铬酸盐黄色-黑色氧化时间间隔对AZ91D膜层质量和耐蚀性的影响  

Effects of Chromate Yellow-black Oxidation Interval on Quality and Corrosion Resistance of AZ91D Film Layer

作　　者：朱伟明 芦刚 陈义斯 晏玉平 李勇 陈晓 严青松 ZHU Weiming;LU Gang;CHEN Yisi;YAN Yuping;LI Yong;CHEN Xiao;YAN Qingsong(National De fense Key Disciplines Laboratory of Light Alloy Processing Science and Technology,Nanchang Hangkong University,Nanchang 330063,China)

机构地区：[1]南昌航空大学轻合金加工科学与技术国防重点学科实验室,江西南昌330063

出　　处：《热加工工艺》2024年第2期114-120,共7页Hot Working Technology

基　　金：国家自然科学基金项目(51861027);南昌航空大学博士启动基金项目(EA202203058);南昌航空大学研究生创新专项资金项目(YC2021-018)。

摘　　要：为进一步优化铬酸盐转化膜层制备工艺,通过调控黄色氧化-黑色氧化时间间隔提升AZ91D镁合金的耐蚀性,系统研究了时间间隔为0、12、24 h合金样品的膜层微观形貌、物相组成、元素分布及其电化学特征,揭示了不同间隔时间后黑色氧化成膜行为及反应机理。结果表明,黑色氧化后AZ91D合金表面生成呈现网状微裂纹结构的微米级转化膜。时间间隔过短,基体析氢显著破坏了黑色氧化膜完整性,微裂纹尺寸较大,成膜厚度较薄;时间间隔过久,衬底氧化膜干燥充分,转化液难以附着,黑色膜层裂纹减少但表面粗糙,并沉积大量Mn3O4颗粒物。当间隔时间为12 h时,AZ91D合金表面膜层相对均匀致密;电化学测试显示,此时样品的耐蚀性最佳,相较于未处理镁合金,自腐蚀电流密度下降两个数量级,自腐蚀电位正移至-1.176 V,提升19.51%。In order to further optimize the preparation process of the chromate conversion coating,the corrosion resistance of AZ91D magnesium alloy was improved by adjusting the time interval between yellow oxidation and black oxidation.The film morphology,phase composition,element distribution and electrochemical characteristics of alloy samples with time intervals of 0 h,12 h and 24 h were systematically studied,and the black oxidation film-forming behavior and reaction mechanism after different time intervals were revealed.The results show that a micron scale conversion film with network microcrack structure is formed on the surface of AZ91D alloy after black oxidation.If the time interval is too short,the hydrogen evolution of the matrix significantly destroys the integrity of the black oxide film,the microcrack size is large,and the film thickness is relatively thin.However,the time interval is too long,the substrate oxide film is too dry to adhere the conversion solution.The black film cracks are reduced,but the surface is rough,and a large amount of Mn3O4 particles are deposited.When the interval time is 12 h,the surface coating of AZ91D alloy is relatively uniform and dense.The electrochemical test shows that the corrosion resistance of the sample is the best at this time.Compared with untreated magnesium alloy,the self-corrosion current density decreases by two orders of magnitude,and the self-corrosion potential is moving to-1.176 V,increased by 19.51%.

关 键 词：AZ91D镁合金 铬酸盐转化膜 时间间隔 耐蚀性 

分 类 号：TG174.4[金属学及工艺—金属表面处理]