| ZHU Zhi-sheng,LI Wen-fang,YI Ai-hua,DU Jun,ZHU Wen,LIAO Zhong-miao.Influence of Electrolyte Temperature on Properties of Black MAO Coating on AZ31B Mg Alloy[J],48(3):53-61 |
| Influence of Electrolyte Temperature on Properties of Black MAO Coating on AZ31B Mg Alloy |
| Received:November 29, 2018 Revised:March 20, 2019 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2019.03.008 |
| KeyWord:micro-arc oxidation electrolyte temperature blackness and chromatic aberration corrosion resistance tinting mechanism process of coating microstructure morphology |
| Author | Institution |
| ZHU Zhi-sheng |
1.School of Materials Science and Engineering, South China University of Technology, Guangzhou , China |
| LI Wen-fang |
1.School of Materials Science and Engineering, South China University of Technology, Guangzhou , China; 2.School of Mechanical Engineering, Dongguan University of Technology, Dongguan , China |
| YI Ai-hua |
2.School of Mechanical Engineering, Dongguan University of Technology, Dongguan , China |
| DU Jun |
1.School of Materials Science and Engineering, South China University of Technology, Guangzhou , China |
| ZHU Wen |
2.School of Mechanical Engineering, Dongguan University of Technology, Dongguan , China |
| LIAO Zhong-miao |
2.School of Mechanical Engineering, Dongguan University of Technology, Dongguan , China |
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| Abstract: |
| The work aims to study the influence of electrolyte temperature on the coating process, coating properties and black coloring process of micro-arc oxidation (MAO) on magnesium alloy surface. The black MAO coatings were prepared on AZ31B substrates by Si-P electrolyte at different temperature (5, 15, 25, 35 ℃). Blackness and chromatic aberration were determined by UV/VIS/NIR spectrophotometer and phase composition, valence state of V contained in coatings and relative content, and varieties of oxidation contained in coatings were analyzed by XRD, XPS and Raman, respectively. SEM was used to observe microstructure morphology of the coating and the corrosion resistance of MAO coating was evaluated by electrochemi?cal workstation. With the increase of electrolyte temperature, the blackness value of coatings increased from 24.80 (5 ℃) to 29.03 (35 ℃), and chromatic aberration of coatings gradually increased. The ratio of V3+ to V5+ in the coating RVO decreased from 3.6 (5 ℃) to 0.28 (35 ℃). The dimension of pores in the coating decreased firstly and then increased. When electrolyte temperature was 25 ℃, the pores on the coating possessed the minimum dimension and the coating obtained the best compact?ness and the corrosion current density of coatings showed puny change. When electrolyte temperature was 25 ℃, the coating possessed the lowest corrosion current density (5.3 μA/cm2) and the best corrosion resistance. Higher electrolyte temperature causes lighter black and higher chromatic aberration, but the compactness of coatings increase firstly and then decreases with the increase of electrolyte temperature and the corrosion resistance is not sensitive to temperature changes. As the temperature increases, the coatings blackness will decline because of the decrease of RVO value. |
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