分子动力学模拟巴氏合金界面磁性液体润滑行为

Molecular Dynamics Simulation of Ferrofluid Lubrication on the Interface of Babbitt Alloy

磁性液体因其顺磁可控的流变特性,可满足极端工况对滑动轴承润滑油膜稳定性不断提高的要求,在轴承润滑方面具有良好的应用前景。为探究磁性液体微观润滑机制,采用分子动力学模拟方法构建和优化巴氏合金界面磁性液体润滑的微观模型,并根据实际工况进行限制性剪切模拟,研究温度和剪切速度对PAO6基磁性液体在巴氏合金界面润滑行为的影响;通过分析滑动过程中相对浓度分布、温度分布、速度分布、均方位移和界面吸附能等参数的变化,从分子层面揭示磁性液体微观润滑的作用机制。结果表明:PAO6基磁性液体具有良好的扩散性和散热性,可以粘附在巴氏合金摩擦界面起到很好的承载和减磨作用;在高温和高剪切速度下,磁性液体润滑膜仍呈现出良好的稳定性,磁性颗粒具有良好的扩散能力。研究结果有助于完善纳米薄膜润滑理论,对磁性液体的工程应用具有现实指导意义。

Ferrofluids can meet the continuously improving stability requirements of lubricating oil film of sliding bear-ing under extreme working conditions due to its paramagnetic controllable rheological properties,and have a good applica-tion prospect in bearing lubrication.To explore the micro lubrication mechanism of ferrofluids,the microscopic model of fer-rofluid lubrication on the interface of babbitt alloy was constructed and optimized by molecular dynamics simulation meth-od,and the confined shear simulation was carried out according to the actual working conditions.The effects of temperature and shear rate on the lubrication behavior of PAO6-based ferrofluid on the interface of babbitt alloy were studied.Through the analysis of the relative concentration distribution,temperature distribution,velocity distribution,mean square displace-ment and interface adsorption energy during the sliding process,the mechanism of ferrofluid micro-lubrication was revealed from the molecular level.The results show that the PAO6-based ferrofluid has good stability and heat dissipation,and can adhere to the friction interface of babbitt alloy to play a good role in bearing and reducing wear.At high temperatures and high shear speeds,the magnetic liquid lubricating film still exhibits good stability,and the magnetic particles have good dif-fusion.The research results are helpful to improve the lubrication theory of nano-film and have practical significance for the engineering application of ferrofluids.