表面未修饰及修饰纳米SiO2对锂基脂摩擦学性能的影响

利用四球摩擦磨损试验机考察了表面未修饰及修饰纳米SiO2作为添加剂对锂基脂摩擦学性能的影响;采用扫描电子显微镜观察了钢球磨损表面形貌,并采用X射线光电子能谱仪分析了钢球磨损表面典型元素的化学状态,以探讨2种纳米SiO2添加剂的减摩抗磨作用机理。结果表明,采用化学法和物理法制备的表面修饰及未修饰纳米SiO2作为添加剂均能通过形成复合边界润滑膜而改善锂基脂的减摩抗磨性能,其中采用物理法制备的未修饰纳米SiO2的减摩作用略优,而采用化学法制备的表面修饰纳米SiO2在高载荷下的抗磨作用较优。

Effect of Unmodified and Surface-modified Nano SiO2 as Additives on the Tribological Properties of Lithium Grease

Nanoparticulates of SiO_2 prepared by means of chemical and physical methods were used as the additives of a commercial lithium grease.The effects of the resulting surface-modified and unmodified SiO_2 nanoparticulates on the tribological properties of the lithium grease were comparatively examined on a four-ball machine.The morphologies of the worn surfaces of the lower steel balls were observed using a scanning electron microscope,while the chemical states of some typical elements on the worn surfaces of the upper steel balls were analyzed by means of X-ray photoelectron spectroscopy.The results show that the two kinds of SiO_2 nanoparticulates are effective to improving the friction-reducing and antiwear abilities of the lithium grease,which is attributed to the formation of the boundary lubricating and protective layers on the worn steel surfaces.Namely,both the unmodified and surface-modified SiO_2 nanoparticulates function to reduce the friction and wear of the steel-steel contact by physical and chemical adsorption on the sliding steel surface,and the former is slightly superior to the latter in terms of the friction-reducing ability,while the latter has stronger antiwear ability at a larger normal load.