镁合金表面新型高耐蚀性植酸化学转化膜的制备  

Preparation of New Phytic Acid Chemical Conversion Coating with Excellent Corrosion Resistance on Magnesium Alloys

作　　者：曾纪勇 郭兴伍[1,2] 郭嘉成 聂乐文 弓磊超 彭立明 丁文江[1,2] ZENG Ji-yong;GUO Xing-wu;GUO Jia-cheng;NIE Le-wen;GONG Lei-chao;PENG Li-ming;DING Wen-jiang(National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composites,School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Shanghai Innovation Institute for Materials,Shanghai 200240,China)

机构地区：[1]上海交通大学,材料科学与工程学院轻合金精密成型国家工程研究中心和金属基复合材料国家重点实验室,上海200240 [2]上海材料创新研究院,上海200240

出　　处：《表面技术》2019年第10期230-237,共8页Surface Technology

基　　金：国家重点研发计划(2016YFB0301005);高等学校学科创新引智计划(B16032)~~

摘　　要：目的提高镁合金的耐蚀性能。方法通过在单一植酸转化膜基础上,利用植酸的强络合作用,在反应溶液中引入金属离子,获得新型高耐蚀性植酸转化膜层。通过正交实验、SEM、EDS和电化学方法,对新型植酸转化膜层的工艺配方、微观形貌、元素组成和耐蚀性进行分析。结果正交试验研究得到了新型植酸转化膜层的最佳工艺参数为:25 g/L Mn(H2PO4)2+10 g/L植酸,反应温度95℃,反应时间10 min。在此工艺下,得到的膜层均匀,和未添加Mn离子的膜层相比,裂纹明显减小。EDS结果表明,膜层的主要元素为Mg、P、O、Mn、C,转化膜的成分可能是锰、镁与植酸形成的络合物。动电位极化曲线的实验结果表明,新型植酸转化膜可以极大地降低镁合金的腐蚀电流密度(Jcorr=0.337μA/cm2),对镁合金的保护效率为96.37%。结论通过在植酸转化膜中添加Mn元素,不仅可以减小植酸膜层的裂纹宽度,还可以极大地提高镁合金的耐蚀性。The work aims to improve the corrosion resistance of magnesium alloy.A new type of phytic acid chemical conversion coating with high corrosion resistance was obtained based on single phytic acid chemical conversion coatings by introducing metal ions into the reaction solution through the strong interaction of phytic acid.The process formula,microstructure,elemental composition and corrosion resistance of the new coating were analyzed by orthogonal experiment,SEM,EDS and electrochemical method.The optimal process parameters of the new phytic acid conversion coating obtained through orthogonal experiment included 25 g/L of Mn(H2PO4)2,10 g/L of phytic acid,reaction temperature of 95℃and reaction time of 10 min.The phytic acid coating prepared by the optimal process had a uniform surface and contained fewer cracks,compared with the coating without Mn ions.The EDS results showed that the main elements of the coating were Mg,P,O,Mn,and C.The composition was a complex of manganese and magnesium phytate.The results of the potentiodynamic polarization curves showed that the new coating could greatly reduce the self-corrosion current density(Jcorr=0.337μA/cm2)of the magnesium alloy,and the protection efficiency for the magnesium alloy was 96.37%.Adding Mn into the phytic acid conversion coating cannot only reduce the width of the phytic acid coating cracks,but also greatly improve the corrosion resistance of magnesium alloy.

关 键 词：镁合金 植酸 化学转化膜 正交试验 耐腐蚀性能 

分 类 号：TG174.4[金属学及工艺—金属表面处理]