Journal of the Korean institute of surface engineering (한국표면공학회지)

The Korean Institute of Surface Engineering (한국표면공학회)
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Effect of NaOH Concentration on the PEO Film Formation of AZ31 Magnesium Alloy in the Electrolyte Containing Carbonate and Silicate Ions

  • Moon, Sungmo (Surface Technology Division, Korea Institute of Materials Science) ;
  • Kim, Yeajin (Surface Technology Division, Korea Institute of Materials Science) ;
  • Yang, Cheolnam (Surface Technology Division, Korea Institute of Materials Science)
  • Received : 2017.10.09
  • Accepted : 2017.10.16
  • Published : 2017.10.31
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Abstract

Anodic film formation behavior of AZ31 Mg alloy was studied as a function of NaOH concentration in 1 M $Na_2CO_3$ + 0.5 M $Na_2SiO_3$ solution under the application of a constant anodic current density, based on the analyses of voltage-time curves, surface appearances and morphologies of the anodically formed PEO (plasma electrolytic oxidation) films. The anodic film formation voltage and its fluctuations became largely lowered with increasing added NaOH concentration in the solution. Two different types of film defects, large size dark spots indented from the original surface and locally extruded white spots, were observed on the PEO-treated surface, depending on the concentration of added NaOH. The large size dark spots appeared only when added NaOH concentration is less than 0.2 M and they seem to result from the local detachments of porous PEO films. The white spots were observed to be very porous and locally extruded and their size became smaller with increasing added NaOH concentration. The white spot defects disappeared completely when more than 0.8 M NaOH is added in the solution. Concludingly it is suggested that the presence of enough concentration of $OH^-$ ions in the carbonate and silicate ion-containing electrolyte can prevent local thickening and/or detachment of the PEO films on the AZ31 Mg alloy surface and lower the PEO film formation voltage less than 70 V.

