| LI Wen-yan,YANG Han-ming,XIA Zu-xi,PENG Hua-qiao,SHI Tao.Superhydrophobic Properties of Aluminum Alloy Surfaces Modified by Two Silane Coupling Agents[J],52(9):340-350 |
| Superhydrophobic Properties of Aluminum Alloy Surfaces Modified by Two Silane Coupling Agents |
| Received:September 11, 2022 Revised:February 24, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.09.030 |
| KeyWord:aluminum alloy superhydrophobic freezing time frosting self-cleaning |
| Author | Institution |
| LI Wen-yan |
The Second Research Institute of Civil Aviation Administration of China, Chengdu , China;Key Laboratory of Aviation Fuel & Chemical Airworthiness and Green Development, Civil Aviation Administration of China, Chengdu , China |
| YANG Han-ming |
Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu , China |
| XIA Zu-xi |
The Second Research Institute of Civil Aviation Administration of China, Chengdu , China;Key Laboratory of Aviation Fuel & Chemical Airworthiness and Green Development, Civil Aviation Administration of China, Chengdu , China |
| PENG Hua-qiao |
The Second Research Institute of Civil Aviation Administration of China, Chengdu , China;Key Laboratory of Aviation Fuel & Chemical Airworthiness and Green Development, Civil Aviation Administration of China, Chengdu , China |
| SHI Tao |
The Second Research Institute of Civil Aviation Administration of China, Chengdu , China;Key Laboratory of Aviation Fuel & Chemical Airworthiness and Green Development, Civil Aviation Administration of China, Chengdu , China |
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| Abstract: |
| In order to investigate the effects of the silane coupling agent on properties of superhydrophobic aluminum alloy surfaces, superhydrophobic surfaces were prepared on AMS 4037 aluminum alloy by chemical etching combining with modification of two kinds of silane coupling agents. Via an etching process with hydrochloric acid and hydrogen peroxide mixed solution, hierarchical honeycomb micro/nano structures were formed on AMS 4037 aluminum alloy surfaces. Then, the etched surface was treated with different concentrations of silane and fluorosilane, respectively. The effect of silane coupling concentration on wettability was also investigated systematically. The wettability and surface free energy of as-prepared samples were characterized and calculated by a contact angle meter. The microscopic appearance and chemical composition were analyzed by SEM, LSCM and energy spectrum. Meanwhile, the freezing process of water droplets on the surface with various wettability was observed with a high speed camera and the freezing time was calculated based on the video images. Anti-icing and self-cleaning behaviors of the surfaces treated with two modifiers were tested respectively. The results showed that the hydrophobicity of as-prepared samples was not always positively related to the concentration of the silane coupling. When the modifier was 0.5wt.%, the contact angle of the etched surface treated with silane coupling agent was 156.3°, but the sliding angle was more than 30°, while the fluorosilane-modified surface reached a maximum contact angle of 164.4° and a rolling angle of 6°, which was definitely a superhydrophobic surface. When the concentration of modifiers continued to increase, the hydrophobicity of both surfaces became worse, which may be due to the effect of the way in which the surface modifier molecules were packed. The freezing time of water droplets with a volume of 5 μL on the superhydrophobic surface modified by silane coupling agent and the fluorosilane was divided into 37 s and 45 s, respectively. And the lower freezing front speed on the surface with better hydrophobicity was observed. The anti-icing for the superhydrophobic surface attributed to the quite small contact area and the high thermal resistance between the liquid-solid interfaces. The anti-icing test illustrated that compared with the original aluminum alloy surface, the superhydrophobic surfaces had longer freezing time and could delay icing, and the surface modified by fluorosilane had better anti-icing performance. It was found that the size of areas frozen was negatively correlated with hydrophobicity of surface. Under the same conditions, the better the hydrophobicity, the less ice is covered on the surface of the aluminum alloy. The frozen area of the etched surface modified with silane coupling agent is smaller than that of the untreated surface. The frozen area of the etched surface modified by the fluorosilane coupling agent is smaller than that of the surface modified by the silane coupling agent. This fact can be explained by the reduction of solid-droplet interface and increase of thermal resistance resulting from trapped gas. The self-cleaning experiments also prove that the surface modified by fluorosilane has better self-cleaning performance than the silane-modified surface, and the small dust particles on the surface are easier to remove. |
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