油酸修饰纳米氟化钙的萃取法制备及其摩擦学性能

Preparation and Tribological Properties of CaF_2 Nanocluster Capped with Oleic Acid as Lithium Grease Additive

采用萃取法制备了油酸修饰的纳米CaF2,用X射线衍射(XRD)对纳米CaF2粉体样品进行物相分析,同时用透射电子显微镜(TEM)及傅立叶变换红外光谱仪(FT-IR)进行表面形貌和成分分析,并在四球摩擦磨损试验机上评价了CaF2在润滑脂中的摩擦学性能.结果表明,制备的纳米CaF2粒径在23 nm左右,油酸以化学吸附的方式吸附在CaF2纳米核表面;作为添加剂油酸修饰纳米CaF2在润滑脂中具有良好的抗磨性能和极压性能,在高载荷时具有良好的减摩性能.SEM,EDS和XPS分析表明在摩擦过程中形成了由CaF2、CaO、氧化铁和有机添加剂所组成的边界润滑膜,从而使OA-CaF2具有良好的摩擦学性能.

An oleic acid surface -modified calcium fluoride （CaF2 ） nanoparticle （OA -CaF2 ） with average diameter of 23 nm was chemically synthesized using an extraction method. The morphologies and crystalline structures of the powder have been characterized by transmission electron microscopy （TEM） and X - ray diffraction （XRD）, while the chemical composition and further information on the structure of the nanoparticles have been characterized by FT-IR. The results showed that surface of CaF2 nanoparticles had been modified by oleic acid successfully. The tribological properties of the prepared OA - CaF2 nanoparticles as an additive in lithium grease were evaluated on a four - ball tester： The results indicated that nanoparticles exhibited excellent anti - wear and extreme pressure （EP） properties. It is also found that OA -CaF2 nanoparticles had good friction -reducing ability at high loads. SEM, EDS and XPS analyses indicated that a boundary film mainly composed of CaF2, CaO, Fe oxide and some adsorbed organic compounds was formed during the friction process. These contributed to the good friction - reducing and good antiwear ability of OA - CaF2 nanoparticles as lithium grease additive.