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References

  1. Nguyen Van Phuong, Sungmo Moon, "The effects of surface pre-treatment methods on the structure and corrosion resistance of zinc phosphate conversion coatings on AZ31 Mg alloy", Science of Advanced Materials, 6 (2014) 1-7. https://doi.org/10.1166/sam.2014.1674
  2. Nguyen Van Phuong, Sungmo Moon, "Comparative corrosion study of zinc phosphate and magnesium phosphate conversion coatings on AZ31 Mg alloy", Materials Letters, 122 (2014) 341-344. https://doi.org/10.1016/j.matlet.2014.02.065
  3. Nguyen Van Phuong, Sungmo Moon, "Deposition and characterization of E-paint on magnesium alloys", Progress in Organic Coatings 89 (2015) 91-99. https://doi.org/10.1016/j.porgcoat.2015.08.014
  4. Basit Raza Fazal, Sungmo Moon, "Formation of Cerium Conversion Coatings on AZ31 Magnesium Alloy", J. Kor. Inst. Surf. Eng., 49 (2016) 1-13. https://doi.org/10.5695/JKISE.2016.49.1.1
  5. Nguyen Van Phuong, Sungmo Moon, "Deposition and Characterization of Electrophoretic Paint on AZ31 Magnesium", J. Kor. Inst. Surf. Eng., 49 (2016) 141-146. https://doi.org/10.5695/JKISE.2016.49.2.141
  6. J. Liang, B. Guo, J. Tian, H. Liu, J. Zhou, T. Xu, Effect of potassium fluoride in electrolytic solution on the structure and properties of microarc oxidation coatings on magnesium alloy, Applied Surface Science. 252 (2005) 345-351. https://doi.org/10.1016/j.apsusc.2005.01.007
  7. H. Duan, C. Yan, F. Wang, Effect of electrolyte additives on performance of plasma electrolytic oxidation films formed on magnesium alloy AZ91D, Electrochimica Acta. 52 (2007), 3785-3793. https://doi.org/10.1016/j.electacta.2006.10.066
  8. L. Chai, X. Yu, Z. Yang, Y. Wang, Masazumi Okido, Anodizing of magnesium alloy AZ31 in alkaline solutions with silicate under continuous sparking, Corros. Sci., 50 (2008) 3274. https://doi.org/10.1016/j.corsci.2008.08.038
  9. S. Moon, Y. Nam, Anodic oxidation of Mg-Sn alloys in alkaline solutions, Corrosion Science 65 (2012) 494-501. https://doi.org/10.1016/j.corsci.2012.08.050
  10. T. S. Lim, H. S. Ryu, S. -H. Hong, Electrochemical corrosion properties of $CeO_2$-containing coatings on AZ31 magnesium alloys prepared by plasma electrolytic oxidation, Corros. Sci. 62 (2012) 104. https://doi.org/10.1016/j.corsci.2012.04.043
  11. S. Moon, Corrosion behavior of PEO-treated AZ31 Mg alloy in chloride solution, Journal of Solid State Electrochemistry. 18 (2014) 341-346. https://doi.org/10.1007/s10008-013-2247-4
  12. S. Moon, C. Yang, S. Na, Effects of Hydroxide and Silicate ions on the Plasma Electrolytic Oxidation of AZ31 Mg Alloy, Kor. Inst. Surf. Eng. 47(2014) 147-154. https://doi.org/10.5695/JKISE.2014.47.4.147
  13. Stojadinovic, Stevan, et al., Characterization of plasma electrolytic oxidation of magnesium alloy AZ31 in alkaline solution containing fluoride, Surface and Coatings Technology 273 (2015) 1-11. https://doi.org/10.1016/j.surfcoat.2015.03.032
  14. X. Lu, C Blawert, Y. Huang, H Ovri, M. L. Zheludkevich, K. U. Kainer, Plasma electrolytic oxidation coatings on Mg alloy with addition of $SiO_2$ particles, Electrochimica Acta 187 (2016) 20-33. https://doi.org/10.1016/j.electacta.2015.11.033
  15. S. Moon, R. Arrabal, E. Matykina, 3-Dimensional structures of open-pores in PEO films on AZ31 Mg alloy, Materials Letters 161 (2016) 439-441.
  16. D. Kwon, S. Moon, Effects of NaOH Concentration on the Structure of PEO Films Formed on AZ31 Mg Alloy in $PO{_4}^{3-}$ and $SiO{_3}^{2-}$ Containing Aqueous Solution, Kor. Inst. Surf. Eng. 49 (2016) 46-53. https://doi.org/10.5695/JKISE.2016.49.1.46
  17. Sungmo Moon, Duyoung Kwon, Anodic Oxide Films Formed on AZ31 Magnesium Alloy by Plasma Electrolytic Oxidation Method in Electrolytes Containing Various NaF Concentrations, Kor. Inst. Surf. Eng. 49 (2016) 225-230. https://doi.org/10.5695/JKISE.2016.49.3.225
  18. Li Wang, Li Chen, Zongcheng Yan, Honglin Wang, Jiazhi 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. https://doi.org/10.1016/j.jallcom.2009.12.123
  19. A. Madhan Kumar, Sun Hwan Kwon, Hwa Chul Jung, Kwang Seon Shin, Corrosion protection performance of single and dual Plasma Electrolytic Oxidation (PEO) coating for aerospace applications, Materials Chemistry and Physics 149-150 (2015) 480-486. https://doi.org/10.1016/j.matchemphys.2014.10.049
  20. Hariprasad S., Gowtham S., Arun S., Ashok M., Rameshbabu N., Fabrication of duplex coatings on biodegradable AZ31 magnesium alloy by integrating cerium conversion (CC) and plasma electrolytic oxidation (PEO) processes, Journal of Alloys and Compounds 722 (2017) 698-715. https://doi.org/10.1016/j.jallcom.2017.06.119
  21. Li Wang, Li Chen, Zongcheng Yan,Honglin Wang, Jiazhi Peng, Effect of potassium fluoride on structure and corrosion resistance of plasma electrolytic oxidation films formed on AZ31 magnesium alloy, Journal of Alloys and Compounds 480 (2009) 469-474. https://doi.org/10.1016/j.jallcom.2009.01.102
  22. M. Toorani, M. Aliofkhazraei, M. Golabadi, A. Sabour Rouhaghdam, Effect of lanthanum nitrate on the microstructure and electrochemical behavior of PEO coatings on AZ31 Mg alloy, Journal of Alloys and Compounds 719 (2017) 242-255. https://doi.org/10.1016/j.jallcom.2017.05.169
  23. Sachiko Ono, Shuichi Moronuki, Yoichi Mori, Akihiko Koshi, Hidetaka Asoh, Effect of Electrolyte Concentration on the Structure and Corrosion Resistance of Anodic Films Formed on Magnesium through Plasma Electrolytic Oxidation, Electrochimica Acta 240 (2017) 415-423. https://doi.org/10.1016/j.electacta.2017.04.110
  24. S. Moon, A Blade-Abrading Method for Surface Pretreatment of Mg Alloys, Kor. Inst. Surf. Eng. 48 (2015) 194-198. https://doi.org/10.5695/JKISE.2015.48.5.194