Journal of Lanzhou University of Technology ›› 2023, Vol. 49 ›› Issue (2): 1-8.

• Materials Science and Engineering •     Next Articles

Effects of K2ZrF6 and EDTA-Na additives, voltage and their interactions on corrosion resistance of micro-arc oxidation coatings on magnesium alloys

WANG Hao, MA Ying, WANG Zhan-ying, AN Ling-yun, LIU Yun-po   

  1. State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals, Lanzhou Univ. of Tech., Lanzhou 730050, China
  • Received:2022-03-06 Online:2023-04-28 Published:2023-05-05

Abstract: Micro-arc oxidation (MAO) coatings were prepared on AZ91D magnesium alloys in alkaline phosphate-based electrolyte. The effects of the additives of K2ZrF6 and EDTA-Na, voltage, and their interactions on the coatings were studied based on orthogonal experiment. The thicknesses, morphologies and phase composition of the coatings were examined by using TT260 eddy-current coating thickness gauge, SEM and XRD, respectively. The corrosion resistance of the coatings in acidic media was evaluated by the HNO3 spot test. The results showed that K2ZrF6, EDTA-Na, voltage and their interactions exhibit different effects on the thickness and corrosion resistance of MAO coatings. The effect of the loading voltage on the thickness and corrosion resistance of the coatings is significant. With the voltage increasing, the thickness and the corrosion resistance of the coatings are both improved significantly. The individual factor of K2ZrF6 has little effect on the coating thickness, but it exhibits a certain impact on corrosion resistance of the coatings. The individual factor of EDTA-Na has little effect on the coating thickness and corrosion resistance, While the interaction between K2ZrF6 and voltage is very significant, and the coatings with more excellent comprehensive properties can be obtained when a high concentration of K2ZrF6 and high concentration of EDTA-Na combine with high loading voltage.

Key words: magnesium alloy, micro-arc oxidation, K2ZrF6, EDTA-Na, interaction, corrosion resistance

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