Du Changhe, Yu Tongtong, Zhang Liqiang, Deng Haoyu, Shen Ruilin, Li Xiaojuan, Feng Yange, Wang Daoai
State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
ACS Appl Mater Interfaces. 2023 Feb 8. doi: 10.1021/acsami.2c22402.
Liquid superlubricity has attracted much attention, due to its ability to significantly reduce friction on the macroscale. However, the severe wear caused by the long running-in period is still one of the bottlenecks restricting the practical application of liquid superlubricating materials. In this work, the obtained polyethylene glycol-phytic acid (PEG-PA) composite liquid lubricants showed outstanding superlubricating properties (μ ≈ 0.006) for SiN/glass friction pairs with an ultrashort running-in period (∼1 s) under high Hertzian contact pressure of ∼758 MPa. More importantly, even after up to 12 h (∼700 m of travel), only about 100 nm deep wear scars were found on the surface of the glass sheet (wear rate = 2.51× 10 mm N m). From the molecular point of view, the water molecules anchored between the two friction pairs have extremely low shear force during the friction process, and the strong hydrogen bond interaction between PEG and PA greatly improves the bearing capacity of the lubricant. This work addresses the challenge of liquid superlubricant simultaneously exhibiting low shear force and high load-carrying capacity and makes it possible to obtain liquid superlubrication performance with an extremely short running-in time.
由于液体超润滑性能够在宏观尺度上显著降低摩擦，因此备受关注。然而，长时间的磨合期所导致的严重磨损仍是制约液体超润滑材料实际应用的瓶颈之一。在这项工作中，所制备的聚乙二醇 - 植酸（PEG - PA）复合液体润滑剂在约758 MPa的高赫兹接触压力下，对于SiN/玻璃摩擦副表现出优异的超润滑性能（μ≈0.006），且磨合期极短（约1 s）。更重要的是，即使在长达12小时（约700米行程）之后，在玻璃板表面仅发现约100纳米深的磨损痕迹（磨损率 = 2.51×10⁻⁶毫米³/牛·米）。从分子角度来看，锚定在两个摩擦副之间的水分子在摩擦过程中具有极低的剪切力，并且PEG与PA之间强烈的氢键相互作用极大地提高了润滑剂的承载能力。这项工作解决了液体超润滑剂同时表现出低剪切力和高承载能力的挑战，并使得在极短的磨合时间内获得液体超润滑性能成为可能。
