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Influence of potential on structure and properties of microarc oxidation coating on Mg alloy

  • Deng Shu-hao Email author
  • Yi Dan-qing 
  • Gong Zhu-qing 
  • Su Yu-chang 
Materials Science and Engineering
  • 66 Downloads

Abstract

In order to obtain optimizing microarc oxidation coating on Mg alloy from a friendly-enviormental electrolyte free of Cr6+ and PO43−, constant potential regime was applied to produce it. The influence of potential on the morphology, composition, structure and other properties, such as microhardness and corrosion resistance were investigated by scanning electron microscopy (SEM), energy dispersive spectroscope (EDS), X-ray diffraction (XRD), hardness tester and electrochemical method. The results clearly show that oxidation potential plays an important role in the formation of coating’s structure and properties. The microarc oxidation coating is smooth and white, which consists of two layers. The external layer is loose and porous and enriched in Al and Si. Moreover, its content of Al and Si increases with the increasing operated potential. While the inner layer is compact and the content of Al and Si are lower than that of the external layer. The coating is composed of several phases and the major phases are MgAl2O4 and MgO, and the minor phases are Al2O3 and SiO2 when the potential is higher. The microhardness of coating is obtained the maximum at the potential of 45 V, so does the corrosion resistance.

Key words

microarc oxidation magnesium alloy structure property 

CLC number

O646.54 

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References

  1. [1]
    Eifert A J, Thomas J P, Rateick R G. Influence of anodization on the fatigue life of WE43A-T6 magnesium[J]. Scripta Materialia, 1999, 40(8): 929–935.CrossRefGoogle Scholar
  2. [2]
    Abulsain M, Berkani A, Bonilla F A. Anodic oxidation of Mg-Cu and Mg-Zn alloys [J]. Electrochim Acta, 2004, 49(6): 929–935.CrossRefGoogle Scholar
  3. [3]
    Zozulin J A, Barcak E. Anodic oxidation for Mg alloy[J]. Metal Finishing, 1994, 92(3): 39–44.Google Scholar
  4. [4]
    Chong K Z, Shih T S. Conversion-coating treatment for magnesium alloys by a permanganate-phosphate solution[J]. Materials Chemistry and Physics, 2003, 80(1): 191–200.CrossRefGoogle Scholar
  5. [5]
    Gonzalez-nunez M A, Nunez-lopez C A, Skeldon P, et al. A non-chromate conversion coating for Mg alloy and Mg-based metal matrix composites[J]. Corrosion Science, 1995, 37(11): 1763–1772.CrossRefGoogle Scholar
  6. [6]
    HAO Jian-min, CHEN Hong, ZHANG Rong-jun, et al. Corrosion resistance of Mg alloy microarcoxidization ceramic coating[J]. The Chinese Journal of Nonferrous Metals, 2003, 13(4): 988–991. (in Chinese)Google Scholar
  7. [7]
    Apelfeld A V, Bespalova O V, Borisov A M, et al. Application of the particle backscattering methods for the study of new oxide protective coatings at the surface of Al and Mg alloys[J]. Nuclear Instruments and Methods in Physics Research B, 2000, 161–163(3): 553–557.CrossRefGoogle Scholar
  8. [8]
    Sharma A K, Suresh M R, Bhojraj H, et al. Electroless nickel plating on Mg alloy[J]. Metal Finishing, 1998, 96(3): 10–18.CrossRefGoogle Scholar
  9. [9]
    Rajan A, Zhou W. Electroless nickel-plating on AZ91D magnesium alloy: effect of substrate microstructure and plating parameters[J]. Surface and Coatings Technology, 2004, 179(2–3): 124–134.Google Scholar
  10. [10]
    YIN Jian-jun, LI Yuan-dong, LIANG Wei-dong, et al. Investigation of pretreatment process with zinc plating for Mg alloy electroplating[J]. Journal of Gansu University of Technology, 2003, 29(1): 36–38. (in Chinese)Google Scholar
  11. [11]
    Truong V T, Lai P K, Moore B T, et al. Corrosion protection of magnesium by electroactive polyprroler/paint coatings [J]. Synthetic Methods, 2000, 110(1): 7–15.CrossRefGoogle Scholar
  12. [12]
    WEI Zhong-ling, CHEN Qin-rong, GUO Xin-cong, et al. Microstructure and corrosion resistance of ceramic coating on magnesium alloys [J]. Materials Protection, 2003, 36(10): 21–23.Google Scholar

Copyright information

© Central South University 2005

Authors and Affiliations

  • Deng Shu-hao 
    • 1
    Email author
  • Yi Dan-qing 
    • 1
  • Gong Zhu-qing 
    • 2
  • Su Yu-chang 
    • 1
  1. 1.School of Materials Science and EngineeringCentral South UniversityChangshaChina
  2. 2.School of Metallurgical Science and EngineeringCentral South UniversityChangshaChina

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