中性溶液中铁电化学腐蚀规律的扫描电化学显微镜研究

【作者】 武素香；

【导师】 牛林；

【作者基本信息】 山东大学 ， 物理化学， 2006， 硕士

【摘要】 扫描电化学显微技术（SECM）是一种具有高空间分辨度的现场电化学新技术。用扫描电化学显微镜研究腐蚀电化学体系，可获得用一般电化学方法及其他技术难以得到的重要信息。可用SECM在电化学现场测量腐蚀电极表面空间形貌、电化学不均一性、化学物种等，研究腐蚀电极的动态过程：扫描电化学显微镜还用来研究金属表面钝化膜的局部破坏、消长、局部腐蚀早期过程机理，在原位从微米或纳米空间分辨率上对腐蚀发生、发展机理进行深入的研究，使得腐蚀机理研究从整体平均的水平深入到微米或纳米空间分辨的水平。 本论文用扫描电化学显微镜，以铂为探针工作电极，高纯铁为基底工作电极，在中性溶液中研究铁腐蚀产物的浓度分布。在铁电极表面的做面扫描、线扫描、逼近曲线和循环伏安，其中面扫描、线扫描、逼近曲线研究溶液中的腐蚀产物的浓度分布。 本论文的主要工作如下： 1．不同条件下腐蚀产物的浓度分布 通过做面扫描、线扫描知道，当探针电位不同，基底开路时探针更易氧化溶液中铁溶解的Fe²⁺离子。研究表明，在同样的条件下做面扫描实验时溶液浓度越高面扫描峰电流越大。 2．循环伏安结果分析 以铁为基底，分别在含和不含碘化钾的中性溶液中做循环伏安，实验结果表明，在含有碘化钾的中性溶液中的碘离子在探针上发生氧化反应。 3．不同基底上的面扫描 比较不同基底上的实验结果，可知在相同的溶液中，以铁为基底的面扫描峰为凸峰，而以金为基底的面扫描无峰。说明铁为基底的面扫描凸峰是溶液中的氧化态碘离子与腐蚀溶解的Fe²⁺离子反应，通过面扫描峰电流可以定性确定溶液中的腐蚀产物的浓度分布。 4．铁基底的腐蚀产物浓度分布 分别改变基底在溶液中的浸泡时间、基底与探针之间的距离及基底电作面扫描及线扫描，研究不同的实验条件下，溶液中铁溶解的腐蚀产物的更多还原

【Abstract】 Scanning electrochemical microscopy (SECM) is a new electrochemical technology with high resolution. The SECM can be used to study the corrosion electrochemical system, and some very important information can be got, which cannot be obtained using the conventional electrochemical methods. The SECM has been applied in studying the space surface topography of the corrosive electrode, the electrochemical heterogeneous character and the chemical species, and so on. So the SECM can be used to study dynamic process of the corrosive electrode. The SECM can also be used to study the local breakdown of passive film, the growth of the passive film and the mechanism of the initiative corrosion. The SECM can study the mechanism of the initiation and propagation of corrosion in the micrometer or nanometer space resolution in situ thoroughly, thus the mechanism of the corrosion can be researched from the integrative average level to the micrometer or nanometer space resolution level.In this paper, the SECM tip was made of a platinum wires sealed in glass capillary, the substrate is an iron electrode (99.99%). The concentration of corrosion products was investigated in neutral aqueous solution. The area scanning, line scanning, approach curve and the cyclic voltammetry on iron surface can be obtained using SECM. Among the above experiment methods, the area scanning, line scanning and the approach curve can be used to investigate the concentration profiles of the corrosion products above the iron surface.The main work is as follows:1. The concentration profiles of the corrosion products in different conditions in neutral aqueous solutionAt different tip potentials, the area scanning and line scanning were did, the results showed that the ferrous can be easily oxidized at the tip while the substrate is at the open circuit potential. The results show that the concentration of the aqueous solution influences the experimental results greatly.2. Analysis of the cyclic voltammetry更多还原