Abstract

The present work is a study of the applicability of linear polarisation resistance technique as a means for corrosion monitoring. Parameters tested were alloy composition, surface finish of specimens before exposure, concentration of aqueous environment and the additional effect of soil to the aqueou􀀂 medium. A simple galvanostatic polarisation circuit was utilized. A polarisation resistance curve was then plotted from which the corrosion current densities and corrosion rates were calculated. The results of this work show that Corrosion reactions depend on both thermodynamic and kinetic parameters, also these reactions are under mixed control and the potential actually measured at the metal surface is a mixed potential. Linear polarisation resistance technique is not a suitable corrosion monitoring technique for type 304 stainless steel. For low alloy steel, the corrosion rate increases with increase of chloride concentration of the aqueous environment to reach a maximum at seawater concentration beyond which the corrosion rate starts to decrease. Presence of soil in addition to the seawater environment causes additional resistance thus explain­ing prevailing of the type resistance overvoltage. The nature of soil affects the extent of corrosion. In the case of soil completely covered with seawater localized crevice corrosion was recognized, that is in contrast to the case where sand is moistened with few drops of seawater, the corrosion rate was very low. Condition of the metal surface before exposure affected the corrosion behaviour. Accelerating rates of corrosion are attributed to surface roughening of the metal.

School

School of Sciences and Engineering

Date of Award

1-1-1987

Online Submission Date

1-1-1987

First Advisor

M. Farag

Committee Member 1

Saad El Raghy

Committee Member 2

O.Habashy

Committee Member 3

H. Omar

Document Type

Thesis

Extent

103, [1] leaves

Library of Congress Subject Heading 1

Corrosion and anti-corrosives

Library of Congress Subject Heading 2

Corrosion

Rights

The American University in Cairo grants authors of theses and dissertations a maximum embargo period of two years from the date of submission, upon request. After the embargo elapses, these documents are made available publicly. If you are the author of this thesis or dissertation, and would like to request an exceptional extension of the embargo period, please write to thesisadmin@aucegypt.edu

Call Number

Thesis 1987/712

Location

mgfth

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