Anodizing of Aluminum Coated with Zirconium Oxide by a Sol-Gel Process I. Effect of Heat Treatment on the Formation of the Anodic Oxide Film

Keiji Watanabe, Masatoshi Sakairi, Hideaki Takahashi, Katsumi Takahiro, Shinji Nagata, Shinji Hirai

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

Aluminum specimens were covered with zirconium oxide films by sol-gel dip coating at Th, = 573 and 873 K, and then anodized galvanostatically in a neutral borate solution. The time-variation in the anode potential during anodizing was monitored, and the structure of anodic oxide films was examined by TEM, EDX, and RBS. During anodizing of specimens coated with ZrO2 at Th = 573 K, the anode potential, Ea, increased linearly with time, ta, and the slope of the Ea vs. ta curve increased with increasing the number of sol-gel coatings. An anodic oxide film, which was composed of an inner Al2O3 layer and an outer Al-Zr composite oxide layer, grew at the interface between the ZrO2 layer and metal substrate during anodizing. The thickness of the inner layer increased with ta, whereas the thickness of the outer layer showed a maximum before decreasing with ta. Specimens coated with ZrO2 at Th=873 K showed Ea -jumps between 40 and 110 V just after the commencement of anodizing, and then a slow Ea increase. An anodic oxide film composed of a single layer of A12O3, formed beneath the ZrO2 layer during anodizing. The mechanism of the formation of anodic oxide films on aluminum coated with ZrO2 films is discussed in terms of ion transport across the anodic oxide film.

Original languageEnglish
Pages (from-to)1243-1248
Number of pages6
JournalElectrochemistry
Volume67
Issue number12
DOIs
Publication statusPublished - 1999 Dec

Keywords

  • Anodizing of Aluminum
  • Composite Oxide Film
  • Sol-gel Coating
  • Zirconium Oxide

ASJC Scopus subject areas

  • Electrochemistry

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