Fabrication of a plasma electrolytic oxidation/anodic aluminum oxide multi-layer film via one-step anodizing aluminum in ammonium carbonate

Tatsuya Kikuchi, Taiki Taniguchi, Ryosuke O. Suzuki, Shungo Natsui

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

A plasma electrolytic oxidation (PEO)/anodic aluminum oxide (AAO) multi-layer film was fabricated via one-step galvanostatic anodizing of high-purity aluminum in 0.3–2.0 M ammonium carbonate ((NH4)2CO3) solutions at 283–333 K and 25–400 Am−2. Anodizing at higher concentrations and higher temperatures caused the formation of relatively uniform anodic oxide film on the aluminum substrate. Characteristic voltage-time curves with two high-plateau voltages at approximately 250 V and 375 V were obtained during galvanostatic anodizing. A multi-layer structure of an outer PEO layer with a crystalline γ-Al2O3 structure and an inner amorphous AAO layer with nano-cylinerical pores was formed by continuous visible sparking occurring after passing the first voltage plateau region. The whole aluminum surface was covered with the multi-layer structure after reaching the second voltage region. The thickness of the multi-layer increased with time via the further anodizing process at the second plateau voltage. Pore sealing of the inner nanoporous film was achieved by immersion post-treatment in boiling water.

Original languageEnglish
Article number137799
JournalThin Solid Films
Volume697
DOIs
Publication statusPublished - 2020 Mar 1

Keywords

  • Aluminum
  • Ammonium Carbonate
  • Anodic Aluminum Oxide
  • Anodizing
  • Plasma Electrolytic Oxidation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry

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