| WANG Hua,LIU Yan-yan.Research Progress in the Preparation of Anti-corrosion Superhydrophobic Coatings on Magnesium Alloys[J],52(11):1-22, 127 |
| Research Progress in the Preparation of Anti-corrosion Superhydrophobic Coatings on Magnesium Alloys |
| Received:September 27, 2023 Revised:November 06, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.11.001 |
| KeyWord:magnesium alloy surface treatment self-healing coating superhydrophobic coating corrosion resistance |
| Author | Institution |
| WANG Hua |
School of Chemical Engineering, Dalian University of Technology, Liaoning Dalian , China |
| LIU Yan-yan |
School of Chemical Engineering, Dalian University of Technology, Liaoning Dalian , China |
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| Abstract: |
| Magnesium alloy is a promising green engineering metal material, but its poor corrosion resistance limits its large-scale application. The corrosion resistance and service life of magnesium alloy can be improved by surface treatment. The surface protection technology of magnesium alloy includes electrochemical method (micro-arc oxidation, electrodeposition), chemical conversion method and organic coating protection method. Superhydrophobic surfaces have great application prospects in daily life, industry and agriculture because of their self-cleaning, oil-water separation, anti-icing and anti-corrosion properties. Superhydrophobic treatment of magnesium alloy surface can greatly improve the corrosion resistance of magnesium alloy. Superhydrophobic surfaces refer to surfaces with a contact angle greater than 150° and a sliding angle less than 10°. When the superhydrophobic sample is immersed in the corrosive solution, the structure will form a solid-gas-liquid interface layer in the corrosive medium, reducing the contact area between the magnesium alloy surface and the corrosive medium, thereby reducing the corrosion rate. The superhydrophobic surface needs to meet the two necessary conditions of micro and nano structure and low surface energy. Superhydrophobic surface can be prepared on the surface of magnesium alloy by two-step method or one-step method. The two-step method for preparing superhydrophobic surface of magnesium alloy generally means that micro and nano structures are constructed on the alloy surface first, and then low surface energy modification is carried out. One step method means that both roughness and low surface energy can be achieved simultaneously on the surface of magnesium alloy. This paper describes in detail the methods of constructing micro and nano structures on the surface of magnesium alloy, including laser treatment, machining, chemical etching, electroless plating, electrochemical deposition, anodic oxidation, micro-arc oxidation, hydrothermal synthesis and spraying. Low surface energy materials for preparing superhydrophobic surfaces include long-chain fatty carboxylic acid, fluorosilane, Long chain alkyl silanes, polydimethylsiloxanes and polypropylene (PP), etc. Common carboxylic acids include stearic acid (SA), myristate acid (MA), lauric acid (dodecanoic acid, LA), octadecylphosphonic acid, perfluorocaprylic acid, oleic acid, etc. Fluorosilane include 1H,1H,2H,2H-Perfluorodecyltriethoxysilane (FAS), 1H,1H,2H,2H-Perfluorodecyltrimethoxysilane (PFDTMS), 1H,1H,2H,2H-Perfluorooctyltriethoxysilane(PFOTES), Hexadecyltrimethoxysilane (HDTMS) , etc. However, when the superhydrophobic surface is used for anti-corrosion, once the superhydrophobic surface is damaged, the "air cushion effect" of the superhydrophobic surface will disappear, and the corrosive medium will directly contact the micro and nano structure. Therefore, in this case, it is also necessary to ensure that the constructed micro and nano rough structure has a good protection effect on the magnesium matrix. To this end, it is necessary to develop composite coatings to improve the self-healing properties of the micro and nano structures and the corrosion resistance of the coating under the superhydrophobic surface. The synergistic effect between the superhydrophobicity of the upper coating and the good physical barrier ability of the lower coating can improve the long-term corrosion resistance of the coating. Due to the layered structure of LDH, the synergistic effect of superhydrophobic effect and chloride ion exchange performance can improve the corrosion resistance of the coating, so there are more superhydrophobic composite coatings prepared together with LDH coatings. It has been studied that the combination of micro-arc oxidation coating (PEO) and layered double hydroxide (LDH) can not only seal the micropore defects on the PEO film, but also enable the composite film to have self-healing function when loaded with corrosion inhibitors. Furthermore, surface superhydrophobic modification can greatly improve the long-term corrosion resistance of the composite coating. In this paper, the anticorrosive mechanism of superhydrophobic surface is introduced, and the method of preparing superhydrophobic surface with good corrosion resistance on magnesium alloy is reviewed. The research direction of superhydrophobic surface protection technology for magnesium alloys is also prospected. |
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