AZ31B镁合金表面钒/锆复合转化膜  

Preparation of Vanadium /Zirconium Composite Conversion Coating on AZ31B Mg Alloy and Evaluation of Its Corrosion Resistance

作　　者：韩强[1] 郭瑞光[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：《材料保护》2014年第5期4-7,共4页Materials Protection

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)资助

摘　　要：目前已有的镁合金无铬化学转化工艺都存在一些不足。通过单因素试验优选了由偏钒酸盐、氟锆酸盐组成的转化液及其成膜工艺条件,在AZ31B镁合金表面制备了无铬复合化学转化膜,并采用扫描电镜、能谱分析和电化学测试考察了转化膜的成分、结构及耐蚀性能。结果表明:最优工艺为2.0 g/L偏矾酸铵,2.0 g/L氟锆酸钾,pH值2.5,温度60℃,转化时间15 min;在此条件下获得了由70.54%Mg,1.88%Al,0.77%Zn,10.63%O,10.36%F,4.75%Zr和1.05%V元素组成的无定形结构转化膜;转化处理后腐蚀电位较基体正移了269 mV,腐蚀电流密度由基体的6.20×10-5A/cm2降低至7.28×10-6A/cm2,耐中性盐雾时间达80 h,使镁合金的耐蚀性能显著增强。Single factor orthorgonal tests were conducted to optimize the composition and film-formation condition of the conversion solution consisting of metavanadate and fluozirconate. As-formulated conversion solution was adopted to prepare Cr-free V /Zr composite chemical conversion coating on AZ31 B Mg alloy surface. The composition,structure,and corrosion resistance of as-prepared V /Cr conversion coating were investigated by scanning electron microscopy,energy dispersive spectrometry,and electrochemical test. Results indicated that the conversion solution with the optimal composition consisted of 2. 0 g /L metavanadate and 2. 0 g /L fluozirconate,while the optimal conversion condition was suggested as pH =2. 5,temperature of 60 ℃,and conversion time of 15 min. The conversion coating obtained under the optimal conversion condition had amorphous structure and consisted of 70. 54% Mg(mass fraction; the same hereafter),1. 88% Al,0. 77% Zn,10. 63%O,10. 36% F,4. 75% Zr and 1. 05% V. Furthermore,the Mg alloy after conversion treatment exhibited greatly improved corrosion resistance. Its corrosion potential was positively shifted by269 mV and the corrosion current density declined from 6. 20 ×10- 5A /cm2 to 7. 28 × 10- 6A /cm2. Moreover,its endurance aganist neutral salt-spray was as much as 80 h.

关 键 词：偏钒酸盐 氟锆酸盐 转化膜 镁合金 耐蚀性 成分 结构 

分 类 号：TG174.44[金属学及工艺—金属表面处理]