Growth of barrier-type anodic films on magnesium in ethylene glycol electrolytes containing fluoride and water

Hiroki Habazaki, Fumitaka Kataoka, Khurram Shahzad, Etsushi Tsuji, Yoshitaka Aoki, Shinji Nagata, Peter Skeldon, George E. Thompson

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

This study demonstrates the formation of uniform barrier-type anodic films on magnetron-sputtered magnesium films at high current efficiency in ethylene glycol electrolytes containing 0.1 mol dm-3 NH4F and various concentrations (0.1-28 mol dm-3) of H2O. The anodic films containing a crystalline MgF2 phase develop both at the metal/film and film/electrolyte interfaces due to simultaneous migrations of anions inwards and cations outwards, respectively. When a Mg -1.2 at% Au/Mg bilayer film is anodized, initial prior oxidation of magnesium proceeds with gold atoms accumulating in a thin layer beneath the anodic film. The accumulated gold atoms are incorporated into the anodic film as a band when the alloy layer is completely anodized. Fluoride-containing gold species are formed by the incorporation and the gold species migrate outwards at a rate of 0.4 times the rate of Mg2+ ions. The addition of phosphate in the electrolyte results in the formation of an amorphous anodic film, and the phosphate incorporated into the anodic film is distributed throughout the film thickness. The transport number of cations is also influenced by the phosphate incorporation.

Original languageEnglish
Pages (from-to)402-410
Number of pages9
JournalElectrochimica Acta
Volume179
DOIs
Publication statusPublished - 2015 Oct 10

Keywords

  • anodic film
  • anodizing
  • fluoride
  • ionic transport
  • magnesium

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Electrochemistry

Fingerprint

Dive into the research topics of 'Growth of barrier-type anodic films on magnesium in ethylene glycol electrolytes containing fluoride and water'. Together they form a unique fingerprint.

Cite this