Wang Kehan, Wang Jin, Ma Ming
State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing, China.
Center for Nano and Micro Mechanics, Tsinghua University, Beijing, China.
Front Chem. 2022 Feb 1;9:807630. doi: 10.3389/fchem.2021.807630. eCollection 2021.
Structural superlubricity (SSL), a state of ultra-low friction between two solid contacts, is a fascinating phenomenon in modern tribology. With extensive molecular dynamics simulations, for systems showing SSL, here we discover two different dependences between friction and normal load by varying the size of the loading area. The essence behind the observations stems from the coupling between the normal load and the edge effect of SSL systems. Keeping normal load constant, we find that by reducing the loading area, the friction can be reduced by more than 65% compared to the large loading area cases. Based on the discoveries, a theoretical model is proposed to describe the correlation between the size of the loading area and friction. Our results reveal the importance of loading conditions in the friction of systems showing SSL, and provide an effective way to reduce and control friction.
结构超润滑（SSL）是指两个固体接触之间的超低摩擦状态，是现代摩擦学中一个引人入胜的现象。通过广泛的分子动力学模拟，对于呈现SSL的系统，我们在此通过改变加载区域的大小发现了摩擦与法向载荷之间的两种不同依赖关系。这些观察结果背后的本质源于法向载荷与SSL系统边缘效应之间的耦合。在保持法向载荷不变的情况下，我们发现，与大加载区域的情况相比，通过减小加载区域，摩擦可降低65%以上。基于这些发现，提出了一个理论模型来描述加载区域大小与摩擦之间的相关性。我们的结果揭示了加载条件在呈现SSL的系统摩擦中的重要性，并提供了一种有效降低和控制摩擦的方法。
