State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing, 100084, China.
Surface Science and Tribology Laboratory, Department of Mechanical Engineering, The University of Tokyo, Tokyo, 113-8656, Japan.
Nat Commun. 2017 Nov 22;8(1):1675. doi: 10.1038/s41467-017-01717-8.
Hydrogenated amorphous carbon (a-C:H) is capable of providing a near-frictionless lubrication state when rubbed in dry sliding contacts. Nevertheless, the mechanisms governing superlubricity in a-C:H are still not well comprehended, mainly due to the lack of spatially resolved structural information of the buried contact surface. Here, we present structural analysis of the carbonaceous sliding interfaces at the atomic scale in two superlubricious solid lubricants, a-C:H and Si-doped a-C:H (a-C:H:Si), by probing the contact area using state-of-the-art scanning electron transmission microscopy and electron energy-loss spectroscopy. The results emphasize the diversity of superlubricity mechanisms in a-C:Hs. They suggest that the occurrence of a superlubricious state is generally dependent on the formation of interfacial nanostructures, mainly a tribolayer, by different carbon rehybridization pathways. The evolution of such anti-friction nanostructures highly depends on the contact mechanics and the counterpart material. These findings enable a more effective manipulation of superlubricity and developments of new carbon lubricants with robust lubrication properties.
氢化非晶碳（a-C:H）在干滑动接触中摩擦时能够提供近无摩擦的润滑状态。然而，a-C:H 中超润滑的机制仍未被很好地理解，主要是由于缺乏埋入接触表面的空间分辨结构信息。在这里，我们通过使用最先进的扫描电子透射显微镜和电子能量损失光谱探测接触区域，对两种超滑固体润滑剂 a-C:H 和掺硅的 a-C:H（a-C:H:Si）的碳质滑动界面进行了原子尺度的结构分析。结果强调了 a-C:H 中超滑机制的多样性。它们表明，超滑状态的出现通常取决于界面纳米结构的形成，主要是通过不同的碳重杂化途径形成的摩擦层。这种抗摩擦纳米结构的演变高度依赖于接触力学和对摩材料。这些发现使我们能够更有效地操纵超滑，并开发具有稳健润滑性能的新型碳基润滑剂。
