Ho Viet Hung, Gianetti Melisa M, Uluca Ahmed, Sinnott Aaron D, Haugen Bjørn, Cross Graham L W, de Wijn Astrid S
Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology (NTNU), 7491, Trondheim, Norway.
School of Physics and CRANN, Trinity College Dublin, Dublin 2, D02 W085, Ireland.
ACS Appl Mater Interfaces. 2025 Oct 8;17(40):56661-56671. doi: 10.1021/acsami.5c16288. Epub 2025 Sep 25.
"Structural superlubricity", a state of frictionless sliding between crystalline surfaces, has been observed at the nanoscale and microscale. However, achieving it at the macroscale requires further investigation. Inspired by recent experimental studies, we theoretically examine the friction behavior of macroscale patterned surfaces composed of microscale bumps coated with superlubricious two-dimensional materials. We performed numerical simulations with the discrete element method. The Hertz contact model, along with a modified tangential Mindlin contact model, is employed to capture the nonlinear relationship between the coefficient of friction and normal load. Our results reveal that the friction behavior is significantly influenced by the radius of the microscale bumps, the durability of the coating, and the elasticity of the surface, and we show how those can be tuned to improve friction properties. Additionally, we analytically investigate the deformation mechanisms of the surface structure and derive scaling laws for parameters and the breakdown of superlubricity. The simulation results show strong agreement with the analytical derivations of power laws for scaling of various quantities with the total macroscopic load. Finally, we examine imperfect conditions by investigating how height variations impact frictional performance.
“结构超润滑性”是晶体表面之间的无摩擦滑动状态，已在纳米尺度和微米尺度上被观测到。然而，在宏观尺度上实现它仍需要进一步研究。受近期实验研究的启发，我们从理论上研究了由涂覆超润滑二维材料的微米级凸起组成的宏观图案化表面的摩擦行为。我们用离散元法进行了数值模拟。采用赫兹接触模型以及修正的切向明德林接触模型来捕捉摩擦系数与法向载荷之间的非线性关系。我们的结果表明，摩擦行为受到微米级凸起的半径、涂层的耐久性和表面弹性的显著影响，并且我们展示了如何对这些因素进行调整以改善摩擦性能。此外，我们分析研究了表面结构的变形机制，并推导了参数的标度律以及超润滑性的失效情况。模拟结果与各种量随总宏观载荷缩放的幂律解析推导结果高度吻合。最后，我们通过研究高度变化如何影响摩擦性能来考察不完美条件。
