成膜时间对镁合金表面Ce-Mn转化膜组织及耐蚀性的影响  

Influence of processing time on microstructure and corrosion resistance of Ce-Mn conversion coating on magnesium alloy

作　　者：杜军[1] 盘艳红[1] 李文芳[1] 穆松林[1] 黄筑艳[2] 

机构地区：[1]华南理工大学材料科学与工程学院,广东广州510640 [2]贵州大学化学与化工学院,贵州贵阳550003

出　　处：《功能材料》2012年第17期2273-2277,共5页Journal of Functional Materials

基　　金：粤港关键领域重点突破(佛山专项)专项基金资助项目(2008Z012);广东省重大科技专项(产业共性技术)基金资助项目(2009A08025002)

摘　　要：以四硼酸钠为添加剂,Ce(NO3)3-KMnO4为主要成膜剂,室温下在AZ91镁合金表面制备了Ce-Mn转化膜。基于优化的成膜剂浓度比,主要研究了成膜时间对膜层组织和耐蚀性的影响。结果表明转化膜层主要由O、Mg、Al、Mn、Ce等元素组成,随成膜时间延长,膜层不断增厚,且产生裂纹甚至膜层剥落。Ce(NO3)3/KMnO4浓度比较低时成膜速率较慢,膜层中Ce/Mn原子较小,但膜层的电化学性能较优。开路电位随成膜时间延长呈现先急剧增大,后缓慢增加并在2min后趋于平稳的趋势。室温下处理2min即可获得组织致密且耐腐蚀性能较好的转化膜,与基体相比,经配方A和B成膜后的试样,其自腐蚀电流密度由34.099μA/cm2分别下降到0.822和1.367μA/cm2,电阻由0.64kΩ.cm2分别增大到32.01和20.96kΩ.cm2。Using sodium borate as additive,Ce-Mn chemical conversion coating was prepared on the surface of AZ91 magnesium alloy in Ce（NO3）3 and KMnO4 solution at room temperature.Based on the optimized concentration ratio of Ce（NO3）3/KMnO4,the influence of processing time on the morphology,composition and corrosion resistance was analyzed.The results show that Ce-Mn chemical conversion coating is mainly composed of O,Mg,Al,Mn and Ce elements.With extending processing time,the thickness of Ce-Mn chemical conversion coating was increased,but cracks in the coating appear and the coating even peels off.When the concentration ratio of Ce（NO3）3/KMnO4 was low,the forming rate and the atomic ratio of Ce/Mn of the coating was low while the corrosion resistance was better.The open circuit potential increases sharply during the first minute,and then gradually approaches a constant value.After 2min,it almost maintains steady.The best compact and corrosion resistant coating can be obtained when treating specimens for 2min.Compared with magnesium matrix,the corrosion current density of samples A and B after treating was decrease from 34.099 to 0.822 and 1.367μA/cm2,and the electric resistance was increase from 0.64 to 32.01 and 20.96kΩ·cm2,respectively.

关 键 词：镁合金 Ce-Mn转化膜 成膜时间 耐蚀性 

分 类 号：TG174.45[金属学及工艺—金属表面处理]