Characteristics of MAO coating obtained on ZK60 Mg alloy under two and three steps voltage-increasing modes in dual electrolyte

17th IUMRS International Conference in Asia

Yang, Jun^1 ; Wang, Ze-Xin^1 ; Lu, Sheng^1 ; Lv, Wei-Gang^2 ; Jiang, Xi-Zhi^1 ; Sun, Lei^1

School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang

212003, China^1

Zhenjiang Naisi New Materials Co Ltd., Zhenjiang, Jiangsu

212000, China^2

关键词: Breakdown strengths;    Coating characteristics;    Depth of field;    Electrical sources;    Maximum thickness;    Microarc oxidation;    Spark discharge;    ZK60 Mg alloys;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/182/1/012050/pdf
DOI  :  10.1088/1757-899X/182/1/012050

来源: IOP

【 摘 要 】

The micro-arc oxidation process was conducted on ZK60 Mg alloy under two and three steps voltage-increasing modes by DC pulse electrical source. The effect of each mode on current-time responses during MAO process and the coating characteristic were analysed and discussed systematically. The microstructure, thickness and corrosion resistance of MAO coatings were evaluated by scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), microscope with super-depth of field and electrochemical impedance spectroscopy (EIS). The results indicate that two and three steps voltage-increasing modes can improve weak spark discharges with insufficient breakdown strength in later period during the MAO process. Due to higher value of voltage and voltage increment, the coating with maximum thickness of about 20.20μm formed under two steps voltage-increasing mode shows the best corrosion resistance. In addition, the coating fabricated under three steps voltage-increasing mode shows a smoother coating with better corrosion resistance due to the lower amplitude of voltage-increasing.