Tian Kaiwen, Li Zhuohan, Liu Yun, Gosvami Nitya N, Goldsby David L, Szlufarska Izabela, Carpick Robert W
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Phys Rev Lett. 2020 Jan 17;124(2):026801. doi: 10.1103/PhysRevLett.124.026801.
Nanoscale silica-silica contacts were recently found to exhibit logarithmic aging for times ranging from 0.1 to 100 s, consistent with the macroscopic rate and state friction laws and several other aging processes. Nanoscale aging in this system is attributed to progressive formation of interfacial siloxane bonds between surface silanol groups. However, understanding or even data for contact behavior for aging times <0.1 s, before the onset of logarithmic aging, is limited. Using a combination of atomic force microscopy experiments and kinetic Monte Carlo simulations, we find that aging is nearly linear with aging time at short timescales between ∼ 5 and 90 ms. We demonstrate that aging at these timescales requires the existence of a particular range of reaction energy barriers for interfacial bonding. Specifically, linear aging behavior consistent with experiments requires a narrow peak close to the upper bound of this range of barriers. These new insights into the reaction kinetics of interfacial bonding in nanoscale aging advance the development of physically based rate and state friction laws for nanoscale contacts.
最近发现，纳米尺度的二氧化硅 - 二氧化硅接触在0.1至100秒的时间范围内呈现对数老化，这与宏观速率和状态摩擦定律以及其他几个老化过程一致。该系统中的纳米尺度老化归因于表面硅醇基团之间界面硅氧烷键的逐步形成。然而，对于对数老化开始之前老化时间小于0.1秒的接触行为的理解甚至数据都很有限。通过结合原子力显微镜实验和动力学蒙特卡罗模拟，我们发现，在约5至90毫秒的短时间尺度上，老化与老化时间几乎呈线性关系。我们证明，在这些时间尺度上的老化需要存在特定范围的界面键合反应能垒。具体而言，与实验一致的线性老化行为需要在该能垒范围的上限附近有一个窄峰。这些关于纳米尺度老化中界面键合反应动力学的新见解推动了基于物理的纳米尺度接触速率和状态摩擦定律的发展。
