State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China.
Department of Physical Chemistry, School of Chemistry, Tel Aviv University, Tel Aviv 6997801, Israel.
Nanoscale. 2019 Jan 31;11(5):2186-2193. doi: 10.1039/c8nr07963c.
Structural superlubricity, a nearly frictionless state between two contact solid surfaces, has attracted rapidly increasing attention during the past few years. Yet a key problem that limits its promising applications is the high anisotropy of friction which always leads to its failure. Here we study the friction of a graphene flake sliding on top of a graphene substrate using molecular dynamics simulation. The results show that by applying strain on the substrate, biaxial stretching is better than uniaxial stretching in terms of reducing interlayer friction. Importantly, we find that robust superlubricity can be achieved via both biaxial and uniaxial stretching, namely for stretching above a critical strain which has been achieved experimentally, the friction is no longer dependent on the relative orientation mainly due to the complete lattice mismatch. The underlying mechanism is revealed to be the Moiré pattern formed. These findings provide a viable approach for the realization of robust superlubricity through strain engineering.
结构超滑，即两个接触固体表面之间几乎无摩擦的状态，在过去几年中引起了人们的极大关注。然而，限制其具有广阔应用前景的一个关键问题是摩擦的各向异性很高，这往往导致其失效。在这里，我们使用分子动力学模拟研究了在石墨烯衬底上滑动的石墨烯薄片的摩擦。结果表明，通过对衬底施加应变，双轴拉伸在减小层间摩擦方面优于单轴拉伸。重要的是，我们发现通过双轴和单轴拉伸都可以实现稳定的超滑，即在实验上已经实现的临界应变以上拉伸，摩擦不再依赖于相对取向，这主要是由于完全的晶格失配。其潜在机制被揭示为莫尔图案的形成。这些发现为通过应变工程实现稳定的超滑提供了一种可行的方法。
