稀土对AZ91镁合金干/湿循环腐蚀产物及阻抗行为的影响  

Effect of Rare Earth on Corrosion Products and Impedance Behavior of AZ91 Magnesium Alloy Under Dry-wet Cycles

作　　者：赵曦[1,2] 贾瑞灵[1,2] 周伟光[1] 郭锋[1,2] 

机构地区：[1]内蒙古工业大学材料科学与工程学院,呼和浩特010051 [2]内蒙古自治区薄膜与涂层重点实验室,呼和浩特010051

出　　处：《材料工程》2017年第4期41-50,共10页Journal of Materials Engineering

基　　金：国家自然科学基金资助项目(51101082);内蒙古自治区自然科学基金资助项目(2016MS0538)

摘　　要：采用扫描电镜(SEM)、X射线衍射(XRD)、能谱分析(EDS)研究添加(La,Ce)混合稀土前后AZ91镁合金在融雪剂溶液中经历干/湿交替循环腐蚀后腐蚀产物的组成和结构。结果表明:未添加(La,Ce)混合稀土的AZ91镁合金的腐蚀产物主要由Mg(OH)_2,MgO,CaCO_3及Mg_6Al_2CO_3(OH)_(16)·4H_2O组成;而添加混合稀土的AZ91镁合金表面生成了(La,Ce)AlO_3等含稀土元素的腐蚀产物,同时腐蚀产物出现致密层。不同周期干/湿交替循环腐蚀的电化学阻抗谱(EIS)测试结果表明,添加(La,Ce)混合稀土的镁合金在相同腐蚀周期的阻抗谱幅值均高于AZ91镁合金的阻抗谱幅值,稀土的添加有助于降低阻抗谱的弥散效应,表明(La,Ce)混合稀土可以提高AZ91镁合金在干/湿交替腐蚀环境中的耐蚀性和腐蚀产物膜的稳定性。The effect of mischmetal of lanthanum and cerium on the composition and structure of the corrosion products on the surface of AZ91 Mg alloy in deicing salt solution under dry-wet cycles was investigated by scanning electron microscopy(SEM),X-ray diffraction(XRD)and energy dispersive spectrometer(EDS).The results show that the corrosion products of AZ91 Mg alloy without mischmetal addition(La,Ce)are mainly composed of Mg(OH)_2,MgO,CaCO_3 and Mg_6Al_2CO_3(OH)_(16)·4H_2O;and(La,Ce)AlO_3 can be found in the products of AZ91 with mischmetal addition,meanwhile dense layer occurs in the corrosion products.Electrochemical impedance spectroscopy(EIS)measurements show that the charge transfer resistance of AZ91 alloy with mischmetal addition tested in the same dry-wet cycles is much higher than that of AZ91 alloy,the addition of mischmetal helps to reduce the dispersing effect of impedance spectroscopy,indicating that the corrosion resistance of AZ91 Mg alloy and the stability of corrosion product films can be improved by mischmetal of La and Ce.

关 键 词：AZ91镁合金 稀土 腐蚀 干/湿交替 电化学阻抗 

分 类 号：TG172.5[金属学及工艺—金属表面处理]