锂基润滑脂流变性及摩擦学性能相关性研究

以锂基润滑脂为例,通过 R／S 锥板式流变仪和四球摩擦磨损试验机,对其流变性能及摩擦磨损性能进行研究,探讨润滑脂流变性能与摩擦磨损性能的相关性。结果表明：润滑脂表观黏度随剪切速率的增大逐渐减小,随锥板间隙的增大逐渐增大,随温度的升高逐渐下降,最后均趋于稳定值。润滑脂的平均摩擦因数和磨斑直径随速度的增大先增大后减小,随载荷的增大逐渐增大,随温度的升高先增大后减小。润滑脂的流变性能和摩擦磨损性能随速度、载荷、温度变化的趋势大体一致,表明锂基润滑脂流变性能与其摩擦磨损性能有一定的相关性,为进一步研究润滑脂流变性能与使用性能之间的关系打下了基础。     

磷酸酯离子液体润滑脂的摩擦学性能研究

用腐蚀性较低、简单易合成的磷酸酯离子液体为基础油,聚四氟乙烯微粉为稠化剂制备一种新型的离子液体润滑脂,在Optimol SRV摩擦试验机上考察其对钢/钢摩擦副的摩擦学性能。结果表明,磷酸酯离子液体润滑脂在室温和高温(100℃)下都表现出优异的减摩抗磨性,并且其减摩抗磨性与离子液体阳离子和阴离子的烷基链长密切相关。磨斑表面扫描电镜和XPS的分析结果表明:摩擦表面既存在离子液体润滑脂与摩擦表面发生摩擦化学反应生成的含有Fe F2、Fe PO4和氮的氧化物的化学反应膜,又存在稠化剂聚四氟乙烯的物理吸附膜。     

Tribological Performance and Surface Analysis of a Borate Calcium as Additive in Lithium and Polyurea Greases

In this work, a borate calcium additive was added to lithium and polyurea greases to investigate the tribological performance. Friction and wear tests were conducted on a four-ball machine under higher load and a reciprocating tribometer under lower load. X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analyses were performed on the worn surface after the tests. It was found that the tribological performance affected the boundary layers formed by the additive and the soap fibers. The boundary films in lithium grease mainly consist of ferrum hydroxide, and more oxide can be found in polyurea-based films. SEM analyses of soap fibers show that the soap fibers in polyurea-based grease were more separated than those in lithium-based grease. Compared to the base grease, the soap shows smaller and shorter fibers.     

Effect of Graphene and Ionic Liquid Additives on the Tribological Performance of Epoxy Resin

In the present study, we have determined the effect of graphene (PG), the ionic liquid (IL) and PG modified by mechanical blend with the IL 1-octyl-3-methylimidazolium tetrafluorobotate (IL + PG) on the tribological performance of epoxy resin (ER). IL + PG stable suspensions have been added to an epoxy resin (ER) matrix to obtain the new nanocomposite (ER + IL + PG), and its tribological performance has been compared with that of neat epoxy resin and with the nanocomposites containing PG (ER + PG) or IL (ER + IL). While neat ER presents a high dynamic friction coefficient of up to 0.31 and a severe wear with a specific wear rate of 8.1 × 10^?4 mm³ N^?1m^?1, the new nanocomposites show negligible surface damage, as determined by surface roughness and profilometry. All nanocomposites show low friction coefficients and negligible wear. The maximum friction reduction, up to a 70 %, is obtained for ER + PG. Results are discussed upon the basis of TEM microscopy, SEM microscopy and EDX analysis, differential scanning calorimetry, thermogravimetric analysis and dynamic mechanical analysis. Addition of IL or IL + PG has a plasticizing effect on ER, while addition of PG increases the thermal stability and stiffness of ER. PG shifts the storage modulus onset and in the loss modulus and tan δ maximum peaks to higher temperatures, while a shift to lower values is observed with addition of IL or IL + PG.     

Tribological Performance of Some Pennzane®-Based Greases for Vacuum Applications

Commercial greases for space applications usually fulfill the requirements imposed by the severe conditions of use (load, ultrahigh vacuum, speed, etc.). The main requirement is their ability to create an elastohydrodynamic lubrication film, boundary film, or both, for the speed, load, and temperature conditions under which the mechanisms will operate. Three greases, all based on a multiply alkylated cyclopentane (Pennzane®) base oil, were studied. The thickeners were an n-octadecylterephthalamate soap, a lithium soap, and a urea derivative. A four-ball tribometer and a spiral-orbit tribometer were employed to evaluate the greases under ultrahigh vacuum. The results indicated that all three greases yielded very low wear rates and extended lifetimes. In addition, routine physical property data are reported for each grease.     

