【作者】 王丽；

【导师】 曹丙强；

【作者基本信息】 济南大学 ， 材料工程（专业学位）， 2020， 硕士

【摘要】 金属纳米颗粒具有低剪切力、高延展性和优良的热稳定性等优点,作为润滑油添加剂表现出优异的抗磨减摩性能。但纳米颗粒的形状不规则,及易团聚等问题极大的限制了其作为润滑油添加剂的工程应用。近年来,一些碳材料如石墨烯,类金刚石薄膜(DLC),由于其独特的碳结构而具有卓越的光学性能,电学性能和力学性能。有些碳材料如石墨烯,可以作为作为润滑油添加剂,表现出优异的抗磨减摩性能;而有些碳材料如DLC则可以作为润滑膜沉积在机械表面,既保护摩擦表面同时又具有良好的润滑效果。金属与碳材料复合不仅可以抑制纳米颗粒的团聚且可构成新的形貌与结构,两者相辅相成达到更好的协同润滑效果。因此如何设计复合添加剂,并寻找简单适宜的制备方法,探索它们在摩擦过程中的润滑机理是摩擦领域的研究重点。本文根据机械摩擦的润滑机理,采用液相激光辐照技术和气相脉冲激光沉积技术制备了球形铜亚微米颗粒,石墨烯负载银纳米球的复合添加剂(L-Ag@rGO)及纳米双层结构Ag/DLC润滑膜,并对其作为润滑油添加剂和润滑膜的抗磨减摩机理进行了系统的探究。(1)球形铜亚微米颗粒的快速激光成型制备及其摩擦学特性研究。在室温下,以纳米铜颗粒为靶材,选用KrF脉冲激光进行液相激光辐照。不规则形状的纳米铜颗粒(100nm)具有较大的比表面积,能够快速吸收高的激光能量,然后瞬间融化并在周围溶液的冷却和表面张力作用下重塑为光滑的球形颗粒。该制备方法简单快速,有效简化了球形金属颗粒制备所需的高温高压等复杂实验条件,且产物球形度高,分散性好。将该光滑的实心铜亚微米球分散在液体石蜡中进行摩擦性能测试,结果表明该铜球颗粒作为润滑油添加剂展现出良好的抗磨减摩性能。这主要得益于铜颗粒的光滑球形形貌,在摩擦过程中将滑动摩擦转变为滚动摩擦,从而显著降低摩擦系数,减少摩擦副表面磨损;此外,在摩擦过程中,铜颗粒沉积在摩擦副的磨损部位,对磨损部位具有自修复的功能。(2)石墨烯负载银纳米球的一步激光辐照制备及摩擦特性研究。室温常压下,以商业银颗粒和氧化石墨烯的混合溶液为靶材,采用简单的一步液相激光辐照技术实现:氧化石墨烯被还原成石墨烯,同时不规则形状的银颗粒被重塑成球形形貌,最终单分散的银纳米球颗粒均匀地生长在石墨烯片上,形成了银/石墨烯复合层状结构。该复合物L-Ag@rGO作为润滑油添加剂,能长期稳定存在于基础油中并表现出优异的润滑性能。该润滑效果得益于L-Ag@rGO独特的复合结构:易剪切的层状结构,球形银纳米颗粒的微轴承作用,从而将滑动摩擦变为滚动摩擦来有效降低摩擦系数;此外,被剥离的银颗粒沉积在摩擦副凹坑处,对摩擦表面进行自修复,从而有效降低摩擦磨损。(3)激光沉积法制备纳米双层结构Ag/DLC润滑膜并探究了其摩擦特性。利用热蒸镀法在合金钢基体上沉积一层Ag膜作为过渡层,运用气相脉冲激光沉积技术,以固体石墨为靶材,通过调控脉冲频率、脉冲次数、脉冲能量、基底温度等条件,调控薄膜的厚度、DLC薄膜的中碳的杂化方式来制备了不同沉积率和不同微观结构的Ag/DLC润滑膜。通过实验找到了制备Ag/DLC薄膜的优化参数,并详细研究了Ag/DLC薄膜的微观结构和性质随沉积条件的变化规律和生长机制。最后对Ag/DLC薄膜的润滑性能进行了测试,发现了在合金钢基底上沉积Ag/DLC薄膜后的摩擦系数大大降低,证明了Ag/DLC薄膜具有良好的润滑性能。更多还原

