7075铝合金在不同pH值NaCl溶液中的腐蚀行为

用Tafel曲线和电化学阻抗谱(EIS)研究7075铝合金在不同pH值(pH=3、5、7、9、11) 的0.6 mol/L NaCl溶液中的腐蚀行为.结果表明，溶液pH值在3~7时，腐蚀电位正移，pH值在7~11时，腐蚀电位负移，pH值为11时腐蚀电位最负. pH值在3~11时，腐蚀速度呈现先降低后增大的过程，pH值为11时腐蚀速度最大，达到2.122 2 mm/a.在强酸溶液中，电化学阻抗谱中出现明显的感抗弧，表明存在不均匀点蚀现象. pH值为7和9时，电化学阻抗谱中只出现1个容抗弧，表明铝合金腐蚀属于金属基体溶解过程. pH值为11时，阻抗谱中出现2个容抗弧，表明铝合金腐蚀伴随铝合金的自溶解行为. 

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.