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. ***
