Journal of Korea Foundry Society (한국주조공학회지)

Korea Foundry Society (한국주조공학회)
권호 표지

Microstructure and Corrosion Properties of AZ91D Magnesium Alloy treated by Plasma Electrolytic Oxidation

플라즈마 전해 산화 처리한 AZ91D 마그네슘합금 피막의 미세조직 및 부식 특성

  • Chang, Si-Young (Department of Materials Engineering, Korea Aerospace University) ;
  • Kim, Ye-Lim (Graduate Student, Korea Aerospace University) ;
  • Kim, Yang-Do (School of Materials Science and Engineering, Pusan National University)
  • 장시영 (한국항공대학교 항공재료공학과) ;
  • 김예림 (한국항공대학교 대학원) ;
  • 김양도 (부산대학교 신소재공학부)
  • Published : 2008.01.20
Download PDF
⟨ Previous Next ⟩

Abstract

The characteristics, such as roughness, thickness, microhardness and corrosion resistance, of plasma electrolytic oxide coatings on AZ91D alloy were investigated under the processing condition of various coating times. The coatings on AZ91D alloy consisted of MgO, $MgAl_{2}O_{4}$ and $Mg_{2}SiO_{4}$ oxides. The surface roughness and thickness of coatings became larger with increasing the coating time. The microhardness in cross section of coatings was much higher than not only that in surface but that in the conventional anodic oxide coatings, which increased progressively as the coating time increased. After being immersed in 3.5%NaCl solution and methyl alcohol, the corrosion resistance of AZ91D alloy was markedly improved by plasma electrolytic oxidation coating treatment, and the AZ91D alloy coated for 50min revealed excellent corrosion resistance.

Keywords

References

  1. E. F. Emley: Principles of Magnesium Technology (Pergamon Press, London 1966)
  2. H. Y. Hsiao, H. C. Tsung and W. T. Tsai: Surf. Coat. Tech., "Anodization of AZ91D magnesium alloy in silicatecontaining electrolytes", 199 (2005) 127-134 https://doi.org/10.1016/j.surfcoat.2004.12.010
  3. A. L. Yerokhin, L. O. Snizhko, N. L. Gurevina, A. Leyland, A. Pilkington and A. Matthews: Surf. Coat. Tech.,"Spatial characteristics of discharge phenomena in plasma electrolytic oxidation of aluminium alloy", 177-178 (2004) 779-783 https://doi.org/10.1016/j.surfcoat.2003.06.020
  4. A. L. Yerokhin, X. Nie, A. Leyland, A. Matthews and S. J. Dowey: Surf. Coat. Tech., "Plasma electrolysis for surface engineering", 122 (1999) 73-93 https://doi.org/10.1016/S0257-8972(99)00441-7
  5. J. Liang, B. Guo, J. Tian, H. Liu, J. Zhou and T. Xu: Appl. Surf. Sci., "Effect of potassium fluoride in electrolytic solution on the structure and properties of microarc oxidation coatings on magnesium alloy", 252 (2005), 345-351 https://doi.org/10.1016/j.apsusc.2005.01.007
  6. J. A. Curran and T. W. Clyne: Surf. Coat. Tech., "The thermal conductivity of plasma electrolytic oxide coatings on aluminium and magnesium", 199 (2005) 177-183 https://doi.org/10.1016/j.surfcoat.2004.11.045
  7. H. Duan, C. Yan and F. Wang: Electrochimi. Acta, "Growth process of plasma electrolytic oxidation filma formed on magnesium alloy AZ91D in silicate solution", 52 (2007) 5002-5009 https://doi.org/10.1016/j.electacta.2007.02.021
  8. Zhenqiang Wu, Yuan Xia, Guang Li and Fangtao Xu: Appl. Surf. Sci., "Structure and mechanical properties of ceramic coatings fabricated by plasma electrolytic oxidation on aluminized steel", 253 (2007) 8398-8403 https://doi.org/10.1016/j.apsusc.2007.04.007
  9. B. G. Yu, Y. L. Kim, K. S. Lee and S. Y. Chang: Proceedings of the 1st Asian Symposium on Mg alloys, "Plasma electrolytic oxidation of Mg-Al alloys: mechanical properties and corrosion resistance of coatings", (2005) 321-324
  10. S. Y. Chang, Y. L. Kim, B. H. Song and J. H. Lee: "Mater. electrochemical properties of plasma electrolytic oxide coatings on magnesium alloys", 539-543 (2007) 1224-1229
  11. Japan Inst. of Magnesium: Handbook of Advanced Magnesium Technology (Kallos Publishing Co., Tokyo 2000)
  12. E. Ghali: Uhlig's Corrosion Handbook, 2nd Ed. (John Wiley and Sons, lnc., 2000)