核-壳MoS_(2)@SiO_(2)纳米复合材料的制备及其高温摩擦学性能

Preparation and high temperature tribological properties of core-shell MoS_(2)@SiO_(2) nanocomposites

二硫化钼(MoS_(2))在高温条件使用易发生氧化导致其摩擦学性能大幅劣化,表现出较高的摩擦系数。为了改善MoS_(2)润滑剂在高温环境下的摩擦学性能,本文通过水热法和改良Stober法生成核-壳MoS_(2)@SiO_(2)纳米复合材料。通过透射电子显微镜(TEM)、扫描电子显微镜(SEM)及X射线衍射仪(XRD)等对制备的纳米材料的形态、尺寸和组成进行表征。微观结果显示了核-壳结构复合材料的成功制备,平均粒径250 nm。对制备的MoS_(2)@SiO_(2)固体润滑涂层进行高温摩擦实验,并以MoS_(2)涂层作为对比。采用SEM、XRD等对涂层的形貌、结构进行了表征,采用三维轮廓仪对涂层磨损率进行表征。结果表明:MoS_(2)@SiO_(2)涂层在680℃下的摩擦系数为0.2且较平稳,MoS_(2)涂层则迅速失效。MoS_(2)@SiO_(2)涂层耐磨性更好,磨损率比MoS_(2)涂层低25.86%。摩擦实验后MoS_(2)@SiO_(2)涂层磨痕区域仍存在MoS_(2),有润滑膜覆盖;而MoS_(2)涂层磨痕区的基体完全暴露。由此表明,SiO_(2)外壳的包覆延缓了MoS_(2)在高温下的迅速氧化,且两者协同润滑,延长了涂层的使用寿命。

Molybdenum disulfide(MoS_(2))is easy to be oxidized when used at high temperature,which leads to significant deterioration of its tribological properties,showing a high friction coefficient.In order to improve the tribological properties of MoS_(2) lubricant under high temperature environment,core-shell MoS_(2)@SiO_(2) nanocomposites was formed by hydrothermal method and improved Stöber method.The morphology,size and composition of the nano materials were characterized by transmission electron microscopy(TEM),scanning electron microscopy(SEM)and X-ray diffraction(XRD).The micro results show that the core-shell structure composite is successfully prepared,with an average particle size of 250 nm.The high temperature friction test of prepared MoS_(2)@SiO_(2) solid lubrication coating was carried out,and the MoS_(2) coating was used as a comparison.The morphology and structure of the coating were characterized by SEM and XRD,and the wear rate of the coating was characterized by a 3D profiler.The results show that the friction coefficient of the MoS_(2)@SiO_(2) coating at 680℃ is 0.2 and relatively stable,while MoS_(2) coating rapidly fail.The MoS_(2)@SiO_(2) coating had better wear resistance,with a wear rate at 25.86%,lower than that of MoS_(2) coating.After the friction tests,MoS_(2) still existed in the wear scar area of the MoS_(2)@SiO_(2) coating,which was covered by the lubricating film.However,the substrate in the wear zone of MoS_(2) coating was completely exposed.It is thus shown that the encapsulation of the SiO_(2) shell retards the rapid oxidation of MoS_(2) at high temperatures and the two synergistically lubricate to prolong the service life of the coating.