超声液相剥离制备二维MoS_(2)作为润滑脂添加剂的摩擦学研究EI北大核心

通过超声液相剥离法制备不同片径的二硫化钼纳米片,并将其作为添加剂应用到锂基润滑脂。通过电子显微镜、拉曼光谱、X射线衍射仪和热重分析仪对所制二硫化钼纳米片的形貌、组成和结构进行表征;利用四球摩擦磨损试验机考察二硫化钼锂基润滑脂摩擦学性能,通过扫描电子显微镜和X射线光电子能谱分析MoS_(2)润滑脂润滑下钢球的磨损表面形貌,初步探究MoS_(2)的润滑机理。结果表明:二硫化钼纳米片表现出优异的抗磨减摩性能,当添加片径为80 nm,添加量为1.0%(质量分数)时,锂基润滑脂摩擦学性能最佳,最大无卡咬负荷和烧结负荷相较于基础脂分别提升了55.4%和61.2%,摩擦因数最高减小了23.15%,磨斑直径最高减小了21.13%。其摩擦学性能的提高主要与形成了Fe的各类氧化物、FeOOH、MoS_(2)和相关有机物构成的摩擦保护膜有关。     

磁控溅射MoS2/WS2复合薄膜的工艺与摩擦学性能研究

采用MoS2/WS2复合靶材在不锈钢和硅基片上溅射MoS2/WS2纳米薄膜,通过多次实验,得到溅射MoS2/WS2薄膜的最佳工艺如下:溅射气压4.0Pa,靶基距为70mm,溅射功率为150W,溅射时间为3h.使用X-射线衍射仪,能谱仪,扫描电子显微镜对薄膜的成分和结构进行分析.采用HH-3000薄膜结合强度划痕试验仪,纳米压痕测试系统,UNT-3摩擦磨损试验机对薄膜进行机械性能和摩擦磨损性能分析,结果表明:在大气环境中,WS2/MoS2 复合薄膜摩擦性能要优于纯MoS2薄膜.     

WS2纳米材料的摩擦学性能研究

在MS-800A四球摩擦磨损实验机上考察了热分解法制备的WS2纳米材料作为润滑油添加剂的摩擦学特性,采用EDS分析磨痕表面元素的化学状态,用扫描电子显微镜观察磨痕表面形貌,通过对钢球磨斑直径、PB值的变化分析了WS2纳米材料的形貌、添加剂含量对润滑油摩擦性能的影响。     

纳米WS_2粉末在发动机模拟台架中的实验研究

采用多能场复合作用下的湿式粉碎法制备出纳米WS2粉末,并加入到发动机润滑油中制备成纳米WS2润滑剂.在自行研制的发动机模拟实验台架上考察了该润滑剂在发动机上的实际应用效果,分析了纳米WS2粉末对发动机润滑油摩擦学性能的影响,研究了其在减少发动机内部磨损和降低发动机油耗方面的效果,最后对比分析了全配方纳米WS2汽机油与2种国外品牌汽机油的性能.结果表明,纳米WS2粉末可以显著延长发动机润滑油的使用寿命和换油周期,并能使发动机活塞环的磨损量减少27.6%,发动机油耗降低13%～28%;同时,全配方纳米WS2汽机油在摩擦学性能、减少活塞环磨损以及降低发动机油耗方面均优于国外品牌汽机油.     

硅烷KH570与聚甲基丙烯酸甲酯改性WS_2固体润滑涂层的性能

为提高WS_2固体润滑涂层的性能,先以甲基丙烯酰氧基三甲氧基硅烷(KH570)改性WS_2颗粒,再在颗粒表面以甲基丙烯酸甲酯(MMA)原位合成聚甲基丙烯酸甲酯(PMMA)进行二次改性,并制备了WS_2固体润滑涂料涂层。采用扫描电子显微镜对涂层微观结构进行表征,采用摩擦磨损试验评价了固体润滑涂层的摩擦学性能,并采用数码相机观察磨痕的形貌。结果表明:KH570改性WS_2固体润滑涂层耐磨性能显著提高,摩擦系数也随KH570用量降低显著减小;MMA原位合成二次改性增加了涂层摩擦系数,但MMA与WS_2质量比为7∶50时,二次改性WS_2固体润滑涂层磨损量仅为纯WS_2涂层的31%。     

