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Author
Nguyen, T. | Lin, C.
Title
Development of a Method to Measure In Situ Chloride at the Coating/Metal Interface. Technical Note (Final).
Coporate
National Institute of Standards and Technology, Gaithersburg, MD Xiamen Univ., People's Republic of China
Report
NIST TN 1266, July 1989,
Distribution
Available from National Technical Information Service
Keywords
chlorides; coatings; metals; corrosion; blistering; electrodes; methodology; interfaces; electric potential; microelectronics; measurement; graphs (charts)
Abstract
One of the main reasons for the lack of a complete understanding of corrosion and adhesion failures of a coated metal is the lack of analytical instrumentation to probe the behaviors of corrosive agents at the coating/steel interface. A procedure has been developed based in microelectrodes for studying in situ the behaviors of potential and chloride ions in blister and at a coating/metal interface. The procedure requires an attachment of a double-barred Cl(-1) selective microelectrode at the coating/metal interface, thus allowing direct measurements of Cl(-1) concentration and corrosion potential changes at localized areas under a coating. Although it is intricate to prepare the microelectrodes, the procedure provided very useful information for mechanistic studies of corrosion under coatings, as well as for transport studies of Cl(-1) ions through a coating on metal. The procedure should also be very useful for studying the roles of Cl(-1) in localized corrosion. The utility of an inverted electrode microsampling method for studies of Cl(-1) in very small volumes such as blisters was also demonstrated.