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Chinese Journal of Materials Research  2020, Vol. 34 Issue (3): 183-190    DOI: 10.11901/1005.3093.2019.430
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Effect of Hydrothermal Treatment on Microstructure and Corrosion Resistance of Micro-arc Oxidization Ceramic Layer on AZ31 Mg-alloy
WANG Zhihu1,ZHANG Jumei2,BAI Lijing1,ZHANG Guojun1()
1. School of Materials Science and Engineering, Xi'an University of Technology, Xi’an 710048, China
2. School of Materials Science and Engineering, Xi'an University of Science and Technology, Xi’an 710054, China
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The micro-arc oxidization (MAO) ceramic layer on AZ31 Mg-alloy was post-treated by hydrothermal treatment at 125℃ for 18 h with two solutions of different compositions. The effect of hydrothermal solutions on the microstructure and corrosion resistance of MAO ceramic layer was studied, and the relevant formation- and corrosion-mechanism of the film generated via hydrothermal treatment were discussed. The results show that MgO on the MAO ceramic layer was partially dissolved during hydrothermal treatment, and the released Mg2+ was combined with OH- in alkaline hydrothermal solution to form Mg(OH)2 nanosheets, which deposited on the surface of ceramic layer and pores; whereas Al3+ and Co2+ in the other solution might replace some Mg2+ in Mg(OH)2 to form layered double hydroxides (LDH) nanoplates, which could seal the micro-poles and cracks on the MAO ceramic layer. Wettability and electrochemical test results show that the sealing effect of hydrophilic Mg(OH)2 coating on MAO ceramic layer can improve the corrosion resistance of MAO ceramic layer to some extent. However, hydrophobic LDH coating can significantly improve the corrosion resistance of MAO ceramic coating due to the sealing effect and the ion exchange ability of LDH.

Key words:  materials failure and protection      magnesium alloy      micro-arc oxidization      hydrothermal treatment      coating     
Received:  03 September 2019     
ZTFLH:  TG174  
Fund: National Natural Science Foundation of China(51701162);Key Laboratory Project of Shaanxi Education Department(17JS083)
Corresponding Authors:  Guojun ZHANG     E-mail:

Cite this article: 

WANG Zhihu,ZHANG Jumei,BAI Lijing,ZHANG Guojun. Effect of Hydrothermal Treatment on Microstructure and Corrosion Resistance of Micro-arc Oxidization Ceramic Layer on AZ31 Mg-alloy. Chinese Journal of Materials Research, 2020, 34(3): 183-190.

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Fig.1  Cross-section and 3D surface morphologies of the three coatings. (a) and (d) MAO, (b) and (e) HT-1/MAO, (c) and (f) HT-2/MAO
Fig.2  XRD patterns of different samples
Fig.3  General and enlarged views of the surfaces of three coatings, (a) and (d) MAO, (b) and (e) HT-1/MAO, (c) and (f) HT-2/MAO
Fig.4  EDS analysis results of the marked regions of three coatings in Fig.3 (d, e, f) (a) MAO, (b) HT-1/MAO, (c) HT-2/MAO
Fig.5  Static contact angles of three coatings (a) MAO, (b) HT-1/MAO, (c) HT-2/MAO
Fig.6  Polarization curves of AZ31 substrate and three coatings
SamplesEcorr, SCE/VIcorr/A·cm-2Rp/Ω·cm2
Table1  Polarization parameters of AZ31 and three coatings
Fig.7  Nyquist (a) and Bode (b) plots of the three coa-tings
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