Investigation of the Stability and Tribological Performance of Ionic Nanoliquids

In previous studies, nanoparticles and ionic liquids (ILs) have been used separately as oil additives and have been shown to reduce friction and wear. In this study, the stability and tribological performance of ionic nanoliquids (INLs), which combine nanoparticles and miscible ionic liquids together as oil additives, were investigated. Zinc oxide nanoparticles were dispersed in a mixture of polyalphaolefin (PAO) oil and ionic liquid (tetradecyltrihexylphosphonium bis (2,4,4-trimethylpentyl phosphinate)) using an ultrasonic homogenizer. The coefficient of friction was studied using a tribometer with a ball-on-disk configuration. The wear track was measured using a Bruker Contour GT-K Optical Profiler and the wear volume was calculated. The effects of concentration and load on the coefficient of friction and wear were investigated. The effects of ultrasonic mixing time and nanoparticle concentration on the stability of the solutions were also studied.     

Tribological Performance of Room-Temperature Ionic Liquids as Lubricant

The tribological performance of room-temperature ionic liquid of alkylimidazolium tetrafluoroborate was evaluated using an Optimol SRV oscillating friction and wear tester in air and a CZM vacuum friction tester in vacuum (1×10^-3 Pa) using a steel/steel (SAE52100) contact. From the results, the ionic liquid exhibits excellent friction-reduction, antiwear proprieties, both in air and vacuum, which are superior to phosphazene (X-1P) and perfluoropolyether (PFPE). During friction, the ionic liquid forms a surface protective film mainly composed of FeF₂ and B₂O₃, which contributes to low friction and wear.     

锡锌复合半流体脂的摩擦学和自修复性能研究

针对钢-铜摩擦副类机械零件表面的磨损,研究了一种用微米级锡粉和锌粉与Li基脂、VG32号油混合制备的锡锌复合半流体脂,通过机械摩擦作用,它能在铜试样上形成较厚的自修复摩擦涂层。在MS-800型改进四球式试验机上考察了涂层在不同载荷和转速下的摩擦磨损性能,用X射线光电子能谱仪(XPS)分析了涂层表面的主要元素。结果表明,涂层主要由Zn、Sn、Cu、C及O等元素组成,它能有效地改善钢-铜摩擦副的摩擦磨损性能。     

Tribological Performance of Lubricating Greases Based on Calcium Carbonate Polymorphs Under the Boundary Lubrication Condition

In this article, we synthesized the calcium sulphonate grease (CSG) based on the calcite using the bright stock (150BS) as the base oil. In order to investigate the tribological performance of lubricating grease containing different calcium carbonate polymorphs under boundary lubrication condition, a calcium sulphonate complex grease (CSCG) based on the vaterite was used as a reference. An oscillating reciprocating friction and wear tester set at a series of applied loads and frequencies was adopted to evaluate the tribological performance under boundary condition. Results showed that the lubricating grease that was composed of crystalline calcite as the partial thickener had excellent friction-reducing and antiwear (AW) properties, regardless of the applied loads and frequencies. The vaterite in CSCG easily experienced a polymorph transformation into calcite or aragonite characterized by Raman spectroscopy. This polymorph transformation was attributed to the highly local friction temperature and activated hydrogen from water or acids oxidated in the rubbing process at high load or frequency. The physical polymorph transformation corresponded to the fluctuations of the friction coefficients, then contributed to the severe wear. XPS analysis indicated that two calcium sulphonate lubricating greases occurred a tribochemical reaction and boundary tribofilms consisted of CaCO₃, CaO, iron oxide and FeSO₄ were formed on the rubbing surfaces. The tribofilm formed by the introduction of the CSG that mainly depended upon the thickeners of calcite structure contributed to an excellent AW protection. The possible boundary friction mechanism for greases based on various calcium carbonate polymorphs was also proposed. Effect of calcium carbonate polymorphs on the tribological performance was discussed.     

离子液体改性环氧树脂复合材料摩擦学性能研究

为探讨离子液体的加入对环氧树脂固化过程及摩擦学性能的影响,制备离子液体(1-丁基-3-甲基咪唑六氟磷酸盐)改性环氧树脂复合材料,并通过红外光谱、核磁共振氢谱、扫描电镜元素分析等考察离子液体在环氧树脂中的存在及分散状态,分析离子液体含量对复合材料动态热力学性能及减摩抗磨性能的影响.结果表明:离子液体与环氧树脂本体及固化剂...     

层状二硅酸盐在润滑脂中摩擦学性能的考察

采用四球摩擦磨损试验,考察了国产层状二硅酸钠的α-、p-、δ-3种晶形和进口二硅酸钠（SKS-6）,以及由二硅酸钠的δ-晶形改性所得的二硅酸镁在润滑脂中的摩擦学性能,并应用扫描电子显微镜（SEM）和X射线能量色散仪（EDX）对磨斑表面进行分析。结果发现：在一定摩擦作用条件下,添加在润滑脂中的层状二硅酸盐可以提高润滑脂的抗磨性能;在相同条件下,几种层状二硅酸盐中以进口二硅酸钠（SKS-6）的抗磨性能最好。     

两种离子液体的摩擦学行为研究

合成了1-丁基-3-甲基咪唑四氟硼酸盐([Bm im]BF4)及1-羟乙基-3-甲基咪唑四氟硼酸盐([C2OHm im]BF4)2种室温离子液体。在四球摩擦机上研究了这2种离子液体的摩擦学性能,用SEM和XPS对磨痕表面的形貌和元素组成进行了表征,并分析了2种离子液体不同的润滑机制。结果表明,由于[C2OHm im]BF4上的功能化基团容易吸附在摩擦副表面,其在中低载荷下有更好的减摩抗磨性能。     

