Duan Zaoqi, Wei Zhiyong, Huang Shuyu, Wang Yongkang, Sun Chengdong, Tao Yi, Dong Yun, Yang Juekuan, Zhang Yan, Kan Yajing, Li Deyu, Chen Yunfei
Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, School of Mechanical Engineering, Southeast University, Nanjing 211189, China.
Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37235-1592, United States.
Nano Lett. 2021 Jun 9;21(11):4615-4621. doi: 10.1021/acs.nanolett.1c00622. Epub 2021 May 21.
Friction represents a major energy dissipation mode, yet the atomistic mechanism of how friction converts mechanical motion into heat remains elusive. It has been suggested that excess phonons are mainly excited at the washboard frequency, the fundamental frequency at which relative motion excites the interface atoms, and the subsequent thermalization of these nonequilibrium phonons completes the energy dissipation process. Through combined atomic force microscopy measurements and atomistic modeling, here we show that the nonlinear interactions between a sliding tip and the substrate can generate excess phonons at not only the washboard frequency but also its harmonics. These nonequilibrium phonons can induce resonant vibration of the tip and lead to multiple peaks in the friction force as the tip sliding velocity ramps up. These observations disclose previously unrecognized energy dissipation channels associated with tip vibration and provide insights into engineering friction force through adjusting the resonant frequency of the tip-substrate system.
摩擦是一种主要的能量耗散模式，然而，摩擦如何将机械运动转化为热量的原子机制仍然难以捉摸。有人提出，过量的声子主要在搓板频率下被激发，即相对运动激发界面原子的基频，随后这些非平衡声子的热化完成了能量耗散过程。通过结合原子力显微镜测量和原子模拟，我们在此表明，滑动探针与基底之间的非线性相互作用不仅可以在搓板频率下，还可以在其谐波频率下产生过量的声子。这些非平衡声子可以诱导探针的共振振动，并在探针滑动速度增加时导致摩擦力出现多个峰值。这些观察结果揭示了以前未被认识到的与探针振动相关的能量耗散通道，并为通过调整探针 - 基底系统的共振频率来控制摩擦力提供了见解。
