Skip to main content
Corrosion-Related Interfacial Defects Formed by Dissolution of Aluminum in Aqueous Phosphoric Acid
Journal of the Electrochemical Society
  • Huiquan Wu, Iowa State University
  • Kurt R. Hebert, Iowa State University
  • Thomas Gessman, Washington State University
  • Kelvin Lynn, Washington State University
Document Type
Publication Date
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.

This article is from Journal of the Electrochemical Society 149 (2002): B108–B116, doi:10.1149/1.1455648. Posted with permission.

Copyright Owner
ECS—The Electrochemical Society
File Format
Citation Information
Huiquan Wu, Kurt R. Hebert, Thomas Gessman and Kelvin Lynn. "Corrosion-Related Interfacial Defects Formed by Dissolution of Aluminum in Aqueous Phosphoric Acid" Journal of the Electrochemical Society Vol. 149 Iss. 4 (2002) p. B108 - B116
Available at: