REVERSAL Of POLARITY OF ZINC COATINGS, URBAN MYTH OR FACT?

摘要

This paper looks at the frequently quoted phenomenon of reversal of polarity of zinc/steel whereby the steel becomes anodic and the zinc cathodic under certain conditions that are said to occur in service conditions under insulation at elevated temperatures. The paper examines some earlier research done 50 or so years ago on the subject by people such as Honxeng, Schilkorr and others. It records the results of experiments over the past 18 months, with some surprising results. Some examples and case studies are also shown. The question as to whether the issue is fact or fiction is left up to the audience to ponder.