Transport processes of hydrated ions at polymer/oxide/metal interfaces Part 1. Transport at interfaces of polymer coated oxide covered iron and zinc substrates

Localised electrochemical and spectroscopic techniques were jointly applied for the evaluation of hydrated ion transport processes along polymer/oxide/metal interfaces. In situ Scanning Kelvin Probe (SKP) studies of the local interfacial potentials of organically coated oxide covered zinc and iron s...

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Bibliographic Details
Published in:Electrochimica acta 2009, Vol.54 (3), p.891-899
Main Authors: POSNER, R, WAPNER, K, STRATMANN, M, GRUNDMEIER, G
Format: Article
Language:English
Subjects:
Applied sciences
Corrosion
Corrosion mechanisms
Exact sciences and technology
Metals. Metallurgy
Online Access:Get full text
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Summary:Localised electrochemical and spectroscopic techniques were jointly applied for the evaluation of hydrated ion transport processes along polymer/oxide/metal interfaces. In situ Scanning Kelvin Probe (SKP) studies of the local interfacial potentials of organically coated oxide covered zinc and iron substrates were performed in humid nitrogen atmospheres. They were supported by ex situ small spot X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) analysis of the interfacial ion distribution. Based on the experimental results it is concluded that also in atmospheres of strongly reduced oxygen partial pressure at which no corrosive delamination takes place, a negatively charged layer of adsorbed hydroxide ions determines ion transport processes along interfaces between polymer films and oxide covered metals. No ion transport was observed for zinc substrates while hydrated cations were selectively transported along the polymer/iron interface. The reduction of oxygen molecules on the highly reactive iron oxide surface is assumed to be responsible for the generation of adsorbed interfacial hydroxide ions. On the other hand such oxygen reduction induced hydroxide formation in humid nitrogen atmospheres with strongly reduced oxygen partial pressure does not seem to take place on oxide covered zinc. The variation of free volumes at the polymer/strate interface did not lead to a principal change of this phenomenon.
ISSN:0013-4686
1873-3859
DOI:10.1016/j.electacta.2008.06.074