Span60在石墨烯润滑油中分子行为及协同作用

石墨烯常被使用在润滑油中，以此提高油的润滑性能，但其在油中极易发生团聚，需要借助分散剂抑制团聚。石墨烯、分散剂及润滑油间分子行为可揭示分散机理、润滑机理及协同作用。本文采用对环境无毒无害的span60作为分散剂，基于分子动力学研究石墨烯润滑油添加span60前后的润滑性能变化，建立氮化硅-润滑油-轴承钢层结构模型，分析span60/石墨烯的含量比、工作温度、压强以及剪切速度等因素对润滑油膜在摩擦副表面吸附能、剪切应力以及形成的类固膜厚度的影响，并通过实验进行验证。分散剂span60与石墨烯在润滑油中起到协同效应，提高了润滑油在Si3N4-GCr15摩擦副表面的润滑能力。当span60/石墨烯含量比为7:1时，润滑效果最好；温度为373 K、压强为102 MPa、剪切速度为25 m?s-1时，润滑油润滑性能最好。添加适量span60可以有效解决石墨烯在润滑油中的团聚问题。石墨烯、分散剂及润滑油间的协同效应受温度、压强及速度的影响。

The Molecular Behavior and Synergistic Effects of span60 in Graphene Lubricants

Graphene is often used in lubricating oil to improve the lubricating properties of the oil, but it is highly prone to agglomerate in the oil, and requires dispersants to inhibit agglomeration. The molecular behavior between graphene, dispersant and lubricant can reveal the dispersion mechanism, lubrication mechanism and synergistic effect. In this paper, we use span60, which is non-toxic to the environment, as a dispersant to study the lubricating property changes of graphene lubricant before and after adding span60 based on molecular dynamics, establish a structural model of silicon nitride - lubricant - bearing steel layer, analyze the content ratio of span60 to graphene, operating temperature, pressure and shear speed on the adsorption energy of lubricant film on the surface of friction substrate, shear stress and the thickness of the solid film formed, and verified experimentally. The synergistic effect of dispersant span60 and graphene in the lubricant improved the lubricating ability of the lubricant on the surface of Si3N4-GCr15 friction subsets. The best lubrication effect is achieved when the span60/graphene content ratio is 7:1; When the temperature is 373 K, the pressure is 102 MPa and the shear speed is 25 m?s-1, the lubricating performance of lubricating oil is the best. The addition of appropriate amount of span60 can effectively solve the agglomeration problem of graphene in lubricant, and the synergistic effect between graphene, dispersant and lubricant is influenced by temperature, pressure and speed.