pH Value of Micro-arc Oxidation Solution on the Properties of ZM5 Film
Received:October 09, 2023  Revised:November 20, 2023
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DOI:10.7643/issn.1672-9242.2023.12.018
KeyWord:magnesium alloy  micro-arc oxidation  pH value  corrosion resistance  impedance  hardness
                 
AuthorInstitution
WANG Hao-wei Key Laboratory of Aviation Science and Technology for Structural Corrosion Protection and Control, China Special Vehicle Research Institute, Hubei Jingmen , China
ZHU Pei Key Laboratory of Aviation Science and Technology for Structural Corrosion Protection and Control, China Special Vehicle Research Institute, Hubei Jingmen , China
YIN Qiang Key Laboratory of Aviation Science and Technology for Structural Corrosion Protection and Control, China Special Vehicle Research Institute, Hubei Jingmen , China
LIU Yuan-hai Key Laboratory of Aviation Science and Technology for Structural Corrosion Protection and Control, China Special Vehicle Research Institute, Hubei Jingmen , China
WANG Yuan-yuan Key Laboratory of Aviation Science and Technology for Structural Corrosion Protection and Control, China Special Vehicle Research Institute, Hubei Jingmen , China
HE Wei-ping Key Laboratory of Aviation Science and Technology for Structural Corrosion Protection and Control, China Special Vehicle Research Institute, Hubei Jingmen , China
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Abstract:
      Magnesium alloys possess high specific strength attributed to their low density, but the inferior corrosion resistance has severely impeded their widespread implementation. In an endeavor to expand the application scope of magnesium alloys in national defense and military apparatus, it is necessary to adopt surface treatment to improve their corrosion resistance. ZM5 magnesium alloy was selected as the research subject, and its surface was altered by micro-arc oxidation technology. Firstly, ZM5 alloy substrate was pretreated. Thereafter, micro-arc oxidation ceramic coating was in-situ engendered on the surface of ZM5 by means of micro-arc oxidation in electrolyte solutions under different pH values. Finally, scanning electron microscope, X-ray diffraction, and electrochemical testing were utilized to systemically study the effect of micro-arc oxidation treatment on the morphology, composition, micro-structure and performance of the ZM5 magnesium alloy substrate. The results demonstrated that adjusting the solution pH effectively produced continuous and complete micro-arc oxidation coatings on the surface. The coating prepared at pH=11 showed superior corrosion resistance and substantially reduced the corrosion current density, with a thickness of 35.1 μm. Micro-arc oxidation surface treatment drastically increased the surface hardness of the magnesium alloy to a maximum of 582HV. The alteration of solution pH enables the ceramic coating to acquire superior corrosion resistance and enhances surface hardness, thus providing feasibility for further expanding the application of magnesium alloys in military equipment.
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