纳米碳酸钙作为润滑脂添加剂的摩擦学性能及流变行为研究

Tribological Properties and Rheological Behaviors of Calcium Carbonate Nanoparticle as Grease Additive

使用碳化法制备出三种具有不同粒径的纳米碳酸钙颗粒,利用透射电镜(TEM)和X射线衍射仪(XRD)对其形貌及结构组成进行表征.通过UMT-2摩擦学试验机及RS6000流变仪分别考察了纳米颗粒作为润滑脂添加剂的摩擦学性能及流变学行为,并通过X射线多功能电子能谱仪(XPS)对磨斑表面进行分析.结果表明:所制备的三种纳米颗粒均为方解石结构,可以显著提高基础脂的减摩抗磨性能;添加剂浓度及添加剂尺寸均会影响润滑脂最终的摩擦学性能;在最佳添加浓度和尺寸条件下,能够同时获得最佳的抗磨减摩性能;过高的添加剂浓度会影响润滑脂的结构稳定性,进而影响其摩擦学性能;三种纳米添加剂在磨斑表面形成以碳酸钙为主要成分的润滑膜,纳米颗粒物理性质的差异可能导致其摩擦学性能的差异.

In this study, three kinds of calcite calcium carbonate nanoparticles （CCNP） with different average diameters were successfully fabricated via the carbonation method. The morphologies and phase compositions of the CCNP were determined via transmission electron microscopy and X - ray diffraction. The effects of the concentration and size of CCNP on the tribological properties and rheological behaviors of grease were investigated to reveal the lubrication mechanism via UMT -2MT friction tester and HAAKE RS6000 （Germany） Rheometer. The results show that the tribological performances can be improved significantly by addition of CCNP. There existed optimum CCNP concentration and size, where the grease can exhibit simul - taneously optimal anti - wear and friction - reducing properties. Meanwhile, the rheological performance of greases greatly influenced their final tribological properties. The excessive concentration of CCNP provided negative effects on rheological performances and further affected the final tribological properties, especially at rigorous test conditions. In addition, X - ray photoelectron spectroscopy show that tribofilms with the similar composition of calcium carbonate, calcium oxide, iron oxides and other organic compounds were found on the contact area. The selectivity of tribological performances of CCNP for the test condition may be due to the difference of the mechanical nroDerties, which deoended on the different sizes of CCNP.