Effects of Current Density on the Formation of Anodic Oxide Films on AZ91

Abstract:

Magnesium must be surface treated to prevent corrosion, since it is a very active metal electrochemically. On anodizing, a compact film several tens of micrometers thick forms on magnesium, which imparts good corrosion resistance. The Mg-Al alloy (AZ91) was anodized in 1 M NaOH solution. The surface morphology of the anodized films was observed using scanning electron microscopy (SEM), energy-dispersive x-ray (EDX), and electrochemical methods. The effects of current density on the formation of anodic oxide films for a Mg-Al alloy in 1 M NaOH were investigated. In the anodic polarization curve, the reference corrosion potentials were far greater at 4-9 mA/cm2 than at 1 mA/cm2. The film that formed at 1 mA/cm2 was thin, suggesting that parts of the film had been dissolved or destroyed during the anodic polarization test. Corrosion resistance differed owing to concentric differences in current flow. Thick anodic oxide films were formed at higher applied currents.

• Periodical: Materials Science Forum (Volumes 510-511)
• Pages: 166-169
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.510-511.166
• Online since: March 2006
• Authors: Seong Jong Kim, Jeong Il Kim
• Keywords: Anodizing, Corrosion, Current Density, Magnesium, Polarization Curve

References

[1] S.J. Kim, M. Okido : Bulletin of the korean chemical society, Vol. 24 (2003), p.975.

[2] S. J. Kim, R. Hara, R. Ichino, M. Okido, N. Wada : Materials Transactions, Vol. 44 (2003), p.782.

[3] Y. Mizutani, S.J. Kim, R. Ichino, M. Okido : Surface and coatings Technology, Vol. 167-179 (2003), p.143.

[4] S.J. Kim, M. Okido, Y. Mizutani, R. Ichino, S. Tanikawa, S. Hasegawa: Materials Transactions, Vol. 44 (2003), p.1036.

[5] V. Moutarlier, M. P. Gigandet, J. Pagetti, B. Normand, Surface & coatings technology, Vol. 182(2004), p.117 �.

DOI: 10.1016/s0257-8972(03)00875-2