Wang Jin, Cao Wei, Song Yiming, Qu Cangyu, Zheng Quanshui, Ma Ming
Nano Lett. 2019 Nov 13;19(11):7735-7741. doi: 10.1021/acs.nanolett.9b02656. Epub 2019 Oct 31.
Structural superlubricity, which promises an ultralow sliding friction due to the cancellation of the lateral force between two incommensurate interfaces, is a fundamental phenomenon in modern tribology. Achieving macroscale superlubricity is critical to its practical application, and the key is understanding how friction scales with real contact area, that is, the scaling law, especially for kinetic friction which accounts for most of the energy dissipation during sliding. Here, inspired by extensive molecular dynamics simulations we introduce an analytical general theory for the scaling law of structural superlubricity, which could well explain existing experimental measurements on the nanoscale. On the microscale, the scaling law is validated by measuring the friction of several microscale superlubric graphite/hexagonal boron nitride heterojunctions. The proposed theory predicts a characteristic size = (100 nm) above which the scaling transits from sublinear to linear. Our results provide insights in the origin of friction for structural superlubricity and benefit its application on macroscale.
结构超润滑性是现代摩擦学中的一种基本现象，由于两个不匹配界面之间的侧向力相互抵消，它有望实现超低滑动摩擦。实现宏观尺度的超润滑性对其实际应用至关重要，关键在于理解摩擦力如何随实际接触面积缩放，即缩放定律，特别是对于在滑动过程中占大部分能量耗散的动摩擦。在此，受大量分子动力学模拟的启发，我们引入了一种关于结构超润滑性缩放定律的解析通用理论，该理论能够很好地解释现有的纳米尺度实验测量结果。在微观尺度上，通过测量几种微观尺度的超润滑石墨/六方氮化硼异质结的摩擦力来验证缩放定律。所提出的理论预测了一个特征尺寸 = (100 纳米)，超过该尺寸后，缩放从亚线性转变为线性。我们的结果为结构超润滑性的摩擦起源提供了见解，并有利于其在宏观尺度上的应用。
