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Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/17233

Title: Improvement of Passivity of Fe - xCr Alloys (x < 10%) by Cycling Through the Reactivation Potential
Authors: Ulaganathan, Jaganathan
Advisor: Newman, Roger C.
Department: Chemical Engineering and Applied Chemistry
Keywords: Fe - Cr
Low-Cr alloys
Potential cycling
Issue Date: 26-Feb-2009
Abstract: Classically 13% Cr is required for stable passivity of steel in acidic and neutral solutions. Some authors (Mansfeld, Fujimoto) have published potential cycling procedures that generate thick Cr-rich films. Fujimoto cycles right to the transpassivity potential and back in H2SO4 solution. Our idea is to work close to the reactivation potential where the passive film (Fe2O3) is reductively dissolved to Fe2+. While using an equimolar acetate buffer (pH 4.7), we have obtained new insights into the reactivation process. It is under a kind of thermodynamic control, in that the film cannot be reduced, and the metal cannot be dissolved, faster than would exceed the equilibrium concentration of Fe2+ at the electrode surface. Reductive dissolution leads to gel-like Cr-rich film, but Fe dissolution occurs through it, if formed in a single step. However alternating formation and reductive dissolution of a Fe-rich film assist the formation of a more robust Cr-rich film
URI: http://hdl.handle.net/1807/17233
Appears in Collections:Master
Department of Chemical Engineering and Applied Chemistry - Master theses

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