Abstract A novel synthesis method of Functionalized Carbon Spheres (FCS) coated with Graphene nanoplatelets (GNP) using a simple sonication technique is reported. The FCS/GNP hybrid nanoparticles were found to be effectively improving the tribological characteristics of lubricating oils. For the synthesis of FCS, Carbon Spheres (CS) synthesized via non-catalytic chemical vapor deposition was functionalized using nitric acid. The hybrid nanoparticles were characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Raman spectroscopy. The tribological behavior of CASTROL-20 W 40 engine oil dispersed with different concentrations of FCS and GNP using ultrasonication was investigated using a four-ball tester. The tribological behavior of FCS and GNP were investigated separately to compare the tribological performance of the FCS/GNP hybrid nanoparticles. The neat oil dispersed with 0.275 wt% of FCS/GNP hybrid nanoparticles in 10:1 ratio shows excellent dispersion and stability for 30 days without the addition of any surfactant. The results indicate that the addition of these hybrid nanoparticles causes a remarkable reduction (~18%) in the Coefficient of Friction (COF) of the neat oil. The optical image of wear scar on the ball immersed in neat oil shows a significant reduction in the Wear Scar Diameter from 425.6 µm to 390.0 µm with the addition of hybrid nanoparticles. The Raman mapping of the wear scar on chromium steel ball reveals that the FCS/GNP hybrid nanoparticles remain unseparated after the tribology test.

中文翻译：

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分散有功能化碳球和石墨烯纳米片的混合纳米颗粒的润滑油的摩擦学性能改进

摘要 报道了一种使用简单的超声技术合成涂覆有石墨烯纳米片 (GNP) 的功能化碳球 (FCS) 的新方法。发现 FCS/GNP 杂化纳米粒子可有效改善润滑油的摩擦学特性。对于 FCS 的合成，通过非催化化学气相沉积合成的碳球 (CS) 使用硝酸功能化。使用扫描电子显微镜 (SEM)、透射电子显微镜 (TEM) 和拉曼光谱对混合纳米粒子进行表征。使用四球测试仪研究了使用超声波处理分散有不同浓度 FCS 和 GNP 的 CASTROL-20 W 40 发动机油的摩擦学行为。分别研究了 FCS 和 GNP 的摩擦学行为，以比较 FCS/GNP 混合纳米粒子的摩擦学性能。以 10:1 的比例分散有 0.275 wt% FCS/GNP 杂化纳米粒子的纯油在不添加任何表面活性剂的情况下显示出优异的分散性和稳定性 30 天。结果表明，这些混合纳米颗粒的添加导致纯油的摩擦系数 (COF) 显着降低 (~18%)。浸入纯油中的球上磨痕的光学图像显示，添加混合纳米颗粒后，磨痕直径从 425.6 µm 显着减小到 390.0 µm。铬钢球磨痕的拉曼图谱显示 FCS/GNP 混合纳米粒子在摩擦学测试后保持未分离。