Real-time lmaging for Initiation of Localized Interfacial Reaction

传统上，由于缺乏研究反应的引发过程的方法，诸如局部腐蚀的局部界面反应的机理和动力学尚未如此清楚。发展了一种能够实时研究局部电化学界面反应引起的表面形貌和产物变化的微观电化学方法，并尝试将其应用于分析局部腐蚀的起始过程。采用零型椭偏仪和CCD摄像显微成像相结合的椭偏显微镜观察了硫酸阳极氧化钛表面，成功地揭示了氧化膜随基体的各向异性生长以及氧化膜在溴离子溶液中的局部降解。在此基础上，发展了一种微毛细管池技术，并将其应用于铁在硫酸溶液中的动、静态极化和电化学阻抗谱研究。结果表明，钝化膜的稳定性和表面的钝化程度与基体的晶向密切相关。微电化学与光学显微镜相结合，可能为研究表面微结构尺度不均匀性引起的局部界面反应的引发带来新的契机。

Conventionally, mechanism and kinetics of localized interfacial reaction such as local corrosion have not been so cleared because of a lack of methods to investigate an initiation process of the reaction. A state-of-art micro-electrochemical method, which enables to investigate real-time changes in surface morphology as well as products due to localized electrochemical interfacial reaction, is developed and tentatively apPlied to analyze the initiation of local corrosion in this study. An ellipso- microscope, that is combination of null-type ellipsometer and CCD camera micro- imaging, is applied to titanium surface anodized in sulfulic acid and successfully revealed an anisotropic growth of oxide film depending on the substrate and localized degradation of the film in bromide ion-containing solution. Furthermore, a micro- capillary cell technique with 50 pm diameter sample combined with a long-distance optical microscope was developed and apPlied to potentio-dynamic and - static polarizations and electrochemical impedance spectroscopy of iron in sulfuric acid. It revealed that the passivation of the surface and stability of the passive film were strongly depended on crystallographic orientation of the substrate. Combinations of microelectrochemistry and optical microscopy might take a new turn of the research for the initiation of localized interfacial reaction caused by non-uniformity in the scale of surface microstructures.