LY12铝合金表面钒–钛复合转化膜的制备与耐蚀性研究  

Preparation and corrosion resistance of vanadium–titanium composite conversion coating on LY12 aluminum alloy

作　　者：李海燕[1] 郭瑞光[1] 何蕾[1] 

机构地区：[1]西安建筑科技大学西北水资源与环境生态教育部重点实验室,陕西西安710055

出　　处：《电镀与涂饰》2015年第7期386-390,共5页Electroplating & Finishing

基　　金：国家自然科学基金项目(20976143);教育部高等学校博士学科点专项科研基金(20096120110007)

摘　　要：为解决单一钒酸盐转化膜表面因存在裂纹而耐蚀性不佳的问题,采用由硫酸氧钛(Ti OSO4)、偏钒酸钠(Na VO3)组成的转化液,在LY12铝合金表面制备出钒–钛复合转化膜。通过中性盐雾(NSS)测试讨论了Ti OSO4和Na VO3质量浓度、时间、温度、p H等工艺条件对转化膜耐蚀性的影响,并通过单因素试验得到了最佳转化条件:Ti OSO4 0.5 g/L,Na VO3 0.4 g/L,p H 4.0,温度25°C,转化时间10 min。用扫描电镜和能谱分析了转化膜的表面形貌及元素组成。结果表明,由O、Ti、V、Al、Mg等元素组成的钒–钛复合转化膜无裂纹。LY12铝合金经转化处理后,在3.5%Na Cl溶液中的腐蚀电位较转化前正移56 m V,腐蚀电流密度减小约1/5,耐盐雾时间达到91 h,耐蚀性得到显著提高。Aiming to solve the problem of poor corrosion resistance caused by cracks existing on the conversion coating from vanadate solution alone, a V–Ti composite conversion coating was prepared on LY12 Al alloy in a solution mainly consisting of titanyl sulfate（Ti OSO4） and sodium metavanadate（Na VO3）. The effects of conversion conditions such as mass concentrations of Ti OSO4 and Na VO3, temperature, p H, and reaction time on the corrosion resistance of conversion coating were discussed through neutral salt spray（NSS） test. The optimal conditions were determined by a single-factor experiment as follows： Ti OSO4 0.5 g/L, Na VO3 0.4 g/L, p H 4.0, temperature 25 °C, and time 10 min. The surface morphology and elemental composition of the conversion coating obtained thereby were analyzed by scanning electron microscopy and energy-disperse spectroscopy. The results showed that the V–Ti composite conversion coating is mainly composed of O, Ti, V, Al, and Mg, and free of cracks. The treated LY12 Al alloy has a positive shift of corrosion potential by 56 m V and a decrease of corrosion current density approximately by 1/5 as compared with the untreated one, and can endure 91 hours in NSS test, showing an improved corrosion resistance.

关 键 词：铝合金 转化膜 硫酸氧钛 偏钒酸钠 耐蚀性 

分 类 号：TG174.4[金属学及工艺—金属表面处理]