Influence of voltage modes on microstructure and corrosion resistance of micro-arc oxidation coating on magnesium alloy

Abstract

Micro-arc oxidation (MAO) technology, as an efficient and widely used technology, can fabricate a ceramic film on magnesium (Mg) alloys in situ to significantly improve corrosion resistance. The study aims to investigate the effect of voltage modes on the preparation and performance of MAO coating on Mg alloys. The scanning electron microscope, X-ray diffractometer, potential dynamic polarization, and electrochemical impedance spectroscopy measurements were applied for characterizing the microstructure, composition, and corrosion resistance of the MAO film, respectively. The results revealed that employed 300/350 V step-up mode, the MAO film showed a more uniform distribution of surface micro-pores, fewer micro-cracks and denser inner layer, lower corrosion current density (1.871 × 10⁻³mA·cm⁻²), and higher electrochemical impedance value, compared to other voltage treated parameters. Therefore, it could be concluded that the step-up voltage parameters are conducive to the optimization of microstructure, improvement of corrosion resistance of MAO coating, and reduction of the energy consumption during processing.

Keywords:

• Magnesium alloys
• micro-arc oxidation
• voltage modes
• microstructure
• corrosion resistance

Disclosure statement

The authors declare no competing financial interest.

Author contributions

Conceptualization: [Lianxi Chen]; Methodology: [Ruifang Zhao], [Dongchu Chen]; Formal analysis and investigation: [Lianxi Chen], [Ruifang Zhao], [Dongchu Chen]; Writing - original draft preparation: [Lianxi Chen]; Writing – review and editing: [Xiaojian Wang], [Dongchu Chen]; Funding acquisition: [Lianxi Chen], [Ruifang Zhao]; Resources: [Shengfeng Zhou]; Supervision: [Wei Li].

Acknowledgments

This work was supported by Supported by National Key R&D Program of China (2017YFB0305100, 2017YFB0305104). Dongchu Chen acknowledges the financial support from Guangdong Provincial Key R&D Programme (2020B010186001) and Foshan Science and Technology Innovation Project (1920001000412).

Data availability statement

The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.

Additional information

Funding

Lianxi Chen acknowledges the financial support from Guangdong Basic and Applied Basic Research Foundation (2019A1515110580; 2022A1515011752). Ruifang Zhao acknowledges the financial support from Guangdong Academy of Science (2019GDASYL-0103017).