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 EFFECT OF CREVICE FORMER ON THE EVOLUTION OF CREVICE DAMAGE Xi Shan and Joe H. Payer  Department of Materials Science and Engineering Case Western Reserve University 10900 Euclid Ave. Cleveland, OH 44106-7204 ABSTRACT One important factor affecting crevice corrosion of passive metals is the c revice geometry, e.g. the gap and shape of the crevice. Depending upon the materials properties, different crevice formers can affect the crevice geometry, e.g. a polymeric crevice former can conform to the surface roughness of a metal specimen. The objectives of this work are to investigate the crevice corrosion damage propagation of alloy 22 (N06022) with different crevice former materials and to address factors that may limit the initiation of localized corrosion and also factors that may slow o r stop the continued propa gation of corrosion. Crevice formers made from ceramic, polymer, polytetrafluoroethylene (PTFE) tape covered ceramic and alloy 22 are compared in controlled crevice corrosion tests under highly aggressive, accelerated conditions. Cyclic potentiodynamic polarization and potentiostatic polarization methods are used to determine the crevice corrosion behavior of alloy 22 in high temperature, concentrated chloride brines. Results show that crevice corrosion of alloy 22 is affected by the crevice former materials and b y the surface finishes of the crevice former and specimen. It is found that crevice corrosion initiates near the edge and under the crevice former and propagates further into the crevice. The corroded alloy can  become re-passivated after undergoing an amount of corrosion. The results provide insight into the localized corrosion process and mechanism of allo y 22 in high temperature brines. Key words: alloy 22 (N06022), crevice former, crevice corrosion, initiation, stifling, localized corrosion 1 Paper No. 08575

Effect of Crevice Former on the Evolution of Crevice Corrosion Damage (51300-08575-SG)

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