Electrochemical studies on the corrosion inhibition of AA2024 aluminium alloy by rare earth ammonium nitrates in 3.5% NaCl solutions

The inhibitive effect of Ce(III) and Ce(IV) ammonium nitrate inhibitors on the corrosion behavior of aluminium alloy AA2024 in 3.5% NaCl solution has been investigated. Four different concentrations (102, 103, 104, and 105M) of the inhibitors were studied. Ce3+ and Ce4+ ions are introduced into the corrosive medium with similar anionic compositions (NH4)2Ce(NO3)5 and (NH4)2Ce(NO3)6. The inhibition efficiency (IE%) of the ions has been evaluated by using electrochemical methods linear voltammetry (LVA) and electrochemical impedance spectroscopy (EIS). Moreover, the inhibitive ability has been investigated at different duration after addition of these salts into the corrosive media. It is established that the pH of the solutions plays an important role on the inhibition process for both cations. The results revealed that at relatively similar conditions, the cerium (III) ions showed higher inhibition efficiency than cerium (IV) ions, when they were compared to the case without inhibitor.