کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
190787 459707 2011 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Chloride-induced filiform corrosion of organic-coated magnesium
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
Chloride-induced filiform corrosion of organic-coated magnesium
چکیده انگلیسی

In-situ scanning Kelvin probe (SKP) potentiometry is used to study the underfilm corrosion of organic-coated, commercial purity (CP) magnesium under conditions of high relative humidity. Following initiation by the application of aqueous hydrochloric acid (HCl) to a penetrative coating defect, underfilm corrosion is characterised by the onset of coalesced filiform-like features, which lengthen with time and propagate at a rate which is largely independent of the quantity of initiating HCl. The potentials of the advancing underfilm corrosion-front range from −1.35 to ca. −1.45 V vs. SHE, with corrosion potentials in the tail region largely similar to those of the intact coated Mg surface. The rate of filiform corrosion (FFC) advance is shown to be insensitive to the presence of oxygen, but highly dependent upon the relative humidity of the holding environment. It is proposed that the mechanism of propagation is not governed by differential aeration, but rather a differential “electrocatalytic activation” phenomenon involving anodic Mg dissolution at the leading edge of the corrosion front, galvanically coupling with hydrogen evolution on a cathodically activated corroded region behind. This proposed mechanism also accounts for observations of FFC upon immersion of CP-Mg in dilute chloride-containing electrolyte, where differential aeration would not be expected to exert an influence.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Electrochimica Acta - Volume 56, Issue 4, 15 January 2011, Pages 1894–1903
نویسندگان
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