Electrochemical noise measurements of steel corrosion in the molten NaCl-K2SO4 system

Frederik Vilhelm Cappeln, Niels Bjerrum, Irina Petrushina

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Abstract

Electrochemical noise measurements have been carried out on AISI347, 10CrMo910, 15Mo3, and X20CrMoV121 steels in molten NaCl-K2SO4 at 630 degrees C. Different types of current noise have been identified for pitting, intergranular and peeling corrosion. The corrosion mechanism was the so-called active corrosion (i.e., the corrosion proceeds with no passivation due to the influence of chlorine), characterized by the formation of volatile metal chlorides as a primary corrosion product. It was found possible to obtain an empirical separation of general and intergranular corrosion using kurtosis (a statistical parameter calculated from the electrochemical noise data). It was found that average kurtosis values above 6 indicated intergranular corrosion and average values below 6 indicated general corrosion. The response time for localized corrosion detection in in-plant monitoring was approximately 90 min on this basis. Approximate values of polarization resistances of AISI347 and 15Mo3 steels were determined to be 250 and 100 Omega cm(2), respectively.
Original languageEnglish
JournalJournal of The Electrochemical Society
Volume152
Issue number7
Pages (from-to)B228-B235
ISSN0013-4651
DOIs
Publication statusPublished - 2005

Bibliographical note

Copyright The Electrochemical Society, Inc. [2005]. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS).

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