Corrosion mitigation of AA6082, Copper-ETP, and their galvanic couple using Ce(OAc)3, Na2SO4, and 1H-BTA in chloride solution

Galvanic coupling between aluminium alloy AA6082 and copper (Cu-ETP) accelerates corrosion through anodic dissolution of aluminium, posing serious durability challenges for mixed-metal structures. This study investigates the inhibition mechanisms of cerium acetate (Ce(OAc) 3 ), sodium sulphate (Na 2 SO 4 ), and 1H-benzotriazole (1H-BTA), individually and in combination, on AA6082, Cu-ETP, and their galvanic couple in 0.1 M NaCl solution. The inhibitors’ performance was evaluated using potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and salt spray testing. Ce(OAc) 3 and Na 2 SO 4 promoted the formation of cerium oxide films on AA6082, while 1H-BTA adsorbed on Cu-ETP, forming a compact film that suppressed anodic dissolution and cathodic oxygen reduction. The combined inhibitor system, compared to the uninhibited system, significantly reduced galvanic corrosion current by a factor ∼4.5 (2.6 μA/cm 2 vs. 11.8 μA/cm 2 ) and enhanced pitting resistance by shifting the pitting potential of AA6082 to more noble values. Furthermore, EIS results confirmed the improved stability of the passive films on Cu-ETP after 72 hours of immersion in inhibitor mixture (∣Z 0.01 Hz ∣ = 4.4 MΩ cm 2 ). SEM and salt spray results showed reduced corrosion and uniform protective deposits, with treated AA6082 retaining over 90% of its orignal volume after 42 days of exposure. This work demonstrates a synergistic inhibition strategy combining cerium salts and organic molecules to protect aluminium–copper assemblies in aggressive environments.