| 摘要: |
| 为探究氧化石墨烯（GO）在金属加工液领域的应用潜能，采用改进Hummers法合成了GO，对其进行正辛胺的边缘功能化修饰，并构建了基于功能化GO的Pickering乳液。研究了功能化GO在液-液界面的油水界面行为，以及GO基Pickering乳液在固-液界面的摩擦学行为。利用全自动界面张力仪研究了功能化GO在不同油水界面的界面张力；利用UMT-tribolab和白光干涉仪研究了GO基Pickering乳液在CoCrMo合金和304不锈钢表面的界面润滑性能；利用Micro-Raman和XPS分析金属摩擦副表面的润滑膜组成，以阐明GO基Pickering乳液的润滑作用机理。研究结果表明：GO基Pickering乳液比空白乳液的减摩性能好，且胺功能化GO在CoCrMo合金上比在304不锈钢上展现出更优的润滑性能。对比空白乳液，在对摩擦副为CoCrMo合金时，GO乳液可降低35.9%的平均摩擦因数和46.7%的钢球磨损率，而Oct-N-GO乳液则可降低48.7%的平均摩擦因数和73.0%的钢球磨损率。机理分析表明，功能化GO良好的界面润湿性能使其所构建的Pickering乳液可以在金属表面形成良好的界面润滑膜；其结构中的烷基胺在摩擦过程中更易发生剪切，降低界面剪切力而起减摩作用；同时，其所形成的润滑膜组分中含有较高的C-O-C/C-OH和C=O，更好地吸附或填补到金属表面而起抗磨作用。 |
| 关键词: 氧化石墨烯 边缘功能化 界面张力 Pickering乳液 摩擦学行为 |
| DOI：10.11933/j.issn.1007-9289.20190318001 |
| 分类号:TH117 |
| 基金项目:国家自然科学基金（21703279） |
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| Triobological Behavior of Pickering Emulsions Stabilized with Alkylamine Edge-functionalized Graphene Oxide |
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YANG Hongmei, LI Jiusheng, ZENG Xiangqiong
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Shanghai Advanced Research Institute, Chinese Academy of Sciences, University of Chinese Academy Sciences, Shanghai 200120, China
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| Abstract: |
| In order to explore the potential application of graphene oxide (GO) in the field of metalworking fluid, GO was synthesized by improved Hummers' method, followed by edge-functionalization with n-octanylamine, and Pickering emulsions based on functionalized GO were constructed. The oil-water interfacial behaviors of functionalized GO at liquid-liquid interfaces, together with the tribological behaviors of GO-based Pickering emulsions at solid-liquid interfaces were respectively studied. The interfacial tension of functionalized GO at different oil-water interfaces was studied by full-automatic interfacial tension tester. And the interfacial lubricating properties of GO-based Pickering emulsions on CoCrMo alloy and 304 stainless steel were studied by UMT-tribolab and white light interferometer. To clarify the lubricating mechanism of GO-based Pickering emulsions, the composition of lubricating films on metal friction pairs was analyzed by Micro-Raman and XPS. The results show that the friction-reducing properties of GO-based Pickering emulsions are better than that of base emulsion, and alkylamine functionalized GO shows better lubrication performance on CoCrMo alloy than on that 304 stainless steel. Compared with base emulsion, when the friction counterpart is CoCrMo alloy, GO emulsion can reduce the average friction coefficient and the steel ball wear rate by 35.9% and 46.7% respectively, while Oct-N-GO emulsion can reduce the average friction coefficient (COF) and the wear rate of steel ball by 48.7% and 73.0% respectively. The mechanism analysis shows that the good interfacial wettability of functionalized GO enables its Pickering emulsion to form a better interfacial lubricating film on metal surfaces. The alkylamine chains at GO edges are more prone to be sheared during friction, which reduces the interfacial shear force and results in reducing friction. At the same time, the lubricating film formed by Oct-N-GO contains higher content of C−O−C/C−OH and C=O, which can adsorb or fill the metal surfaces and play an anti-wear role. |
| Key words: graphene oxide edge-functionalization interfacial tension Pickering emulsion tribological behavior |
