix and the Al3Fe i ntermetallic particles.