ISSN   1004-0595

CN  62-1095/O4

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陈晶晶, 王成鑫, 林强. 基于分子动力学方法的多层石墨烯超滑失效机理分析[J]. 摩擦学学报, 2017, 37(5): 594-601. DOI: 10.16078/j.tribology.2017.05.005
引用本文: 陈晶晶, 王成鑫, 林强. 基于分子动力学方法的多层石墨烯超滑失效机理分析[J]. 摩擦学学报, 2017, 37(5): 594-601. DOI: 10.16078/j.tribology.2017.05.005
CHEN Jingjing, WANG Chengxin, LIN Qiang. Mechanism Analysis for the Breakdown of Superlubricity with Multilayer Graphene Based on Molecular Dynamics Method[J]. TRIBOLOGY, 2017, 37(5): 594-601. DOI: 10.16078/j.tribology.2017.05.005
Citation: CHEN Jingjing, WANG Chengxin, LIN Qiang. Mechanism Analysis for the Breakdown of Superlubricity with Multilayer Graphene Based on Molecular Dynamics Method[J]. TRIBOLOGY, 2017, 37(5): 594-601. DOI: 10.16078/j.tribology.2017.05.005

基于分子动力学方法的多层石墨烯超滑失效机理分析

Mechanism Analysis for the Breakdown of Superlubricity with Multilayer Graphene Based on Molecular Dynamics Method

  • 摘要: 本文作者采用混合势函数(Lennard-Jones势和REBO势),基于Verlet算法动态模拟了金刚石探针(100)与多层石墨烯间的压入和滑动摩擦过程,分析了不同压深下多层石墨烯的摩擦力及平均摩擦系数变化的特点,统计了不同压深下的层间键合作用、层内断键数量以及实际原子接触面积,阐述了多层石墨烯超滑失效的机理. 结果表明:压深对多层石墨烯间的超滑失效有着重要影响,探针压深增加导致的摩擦力振幅上升与悬空石墨烯压缩应变增加产生的影响非常相似;6.1 Å是石墨烯超滑失效的临界压入深度值,压深小于6.1 Å时,石墨烯有着明显的超滑特性,且摩擦力变化周期不受压深的影响,并等于石墨烯晶格常数;压深大于6.1 Å后,摩擦力变化完全失去周期性,探针在滑动中需要克服的势垒急剧上升,摩擦力显著增大,超滑明显失效. 当压深为6.1 Å时,石墨烯层间开始出现键合作用,层内也出现断键现象,且随压深的增加越加剧烈,层内的断键和层间键的形成是引起石墨烯超滑失效和摩擦力突变的主要原因,而实际原子接触面积与此突变的相关性很小.

     

    Abstract: Molecular dynamics simulation of indenting and sliding process between a diamond(100) tip and multilayer graphene was accomplished by using two incorporated potential functions with Verlet algorithm. Then the friction force and the average coefficient of friction at different indentation depth were analysed, after that, the number of interlayer bonding, intralayer broken bond and the actual atomic contact area were calculated to elucidate the mechanism for the breakdown of superlubricity. It is shown that the indentation depth had a significant influence on the breakdown of superlubricity, and the amplitude increment of friction force due to a deeper indentation by the tip was similar to that of suspended graphene by a larger compressive strain. The indentation depth of 6.1 Å, was found to be a critical point, the graphene showed an obvious superlubricity when the indentation depth was lower than 6.1 Å, before which the period of Stick-Slip, which is equal to the lattice constant of graphene, hardly changed as indentation depth varied. On the contrary, when the indentation depth was somewhat deeper than 6.1 Å, the friction force versus sliding distance didn’t show a periodic change anymore, and the tip got a much harder potential barrier to overcome, which led to friction force sharply increased and thus the superlubricity evidently broken. It was discovered that the critical depth, at which the interlayer bond/interlayer bond were unprecedentedly formed/broken and increased as indentation depth went deeper, which as a result made the superlubricity broken. The existence of interlayer bond and the broken of intralayer bond were considered to be the main factor causing superlubricity broken and the period of friction force abruptly changed, however, the actual atomic contacting area was hardly relative to phenomenon .

     

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