镁合金微弧氧化膜在三种饱和盐溶液中的耐蚀性研究  

Study on Corrosion Resistance of Micro-arc Oxidation Modified Magnesium Alloy in Three Kinds of Saturated Salt Solutions

作　　者：安凌云 常成功[2,3] 康迪菘 王钊 孟雷超 彭建洪[1] AN Lingyun;CHANG Chenggong;KANG Disong;WANG Zhao;MENG Leichao;PENG Jianhong(Qinghai Provincial Key Laboratory of Nanomaterials and Technology,College of Physics and Electronic Information Engineering,Qinghai Minzu University,Xining 810007,China;Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources,Qinghai Institute of Salt Lake,Chinese Academy of Sciences,Xining 810008,China;Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province,Xining 810008,China)

机构地区：[1]青海民族大学物理与电子信息工程学院,青海省纳米材料与技术重点实验室,西宁810007 [2]中国科学院青海盐湖研究所,中国科学院盐湖资源综合高效重点实验室,西宁810008 [3]青海省盐湖资源化学重点实验室,西宁810008

出　　处：《材料导报》2023年第7期178-187,共10页Materials Reports

基　　金：青海省自然科学基金(2020-ZJ-966Q);青海民族大学高层次人才项目(2021XJG13);青海省“昆仑英才·高端创新创业人才”拔尖人才。

摘　　要：在硅酸盐体系中,在AZ31B镁合金上制备微弧氧化膜。通过TT260数字式涡流测厚仪测量膜层厚度,利用SEM、EDS、XRD和XPS检测膜层微观形貌、成分、物相组成和元素化学结合状态。应用循环伏安曲线、动电位极化曲线和电化学阻抗谱评价膜层在硫酸钠、氯化钠和碳酸氢钠三种饱和盐溶液中的耐蚀性能。结果表明,镁合金微弧氧化膜在不同饱和盐溶液中耐蚀性和腐蚀行为不同。在硫酸钠腐蚀介质中,SO_(4)^(2-)不与膜层物质反应,且其半径较大,穿透能力较弱,故膜层循环伏安曲线所围成的环面积最小,比氯化钠中的和碳酸氢钠中的分别小了二个和四个数量级,腐蚀电流密度为氯化钠中的41.6%,比碳酸氢钠中的低了四个数量级,且其阻抗模值也较高,呈现最佳的耐蚀性能。在氯化钠溶液中,由于Cl^(-)活性高、半径小、穿透力强,膜层耐蚀性较差,显现较强的点腐蚀特征。在碳酸氢钠介质中,因HCO_(3)^(-)和膜层物质反应,以及膜层的多孔特性,导致膜层耐蚀性最差。随浸泡时间延长,膜层在硫酸钠和氯化钠溶液中,耐蚀性呈现先增加后降低的趋势,而在碳酸氢钠中,先降低后波动。Micro-arc oxidation(MAO)coatings were prepared on AZ31B magnesium alloy in the silicate system.The thickness of the coatings was measured by the TT260 digital eddy current thickness gauge,and the microscopic morphology,element and phase compositions as well as elemental chemical bonding state of the coatings were measured by SEM,EDS,XRD and XPS.Cyclic voltammetry curve,potentiodynamic polarization curve and electrochemical impedance spectroscopy were applied to evaluate the corrosion resistance of the coatings in saturated sodium sulfate,sodium chloride and sodium bicarbonate corrosive media.The results shown that the corrosion resistance and corrosive behavior of the coatings are different in diverse saturated salt solutions.In sodium sulfate corrosive media,SO_(4)^(2-)ions can not react with the coating,and its ability of penetrating coating is also weaker ascribed to its larger radius.Therefore,the ring area enclosed by the cyclic voltammetry curve is the smallest,which is 2 and 4 orders of magnitude smaller than those of sodium chloride and sodium bicarbonate,respectively.The corrosion current density of the coating is 41.6%of that of saturated sodium chloride,and is 4 orders of magnitude lower compared to that of sodium bicarbonate.Meantime,its impedance modulus is also higher.Thus it presents the best corrosion resistance.In sodium chloride media,the corrosion resis-tance of the coating is poorer due to the high activity,small radius and strong penetrating power of Cl^(-)ions,and the coating exhibits the stronger pitting corrosion characteristics.In sodium bicarbonate solution,the coating possesses the worst corrosion resistance owing to the reaction of HCO_(3)^(-)with the coating and porous characteristics of the coating.With the immersion time prolonging,the corrosion resistance of the coating in saturated sodium sulfate and sodium chloride corrosive media increases first and then decreases,while in saturated sodium bicarbonate,the corrosion resistance first reduces and then fluctuates.

关 键 词：镁合金 微弧氧化 微观结构 饱和硫酸钠溶液 饱和氯化钠溶液 饱和碳酸氢钠溶液 耐蚀性 

分 类 号：TG174[金属学及工艺—金属表面处理]