The electrochemical measurement techniques of potentiodynamic polarization and AC impedance, combined with the observation on electrode surface micro-morphology, were applied to investigate the electrochemical behavior of 2024-T3 aluminum alloy in aqueous solutions with different acids (including acetic acid, sulfuric acid and hydrochloric acid) and different pH values.Results show that with the decrease of pH value, the self-corrosion potential shifts negatively, the self-corrosion current density and the corrosion rate increase, the passivation film covering on the electrode surface is more easily damaged, and the corrosive characteristic of the solution becomes stronger.Under different pH values, the reaction course of cathodic polarization is different.When pH value is the same, the corrosive characteristic of hydrochloric acid solution is the strongest, sulfuric acid aqueous solution is close but inferior, and acetic acid aqueous solution is the weakest.This is due to the different hydrolysis ability of the acid and the presence of the chloride in hydrochloric acid solution.Because of the existence of the passivation film, the electrochemical behavior of the electrode in different corrosive environment is various.The passivation film loses the stability and dissolves under the acidic condition, so the alloy matrix is exposed and contacts with the reaction solution directly.In the weak acidic solution, the passivation film can maintain relative integrity, and have a certain protective effect on the alloy substrate.%采用动电位极化和交流阻抗两种电化学测量技术,结合表面微观形貌观察,研究了2024-T3铝合金在不同种酸(包括乙酸、硫酸和盐酸)以及不同pH值水溶液中的电化学行为.结果表明:随pH值降低,合金自腐蚀电位负移,自腐蚀电流密度和腐蚀速率增大,合金表面钝化膜越易遭到破坏,溶液的腐蚀作用越强,且在不同pH值下,阴极极化过程的控制反应有所不同;在相同pH值下,以盐酸水溶液的腐蚀作用最强,硫酸水溶液相近但次之,乙酸水溶液最弱,这是酸的不同水解能力和氯离子的存在共同导致的;铝合金表面钝化膜的存在使得其在不同环境中的电化学行为表现不同,酸性条件下钝化膜失稳溶解,合金基体裸露并与溶液直接接触发生反应,而弱酸性条件下,钝化膜则能够保持相对完整性,对合金基体起到一定保护作用.
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