| CAO Ya-xin,WANG Meng-jie,ZHOU Fan,YANG Hong-fei.Effect of KOH Concentration on the Growth Process and Corrosion Resistance of Micro-arc Oxidation (MAO) Coatings on LA103Z Mg-Li Alloy[J],50(3):348-355 |
| Effect of KOH Concentration on the Growth Process and Corrosion Resistance of Micro-arc Oxidation (MAO) Coatings on LA103Z Mg-Li Alloy |
| Received:March 16, 2020 Revised:June 22, 2020 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2021.03.038 |
| KeyWord:magnesium lithium alloy MAO potassium hydroxide growth process corrosion resistance |
| Author | Institution |
| CAO Ya-xin |
State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an , China |
| WANG Meng-jie |
State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an , China |
| ZHOU Fan |
State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an , China |
| YANG Hong-fei |
Xi’an Flit Heat Treatment Co., Ltd, Xi’an , China |
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| Abstract: |
| This paper aims to explore the effect of KOH concentration on the growth process and corrosion resistance of MAO coatings on LA103Z Mg-Li alloy. The method adopted in this paper is to prepare the MAO coatings by constant voltage MAO method in the silicate electrolyte system with KOH concentration of 2 g/L, 4 g/L, 6 g/L, respectively. Surface and cross-section morphologies of the MAO coatings were observed by scanning electron microscope (SEM), the porosity and thickness of the MAO coatings were analyzed by Image-J software, and the corrosion resistance of MAO coatings was characterized by electrochemical test. The results showed that with the increase of KOH concentration, the current density passing through the sample increased during micro-arc oxidation process, the number of micropores decreased, the pore size increased, and the thickness of the coating also increases. The corrosion resistance of the sample increases first and then decreases with the increase of KOH concentration. When the KOH concentration is 4 g/L, the micropores on the surface of the coating are uniform and evenly distributed, and the pore size is small (about 2~4 μm), the porosity is the lowest (about 3.56%), and the internal structure of the filmcoating is relatively dense. The coating exhibits the best corrosion resistance, and its self-corrosion current density is 0.26 μA/cm2, which is 2 orders of magnitude lower than that of the substrate. The change of KOH concentration mainly effects the morphology of the coating in the spark discharge stage during the MAO process. Increasing KOH concentration properly can effectively improve the micropores distribution, increase the thickness and the density of the coating, so as to improve the corrosion resistance of the coating. However, when the KOH concentration is too high, the defects such as large holes and cracks inside the coating increase, and the corrosion resistance of the coating decreases. |
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