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Article
Atomic Force Microscopy Study of the Initial Stages of Anodic Oxidation of Aluminum in Phosphoric Acid Solution
Journal of the Electrochemical Society
  • Huiquan Wu, Iowa State University
  • Xiao Zhang, Iowa State University
  • Kurt R. Hebert, Iowa State University
Document Type
Article
Disciplines
Publication Date
1-1-2000
DOI
10.1149/1.1393496
Abstract
Aluminum foils with two different surface topographic textures were anodically oxidized at constant current in a phosphoric acid bath. In situatomic force microscopy (AFM) was used to follow the initial development of surface topography on a 1 μm scale, during the early stages of porous oxide film formation. Microscopic convex features such as ridges on both foils begin to increase in height and width when the anodic film thickness exceeds the initial feature height. Equations of a mathematical model are presented incorporating established interfacial reactions and oxide conduction behavior. The model indicates that the film‐solution interface recedes into the metal during anodizing, since the current efficiency for oxide formation is smaller than the oxygen ion transport number in the film. Ridge surfaces increase in height due to the higher local conduction resistance to the film‐solution interface, while film deposits rapidly at ridges because of the low local resistance to the metal‐film interface. In agreement with the AFM results, enhanced oxide growth at ridges should start when the potential field in the film becomes two‐dimensional, as a result of the film growing to a thickness larger than the ridge height.
Comments

This article is from Journal of the Electrochemical Society 147 (2000): 2126–2132, doi:10.1149/1.1393496. Posted with permission.

Copyright Owner
ECS—The Electrochemical Society
Language
en
File Format
application/pdf
Citation Information
Huiquan Wu, Xiao Zhang and Kurt R. Hebert. "Atomic Force Microscopy Study of the Initial Stages of Anodic Oxidation of Aluminum in Phosphoric Acid Solution" Journal of the Electrochemical Society Vol. 147 Iss. 6 (2000) p. 2126 - 2132
Available at: http://works.bepress.com/kurtr_hebert/39/