| YE Zhipeng,SHAO Zhisong,HUANG Wentao,WANG Kun.Improving the Hydrophilicity of Copper-based Surfaces through L-Cysteine Treatment[J],53(22):191-201 |
| Improving the Hydrophilicity of Copper-based Surfaces through L-Cysteine Treatment |
| Received:December 14, 2023 Revised:July 12, 2024 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.22.017 |
| KeyWord:surface modification absorbent core super-hydrophilic homogeneous plate L-cysteine heat transfer performance |
| Author | Institution |
| YE Zhipeng |
Nanchang Hangkong University, Nanchang , China |
| SHAO Zhisong |
Nanchang Hangkong University, Nanchang , China |
| HUANG Wentao |
Nanchang Hangkong University, Nanchang , China |
| WANG Kun |
Nanchang Hangkong University, Nanchang , China |
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| Abstract: |
| This study investigates the impact of L-Cysteine impregnation process on the wettability of copper surfaces, and applies the optimal process obtained to achieve surface modification of absorbent cores. This enhances the capillary ability of the absorbent cores, thereby optimizing heat transfer efficiency of a homogeneous plate. A three-factor five-level orthogonal impregnation experiment was conducted with temperature, time, and concentration as variables. The contact angle between the sample surface and water was measured with a contact angle measurement instrument. The capillary climbing height of water in the liquid absorption core layer was used to characterize the capillary climbing ability. A scanning electron microscopy (SEM) was used to observe the microstructure of the liquid absorption core before and after treatment. An energy dispersive spectrometry (EDS) was used to study the surface element changes of the liquid absorption core before and after treatment. An X-ray photoelectron spectroscopy (XPS) was used to study the changes in the valence states of surface elements of the liquid absorption core before and after treatment. The thermal resistance of the heat plate made from the liquid absorption core before and after L-cysteine impregnation was measured with a temperature measurement platform. The range analysis of the orthogonal experiment showed that the concentration, time, and temperature had different effects on the contact angle between the treated copper plate and water, from high to low. The contact angle decreased from 90° to 7°, indicating superhydrophilicity. The optimal process for obtaining the smallest contact angle of the copper sample was found to be reaction at L-cysteine concentration of 0.1 g/L at 50 ℃ for 90 minutes. The liquid absorption core treated with L-cysteine showed a significant increase in the capillary climbing height of water within 20 seconds, with an improvement in capillary ability of about 40%. The microstructure of the liquid absorption core before and after treatment changed significantly, and flocculent substances could be clearly observed on the dendritic structure surface at 20 000 times magnification. Elemental analysis of the flocculent substances revealed the presence of sulfur (S) elements, with atomic percentages of 1.72%, respectively. XPS showed a shift of the S peak binding energy towards lower binding energy, and some copper was converted from monovalent to divalent, indicating electron transfer between S and Cu and the formation of chemical bond structure between the L-cysteine thiol group and the copper surface. In terms of heat transfer efficiency, the sample treated with L-cysteine showed a temperature difference advantage of obvious compared with that before treatment at the same power, and the maximum heat transfer power was increased by about 200 W. In conclusion, L-cysteine impregnation treatment can significantly improve the hydrophilicity of copper surfaces, and using the optimal process can improve the capillary ability of the heat plate liquid absorption core, thereby improving the heat transfer performance of the heat plate. |
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