Localized Corrosion Influenced by Changing Mechanisms

Abstract

This chapter presents electrochemical methods and tools including the wire beam electrode-video technique and integrated three-dimensional corrosion probes for in situ monitoring of corrosion and materials degradation affected by changing mechanisms. The design of corrosion probes should focus on the simulation of such local chemistry changes in order to effectively mimic and monitor the dominating mechanisms over every period of corrosion and materials degradation processes. Since coating disbondment is a critical step leading to corrosion under disbonded coatings (CUDC), ideally coating disbondment could be prevented or significantly reduced in order to protect a buried pipeline from CUDC. Corrosive electrolyte from the surrounding environment can access these crevices, resulting in an enclosed corrosive environment within the crevice and CUDC. It was found that in nonsaturated soil, CUDC behavior changed significantly under the effect of a number of environmental factors and coting disbondment parameters, in particular with coating disbondment gap size.