Development of Corrosion Crack Initiation Monitor Based upon Scanning Vibrating Electrode Technique

研制了一种能够评价水溶液中局部腐蚀(包括腐蚀坑和腐蚀裂纹)的萌生和扩展速率的监测仪。利用计算机控制的扫描振动电极系统对腐蚀电流密度随时间的分布进行了空间测量。测量了高强度钢焊接件和模型点焊奥氏体不锈钢试件上的电流密度分布，并以三维曲线图和等高线图的形式显示出来。讨论了样品和微电极之间的差异对测量的腐蚀电流密度和对应于局部腐蚀的阳极位置的空间分辨率的影响。我们还强调，计算机图像处理技术为分析腐蚀电流密度分布，提取局部腐蚀部位提供了强有力的工具。

The monitor, which can evaluate the initiation and growth rate of localized corrosion including corrosion pit and corrosion crack in aqueous solution, has been developped. It spatially measures distributions of corrosion current density with time by using the computer controlled scanning vibrating electrode system. Distributions of current density on the samples including high-tensile strength steel weldments and model pit, i.e., austenitic stainless steels with spots filled with solder, are measured, and are displayed in three-dimensional plots and contour maps. The influences of differences between a sample and a micro-electrode on measured corrosion current density, and spatial resolution of anodic sites which correspond to localized corrosion are discussed. We also emphasize that computer image processing techniques provide powerful tools to analyze distributions of corrosion current density to extract localized corrosion sites.