Han Zongfang, Ru Guoliang, Li Yuqiong, Ma Ming
Key Laboratory for Mechanics in Fluid Solid Coupling Systems, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
Guangdong Aerospace Research Academy, Guangzhou (Nan Sha) 511458, People's Republic of China.
J Phys Condens Matter. 2024 Jul 22;36(42). doi: 10.1088/1361-648X/ad604f.
Molecular dynamics simulations and first principles calculations were performed to study the tribological behavior of graphene/h-BN (G/h-BN) heterostructures with vacancy and Stone-Wales (SW) defect under uniform normal load, revealing the mechanism of the effect of defect types on friction, and discussing the coupling effect of temperature and interfacial defects on the tribological behavior of G/h-BN heterostructures. Under the normal force of 0.2 nN/atom, the friction force of the four systems is 0.0057, 0.0096, 0.0077, and 0.26 nN, respectively. The friction force of SW defect heterostructure is 45 times that of perfect interface heterostructure. The influence of defect type on friction force is SW > SV > DV. By observing the dynamic change of the-direction coordinate position of the sliding layer atoms, the slip potential energy curves and the evolution law of the moiré pattern, the relationship between the structural morphology and the energy change of different defective heterostructures and the frictional behavior was investigated comprehensively and intuitively for the first time. From the perspective of atomic strain, the deformation of heterostructures at the atomic level was quantified. The results showed that at 300 K and 0 K, the maximum strain of atoms in the sliding layer was 11.25% and 9.85%, respectively. The thermal perturbation mainly occurs in the out-of-plane direction, which in turn affects the friction. Through density functional theory, it is found that under uniform load, it is difficult to form bonds between the graphene sliding layer and the substrate layer when the defects are in the h-BN substrate layer, which has less influence on the friction of the system, thus making the defective heterostructures also remainsuperlubricity state. These results provide a new understanding of the interfacial friction of G/h-BN defective heterostructure.
通过分子动力学模拟和第一性原理计算，研究了具有空位和斯通-威尔士（SW）缺陷的石墨烯/六方氮化硼（G/h-BN）异质结构在均匀法向载荷下的摩擦学行为，揭示了缺陷类型对摩擦影响的机制，并探讨了温度和界面缺陷对G/h-BN异质结构摩擦学行为的耦合效应。在0.2 nN/原子的法向力下，四个系统的摩擦力分别为0.0057、0.0096、0.0077和0.26 nN。SW缺陷异质结构的摩擦力是完美界面异质结构的45倍。缺陷类型对摩擦力的影响为SW＞SV＞DV。通过观察滑动层原子的方向坐标位置的动态变化、滑移势能曲线和莫尔条纹的演化规律，首次全面直观地研究了不同缺陷异质结构的结构形态与能量变化以及摩擦行为之间的关系。从原子应变的角度，对异质结构在原子水平上的变形进行了量化。结果表明，在300 K和0 K时，滑动层中原子的最大应变分别为11.25%和9.85%。热扰动主要发生在面外方向，进而影响摩擦。通过密度泛函理论发现，在均匀载荷下，当缺陷位于h-BN基底层时，石墨烯滑动层与基底层之间难以形成键，对系统摩擦的影响较小，从而使缺陷异质结构也保持超润滑状态。这些结果为G/h-BN缺陷异质结构的界面摩擦提供了新的认识。
