A superhydrophilic aluminum surface with fast water evaporation based on anodic alumina bundle structures via anodizing in pyrophosphoric acid

Daiki Nakajima, Tatsuya Kikuchi, Taiki Yoshioka, Hisayoshi Matsushima, Mikito Ueda, Ryosuke O. Suzuki, Shungo Natsui

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

A superhydrophilic aluminum surface with fast water evaporation based on nanostructured aluminum oxide was fabricated via anodizing in pyrophosphoric acid. Anodizing aluminum in pyrophosphoric acid caused the successive formation of a barrier oxide film, a porous oxide film, pyramidal bundle structures with alumina nanofibers, and completely bent nanofibers. During the water contact angle measurements at 1 s after the water droplet was placed on the anodized surface, the contact angle rapidly decreased to less than 10°, and superhydrophilic behavior with the lowest contact angle measuring 2.0° was exhibited on the surface covered with the pyramidal bundle structures. As the measurement time of the contact angle decreased to 200-33 ms after the water placement, although the contact angle slightly increased in the initial stage due to the formation of porous alumina, at 33 ms after the water placement, the contact angle was 9.8°, indicating that superhydrophilicity with fast water evaporation was successfully obtained on the surface covered with the pyramidal bundle structures. We found that the shape of the pyramidal bundle structures was maintained in water without separation by in situ high-speed atomic force microscopy measurements.

Original languageEnglish
Article number3497
JournalMaterials
Volume12
Issue number21
DOIs
Publication statusPublished - 2019 Nov 1

Keywords

  • Alumina nanofiber
  • Aluminum
  • Anodizing
  • Pyrophosphoric acid
  • Superhydrophilicity

ASJC Scopus subject areas

  • Materials Science(all)

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