Corrosion behavior of 7075 aluminum alloy in NaCl solutions with different pH values

Corrosion performance of 7075 aluminum alloy in 0.6 mol/L NaCl solutions with different pH values were investigated by Tafel curve and electrochemical impedance spectroscopy (EIS).The results reveal that corrosion potential shifts positively with pH value from 3 to 7, corrosion potential moves negatively with pH value from 7 to 11. The corrosion rate increases initially, and then decreases gradually with variation of pH value from3 to11.The corrosion rate is maximum when pH is 11, reaching 2.122 2 mm/a.The obvious inductance arc has arisen in strong acid solution, indicating discrete pitting corrosion.There is only one capacitive arc at pH 7 and 9, illustrating the corrosion is the dissolution process of metal substrate, but two at pH 11, illustrating that the corrosion is along with self-dissolution.