磷酸盐后处理对Mg-Gd-Y合金微弧氧化涂层耐蚀性能的影响  

Effect of Phosphate Post-treatment on Corrosion Resistance of Micro-arc Oxidation Coating on Mg-Gd-Y Alloy

作　　者：国泰榕 卢小鹏 李岩 张涛 王福会 GUO Tai-rong;LU Xiao-peng;LI Yan;ZHANG Tao;WANG Fu-hui(School of Materials Science and Engineering,Northeastern University,Shenyang 110819,China)

机构地区：[1]东北大学材料科学与工程学院,沈阳110819

出　　处：《表面技术》2021年第9期278-285,310,共9页Surface Technology

基　　金：国家自然科学基金(52071067)。

摘　　要：目的为进一步提高镁稀土合金微弧氧化涂层的耐蚀性能。方法首先在镁稀土合金表面制备了微弧氧化涂层,随后用磷酸盐后处理溶液,对Mg-Gd-Y合金硅酸盐微弧氧化涂层进行了封孔后处理,并在此过程中添加了缓蚀剂。利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对涂层表面形貌和成分进行分析,利用极化曲线和电化学阻抗(EIS)测试了涂层的耐蚀性能。结果后处理能够在微弧氧化涂层表面形成MgHPO_(4)沉积层,沉积层的产生有效地封闭了微弧氧化涂层表面的微孔、裂纹等缺陷。缓蚀剂的添加显著增加了沉积物的量,使涂层的磷元素原子数分数由5.37%增加至14.90%,沉积效果显著。极化实验证明,封孔后处理涂层的腐蚀电流密度由1.51×10^(-7)A/cm^(2)降至4.91×10^(-8)A/cm^(2),负载缓蚀剂后,涂层的腐蚀电流密度进一步降低至5.76×10^(-9)A/cm^(2),表明其耐蚀性能显著提高。微弧氧化涂层在3.5%NaCl溶液中浸泡384 h后,含缓蚀剂的涂层的总阻抗值可达7825.3Ω·cm^(2),明显高于未封孔处理的微弧氧化涂层(403Ω·cm^(2)),这证明,后处理可有效提高微弧氧化涂层的耐蚀性能。结论磷酸盐后处理能够在微弧氧化涂层表面生成MgHPO_(4)沉积层,有效地对微弧氧化涂层表面的微孔和微裂纹进行了封闭。缓蚀剂的添加能够显著增强磷酸盐的沉积效果,使涂层的耐蚀性能在后处理的基础上进一步提高。To improve the corrosion resistance of Mg-RE alloy,micro-arc oxidation coating was formed on the surface of the Mg-RE alloy.The Mg-Gd-Y alloy silicate microarc oxide coating was subsequently post-treated with a phosphate post-treatment solution to seal the holes,and the corrosion inhibitor was added in the process.Scanning electron microscope(SEM)and X-ray diffractometer(XRD)were used to analyze the surface morphology and composition of the coating.The polarization curve and electrochemical impedance spectroscopy(EIS)were used to test the corrosion resistance of the coating.Post-treatment can form a MgHPO_(4) deposition layer on the surface of the micro-arc oxidation coating.The generation of the deposition layer effectively sealed the micro-holes,cracks and other defects on the surface of the micro-arc oxidation coating.The addition of corrosion inhibitors significantly increased the amount of deposits,which increased the phosphorus content of the coating from 5.37%to 14.90%,which significantly enhanced the deposition.The polarization experiment shows that the corrosion current density of the coating after post-treatment decreased from 1.51×10^(-7)A/cm^(2)to 4.91×10^(-8)A/cm^(2).The corrosion current density is further reduced to 5.76×10^(-9)A/cm^(2)after loading the corrosion inhibitor,indicating that the corrosion resistance is significantly improved.After the coating is soaked in 3.5 wt.%NaCl solution for 384 hours,the total impedance of the post-treatment coating loaded with corrosion inhibitor can reach to 7825.3Ω·cm^(2),which is significantly higher than the 403Ω·cm^(2)of the micro-arc oxidation coating.It can effectively improve the corrosion resistance of the micro-arc oxidation coating.Furthermore,when the high efficiency corrosion inhibitor SDS was added,the resistance increased tenfold.The resistance of the sealed MAO coating with inhibitor increased from 0~48 h,which is related to the release of the inhibitor.The gradual release of the inhibitor guarantees a long-time corrosion resistance of t

关 键 词：镁稀土合金 微弧氧化 磷酸盐后处理 缓蚀剂 耐蚀性能 

分 类 号：TG174.4[金属学及工艺—金属表面处理]