摘要
为分析镁合金表面膜的活性位置,建立起镁负极的点蚀破坏与电化学特性的关联性,本文采用循环伏安和电化学阻抗技术研究了AZ镁合金在MgSO_4溶液中的点蚀行为,从电解质浓度、电位扫描速度、阴极极化角度探讨腐蚀膜对镁合金点蚀的影响。电化学阻抗谱由两个连续容抗弧构成,其电荷转移电阻和膜电阻均随MgSO_4溶液浓度增大而减小,当MgSO_4溶液浓度为1.5 mol/L时,AZ31B合金表面膜阻抗最低,容易发生点蚀。扫描速率从3.3 m V/s下降至0.17 m V/s时,AZ63合金点蚀滞后环面积先增加后减小,击穿电位负移。控制阴极极化起始电位负移,则击穿电位降低,滞后环的面积增加,AZ镁合金的点蚀倾向变大;而在阴极过电位下停留可降低表面膜的腐蚀破坏程度,有利于抑制镁合金点腐蚀的发展。
The cyclic voltammetry and the electrochemical impedance spectra were employed to study the pitting corrosion behavior of AZ Mg alloys in MgSO4 solution,and to analyze the active sites and build the relationship of the factor for film breakdown with electrochemical behavior.The types of electrolyte,potential scanning speed and cathodic polarization significantly influence the anodic corrosion film and the pitting corrosion behavior of AZ Mg alloys. The electrochemical impedance spectra of AZ Mg alloys were characterized by two capacitive loops.The charge chansfer resistance and film resistance decreased with increasing the concentration of magnesium sulfate.The film with low-resistances in MgSO4 concentration of 1. 5 mol / L might be more prone to coming about pitting corrosion.When the potential sweep rate decreased from 3. 3 m V / s to 0. 17 m V / s,the area of pitting hysteresis loop firstly increased and then decreased,and the breakdown potential（ Eb100） shifted to more negative values.When the cathodic polarization potential turned negative,Eb100 diminished,and the area of pitting hysteresis loop increased,signifying a bigger tendency for pitting corrosion occurrence.However,remaining at some cathodic overpotential would reduce the corrosion damage of the surface film,and inhibit the pitting corrosion growing of AZ Mg alloys.
作者
陈琳
龚有来
杨巧玲
陈昌国
CHEN Lin GONG You- lai YANG Qiao- ling CHEN Chang- guo(College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China College of Materials and Chemical Engineering,Sichuan University of Science and Engineering,Zigong 643000,China Material Corrosion and Protection Key Laboratory of Sichuan Province,Zigong 643000,China)
出处
《化学研究与应用》
CAS
CSCD
北大核心
2016年第11期1599-1604,共6页
Chemical Research and Application
基金
国家自然科学基金项目(21273292)
材料腐蚀与防护四川省重点实验室项目(2014CL12)
四川理工学院人才引进项目(2015RC58)
关键词
AZ镁合金
表面膜
点蚀
AZ magnesium alloy
surface film
pitting corrosion
