纳米结构对二硫化钼摩擦学性能的影响

目的探究二硫化钼结构以及尺寸对其宏观摩擦学性能以及滑移机制的影响。方法采用水热法制备了尺寸不同的二硫化钼微球花,并与购买的商业化块状二硫化钼以及单层二硫化钼进行对比,将四种二硫化钼粉末在乙醇中进行分散,采用喷涂的方式在硅基底上制备了四种二硫化钼涂层。采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和透射电子显微镜(TEM)对粉末和涂层的形貌、结构进行了表征,并对比研究了涂层的摩擦学性能,通过光学显微镜观察了对偶的形貌,利用SEM和TEM对摩擦界面的结构和形貌进行了研究。结果四种二硫化钼材料均为层状结构的纳米片或微片组成,摩擦系数平稳且均小于0.05。块状二硫化钼寿命最短,摩擦界面覆盖了较少的润滑膜;单层二硫化钼摩擦系数平稳,且寿命最长,摩擦界面由大量纳米片组成,摩擦过程主要是单纯的物理剥离;二硫化钼微球花的寿命介于二者之间,微球花在摩擦力的作用下很容易发生剥离,在摩擦过程中起润滑作用的是剥离的二硫化钼纳米片,摩擦界面覆盖了较厚的致密润滑膜。二硫化钼微球花摩擦后,层间距由0.62 nm增至0.7 nm,层间距的增大有利于良好的润滑。结论尺寸对二硫化钼的滑移机制有影响,从而显著影响其耐磨寿命,层数和尺寸的减小有利于耐磨寿命的提升。

Effect of Nanostructure on Tribological Properties of Molybdenum Disulfide

The work aims to study the effect of the structure and the size of MoS2 on its macro tribological properties and the sliding mechanism. The flower-like MoS2 microspheres of different sizes were synthesized by hydrothermal method and compared with the purchased commercial bulk MoS2 and single-layer MoS2. Four kinds of MoS2 powder were dispersed in ethanol, and four MoS2 coatings were prepared on the silicon wafer by spraying. Scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscope (TEM) were used to characterize the morphology and structure of the powder and coatings. The tribological properties of the coatings were compared and studied. The morphology of the friction pair was observed by the optical microscopy. The SEM and TEM were used to study the structure and morphology of the friction interface. The four MoS2 samples were all composed of micro- or nano-sheets with the layered structure. The friction coefficients of the four materials were stable and less than 0.05. The wear life of bulk MoS2 was the shortest and the friction interface was covered by the less lubricating film. The single-layer MoS2 had a stable friction coefficient and the longest life. The friction interface was composed of numerous nanosheets and the friction process was mainly pure physical peeling. The life of the flower-like MoS2 microspheres was intermediate between those of bulk MoS2 and single-layer MoS2. The flower-like MoS2 microspheres were easy to be exfoliated under the action of friction force, and the exfoliated MoS2 nanosheets played an important role of lubrication during the friction process. The friction interface was covered with a thick and dense lubricant film. After the rubbing, the interlayer distance of flower-like MoS2 microspheres increased from 0.62 nm to 0.7 nm, which was conducive to good lubrication. The size can affect the sliding mechanism of MoS2, which significantly affects its wear life. The reduction of the layer and size is beneficial to improve the wear life.