【作者】 吴凯；

【导师】 胡献国；

【作者基本信息】 合肥工业大学 ， 机械设计及理论， 2018， 硕士

【摘要】 为了提高润滑油的润滑性能,添加润滑添加剂成为改善润滑性能,提高机械设备使用寿命和可靠性的重要方式之一。碳基纳米颗粒具有优异的力学性能,具有良好的应用前景。但是,由于纳米颗粒比表面积大,比表面能高,易团聚,难以在润滑体系中形成稳定均匀的分散体系,严重制约着其性能的发挥和生产应用。本学位论文以两种不同结构的碳基纳米颗粒作为润滑添加剂,通过不同的处理工艺对其进行分散改性,实现了碳基纳米颗粒在润滑油中的稳定分散,并在此基础上,考察了不同含量的碳基纳米颗粒添加剂在不同载荷下的摩擦学性能。利用Zeta电位、FIRT、XRD、Raman等表征仪器分析了颗粒特性。采用扫描电镜及其能谱仪,3D激光扫描仪,拉曼等手段对摩擦副表面进行了表征,进而探讨了碳基纳米颗粒在润滑油中的摩擦磨损机理。首先论文探讨了纳米金刚石在润滑油中的分散工艺。结果表明,强酸处理和高温处理后的纳米金刚石,粒度明显降低;红外光谱分析结果表明,改性后的纳米金刚石表面含氧官能团明显增多;静置法和离心法表明,纳米金刚石在32~#液压油中具有优异的分散稳定性,分散机理归于颗粒粒度降低和表面基团的空间位阻效应。由于氧化石墨烯具备比石墨烯更佳的分散前提条件,故论文又对石墨经改进的Hummers方法制备得到的氧化石墨烯作为原料,通过两种不同处理工艺对其进行分散处理。结果表明,氧化石墨烯在油胺、分散剂和清净剂的作用下可以稳定分散在柴油机油中。同时,对氧化石墨烯进行高速离心筛选的前处理,可获得透明性良好的稳定氧化石墨烯/柴油机油润滑体系。另外,论文还研究了分散稳定的纳米金刚石/32~#液压油润滑体系的摩擦学性能,考察了随纳米金刚石的添加量和载荷对其摩擦学特性的影响。结果表明,高载荷下,平均摩擦系数和磨斑直径随纳米金刚石的添加量的增加,呈现先降低后增加的趋势;低载荷下,平均摩擦系数和磨斑直径随纳米金刚石添加量的增加,表现出先降低,后来逐渐稳定的变化规律;低含量的纳米金刚石不改变润滑油的最大无卡咬负荷(P_B值),而高含量下却提高了润滑油的P_B值。最后,论文研究了分散稳定的氧化石墨烯/柴油机油润滑体系的摩擦学性能。结果表明,高载荷下,氧化石墨烯不利于柴油机油的抗磨作用,但对减摩性能影响不大;低载荷下,氧化石墨烯明显提高了柴油机油的抗磨减摩性能。其机理归功于低载荷下氧化石墨烯在摩擦过程中形成良好的润滑膜,有效的降低了摩擦副间的摩擦和磨损。更多还原

【Abstract】 Using lubricating additives has become one of important ways to improve lubrication performance and increase the use life and reliability of mechanical parts in order to improve the lubricity of lubricants.Carbon based nanoparticles have excellent mechanical properties,and thus have good prospects for application.However,due to the large specific surface area and high specific surface energy,nanoparticles are easy to agglomerate and difficult to form stable lubricating system with uniform dispersion,which restricts seriously their performance and production applications.In the present thesis,two kinds of carbon nanoparticles with different structure were used as lubricating additives,and dispersed and modified through different treatment processes,so as to achieve stable dispersion of particles in lubricating oil.On this basis,it was investigated their tribological properties containing carbon base nanoparticles with different contents under different loads.The characteristics of the particles were analyzed by means of Zeta potential,FIRT,XRD and Raman etc.The surfaces of the friction pair after rubbing process were analyzed by scanning electron microscope(SEM)and its energy spectrometer,3D laser scanner and Raman.It was also studied the friction and wear mechanisms of carbon base nanoparticles in the lubricating oils.It was studied firstly the dispersing process of nanodiamond in lubricating oil.The results showed that the size of nanodiamond was obviously reduced by strong acid treatment and high temperature treatment.The results of infrared spectrum analysis showed that the oxygen functional groups increased obviously on the modified nanodiamond surface.Static and centrifugal methods showed that nanodiamond had excellent dispersion stability in 32~#hydraulic lubricating oil.The dispersion mechanism was attributed to the decrease of particle size and the space steric effect on the surface groups.Graphene oxide has better dispersing precondition than graphene.Thus,the graphene oxide prepared by improved Hummers method was dispersed by two different processes.The results showed that the graphene oxide could be stably dispersed in diesel engine oil with help of oil amine,dispersing agent and detergent effect.However,the pre-treatment of high speed centrifugation for graphene oxide could obtain a clear and stable lubricating system of diesel engine oil containing graphene oxide.The tribological properties of the dispersed and stable 32~#hydraulic lubricating oil containing nanodiamond were studied with nanodiamond content and different loads.The results showed that the average friction coefficient and the wear spot diameter decreased firstly and then increased with the increase of nanodiamond under high load.However,the average friction coefficient and the wear scar diameter decreased and then stabilized with the increase of nanodiamond under low load.The maximum non-seizure load(P_B)of the tested lubricating oil was not changed under the low content of nanodiamond,and P_B of the tested lubricating oil was increased under high content of nanodiamond.The tribological properties of the dispersed and stable diesel engine oil containing graphene oxide were studied with the content of graphene oxide and different loads.The results showed that the graphene oxide had adverse antiwear effect on diesel engine oil and had little effect on antifriction performance under high load.The antiwear and antifriction performance of diesel engine oil could be improved obviously under low load.The friction reduction and wear resistance mechanisms were attributed to that graphene oxides formed a good lubricating film during rubbing under low load,which reduced the friction and wear effectively.更多还原