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Korean Journal of Chemical Engineering

, Volume 21, Issue 4, pp 915–920 | Cite as

Sealing effects of anodic oxide films formed on Mg-Al alloys

  • Seong-Jong Kim
  • Jeong-Il Kim
  • Masazumi Okido
Article

Abstract

Mg alloys were anodized in alkaline NaOH solutions with various additives as a non-chromate method. Specimen AZ91 was anodized at a potential that produced a strong surface dissolution reaction and generated a large amount of Mg(OH)2. The effect of sealing after anodizing was investigated, focusing on the effects of sealing time, temperature and solution conditions. The current density decreased with increasing A1(OH)3 concentration in 1 M NaOH solution during anodizing; sparking occurred at potentials above 80 V. The best corrosion resistance with anodizing in 1 M NaOH solution occurred at a potential of 4 V, which caused the strongest active dissolution reaction. The sealing effect improved with increasing time and temperature, and corrosion resistance was proportional to the relative ratio of Mg(OH)2. If the oxygen thickness observed by EDX equaled the film thickness, the film formed at 4 V in 1 M NaOH was 10–15 Μm thickness. The optimum corrosion resistance in sealing at various solutions after anodizing was 1M-NaOH solution.

Key words

AZ91 Anodizing NaOH Solution Sealing Corrosion Resistance 

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Copyright information

© Korean Institute of Chemical Engineering 2004

Authors and Affiliations

  • Seong-Jong Kim
    • 1
    • 2
  • Jeong-Il Kim
    • 1
    • 2
  • Masazumi Okido
    • 2
  1. 1.Division of Marine EngineeringMokpo Maritime UniversityChonnamKorea
  2. 2.Graduate School of EngineeringNagoya UniversityNagoyaJapan

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