针对空间滚动轴承往复运动状态下二硫化钼薄膜润滑失效机理不明的难题，提出了采用分子动力学对薄膜润滑过程进行分析的方法。建立了单层二硫化钼薄膜摩擦原子模型，针对载荷和环境温度这2个空间滚动轴承的重要影响因素展开了二硫化钼薄膜的往复摆动模拟，得到了摩擦过程中二硫化钼薄膜的摩擦力、粘附力和磨损情况。模拟结果表明：Fe-Ni-Cr合金探针在单层二硫化钼薄膜上的摩擦为黏滑运动，载荷在20～100 nN范围内探针的摩擦过程不会对薄膜造成磨损，但在往复运动过程中润滑性能有所提高；载荷从200 nN开始探针的摩擦过程会对薄膜造成磨损，往复运动过程中摩擦系数不断提高，润滑性能下降；400 nN为单层薄膜的载荷极限，在该载荷下探针会刺穿薄膜与基底接触此时薄膜迅速磨损失去润滑作用。环境温度在1 773.15 K以下对薄膜的润滑作用影响不明显，但达到该温度后薄膜边界处开始缓慢熔化，当环境温度达到二硫化钼熔点时薄膜的熔化速度加快并失去润滑作用。从这些发现得到如下结论：二硫化钼单层薄膜在接触载荷8 GPa以下拥有优异的耐磨性和润滑性；在薄膜未破损的条件下，反复摩擦过程提升了润滑性能；二维层状结构对单层二硫化钼薄膜润滑性能有重要的影响，高温和重载都会对薄膜层状结构造成破坏。

The failure mechanism of molybdenum disulfide thin-film lubrication under the reciprocating motion of space rolling bearings remains unclear. This study proposed a method to analyze the thin-film lubrication process using molecular dynamics. A friction atomic model of the single-layer molybdenum disulfide film was established. The reciprocating oscillation simulation of the molybdenum disulfide film was carried out based on two important factors affecting space rolling bearing: load and ambient temperature, focusing on friction, adhesion, and wear. Simulation results reveal that friction of the Fe-Ni-Cr alloy probe on the single-layer molybdenum disulfide film exhibits stick-slip motion. The probe’s friction within the range of 20~100 nN does not induce wear on the film; however, it enhances the film’s lubrication performance during reciprocating motion. Starting from 200 nN, the probe’s friction process causes wear on the film, leading to a continuous increase in friction coefficient during reciprocating motion and a decrease in lubricating performance. The load limit for a single-layer film is found to be 400 nN, beyond which the probe pierces the film and contacts the substrate, resulting in rapid wear and loss of lubrication effect. Ambient temperature below 1 773.15 K has no significant effect on the film’s lubrication effect. However, above this temperature, the film boundary starts to melt slowly. Upon reaching the melting point of molybdenum disulfide, the film's melting speed accelerates, leading to a loss of lubricating effect. Conclusions drawn from the study are as follows: The contact load of the molybdenum disulfide monolayer film exhibits excellent wear resistance and lubricity below 8 GPa; in the event of film damage, repeated friction processes can improve lubricating performance; the two-dimensional layered structure significantly influences the lubricating properties of the monolayer molybdenum disulfide film, and exposure to high temperature and heavy load can damage the film's layered structure.

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国家自然科学基金资助项目(51775072)；重庆市科技创新领军人才支持计划项目(CSTCCCXLJRC201920)；重庆市高校创新研究群体(CXQT20019)；重庆市北碚区科学技术局技术创新与应用示范项目(2020-5)。