Influence of Negative Voltage on Micro-Arc Oxidation of Magnesium Alloy under Two Steps Voltage-Increasing Mode

Abstract:

The effects of different negative voltages on micro-arc oxidation coating fabricated on ZK60 Mg alloy were investigated under two steps increasing mode of 280-360V. The microstructure, coating thickness and corrosion resistance of coatings were evaluated by scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), microscope with super-depth of field and electrochemical impedance spectroscopy (EIS). Current-time responses during MAO process were also analyzed combined with coating characteristic. The results reveal that higher negative voltage helped to develop a compact, smooth, thicker and better corrosion-resistant coating. The coating with maximum thickness of about 20.2μm formed under negative voltage of 20V exhibits higher impedance value and the best corrosion resistance.

• Periodical: Key Engineering Materials (Volumes 575-576)
• Pages: 472-476
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.575-576.472
• Online since: September 2013
• Authors: Xi Zhi Jiang, Sheng Lu, Li Tang, Ze Xin Wang, Jing Chen
• Keywords: Coating, Magnesium Alloy, Micro-Arc Oxidation, Negative Voltage, Two Steps Voltage-Increasing

References

[1] G.L. Makar, J. Kruger, Corrosion studies of rapidly solidified magnesium alloy, J. Electrochem. Soc. 137 (1990) 414-421.

DOI: 10.1149/1.2086455

[2] E. Aghion, B. Bronfin, D. Elezer, The role of the magnesium industry in protecting the environment, J. Mater. Process Technol, 117 (2001) 381.

[3] H. F. Guo, M. Z. An, Growth of ceramic coatings on AZ91D magnesium alloys by micro-arc oxidation in aluminate-fluoride solutions and evaluation of corrosion resistance, Applied Surface Science, 246 (2005) 229-238.

DOI: 10.1016/j.apsusc.2004.11.031

[4] H. Y. Hsiao, W. T. Tsai, Characterization of anodic films formed on AZ91D magnesium alloy, Surface and Coatings Technology, 190 (2005) 299-308.

DOI: 10.1016/j.surfcoat.2004.03.010

[5] G. J. Li, L. Li, C.Q. Xu, Research process of micro-arc oxidation ceramic coating on magnesium alloy, Hot Working Technology, 37 (2008) 94-97.

[6] A. Da Forno, M. Bestetti, Effect of the electrolytic solution composition on the performance of micro-arc anodic oxidation films formed on AM60B magnesium alloy, Surface and Coatings Technology, 205 (2010) 1783-1788.

DOI: 10.1016/j.surfcoat.2010.05.043

[7] Y. Yang, H. Wu, Effect of current density on corrosion resistance of micro-arc oxide coatings on magnesium alloy, Trans. Nonferrous Met. Soc. China, 20 (2010) 688-692.

DOI: 10.1016/s1003-6326(10)60563-8

[8] L. Wang, L. Chen, Z.C. Yan, H.L. Wang, J.Z. Peng, The influence of additives on the stability behavior of electrolyte, discharges and PEO films characteristics, Journal of Alloys and Compounds, 493 (2010) 445-452.

DOI: 10.1016/j.jallcom.2009.12.123

[9] L.R. Chang, F.H. Cao, J.S. Cai, W.J. Liu, Z. Zhang, J.Q. Zhang, Influence of electric parameters on MAO of AZ91D magnesium alloy using alternative square-wave power source, Transactions of Nonferrous Metals Society of China, 21 (2011) 307-316.

DOI: 10.1016/s1003-6326(11)60714-0

[10] Y. Xu, Recent development of microarc oxidation technology in China, Corrosion and Protection, 24 (2003) 154-157.

[11] P. Bala Srinivasan, J. Liang, C. Blawert, M. Störmer, W. Dietzel, Effect of current density on the microstructure and corrosion behaviour of plasma electrolytic oxidation treated AM50 magnesium alloy, Applied Surface Science, 255 (2009).

DOI: 10.1016/j.apsusc.2008.11.008

[12] B.L. Jiang, L.L. Bai, Y.F. Jiang, S.F. Zhang, The technique of microarc oxidation on aluminum alloy, Journal of Xi`an University of Technology, 16 (2000) 138-142.

[13] J.M. Hao, H. Chen, R.J. Zhang, Effects of electric parameters on density and electrochemical impedance of ceramic layer made by micro-arc oxidation on magnesium alloy, Corrosion and Protection, 24 (2003) 249-251.

[14] S. Lu, L. Tang, X.Z. Jiang, Z.X. Wang, J. Chen, Growth characteristics, microstructure and corrosion resistance of micro-arc oxidation coatings fabricated on ZK60 Mg alloy under two steps voltage-increasing mode, Advanced Materials Research, 337 (2011).

DOI: 10.4028/www.scientific.net/amr.337.101

[15] Z.D. Liu, H. Fu, M.J. Sun, Z.Y. Zhang, Influence of negative voltage on coating of magnesium alloy micro-arc oxidation, Light Metals, (2009) 45-48.

[16] W. Han, Y.D. He, D.R. Wang, R.D. Xue, W. Gao, ZrO2-Y2O3 coating prepared by cathodic plasma electrolysis deposition, Chinese Journal of Rare Metals, 28(2004) 622-625.

[17] M. Chen, Research on the local arc discharge mechanism and the characteristics of power supply in micro-arc oxidation of magnesium alloy, Lanzhou University of Technology, 2010, pp.42-44.

[18] S. Lu, Z.X. Wang, J. Chen, X.S. Zhou, Optimization of dual electrolyte and characteristic of micro-arc oxidation coating fabricated on ZK60 Mg alloy, Transactions of Nonferrous Metals Society of China, 21 (2011) 929-935.

DOI: 10.1016/s1003-6326(11)60803-0

[19] Z. Zhang, The research on waveform and negative pulse effect for microarc oxidation, Lanzhou University of Technology, 2012, pp.35-41.

[20] G.H. Peng, X.F. Guo, L. Fang, B.J. Han, X.L. Zhang, Effect of negative pulse voltage on microstructure and corrosion resistance of microarc oxidation film on A356 aluminum alloy, Surface Technology, 39 (2010) 77-79.

DOI: 10.4028/www.scientific.net/msf.675-677.1193