Self-Organization Process in Active-State Pitting-Instability of Active-State Pit Formation

• Asanuma Miki

  Department of Information Technology, Yokohama Polytechnic College

• Yamada Akifumi

  Department of Chemistry, Nagaoka University of Technology

• Aogaki Ryoichi

  Department of Product Design, Polytechnic University

Abstract

From the viewpoint of unstable growth of nonequilibrium fluctuations, the self-organization process of the pit in an active state was examined. At less-noble potentials, anodic dissolution of passive metal initially generates a specific pit, called the active-state pit, having a size similar to that of the conventional polishing-state pit formed at more-noble potentials. The inside of the active-state pit has a random irregular surface, sometimes as a result of crystalline micrograins. It was first concluded that the diameter of the pit in the active state as well as in the polishing state is determined by the same fluctuations arising from metal-ion formation due to the presence of specifically adsorbed anions on the metal surface. Then, the irregularity of the inside of the pit was attributed to the fluctuations arising from metal-complex formation following metal-ion formation; the aggressive anions autocatalytically bind with the metal ions, so that the fluctuations, unlike the fluctuations due to metal-ion formation, are randomly distributed. In active dissolution without passive film at much less-noble potentials, because of the high growth rates of the fluctuations due to metal-ion formation, the fluctuations of complex formation regulate the total reaction as the rate-determining step, so that the random irregularity characteristic of such fluctuations appears in the surface morphology. As the potential shifts toward the more-noble side, however, owing to the development of the concentration overpotential, the fluctuations of metal-ion formation are suppressed from growing, so that instead of the fluctuations of complex formation, the fluctuations of metal-ion formation control the total reaction of the formation of the active-state pit. Finally, after computer simulation of the self-organization process, the morphology of the active-state pit was compared with that of the polishing-state pit, and the morphological dependence on the passive film coverage and pitting time was examined.

Journal

• Japanese Journal of Applied Physics

  Japanese Journal of Applied Physics 43 (9A), 6303-6314, 2004

  The Japan Society of Applied Physics

Keywords

• self-organization
• instability
• stability
• specific adsorption
• nonequilibrium fluctuation
• pitting corrosion
• pit formation
• active-state pit
• polishing-state pit
• aggressive anion

Details

• CRID: 1390001206264713984
• NII Article ID: 10013574245
• NII Book ID: AA10457675
• DOI: 10.1143/jjap.43.6303
• ISSN: 13474065
• ISSN: 00214922
• NDL BIB ID: 7079971
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I7079971
• Web Site: https://iopscience.iop.org/article/10.1143/JJAP.43.6303
• Web Site: https://iopscience.iop.org/article/10.1143/JJAP.43.6303/pdf
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
• Abstract License Flag: Disallowed