【摘要】 采用分子动力学方法建立了基底支撑的多层石墨烯摩擦力模型,统计了不同层数石墨烯在法向载荷作用下的摩擦系数,确立了摩擦力随层数的变化关系;通过针尖吸附薄片所受的范德华力和石墨烯法向变形能与摩擦力的对应关系,得出了法向变形能和界面褶皱势是导致摩擦产生的直接原因,定量分析了界面势垒高度与法向刚度对摩擦力的贡献.结果表明:在不同载荷作用下,3层石墨烯的摩擦系数比1层的摩擦系数高36%、比2层的摩擦系数高40%,1~3层石墨烯的摩擦力均大于范德华力,且随着层数的增加摩擦力与范德华力差值增大;石墨烯层间以刚度串联方式连接,当法向载荷恒定时,3层石墨烯的法向变形能约为2层的1.5倍、1层的3倍,每层石墨烯的变形能对摩擦力的贡献相同,石墨烯摩擦力的产生是层间法向刚度与界面褶皱势刚度共同竞争作用的结果.更多还原

【Abstract】 Based on molecular dynamics simulations,a supported multilayer graphene friction model was constructed.First,the statistics on the friction coefficient of graphene with different layers under normal loads was carried out,and the relationship between the friction and layer numbers was obtained.Then the contributions of van der Waals force of the tip and the elastic deformation on the top layer of the multilayer graphene substrate on the friction force were analyzed.Finally,it was demonstrated that the effects on normal deformation energy and surface compliance were directly related to the observed friction force,and the contributions of surface energy barrier height and normal stiffness on the friction were quantitatively analyzed.The results indicate that under different loads the friction coefficient of 3 layers is 36% higher than that of 1 layer,and 40% higher than that of 2layers; all friction forces are greater than van der Waals forces and the difference value between them becomes larger with the numbers of layers increasing; when the normal load is constant,the elastic energy of 3 layers is about 1.5 times as much as that of 2 layers and threefold of that of 1 layer,that is,the elastic energy of each layer has equal contribution to the friction due to the stiffness between layers is in series,the friction of graphene is caused by the competition between the stiffnesses of normal deformation energy and surface compliance.更多还原