Fabrication and characterization of micro-arc oxidation (MAO) coatings on Mg-Li alloy in alkaline polyphosphate electrolytes without and with the addition of K2TiF6
✍ Scribed by L. Song; Y. Kou; Y. Song; D. Shan; G. Zhu; E.-H. Han
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- German
- Weight
- 990 KB
- Volume
- 62
- Category
- Article
- ISSN
- 0947-5117
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✦ Synopsis
Micro-arc oxidation (MAO) has been accomplished on Mg-Li alloy in alkaline polyphosphate electrolytes without and with the addition of 10 g/L K 2 TiF 6 . The surface/cross-section microstructures of the fabricated coatings were analyzed by scanning electron microscope (SEM); the compositions of the fabricated MAO coatings were analyzed by X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDAX); the corrosion behaviors of bare and MAO coated Mg-Li alloys were evaluated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) in 3.5 wt% NaCl solution. Novel hybrid MAO coatings which showed hybrid composition of MgF 2 /Ti 2 O 5 /Ti 6 O 11 /MgO, as well as hybrid structure of a dense inner layer, a dense outer layer and an intermediate layer with some sealed/semi-sealed pores, had been fabricated on Mg-Li alloy in alkaline polyphosphate electrolytes with the addition of K 2 TiF 6 . Meanwhile, the corrosion resistance of the fabricated MAO coatings was improved obviously as the result of the addition of K 2 TiF 6 in the electrolytes. Moreover, the multiple roles of TiF 2- 6 on the MAO process accounted for the fabrication of the corrosion-resistant hybrid MAO coatings.