【Abstract】 Metal nanoparticles have the advantages of low melting point,low shear force,high ductility and excellent thermal stability.As a lubricant additive,they show excellent lubrication effect and self-repair performance.However,the irregular shape,uneven particle size and easy agglomeration of nano-additive greatly limit its practical application as a lubricant additive.In recent years,some carbon materials,such as graphene and diamond-like film(DLC),have excellent properties of optical,electrical and mechanical due to their unique carbon structure.It can be not only used as lubricating oil additive,but also deposited on the mechanical surface as lubricating film,which can protect the friction surface and have good lubrication effect.The combination of metal and carbon can not only inhibit the agglomeration of nanoparticles but also form new morphology and structure,and the two can complement each other to achieve better synergistic lubrication effect.Therefore,it is the research emphasis in the field of friction to design the morphology and structure of composites,to search for suitable preparation methods and to explore their lubrication mechanism in the friction process.In this paper,according to the lubrication mechanism of mechanical friction,copper submicrospheres particles were prepared by using laser irradiation technology and laser deposition technology.Graphene was loaded with silver nanometer spheres particles and nanometer double-layer Ag/DLC lubrication film,and their anti-wear and anti-wear mechanism as lubricating oil additive and lubricating film was systematically investigated.(1)Preparation of copper submicrospheres particles by laser irradiation and tribological properties.At room temperature,copper nanoparticles were used as targets for liquid phase laser irradiation.With irregular shape and large specific surface area,nanoscale commercial copper particles(100 nm)absorb high laser energy and instantly melt and are reshaped into smooth copper spherical particles under the cooling effect of the surrounding solution and surface tension.The preparation method can effectively solve the complex experimental conditions such as high temperature and high pressure required for the preparation of spherical metal particles,and the products have high sphericity and good dispersibility.The smooth solid copper submicrospheres was dispersed in the liquid paraffin to test the friction performance.The results showed that the copper submicrospheres particle showed good anti-friction and anti-wear performance as a lubricant additive.This is mainly due to the spherical morphology of the copper particles,which transforms the sliding friction into rolling friction in the friction process.In addition,the residual copper particles are deposited in the wear part of the friction pair,which has the function of self-repair to the friction parts.(2)Preparation and friction properties of graphene-loaded silver nanospheres particles by laser irradiation.Using a mixture of commercial silver particles and graphene oxide(GO)as a target,through adjusting experimental conditions of the laser energy density and irradiation time,irradiation frequency,the GO was reduction of graphene,meanwhile the irregular shape of Ag particles be reshaped into spherical morphology,eventually monodisperse silver nanospheres particles evenly growth in graphene sheet,formed the silver/graphene composite layer structure(L-Ag@rGO).As a lubricant additive,the compound can be stable in the base oil for a long time and has excellent lubrication performance.Firstly,the lubrication effect is due to the sheared layered structure.secondly,the spherical silver nanoparticles act as microbearings,effectively changing the sliding friction into rolling friction,thus reducing the friction coefficient.Finally,the stripped silver particles are deposited in the pits of the friction pair to repair the friction surface,thus effectively reducing wear.(3)Study on the preparation of nanometer bilayer Ag/DLC lubrication film by laser deposition method and its friction characteristics.Using thermal evaporation method deposits a layer of Ag film on the steel substrate as a transition layer,using pulsed laser deposition technique,with solid graphite as the target material,through the control pulse frequency,pulse energy,basal condition such as temperature,control the thickness of the film,carbon hybridization method such as the preparation of different performance of DLC thin.It is concluded that Ag/DLC film has good lubrication performance through friction test.更多还原