空间分辨电化学研究新方法

Novel Electrochemical Techniques with Spatial Resolution and Its Applications in the Investigation of Localized Corrosions

简述当前国内外主要的原位 (In Situ)空间分辨技术及其在电化学研究中的应用 ,包括扫描微电极技术、扫描电化学显微镜、扫描探针显微镜、扫描 Kelvin探针技术、扫描光电流谱技术、显微激光拉曼光谱技术等 ,其中扫描微电极技术、扫描电化学显微镜、扫描 Kelvin探针技术可直接测定腐蚀电极表面或界面电化学不均一性的分布图象 ,而其它方法则是通过测量表面分子振动光谱、表面隧道电流及光电响应等 ,进而从分子水平研究腐蚀电极过程 .并侧重介绍作者已建立的具有微米空间分辨度的电化学方法 ,主要有多种形式的扫描微电极技术及阵列电极技术等 ,并用于研究金属 /溶液界面电化学不均一性及局部腐蚀过程 .结果表明 ,空间分辨电化学方法的发展及应用 ,使得人们对金属表面和金属 /溶液界面电化学不均一性 ,特别是金属局部腐蚀发生、发展过程机理的认识得以深化 .

The electrochemical inhomogeneities at interface of metal/solution play an important and often controlling role in localized corrosion of metals. The traditional electrochemical techniques involving potential, current density or ac impedance measurements over bulk specimens can only provide average and whole information. It is necessary to develop in situ imaging techniques for further characterizing electrochemical inhomogeneities at the interface of metal/solution of localized corrosion system. The electrochemical techniques with spatial resolution, including scanning single micro electrode, scanning double micro electrodes and scanning micro chemical probes have been reviewed. The effects of electrochemical inhomogeneities on the corrosion behavior, and the mechanism for various localized corrosion of metals have been further understood by appropriately using these new electrochemical techniques. An array electrode composed of 64 steel wires and potential imaging system were developed as a new electrochemical technique for probing the corrosion potential distribution at the interface of polymeric coating/metals. The measuring technique was described, and the availability of the technique was examined. The novel data related to the corrosion behaviors at interface of coating/metals and the effects of the defects in the coating on its degradation was obtained and discussed. It was demonstrated by the potential imaging that there always exist inhomogeneities in the coatings, including intrinsic defects or damage in service (artificial defects). Corrosion preferentially initiated at the defect sites. The anodic sites surrounding cathodic area of corrosion reaction and its development process had been in situ imaged for the first time for organic coated steel system. The relevant and direct information provided by this unique technique will be very helpful for further understanding some important physicochemical process associated with degradation of coated metals.