An Investigation of the Fundamental Aspects of Underfilm Corrosion

9708148 Latanision过去在了解膜下腐蚀界面过程的结构和动力学方面所做的努力，导致了监测膜下腐蚀的非破坏性电化学技术。目前文献中报道的大部分数据都是由电化学阻抗谱（EIS）技术产生的。这些数据表明：(1)腐蚀在光学检测到之前就开始了；(2)脱层是由聚合物-金属界面失去附着力或腐蚀造成的；(3)分层和腐蚀速率只能通过EIS来估计。为了更好地了解膜下降解，必须充分了解电化学、金属损失和分层率之间的关系。虽然电化学和腐蚀速率之间的相关性已经很好地建立在非涂层样品上，但没有精确测量聚合物涂层下的质量损失。这个FRG（重点研究小组）项目通过跟踪聚合物涂层铁磁样品的磁饱和度变化来解决与确定涂层基板质量变化相关的问题。质量损失是用振动样品磁强计（VSM）评估的，这为确定涂层样品的腐蚀速率提供了一种明确的方法。此外，样品是目测和EIS监测。当与视觉和电化学数据相关联时，这些结果将为膜下腐蚀的评估和涂层性能的评估提供重要的见解。目前的研究还应该能够区分由于失去附着力或腐蚀造成的分层。在实验过程中，如果VSM上没有记录金属损失，但视觉和电化学检测到分层，则不能将其与腐蚀联系起来。在这个FRG项目中，重点还放在原位/实时电化学技术（快速瞬变技术，FTT）的开发上，以监测溶质吸收和涂层降解的初始阶段。该基金由MPS多学科活动办公室和材料研究司共同资助。该项目预计将提高人们对保护有机涂层可靠性和电化学技术（EIS和FTT）使用的理解，从而为选择最合适的商用保护涂层提供基础。＊＊＊

9708148 Latanision Past effort on understanding the structure and dynamics of interfacial processes in underfilm corrosion has resulted in non-destructive electrochemical techniques to monitor underfilm corrosion. Most of the data reported in the current literature have been generated by the technique of Electrochemical Impedance Spectroscopy (EIS). These data suggest that: (1) corrosion initiates well before it can be detected optically; (2) delamination results from either a loss of adhesion or corrosion at the polymer-metal interface; and (3) delamination and corrosion rate can only be estimated by EIS. In order to achieve a better understanding of underfilm degradation, it is imperative that the correlation between electrochemistry, loss of metal, and delamination rate is fully understood. While a correlation between electrochemistry and corrosion rate is well established for non-coated samples, no accurate measurement of mass loss beneath a polymer coating has been achieved. This FRG (Focussed Research Group) project circumvents the problems associated with determining the change in mass of a coated substrate by following the change in the magnetic saturation of a polymer-coated ferromagnetic sample. Mass loss is assessed with a vibrating sample magnetometer (VSM), which provides an unambiguous method for determining the corrosion rate of a coated sample. In addition, the sample is monitored visually and with EIS. When correlated to visual and electrochemical data, these results should provide significant insight into the evaluation of underfilm corrosion and assessment of coating performance. The current research should also be able to distinguish between delamination resulting from loss of adhesion or from corrosion. During an experiment, if no metal loss is recorded on the VSM but delamination is visually and electrochemically detected, it can not be associated with corrosion. In this FRG project emphasis is also placed on the development of an in-situ/real-time electrochemical technique (Fast Transient Technique, FTT) to monitor solute uptake and the initial stage of coating degradation. The grant is co-funded by the MPS Office of Multidisciplinary Activities and the Division of Materials Research. %%% This project is expected to lead to an improved understanding of both the reliability of protective organic coatings and the use of electrochemical techniques (EIS and FTT), thereby providing a basis for the selection of the most suitable commercially available protective coatings. ***