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1.
分子量级超薄油膜的润滑特性与流体润滑及边界润滑的都有所不同,而且在超薄油膜中也同样存在着润滑剂的流动。因此,利用分子动力学方法模拟了超薄油膜中的压力流动,模拟中采用了刚性分子流体模型,重点研究固体壁面对流动的影响,结果表明,当油膜厚度远比流体分子“直径”大时,模拟所得速度剖面和流量均与流体力学的理论值基本一致;随着油膜厚度逐渐变薄,压力流动或动压流因受到固体壁面的阻碍作用而不断减小;当油膜厚度减小到几个分子直径量级时,两固体壁面之间的流体分子发生固化或晶体化,由此而导致压力流动消失。这可能是流体动力润滑向边界润滑转化的机理之一。由这些研究结果可见,分子动力学模拟在薄膜润滑研究中具有广阔的应用前景。 相似文献
2.
Molecular dynamic simulation of lubricant spreading: effect from the substrate and endbead 下载免费PDF全文
Molecular dynamic simulations based on a coarse-grained, bead-spring model
are adopted to investigate the spreading of both nonfunctional and
functional perfluoropolyether (PFPE) on solid substrates. For nonfunctional
PFPE, the spreading generally exhibits a smooth profile with a precursor
film. The spreading profiles on different substrates are compared, which
indicate that the bead-substrate interaction has a significant effect on the
spreading behaviour, especially on the formation of the precursor film. For
functional PFPE, the spreading generally exhibits a complicated terraced
profile. The spreading profiles with different endbeads are compared, which
indicate that the endbead-substrate interaction and the endbead--endbead
interaction, especially the latter, have a significant effect on the
spreading behaviour. 相似文献
3.
超滑和界面摩擦及耗散过程——关于摩擦机理微观研究的思考与展望 总被引:8,自引:3,他引:5
评述了近年来关于摩擦现象基础研究的进展与成果,包括超滑的分子动力学模型,界面摩擦试验,表面微观结构的相对称性以及摩擦的能量耗散过程等。肯定了超滑的模拟结果及其理论解释对于摩擦机理和控制研究的启迪和促进作用,分析了模拟结果与现实世界差异的深层次原因,并指出了这一差别将促使人们超越经典力学的框架,为探索和发现尚未认识的摩擦机制创造新的机遇。 相似文献
4.
纳米润滑膜全氟聚醚(perfluoropolyether,简称PFPE)在固体表面的结构和迁移特性对于计 算机磁盘磁头驱动系统的可靠性具有重要的作用. 采用基于粗粒珠簧模型的分子动力学模拟 方法,考察了不同壁面和端基极性对于PFPE膜静态特性(如分子构型、单体密度分布、端基 密度分布)以及动态特性(如自扩散系数)的影响. 静态特性的模拟结果表明,非极性PFPE 膜在壁面附近具有单层厚度为一个单体直径的层状结构,而极性PFPE膜则具有复杂的层状结 构. 动态特性的模拟结果表明,PFPE膜的扩散能力因壁面作用而增强并因端基极性作用而减 弱.
关键词:
全氟聚醚膜
分子动力学模拟
薄膜润滑
固液界面结构 相似文献
5.
Lubricant spreading on solid substrates has drawn considerable attention not only for the microscopic wetting theory but also for the dramatic application in head-disk interface of magnetic storage drive systems. Molecular dynamic simulation based on a coarse-grained bead-spring model has been used to study such a spreading process. The spreading profiles indicate that the hydrogen bonds among lubricant molecules and the hydrogen bonds between lubricant molecules and polar atoms of solid substrates will complicate the spreading process in a tremendous degree. The hydrogen bonds among lubricant molecules will strengthen the lubricant combination intensity, which may hinder most molecules from flowing down to the substrates and diffusing along the substrates. And the hydrogen bonds between lubricant molecules and polar atoms of solid substrates will confine the lubricant molecules around polar atoms, which may hinder the molecules from diffusing along the substrates and cause precursor film to vanish. 相似文献
6.
The spread of perfluoropolyether (PFPE) droplets on solid surfaces has been measured from the top-down view through a microscope system. Effects of substrates, molecular weight and end-group functionality on spreading of the PFPE droplets have been studied experimentally and the results were compared with those by molecular dynamics (MD) simulations. Silicon wafer and diamond-like carbon (DLC) substrates were used to study the effect of substrates on spreading. Two types of PFPE, Z-dol and Z-tetraol, with the same chain structure and various molecular weights (2000 and 4000 g/mol) were employed in experiments. Effect of molecular weight has been investigated through comparing the spreading of Z-dol 2000 and Z-dol 4000, and it is found that the increase of molecular weight will decrease the mobility of PFPE. Comparison between spreading of Z-dol and Z-tetraol of the same molecular weight proved that functional end group plays a significant role on the spreading of PFPE, which confirmed the MD simulation results. 相似文献
7.
Nano-tribology through molecular dynamics simulations 总被引:1,自引:0,他引:1
The solidification and interfacial slip in nanometer-scale lubricating films as well as the contact and adhesion of metal
crystals have been studied via molecular dynamics simulations. Results show that the critical pressure for the solid-liquid
transition declines as the film thickness decreases, indicating that the lubricant in the thin films may exist in a solid-like
state. It is also found that the interfacial slip may occur in thin films at relatively low shear rate, and there is a good
correlation between the slip phenomenon and the lubricant solidification. The simulations reveal that a micro-scale adhesion
may take place due to the atomic jump during the process of approaching or separating of two smooth crystal surfaces, which
provides important information for understanding the origin of interfacial friction. 相似文献
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10.
利用分子动力学模拟方法研究了2—3nm厚的类金刚石(DLC)薄膜在金刚石基体(100)表面上的生长过程. 分析了用来表征沉积后无定型碳膜质量的重要结构特性,如sp3杂化比例、薄膜密度、径向分布函数等,计算结果和现有的实验结果基本一致. 不同入射原子能量对结构特性进而对薄膜性能有重要影响,入射原子能量在20—60eV时,薄膜可以获得最优性能. 载能原子入射是生长均匀、连续、致密固体薄膜的前提,稳定的中间区域对于保证薄膜优良的力学性质是必需的.
关键词:
DLC膜
分子动力学模拟
3杂化比例')" href="#">sp3杂化比例 相似文献