液相等离子体法制备石墨烯及其摩擦学性能

为制备一种低成本的石墨烯作为润滑油添加剂,采用液相等离子体法制备了石墨烯粉末,研究放电电压与电流的对应关系及电解质浓度对起始放电电压的影响。利用扫描电子显微镜、X射线衍射仪和拉曼光谱对石墨烯的微观形貌和组成进行表征,利用分光光度计研究不同石墨烯添加量在润滑油中的分散性和透光性,利用往复式摩擦试验机对不同石墨烯添加量的润滑油的摩擦学性能进行测试。结果表明:在相同电解质环境下,等离子体放电所需的功率基本恒定,当电解质Na2CO3浓度为0.3 g/L时,所需的起始电压(1.24 k V)和功率(0.258 kW)最低;制备的石墨烯粉末呈片层结构,在润滑油中的分散稳定性较好,静置48 h后透光率略有下降;当石墨烯添加量为0.4%和0.5%时,润滑油摩擦系数较低,约0.04,缸套和活塞环的磨损率下降至(2.5～2.8)×10-7mm3/(N·m),且随石墨烯添加量的增加继续稳定在较低水平;石墨烯作为润滑油添加剂可在摩擦表面形成稳定的吸附膜和化学反应膜,减少摩擦副的直接接触,使黏着磨损转变为轻微的磨粒磨损和腐蚀磨损,降低了摩擦系数和磨损率。     

石墨对Ni-Cr和Ni-Cr-W复合材料摩擦性能的影响

采用粉末冶金方法制备了Ni-Cr基自润滑复合材料,研究了Ni20Cr-石墨与Ni20Cr-10W-石墨复合材料中石墨含量和添加W后对材料力学性能和摩擦性能的影响.结果表明:随着石墨体积分数的增加,Ni20Cr-石墨复合材料的显微硬度和致密度不断降低;将石墨添加到Ni20Cr-10W复合材料中,材料摩擦系数明显降低,在每个试验温度下,复合材料的摩擦系数都随石墨含量的增加出现先增加后降低的变化规律;在Ni20Cr-石墨复合材料中添加体积分数10%的W后,复合材料显微硬度有所增加;当石墨体积分数为10%时,材料的摩擦系数在各个试验温度下均有所增加,当石墨体积分数为5%和15%时,复合材料的摩擦系数在整个温度范围内均有所降低;在整个温度范围内,Ni20Cr-10W-15石墨复合材料的摩擦系数最低.     

Preparation and tribological properties of homogeneously dispersed graphene-reinforced aluminium matrix composites

Aluminium matrix composites reinforced with homogeneously dispersed graphene (Gr/Al) were fabricated by electrostatic self-assembly and powder metallurgy. The microstructure of the composites was observed. The effects of graphene content, applied load and sliding speed on the tribological properties of the composites were also investigated. The results show that graphene is homogeneously dispersed in the aluminium matrix. The coefficient of friction for the composites initially increases and later decreases with increasing graphene content. It is lowest in the 0.3 wt-% Gr/Al composite, which is a decrease of approximately 20% when compared to that of pure aluminium. The coefficient of friction of the composites appears to increase significantly when increasing the applied load. However, it decreases with increases in the sliding speed.     

PMMA/SiO2纳米杂化材料的制备及作为润滑油添加剂的摩擦学性能

用无皂乳液聚合法，一步制备了聚甲基丙烯酸甲酯，表面有机化二氧化硅（PMMA／SiO2）纳米杂化材料，采用了红外光谱（FT-IR）、透射电子显微镜（TEM）以及热分析（TGA-DSC）等仪器对材料的核一壳结构进行表征，利用四球机考察了添加剂在AN10全损耗系统用油中的摩擦学性能。结果表明，合成的PMMA／SiO，纳米杂化材料能提高润滑油的抗磨性能及承载能力，并能降低摩擦系数，其最佳用量为1．5％，同时，PMMA／SiO2纳米杂化材料能极大地提高润滑油的极压性能。     

Synthesis of ionic liquid functionalized graphene oxides and their tribological property under water lubrication

