Contact forces at the sliding interface: mixed versus pure model alkane monolayers.
Contact forces at the sliding interface: mixed versus pure model alkane monolayers.
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滑动界面处的接触力：混合与纯模型烷烃单层。
DOI：
10.1063/1.1828035
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
J. Harrison
中科院分区：
文献类型：
--
作者：
P. Mikulski;G. Gao;G. M. Chateauneuf;J. Harrison
采用经典分子动力学方法模拟了无定形碳针尖与正构烷烃分子链的相互作用。将由含有14个碳原子的链组成的紧密堆积的纯单层的摩擦学行为与随机联合收割机结合等量的12-和16-碳原子链的混合单层进行比较。当在排斥（正）载荷下沿链斜面方向滑动时，纯单分子膜始终表现出比混合单分子膜更低的摩擦。单个单层链组和尖端之间的接触力的分布表明，纯和混合单分子膜抵抗尖端运动相似。相反，“推动”尖端沿着的接触力在两个单层中不同。纯单分子膜在阻力和推力之间表现出高水平的对称性，这导致了较低的净摩擦。这两个系统都表现出明显的摩擦各向异性。由于滑动方向的改变，接触力分布发生显著变化，导致摩擦力增加。在垂直于链斜面的方向上继续滑动时，两种类型的单层通常能够转变到其中链主要以斜面沿着滑动方向取向的状态。接触力分布的大变化和摩擦的减少伴随着这种转变。
Classical molecular dynamics simulations of an amorphous carbon tip sliding against monolayers of n-alkane chains are presented. The tribological behavior of tightly packed, pure monolayers composed of chains containing 14 carbon atoms is compared to mixed monolayers that randomly combine equal amounts of 12- and 16-carbon-atom chains. When sliding in the direction of chain cant under repulsive (positive) loads, pure monolayers consistently show lower friction than mixed monolayers. The distribution of contact forces between individual monolayer chain groups and the tip shows pure and mixed monolayers resist tip motion similarly. In contrast, the contact forces "pushing" the tip along differ in the two monolayers. The pure monolayers exhibit a high level of symmetry between resisting and pushing forces which results in a lower net friction. Both systems exhibit a marked friction anisotropy. The contact force distribution changes dramatically as a result of the change in sliding direction, resulting in an increase in friction. Upon continued sliding in the direction perpendicular to chain cant, both types of monolayers are often capable of transitioning to a state where the chains are primarily oriented with the cant along the sliding direction. A large change in the distribution of contact forces and a reduction in friction accompany this transition.