纳米铜颗粒添加剂粒径对润滑油摩擦性能影响的分子动力学和试验  

Tribological Properties of Different-sized Copper Nanoparticles Employed as Lubricating Oil Additives Using MD Simulations and Experiments

作　　者：潘伶[1,2] 郭锦阳 林国斌 PAN Ling;GUO Jinyang;LIN Guobin(School of Mechanical Engineering and Automation,Fuzhou University,Fuzhou 350108,China;Fuzhou Friction and Lubrication Industry Technology Innovation Center,Fuzhou 350108,China)

机构地区：[1]福州大学机械工程及自动化学院,福州350108 [2]福州市摩擦与润滑行业技术创新中心,福州350108

出　　处：《中国表面工程》2023年第3期160-170,共11页China Surface Engineering

基　　金：国家自然科学基金(51875105,51975123);福建省产学合作(2020H6025)资助项目。

摘　　要：在润滑油中添加纳米颗粒可以有效减少摩擦磨损,大多数研究只集中在纳米颗粒的性质对摩擦性能的影响,很少考虑到颗粒粒径与表面粗糙度对摩擦性能的耦合作用。采用分子动力学(MD)模拟和试验的方法研究纳米铜颗粒添加剂粒径对润滑油摩擦性能的影响。建立具有凸峰和凹槽的粗糙壁面边界润滑MD模型,模拟300 MPa下两固体壁面相对剪切速度为5 m/s时,5种粒径的纳米Cu颗粒分别在不同粗糙度壁面下的力学性能。定量计算出摩擦表面的应力、磨损量、摩擦力、正压力和摩擦热。同时,采用微纳米划痕仪测量含纳米Cu颗粒润滑油的摩擦因数。结果表明,颗粒的粒径和壁面粗糙度对润滑油的摩擦性能具有耦合作用;在剪切过程中纳米颗粒会填充壁面凹坑、形成保护膜、减少摩擦磨损、提高承载能力和降低壁面摩擦热。当壁面粗糙度较小、处于边界润滑状态时,Cu颗粒添加剂会增大体系的摩擦力;当壁面粗糙度较大、处于混合润滑状态时,Cu颗粒添加剂会减小体系的摩擦力;当颗粒粒径与壁面凹槽深度的比值D/h在1.05~1.12范围内,即颗粒直径略大于凹槽深度时,润滑油的摩擦性能最优,摩擦力和磨损量较小、油膜承载能力最大。分子动力学模拟和试验相结合,建立微纳观结构和宏观特性之间的联系,探究壁面粗糙度与颗粒粒径对润滑油摩擦性能的影响机理,为预测和开发高性能新型润滑剂提供理论基础。An effective method of reducing friction and wear is through the addition of nanoparticles to lubricating oil.However,although many researchers have linked the tribological properties of nanoparticles to their intrinsic properties,very few have related the tribological properties to the coupling effect of the nanoparticle size and surface roughness.Thus,the effect of the particle size of Cu nanoparticle additives on its tribological properties was investigated in this study using simulations and experiments.A boundary lubrication system model with peaks and grooves was established,and molecular dynamics(MD)simulations were used to simulate the mechanical properties of five types of nanoparticles with different sizes under a stress and relative shear velocity between the two solid walls of 300 MPa and 5 m/s,respectively.The stress,wear,friction force,positive pressure,and friction heat on the friction surface was quantitatively calculated,and the friction coefficient of the lubricating oil containing the Cu nanoparticles was measured using a micro-scratch tester.The results showed that the Cu nanoparticles increased the friction coefficient when the asperity was small and during boundary lubrication,and reduced the friction coefficient when the asperity was large and during mixed lubrication.Particularly,when the ratio of the particle diameter to the groove depth D/h was in the range of 1.05-1.12,namely,when the nanoparticle diameter was slightly larger than the groove depth,the tribological performance of the lubricating oil was excellent,the friction and wear was low,and the oil film bearing capacity was optimal.The Von Mises stress nephogram of the metal revealed that when the ratio of the particle diameter to the groove depth D/h was 1.12,the maximum stress on the solid surface was 2.45×104 MPa,which appears in the direct contact area between the upper and lower contact surface,compared to the maximum stress on the solid surface of 31.2 GPa in the lubrication system without Cu nanoparticles.Additionally,the m

关 键 词：边界润滑 纳米颗粒 表面粗糙度 分子动力学 

分 类 号：TH117[机械工程—机械设计及理论]