铝合金剥蚀过程的电化学阻抗谱分析

ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY OF Al ALLOYS DURING EXFOLIATION CORROSION

研究了轧制态及峰时效 80 90铝 -锂合金、拉应力作用下及无应力作用时双级过时效 70 75铝合金的剥蚀发展过程 ,测量并拟合了合金发生剥蚀后的电化学阻抗谱 .结果表明 :发生剥蚀后 ,合金电化学阻抗谱由高—中频和中—低频容抗弧组成 ;可从电化学阻抗谱的拟合参数 (变化趋势 )得到剥蚀的相关信息 ,如剥蚀发展速度、剥蚀形貌、剥蚀表层是否脱落等 .

The exfoliation development of 8090 Al-Li alloy and 7075 Al alloy was studied.The electrochemical impedance spectroscopy (EIS) of these alloys in EXCO solution was measured and simulated.At the beginning of immersion,the EIS is comprised by a capacitive arc at high-mediate frequency and an inductive arc at mediate-low frequency.Once exfoliation occurs,two capacitive arcs appear at high-mediate frequency and mediate-low frequency respectively.Some information about exfoliation,such as exfoliation development rate and exfoliation morphology,can be obtained through the simulated EIS data.