电场作用下硬脂酸作为有机摩擦改进剂的润滑行为的分子模拟  

Molecular Simulation of Lubrication Behavior of Stearic Acid as an Organic Friction Modifier under Electric Field

作　　者：李姗玲 霍传腾 易晓彬 史俊勤 范晓丽 LI Shanling;HUO Chuanteng;YI Xiaobin;SHI Junqin;FAN Xiaoli(Center of Advanced Lubrication and Seal Materials,School of Materials Science and Engineering,Northwestern Polytechnical University,Shaanxi Xi’an 710072,China)

机构地区：[1]西北工业大学材料学院先进润滑与密封材料研究中心,陕西西安710072

出　　处：《摩擦学学报（中英文）》2024年第9期1204-1210,共7页Tribology

基　　金：国家重点研发计划项目(2022YFB3809000);凝固技术国家重点实验室(西北工业大学)自主研究课题(2023-TZ-01)资助。

摘　　要：采用分子动力学模拟方法研究电场作用下硬脂酸作为有机摩擦改进剂的边界润滑行为,从分子尺度揭示硬脂酸在SiO_(2)表面的吸附和摩擦学特性.电场由表面电荷密度反映,其强度与方向决定了硬脂酸分子的极性基团与表面的相互作用强弱.微观构型、密度分布以及分子倾斜率等分析表明,表面正电荷促进硬脂酸形成致密、规则的吸附膜,负电荷下吸附膜结构疏松,表面零电荷时吸附膜无序.摩擦过程模拟表明,电荷密度由负向正增大时摩擦系数显著降低,即通过电场调控可实现摩擦系数降低和润滑性能提升.The increasingly severe operating conditions of friction and contact components place higher demands on lubrication systems.In the boundary lubrication regime,organic friction modifiers(OFMs)in lubricants play an important role in separating the contact surfaces and thereby reducing friction and wear.However,the lubricating effect of OFMs is mainly controlled by the interaction between the OFM molecules and the contact surface,which is usually influenced by many factors,such as temperature,pressure,shear rate,surface humidity,etc.In recent years,the electric field has been used to regulate the structure of liquid lubricant molecules to achieve excellent lubrication performance.This method can overcome the limitations of the physicochemical properties of the frictional surface and other influencing factors,and thus achieve significant improvement in boundary lubrication performance.In this work,molecular dynamics simulation was used to study the lubrication behavior of stearic acid as an organic friction modifier under the action of an electric field,and to reveal the adsorption behavior and tribological properties of stearic acid on SiO_(2) surfaces at the molecular scale.Poly-alpha-olefin(PAO4)was used as the base oil.The electric field intensity was reflected by the surface charge density based on its relevance.The microscale configurations,density distribution and the probability profiles of both molecular adsorption angle and tilt degree(ΔZ)were analysed to represent the adsorption structure of OFM film.The results indicated that the positive surface charges promoted the formation of a dense and regular adsorption film of stearic acid,while the negative charges showed an opposite effect.The adsorption film was disordered on the surface without charges.This means that the strength and direction of the electric field determined the interactions between the polar head group of stearic acid molecule and the friction surface.The shear configurations and velocity of lubricants were extracted to show the friction p

关 键 词：硬脂酸 有机摩擦改进剂 边界润滑 电场调控 分子动力学模拟 

分 类 号：TH117.2[机械工程—机械设计及理论]