Title
Corrosion-Related Interfacial Defects Formed by Dissolution of Aluminum in Aqueous Phosphoric Acid
Document Type
Article
Research Focus Area
Advanced and Nanostructured Materials
Publication Date
2002
Journal or Book Title
Journal of the Electrochemical Society
Volume
149
Issue
4
First Page
B108
Last Page
B116
DOI
10.1149/1.1455648
Abstract
The mechanism was investigated by which pit initiation on aluminum foils during anodic etching is affected by the use of phosphoric acid as a pretreatment. Positron annihilation measurements, coupled with atomic force microscope images of foils with chemically stripped oxide layers, show evidence that the pretreatment introduces nanometer-scale voids in the metal, at or near the metal-oxide film interface. The location and morphology of voids compares favorably with those of pits, suggesting that voids act as pit initiation sites. The number of void sites was estimated to be 107 cm−2, the same magnitude as the maximum number of pits formed by anodic etching. Capacitance measurements further indicate that the treatment decreases the surface oxide thickness to about 2 nm. Formation of large numbers of pits during etching is promoted by either reduced oxide thicknesses or more positive etching potentials. It is suggested that the rate of initiation of pits at interfacial voids is determined by the electric field in the overlying surface oxide.
Copyright Owner
ECS—The Electrochemical Society
Copyright Date
2002
Language
en
File Format
application/pdf
Recommended Citation
Wu, Huiquan; Hebert, Kurt R.; Gessman, Thomas; and Lynn, Kelvin, "Corrosion-Related Interfacial Defects Formed by Dissolution of Aluminum in Aqueous Phosphoric Acid" (2002). Chemical and Biological Engineering Publications. 56.
https://lib.dr.iastate.edu/cbe_pubs/56
Comments
This article is from Journal of the Electrochemical Society 149 (2002): B108–B116, doi:10.1149/1.1455648. Posted with permission.