Abstract
Ceramic coatings were prepared on the surface of AZ91D magnesium alloy by microarc oxidation technology. The effects of different voltages on morphology, phase composition and thickness of the coatings were characterized by SEM and XRD. The corrosion resistance of the coatings was measured by electrochemical workstation. Results indicated that the microarc oxidation coatings prepared in sodium silicate electrolyte exhibited porous surface and mainly comprised MgO, Mg2SiO4 and a small amount of MgAl2O4. The thickness of the oxide coatings increased rapidly with the increase of voltage. The coating prepared at 400V voltage had good electrochemical corrosion resistance in 3.5wt% NaCl solution.
Highlights
In light metal structural materials, magnesium alloys possess many excellent properties such as high specific strength, good electric conductivity and thermal conductivity, vibration damping, electromagnetic shielding, easy processing molding and recycling use [1]
Microarc oxidation (MAO) has the advantages of simple process, high efficiency and low pollution, which has became the most potential surface treatment technology for magnesium alloys[8]
In the process of MAO, the oxidation reaction of the magnesium substrate and oxygen produced MgO under the action of arc, Mg2SiO4 was generated owing to the participation of the electrolyte
Summary
In light metal structural materials, magnesium alloys possess many excellent properties such as high specific strength, good electric conductivity and thermal conductivity, vibration damping, electromagnetic shielding, easy processing molding and recycling use [1]. They have wide prospect in the fields of electronic industry, aerospace, automobile, biomedicine, etc. The ceramic oxide coating in-situ forms on the surface of nonferrous metal such as Al, Ti and Mg. MAO has the advantages of simple process, high efficiency and low pollution, which has became the most potential surface treatment technology for magnesium alloys[8].
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