Comparative analysis of unipolar and bipolar plasma electrolytic oxidation coatings on Al-Mg laminated macro composites
作者机构：Department of Materials Engineering， Isfahan University of Technology Yekta Mobaddel Pars Co.， Science and Technology Campus， Yazd University Dental Materials Research Center， Dental Research Institute， School of Dentistry， Isfahan University of Medical Sciences
出 版 物：《Transactions of Nonferrous Metals Society of China》 (中国有色金属学报(英文版))
年 卷 期：2024年
核心收录：
学科分类：080503[工学-材料加工工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）]
摘 要：Al-Mg laminated macro composites （LMC） have garnered attention due to their excellent mechanical properties and low density. However， their weak corrosion resistance has limited their industrial applications. Plasma electrolytic oxidation （PEO） has been explored as a potential solution to this issue by producing hard and thick oxide coatings on the surface of Al-Mg LMCs manufactured through hot extrusion bonding. In this study， PEO coatings were prepared on Al-Mg LMCs using both unipolar and bipolar waveforms in an appropriate electrolyte for both aluminum and magnesium alloys. The techniques of FESEM/EDX， GIXRD， and electrochemical methods of Potentiodynamic polarization and EIS were carried out. The results revealed that the coatings produced using the bipolar waveform exhibited lower porosity and higher thickness than those produced using the unipolar one. The corrosion performance of the specimens cut edge was investigated using electrochemical impedance spectroscopy （EIS） after 1， 8， and 12 hours of immersion in a 3.5%wt. NaCl solution. It was observed that the coating produced using the bipolar waveform demonstrated the highest corrosion resistance after 12 hours of immersion， with an estimated corrosion resistance of 41.87 kΩ.cm2， which was approximately three times higher than that of the unipolar coating. Notably， no signs of galvanic corrosion were observed in the LMC， and only minor corrosion attacks were observed on the magnesium layer in some areas.
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