Two-Step Anodization of AZ91 Magnesium Alloy

Abstract:

Among four AZ91 samples, two were once anodized and the others were twice anodized in two electrolytic baths. After twice anodization, two coatings coexist on the base metal. Surface morphology showed that for one of twice anodic coatings (sample 2), the second coating only existed on some places and sealed some pores of the first coating after short time on the second anodizing. However, for another twice anodic coating (namely sample 4), the second anodization spent very long time and the coating was thick and loose. Salt spray testing showed that sample 2 had the most excellent corrosion resistance and the reason is discussed.

• Periodical: Materials Science Forum (Volumes 488-489)
• Pages: 653-656
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.488-489.653
• Online since: July 2005
• Authors: Rong Fa Zhang, Da Yong Shan, En-Hou Han
• Keywords: Corrosion Protection, Film, Magnesium Alloy, Twice Anodization

References

[1] Decker.R. F, Advanced Materials and Processes, 9(1998), p.31.

[2] Sharma A.K. et al., Metal Finishing, 95(3)(1997), p.43.

[3] Creffield. et al., Anodizing aluminum(P). U.S. Patent: 4278737, (1981).

[4] Bartak. et al., Two-step electrochemical process for coating magnesium alloys(P). U.S. Patent: 5264113, (1993).

[5] Bartak. et al., Hard anodic coating for magnesium alloys (P). U.S. Patent: 5470664, (1995).

[6] Burger.F. J and Wu.J. C,J. Electrochem. Soc, 118(12)(1971), p. (2039).

[7] Zozulin.A. J and Bartak.D. E, Metal Finishing, 92(3)(1994), p.39.

[8] Khaselev.O. et al., Journal of The Electrochemical Society, 146(5)(1999), p.1757.

[9] Ono.S. et al. ,J. Electrochem. Soc, 143(3)(1996), p. L62.

[10] DгTTRKICH.K. -H. et al., Crystal Res and Technol, 19(1)(1984), p.93.