片状纳米石墨和无机类富勒烯二硫化钼作为润滑油添加剂的摩擦学性能

【作者】 黄海栋；

【导师】 涂江平；

【作者基本信息】 浙江大学 ， 材料学， 2006， 硕士

【摘要】 本文以研究和发展具有良好抗磨性能、高承载能力、对磨损表面具有一定修复功能的润滑油添加剂为背景,对纳米材料作为润滑油添加剂的摩擦学性能进了研究,并讨论了它们的摩擦机理。 利用搅拌球磨法制备了片状纳米石墨,通过脱硫化学共沉淀法制备获得的MoS₃前驱体制备了无机类富勒烯二硫化钼（IF-MoS₂）。采用透射电子显微镜（TEM）和X射线衍射仪（XRD）分别对它们的形貌和结构进行了分析。结果表明,通过搅拌球磨法制备获得的片状纳米石墨粒径在100～300nm,厚度在10～20nm,保持了原始的片状结构。通过化学共沉淀法制备非晶态MoS₃,并脱硫制备获得的IF-MoS₂平均粒径在100nm左右,其结构为球状嵌套封闭结构。 采用四球摩擦副的MMW-1立式万能摩擦磨损机考察了它们作为润滑油添加剂的摩擦学性能。结果表明: （1）添加片状纳米石墨可以提高基础油的抗磨能力和极压性能,降低摩擦系数,且其最佳添加值在1.0×10^-2wt.%左右。其摩擦机理为:在分散剂分子的作用下沉积到摩擦副表面,在摩擦剪切力和法向载荷的作用下,片状纳米石墨层与层之间发生解理,并沿着解理平面滑动,在摩擦副表面形成一层牢固的薄片状物理吸附膜,隔离了两个摩擦副的直接接触,从而起到抗磨减摩作用。 （2）添加IF-MoS₂纳米颗粒可以提高基础油的抗磨减摩性能。且随着添加剂浓度的增高,抗磨减摩能力也随之提高,即浓度越高,抗磨减摩效果越好。其摩擦机理为:首先,球状二硫化钼可以随着基础油进入摩擦副之间,起到滚珠作用;其次,在摩擦过程中,球状的二硫化钼颗粒被压平,形成物理摩擦膜,同时,有些颗粒填充到沟犁或是凹坑中,阻隔两个摩擦副的直接接触,从而起到抗磨减摩作用。 综上所述,添加纳米粒子可以提高基础油的摩擦学性能,且有不同于传统抗磨减摩添加剂的摩擦机理。更多还原

【Abstract】 Upon researching and developing lubricating oil additives with good antiwear, high load-carrying capacity and self-repair of the worn surface, the tribological properties of nanoparticles as oil additives were investigated, and their tribological mechanisms were also evaluated.Graphite nanosheets, which keep the previous laminated structure, were prepared by stirring ball milling, and IF-MoS₂ nanoparticles were synthesized by desulphurizing the precipitated MoS₃ precursor. Their morphology and structure were observed using transimission electron microscope （TEM） and X-ray diffraction （XRD）. It is found that graphite nanosheets have a diameter of 100-300 nm, thickness of 10-20 nm, and its structure is laminated. IF-MoS₂ nanoparticles have an average diameter of 100 nm, and its structure is spherical and nested.Their tribological properties as oil additives were evaluated with MMW-1 four-ball tribotester respectively. The results indicated that:（1） The load-carrying capacity and antiwear ability of the base oil were improved, and the friction coefficient was decreased by the addition of graphite nanosheets. The optimal concentration of the additive in paraffin oil is about 1.0 ×10^-2 wt.%. The worn surface were analysed with SEM also. It is found that graphite nanosheets deposited on the rubbing surface. Its mechanism is: The graphite nanosheets form a continuous, compact and firm physical film under the shear force, which not only bears the load of the steel ball but also separates the rubbing faces and prevents them from direct contact, so the wear and friction decrease.（2） The wear resistance of the paraffin oil was improved and the friction coefficient of the oil was decreased by the addition of the IF-MoS₂ nanoparticles. The higher the concentration is, the more effective the antiwear and friction-reducing are. Analysing its worn surface, it is found that spherical nanoparticles were flattened. Its mechanism is: IF-MoS₂ penetrated into the rubbing surface and rolled in the rubbing surface. During the friction test, the spherical nanoparticles were flattened, and formed physical tribofilm, meanwhile, some nanoparticles filled into the valley. IF nanoparticles can be furnished form the valleys to thecontact surface, so the antiwear ability of base oil was improved, and the friction coefficient was decreased significantly.In conclusion, the tribological properties of the base oil could be improved by the addition of nanopartilces, and their possessed different mechanism from traditional anti-wear and friction-reducing additives.更多还原