| REN Wei-wei,LIANG Si-yan,FU Dian-bao,LI Qiang,CHEN Jun-feng.In-situ Preparation of Mg-Al LDH/PEO Film on Aluminum Alloy PEO Coatings and Its Corrosion Resistance[J],49(4):254-262 |
| In-situ Preparation of Mg-Al LDH/PEO Film on Aluminum Alloy PEO Coatings and Its Corrosion Resistance |
| Received:April 29, 2019 Revised:April 20, 2020 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2020.04.029 |
| KeyWord:aluminum alloy micro-arc oxidation hydrotalcite corrosion performance |
| Author | Institution |
| REN Wei-wei |
School of Materials Science and Engineering, Fuzhou University, Fuzhou , China |
| LIANG Si-yan |
School of Materials Science and Engineering, Fuzhou University, Fuzhou , China |
| FU Dian-bao |
School of Materials Science and Engineering, Fuzhou University, Fuzhou , China |
| LI Qiang |
School of Materials Science and Engineering, Fuzhou University, Fuzhou , China |
| CHEN Jun-feng |
School of Materials Science and Engineering, Fuzhou University, Fuzhou , China |
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| Abstract: |
| The work aims to optimize the preparation process of Mg-Al LDH/MAO coating and improve the corrosion resistance of aluminum alloy. The micro-arc oxidation samples were placed in different pH solutions. Under different reaction time and at different reaction temperature, MgAl-LDH/MAO composite coating containing NO3– between layers was successfully prepared by in-situ growth method on the surface of 2024 aluminum alloy. The microstructure of LDH/MAO was studied by SEM, EDS and XRD. The corrosion behavior of MgAl-LDH/MAO composite coating samples was characterized by electrochemical method, revealing the corrosion resistance mechanism of the composite coating and the best process conditions. The coatings prepared in solutions with pH=6 and pH=7 produced a small amount of LDHs, mostly concentrated near the pores and incompletely grown. The coating prepared by the solution with pH=9 had more uniform flaky hydrotalcite, lower corrosion current and higher corrosion potential. When the reaction time was 12 h, only some holes produced LDHs. The morphology of the alloy prepared by the reaction time of 24 h and 48 h was not much different, the hydrotalcite was obviously more than that of 12 h, and was more uniform; the LDHs formed by the alloy with the reaction temperature of 180 ℃ and 220 ℃ were more uniform and the growth was better, which had Obvious sheet structure. The results show that the preparation environment of weak base, the increase of reaction temperature and the prolongation of reaction time promote the preparation of Mg-Al LDH/MAO composite coating, which effectively improves the corrosion resistance of 2024 aluminum alloy. |
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