磁致涡流效应对化成铝箔Al_2O_3-TiO_2复合膜结构及性能的影响

Effects of Magnetohydrodynamic on Structure and Performance of Al_2O_3-TiO_2 Composite Oxide Film for Formed Aluminum Foil

以TiCl_4为前驱体溶液,通过磁场辅助电沉积法在腐蚀箔表面形成具有高介电常数的Al_2O_3-TiO_2复合氧化膜。系统研究了磁致涡流效应(MHD效应,Magnetohydrodynamics)对电解液中离子扩散行为及Al_2O_3-TiO_2复合氧化膜结构与性能的影响规律。采用XRD能谱、扫描电镜SEM以及EDS能谱等手段对氧化膜晶相、表面/截面形貌以及Ti元素分布进行表征。结果表明,随着磁感应强度B的增强,电解液中Ti4+向箔面及蚀孔内的扩散速率增大,复合膜层中锐钛矿型TiO_2含量提高,且其在箔面及蚀孔内部分布均一性提升。另外,氧化膜阳极升压曲线、Tafel极化曲线及交流阻抗曲线的分析结果表明,MHD效应提高了复合氧化膜介电常数,减少了阳极氧化阶段的形成电量,对应的化成箔比电容增大至58.29μF/cm2,较之无MHD制备的Al_2O_3-TiO_2化成箔,其形成电量减少了24.6%,比电容增加了10.1%。

The Al2O3-TiO2 film with high dielectric constant was formed on etched foil surface with TiCl4 as precursor solution by introducing magnetic field into the electrodeposition process.The effect of magnetohydrodynamics(MHD) on the behavior of ion diffusion in electrolyte was studied in detail,as well as that on the structure and performance of Al2O3-TiO2 composite oxide film.The crystalline phase,surface/cross-section morphology and Ti-distribution of the samples were characterized by XRD,SEM and EDS.The results show that MHD effect increases the Ti^4+ diffusion rate in electrolyte,anatase TiO2 amount and its distribution uniformity on etched foil surface and tunnel.Additionally,from the analysis results of anodization-time curve,Tafel curve and electrochemical impedance spectra(EIS),the MHD effect also enlarges the relative dielectric constant of composite oxide film,reduces the forming power of anodizing process and raises its specific capacitance up to 58.29 μF/cm^2.Compared with the Al2O3-TiO2 formation foil without MHD,its forming power decreases by 24.6%,accompanying by 10.1% increment of specific capacitance.