Ionic liquid functionalized graphene oxides (GOs-IL) were synthesized by the amidation and cation-π stacking, and their tribological property as the water-based lubricant additives was investigated. The GOs-IL exhibited superior friction-reducing and antiwear performance. Specifically, under the same test conditions, the mean friction coefficient and wear volume of 0.02 wt% GOs-IL/base liquid suspension were 57% and 76% lower than that of base liquid. The worn surface analyses revealed that the boundary tribofilm composed of the GOs-IL deposition film and chemical reaction film should formed on the wear scar lubricated by the GOs-IL/base liquid suspension. The proposed lubrication mechanism illustrated that the IL functional groups of GOs-IL improved their absorption and embedded stability on the rubbing surfaces by the electrostatic interactions, and then promoted the formation of the above boundary tribofilm. The tribofilm directly prevented the rubbing surfaces from the immediate contact and hence greatly reduced the friction and wear.     

石墨、MoS2填充PTFE的摩擦学转移特性研究

利用改装的MM - 2 0 0型磨损试验机 ,评价了石墨、MoS2 填充的PTFE的摩擦学性能 ,实验表明 ,MoS2 填充的复合材料在上下两个试验环上形成转移膜的能力较强 ,且转移膜寿命较长。EDS、XPS等分析测试结果显示 ,MoS2 填充的PTFE复合材料形成的转移膜与底材金属之间发生了以S的氧化为特征的摩擦化学反应。认为 ,二硫化钼与底材表面由于摩擦引发的活性中心的化学反应提供了转移膜与底材间的牢固结合 ,导致体系具有较高的耐摩性     

Evaluation of different polyolefins as rheology modifier additives in lubricating grease formulations

The purpose of the present work is to evaluate the effect that different polyolefins, used as additives in small proportions, exert on the rheological properties of standard lithium lubricating greases. Grease formulations containing several polyolefins, differing in nature and molecular weight, were manufactured and rheologically characterized. The influence of the type of polymer, molecular weight, crystallinity degree and vinyl acetate content has been analyzed. Small-amplitude oscillatory shear (SAOS) and viscous flow measurements, as well as calorimetric (DSC) and thermogravimetric (TGA) analysis, were carried out. In general, the addition of polymers such as HDPE, LDPE, LLDPE and PP to lithium lubricating greases significantly increases the values of the rheological parameters analyzed, consistency and mechanical stability. However, the use of polyolefins as rheology modifiers does not significantly affect the friction coefficient determined in a tribological contact. The crystallinity degree, mainly dependent on the nature of the polymer, has been found the most highly influencing parameter on the rheology of the lubricating greases studied. However, the rheological modification exerted by EVA copolymers mainly depends on the vinyl acetate content. Thus, a negative effect in both apparent viscosity and linear viscoelastic functions of greases was obtained when polymer vinyl acetate content is higher than 28% (w/w).     

硬脂酸修饰LaPO4和Ce/LaPO4纳米微粒的制备及其摩擦学性能

采用共沉淀表面修饰法,制备了硬脂酸修饰LaPO4和Ce/LaPO4纳米微粒,用红外光谱仪、X射线衍射和透射电子显微镜对表面修饰纳米微粒的结构、形貌进行了表征,考察了表面修饰纳米微粒在溶剂中的分散性,利用四球试验机考察了表面修饰纳米微粒的摩擦学性能,并用扫描电镜对钢球磨斑表面形貌进行了分析.结果表明,硬脂酸修饰LaPO4...     

PBII制备TiNx/DLC多层膜的结构及摩擦学性能

采用等离子体基离子注入技术在30CrMnSi钢上制备了TiNx/DLC多层膜，通过X射线光电子谱和激光喇曼光谱测试分析了膜的结构特征，TiNx/DLC膜大气下的摩擦性能和在球盘式摩擦磨损试验机上进行。结果表明：DLC膜的结构强烈依赖于基权脉冲偏压，－5kV制得的DLC膜具有较多的C－H键结构，因而硬度最低，仅有8.3GPa；而-15kV的DLC膜由于含有较多的sp^3键，获得了最高的显微努氏硬度（23.6GPa)。DLC膜与GCr15钢球大气下的摩擦因数为0.17左右，其磨损性能由于TiNx，过渡层引入而显著提高。