Xu Chaochen, Zhang Shuai, Du Hongzhi, Xue Tao, Kang Yilan, Zhang Yang, Zhao Pei, Li Qunyang
Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, PR China.
State Key Laboratory of Tribology in Advanced Equipment, Tsinghua University, Beijing 100084, PR China.
ACS Appl Mater Interfaces. 2022 Sep 14;14(36):41571-41576. doi: 10.1021/acsami.2c10449. Epub 2022 Aug 30.
Supreme mechanical performance and tribological properties render graphene a promising candidate as a surface friction modifier. Recently, it has been demonstrated that applying in-plane strain can effectively tune friction of suspended graphene in a reversible manner. However, since graphene is deposited on solid surfaces in most tribological applications, whether such operation will result in a similar modulation effect becomes a critical question to be answered. Herein, by depositing graphene onto a stretchable substrate, the frictional characteristics of supported graphene under a wide range of strain are examined with an in situ tensile loading platform. The experimental results show that friction of supported graphene decreases with increasing graphene strain, similar to the suspended system. However, depending on the adherence state of the graphene/substrate interface, the system exhibits two distinct friction regimes with significantly different strain dependences. Assisted by detailed atomic force microscopy imaging, we attribute the unique behavior to the transition between two friction modulation modes, i.e., contact-quality-dominated friction and puckering-dominated friction. This work provides a more comprehensive view of the influence of strain on surface friction of graphene, which is beneficial for active modulation of graphene friction through strain engineering.
卓越的机械性能和摩擦学特性使石墨烯成为一种很有前景的表面摩擦改性剂候选材料。最近，已经证明施加面内应变可以以可逆的方式有效调节悬浮石墨烯的摩擦力。然而，由于在大多数摩擦学应用中石墨烯是沉积在固体表面上的，这种操作是否会产生类似的调制效果就成为一个亟待回答的关键问题。在此，通过将石墨烯沉积在可拉伸基板上，利用原位拉伸加载平台研究了在广泛应变范围内支撑石墨烯的摩擦特性。实验结果表明，与悬浮系统类似，支撑石墨烯的摩擦力随着石墨烯应变的增加而降低。然而，根据石墨烯/基板界面的粘附状态，该系统表现出两种截然不同的摩擦状态，其应变依赖性明显不同。借助详细的原子力显微镜成像，我们将这种独特行为归因于两种摩擦调制模式之间的转变，即接触质量主导的摩擦和褶皱主导的摩擦。这项工作为应变对石墨烯表面摩擦的影响提供了更全面的视角，这有利于通过应变工程对石墨烯摩擦进行主动调制。
