镁合金表面微弧氧化/自组装复合膜的耐蚀性能  

Corrosion Resistance of Micro-arc Oxidation/Self-assembled Composite Coating on Magnesium Alloy

作　　者：蒋世权 吴方 王媛媛 尚伟 温玉清 JIANG Shi-quan;WU Fang;WANG Yuan-yuan;SHANG Wei;WEN Yu-qing(Guangxi Key Laboratory of Electrochemical and Magnetochemical Function Materials,School of Chemical and Biological Engineering,Guilin University of Technology,Guilin 541004,China)

机构地区：[1]桂林理工大学化学与生物工程学院广西电磁化学功能物质重点实验室,广西桂林541004

出　　处：《表面技术》2021年第4期294-303,共10页Surface Technology

基　　金：国家自然科学基金(51664011);桂林理工大学博士科研启动基金(GUT2001018)。

摘　　要：目的提高镁合金基体的耐蚀性能。方法采用微弧氧化工艺对镁合金进行预处理,再通过自组装技术处理,在镁合金表面制备微弧氧化/十六烷基三甲氧基硅烷自组装复合膜层。通过SEM、EDS对复合膜的微观组织结构进行分析,并通过XPS、拉曼光谱分析了复合膜的表面成分,利用电化学阻抗谱、极化曲线、盐雾实验和浸泡实验检测了复合膜层的耐腐蚀性能。结果复合膜均匀覆盖在镁合金表面,且复合膜较为光滑,主要含有C、O、F、Si等元素。经过自组装处理后,膜层从亲水性转为疏水性,接触角达到145.07°。经电化学性能测试,复合膜的Rct值能达到2.242×106Ω·cm^(2),与微弧氧化膜相比,增大了2个数量级;此外,复合膜的腐蚀电流密度为1.314×10-8 A/cm^(2),与微弧氧化膜相比也降低了2个数量级,具有较好的耐腐蚀性。浸泡120 h后,复合膜的腐蚀电流密度仍有1.061×10^(-5) A/cm^(2),盐雾实验进行120 h也没有出现明显的腐蚀现象。结论自组装技术明显提高了镁合金基体的耐蚀性能,微弧氧化膜在一定程度上增强了自组装膜层对基材的粘附力。由于复合膜的疏水性使得水滴在膜层表面停留的时间减少,所以膜层的耐蚀性会随着疏水性增大而大大提高。The purpose is to increase the corrosion resistance of magnesium alloy.First,magnesium alloy is pretreatment by micro-arc oxidation craftsmanship,and micro-arc oxidation/hexadecyltrimethoxysilane self-assembled composite coating is drawn up on surface of magnesium alloy by self-assembly machinery.The micro-structure and construction of the composite coating are analyzed by SEM and EDS,and the surface composition of composite coating spectroscopy is analyzed by XPS and Raman.Magnesium alloy composite coating is detected by electrochemical impedance spectroscopy,polarization curve,salt spray test and immersion test corrosion resistance of the coating.The composite coating even provides for the surface of magnesium alloy,and the surface of composite coating is relatively smooth.The composite coating main contains C,O,F,Si and other elements.After self-assembly,the coating changes from hydrophilic to hydrophobic,and the contact angle reaches 145.07°.According to the electrochemical performance evaluation,the composite coating has excellent corrosion resistance,and its Rct value can reach 2.242×106Ω·cm^(2),which is to improve by 2 orders of magnitude based on micro-arc oxidation coating;In contrast,the corrosion current density of composite coating is 1.314×10-8 A/cm^(2),which is 2 orders of magnitude discounted than that of the micro-arc oxide film.After immersion for 120 h,the corrosion current of the composite coating is still 1.061×10^(-5) A/cm^(2).There is no obvious corrosion phenomenon after salt spray test for 120 h.Self-assembly technology obviously improves the corrosion resistance of magnesium alloy substrate.The micro-arc oxidation coating also enhances the adhesion of self-assembly coating to magnesium alloy substrate to a certain extent.Because of the hydrophobicity of composite coating,the time that water droplets stay on the surface of the coating is lowered,so it will enormously develop the corrosion protection of the film as the hydrophobicity increases.

关 键 词：镁合金 微弧氧化 自组装 耐蚀性 疏水性 复合膜层 

分 类 号：TG174.4[金属学及工艺—金属表面处理]