王超颖,章亦乐,徐兵,杨华勇,陈哲.醇分子吸附对石墨基面纳米摩擦行为的影响研究[J].表面技术,2024,53(21):1-5, 33.
WANG Chaoying,ZHANG Yile,XU Bing,YANG Huayong,CHEN Zhe.Effect of Alcohol Molecules Adsorption on Nanoscale Friction Behaviour of Graphite Basal Plane[J].Surface Technology,2024,53(21):1-5, 33 |
| 醇分子吸附对石墨基面纳米摩擦行为的影响研究 |
| Effect of Alcohol Molecules Adsorption on Nanoscale Friction Behaviour of Graphite Basal Plane |
| 投稿时间：2024-10-21 修订日期：2024-11-05 |
| DOI：10.16490/j.cnki.issn.1001-3660.2024.21.001 |
| 中文关键词: 石墨 醇分子吸附 纳米摩擦 摩擦化学反应 原子力显微镜 |
| 英文关键词:graphite alcohol molecules adsorption nanoscale friction tribochemical reactions atomic force microscopy |
| 基金项目:浙江省自然科学基金资助项目(LR24E050001);浙江省“尖兵”研发攻关计划项目(2023C01086);国家自然科学基金项目 |
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| Author | Institution |
| WANG Chaoying | State Key Laboratory of Fundamental Components of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310058, China |
| ZHANG Yile | State Key Laboratory of Fundamental Components of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310058, China |
| XU Bing | State Key Laboratory of Fundamental Components of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310058, China |
| YANG Huayong | State Key Laboratory of Fundamental Components of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310058, China |
| CHEN Zhe | State Key Laboratory of Fundamental Components of Fluid Power and Mechatronic Systems, Zhejiang University, Hangzhou 310058, China |
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| 中文摘要: |
| 目的 探究石墨基面的纳米尺度摩擦行为及其调控机制。方法 将表面洁净的高定向热解石墨块状晶体浸没在高纯度的醇中，一段时间后取出并用干燥氮气吹干。用原子力显微镜对石墨基面上的摩擦力和黏附力进行测量。结果 石墨基面的摩擦力和黏附力在醇中处理后发生显著变化，且随着醇分子碳链的增长而减小，石墨基面上的超低摩擦在正庚醇中处理后减少了约50%，而在甲醇中处理后则增加了8倍。研究表明，吸附在接触界面的醇分子能够调节相对滑动界面的接触公度性，构象熵大的高碳醇分子促进了界面滑动从而减小摩擦力。接触区域发生的摩擦化学反应也是造成石墨表面摩擦力变化的重要原因，反应产物的生成增大了探针与石墨之间的接触面积，从而增大摩擦力。此外，摩擦化学反应速率随着醇分子碳链长度的增加而减慢，进一步影响了摩擦性能。结论 本研究揭示了通过物理吸附醇分子来调节石墨表面摩擦学性能的新机制，结果表明醇类分子的结构和摩擦化学反应对润滑性能有显著影响，这一发现为调控石墨以及石墨烯的摩擦性能提供了新思路。 |
| 英文摘要: |
| The work aims to investigate the nanoscale friction behaviour of graphite basal planes, as well as the mechanisms underlying its modulation. Highly oriented pyrolytic graphite (HOPG) crystals with freshly cleaved surfaces were immersed in high-purity alcohols for a controlled duration. After immersion, the crystals were dried with dry nitrogen gas to eliminate residual solvents for further analysis. The friction and adhesion forces on the graphite basal planes were then analyzed by atomic force microscopy (AFM). It was observed that both the friction and adhesion forces on the graphite surface notably changed following exposure to different alcohols. Specifically, the friction and adhesion forces decreased as the carbon chain length of the alcohol molecules increased. This result suggests a strong correlation between the molecular structure of alcohols and their ability to modulate the tribological properties of graphite basal planes. Under an applied load of 5 nN, the initially ultra-low friction on the graphite basal plane ((0.030±0.024) nN) was reduced by approximately 50% ((0.014±0.009) nN) after treatment in n-heptanol, a long-chain alcohol. In stark contrast, treatment with methanol, a short-chain alcohol, caused an eightfold increase in friction ((0.237±0.024) nN). This striking variation in friction behaviour highlights the significant effect of alcohol chain length on the performance of sliding interface. The underlying mechanism for this modulation lies in the interaction between the alcohol molecules and the contact interface. Alcohol molecules adsorbed at the sliding interface are able to regulate the contact quality. Long-chain alcohols, such as n-heptanol, possess higher conformational entropy, which facilitates easier interfacial sliding, thereby reducing friction. In contrast, short-chain alcohols like methanol induce less conformational entropy and thus hinder the sliding process, leading to increased frictional resistance. Another crucial aspect of this study is the role of friction-induced chemical reactions. The Si atoms in the SiO2 tip are highly susceptible to attack by the oxygen atoms in alcohol molecules, triggering nucleophilic substitution reactions, resulting in the formation of silica gel on the surface of the tip. The presence of this silica gel increases the contact area between the AFM tip and the graphite surface, which in turn contributes to higher friction and adhesion forces. Moreover, with the increase of the size of alcohol molecules, the nucleophilicity decreases, and the low carbon alcohol molecules are easier to approach silicon atoms in the process of nucleophilic substitution, and the tribochemical reaction rate is faster, which further affects the frictional behaviour. This study reveals a novel mechanism for regulating the frictional properties of graphite through the physical adsorption of alcohol molecules and friction-induced chemical reactions. The results demonstrate that the molecular structure of alcohols, particularly the length of their carbon chains, along with the rate of tribochemical reactions, play a critical role in determining the lubrication performance of graphite. These findings provide insights into the control and optimization of tribological properties of graphite, offering new opportunities for its application in nanoscale devices and lubrication systems. |
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