NaCl溶液中Al-Li合金腐蚀过程的电化学特征

ELECTROCHEMICAL FEATURES OF THE CORROSION OF AN ALUMINUM-LITHIUM ALLOY IN 3.0% NaCl SOLUTION

采用电化学噪声技术,结合电化学阻抗谱及极化曲线测量,研究了峰时效AA2195-T8铝合金在3.0％NaCl溶液中的腐蚀电化学特征.结果表明,腐蚀初期,合金表面钝化膜上不断有孔核的形成与修复,并导致阻抗谱上感抗成分的存在.随腐蚀时间的延长,其感抗成分消失且阻抗模值降低.阳极极化时,由于其孔蚀电位与自腐蚀电位接近,钝化电位区间很小;随腐蚀时间的延长,极化电阻先增加而后减小,自腐蚀电流则呈相反趋势变化.

The electrochemical features of the corrosion of AA2195-T8 aluminum alloy in 3.0% NaCl solution were studied by electrochemical noise(EN) technique, electrochemical impendence spectroscopy(EIS) and potentiodynamic scanning(PDS). At the initial stage, the pitting cores are formed. and the passive film is repaired continuously, which results in the inductive component in the electrochemical impendence spectrum. With prolonging the immersion time, the inductive component is disappeared gradually, and the impendence module is decreased largely. The passive region is very small, due to the little difference between pitting corrosion potential (E-pit) and self-corrosion potential (E-corr,). The polarization resistance (R-p) is increased and then decreased as the immersion time is prolonged, the self-corrosion current is changed in the form of reverse tend.