Characterization of the Corrosion Mechanism of Cu/Al Clad Plates in Simulated Acid Rain Solution

Cu/Al clad plates are widely used in the aerospace, electric power, metallurgical and chemical industries and for architectural decoration. Understanding the corrosion behavior of Cu/Al clad plates is of vital importance to effectively avoid catastrophic failures due to acid rain. The impact of H+ on the corrosion behavior of Cu/Al clad plates was studied. The corrosion mechanism of Cu/Al clad plates was dominated by both chemical corrosion and electrochemical corrosion, which was influenced by the pH values of the acid solution and the types of anions. The corrosion current density decreased from 0.51 mu A cm-2 to 0.02 mu A cm-2 as the pH increased, while Rct increased from 6.5 x 103 +/- 1.3 x 103 ohm cm2 to 1.3 x 104 +/- 8.8 x 103 ohm cm2, indicating that the corrosion rate decreased as well. Furthermore, numerous copper ions were replaced by Cu particles due to chemical corrosion. The Cu particles (the cathode) covered the aluminum, which formed countless microgalvanic cells with aluminum (the anode) to accelerate the corrosion rate.