Influence of Current Density on Structure and Performance of Micro-Arc Oxidation Coatings on AZ31 Magnesium Alloy

Abstract:

In the Na₂SiO₃-NaOH-C₃H₈O₃ electrolyte system,the micro-arc oxidation (MAO) coatings were prepared on AZ31 magnesium alloy when J=2A/dm²,4A/dm²,8A/dm² and 12A/dm².The relations of current density with microstructure and performance of the MAO coatings on AZ31 were studied by means of SEM, XRD, HVS-1000 micro Vicker, MFT-4000 Scratch Tester and electro-chemical method. The results show that when current density increases,the thickness,growth rate,micro-hardness and the contents of MgO and Mg₂SiO₄ of MAO coatings increase,but the adhesion force between MAO coating and substrate decreases, the millipores and the roughness become larger.The corrosion resistance of MAO coatings increases firstly and then decreases with the increasing current density.The corrosion resistance of MAO coating,which J=6 A/dm²,is the best in 4.5% NaCl water solution,whose corrosion current density reduces by 3 orders of magnitude, and corrosion potential increases 1078mV in positive direction.

• Periodical: Advanced Materials Research (Volumes 189-193)
• Pages: 562-566
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.189-193.562
• Online since: February 2011
• Authors: Mei Yang, Zheng Lei, Xiao Hong Wang, Ping Wang, Jun Yang
• Keywords: AZ31 Magnesium Alloy, Current Density, Micro-Arc Oxidation (MAO), Performance

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