Corrosion Science and Technology

The Corrosion Science Society of Korea (한국부식방식학회)
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An Investigation of Pulse Anodization Duty Ratio and Sealing Treatment on the Corrosion Behavior of the Anodic Coating Layer in Magnesium AZ31B

  • Setiawan, Asep Ridwan (Department of Materials Engineering, Faculty of Mechanical and Aerospaces Engineering, Institute of Technology Bandung) ;
  • Rachman, Muhammad Dani (Department of Materials Engineering, Faculty of Mechanical and Aerospaces Engineering, Institute of Technology Bandung)
  • Received : 2021.01.27
  • Accepted : 2021.03.28
  • Published : 2021.04.30
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Abstract

In this work, we describe the effect of pulse anodizing duty ratio on the corrosion resistance of anodic films in magnesium AZ31B. The process involves the application of square pulse potential for a constant period with a duty ratio varying from 40, 60 and 80%. In several samples, a sealing treatment for 30 minutes was conducted after anodization in order to seal the pores available in the anodic layer. After anodizing, the surface morphology of the anodic layer was examined using a scanning electron microscope (SEM Hitachi SU3500). The corrosion characteristics of the sample were evaluated through an open circuit potential (OCP) and potentiodynamic polarization test using potentiogalvanostat. SEM observation shows that the increase of anodization duty ratio (α) results in a more uniform anodic layer, with fewer pores and cracks. The increase of duty ratio (α) decreases the OCP value from approximately -1.475 to about -1.6 Volt, and significantly improves the corrosion resistance of the anodic coating by 68%. The combination of anodization and sealing treatment produces an anodic coating with a very low corrosion rate of 4.4 mpy.

Keywords

Acknowledgement

This work was financially supported by the P3MI ITB 2020 Research Grant and Department of Materials Engineering, Faculty of Mechanical and Aerospace Engineering, Institute of Technology Bandung.

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