Tribological Investigations of Silicon Nitride Lubricated by Ionic Liquid Aqueous Solutions

Water-lubricated ceramic components are promising material combinations for tribological applications because they are wear resistant and can exhibit low coefficients of friction under different loads. The aim of the work was to show in model tribological experiments with silicon nitride that the lubricating properties of water can be improved by adding water-soluble ionic liquids (ILs). The geometry used and the experimental parameters were selected to approximately simulate a piston ring–cylinder liner contact. We found that the addition of 1% IL tributyl methyl phosphonium acetate [P4441][OAc] leads to a reduction of the maximum friction work by 58% compared to pure water lubrication and even by 96% compared to oil-lubricated steel. It was shown that suitable running-in conditions and sufficient cooling by the lubricant at an early stage are important prerequisites for achieving low friction and wear values. In addition, the chemical interaction of water and IL with silicon nitride strongly affects the tribological behavior. As increasing demands on sustainability (green tribology) become more important due to environmental aspects, this work provides important insights for the development of novel water-based lubricant systems.     

A Comparative Study on the Tribological Behavior of Nanocrystalline Nickel and Coarse-grained Nickel Coatings under Ionic Liquid Lubrication

Tribological properties of nanocrystalline (NC) nickel coating and coarse-grained nickel coating were evaluated using a ball-on-flat sliding tester. Results indicated that the NC nickel coating had excellent tribological properties. This was partly attributed to the high hardness of the NC nickel coating and the tribochemical interactions between rubbing pairs and ionic liquid.     

几种纳米粒子作为润滑脂修复添加剂的试验研究

在MRH-3高速环块摩擦磨损实验机上,研究了纳米微粒Cu,Al,Al2O3,MgO加入到通用锂基脂中的摩擦学性能。并采用扫描电子显微镜,能量色散谱仪分析了摩擦表面的形貌和元素组成。结果表明:含有纳米Cu,Al,Al2O3,MgO粒子的润滑脂对摩擦表面均有很好的减摩和修复能力,但各种粒子的效果有所不同,其中Al2O3,Cu,Al3种粒子要比MgO具有更好的效果。     

增黏剂对锂基润滑脂流变性能的影响

制备含有不同种类增黏剂的锂基润滑脂,测试润滑脂的锥入度和相似黏度;采用流变仪通过剪率控制下的稳态流变试验和应变控制下的动态流变试验,研究增黏剂种类对锂基润滑脂流变性的影响。结果发现,加入增黏剂后,锂基脂的弹性模量减小,形变增大,即弹性特征相对减弱,黏性特征相对增强,从而润滑脂更易变形,不易流动,产生的形变更易恢复;在本研究试验条件下,不同增黏剂对基础脂流变性的影响程度不同,聚甲基丙烯酸酯的影响最为显著,小分子量的乙丙共聚物的影响最小。     

离子液体在微量润滑磨削界面的摩擦学机理研究

采用电镀CBN砂轮,以镍基合金GH4169为工件材料,实验研究了两种离子液体的微量润滑磨削加工性能,分别是1-丁基-3-甲基咪唑四氟硼酸盐(［BMIM］BF4)和1-己基-3-甲基咪唑四氟硼酸盐(［HMIM］BF4),并采用分子动力学模拟,揭示了离子液体在磨粒/工件界面物理吸附膜的形成机制,进一步开展了工件已加工表面的X射线光电子能谱（XPS）分析,揭示了离子液体在磨粒/工件界面化学反应膜的形成机制。研究结果表明：上述两种离子液体适合作为磨削液应用于微量润滑磨削加工中,既能较干磨大幅降低磨削比能和磨削力比,提高工件已加工表面质量,又能较干磨大幅降低磨削温度达100 ℃以上,避免磨削烧伤;磨粒磨钝表面由于微破碎所形成的凹槽状断口是离子液体进入磨粒/工件界面的输运通道,离子液体分子通过吸附在凹槽状断口内形成边界润滑膜,通过减小磨粒工件之间的直接接触面积来减小摩擦力;在微量润滑磨削加工过程中,以上两种离子液体均与工件在磨削界面上发生化学反应,形成了氟化物与氧化物共存的化学反应膜。     

超细软金属铜粉在润滑脂中摩擦学性能的考察

通过四球试验，考察了软金属微米铜粉在润滑脂中的摩擦学行为和抗磨性。试验结果表明：在适当含量和载荷条件下，铜粉加入润滑脂中可以提高脂的抗磨性。通过对磨斑表面形貌分析，含有铜粉的润滑脂的磨斑表面要比基础脂的磨斑表面光洁度高。     

润滑脂对膨胀管材料摩擦性能的影响

膨胀管膨胀过程中的摩擦影响到膨胀的难易程度和胀后套管的性能,选择一种合适的润滑介质降低膨胀过程中的摩擦因数对膨胀管技术来说非常重要。使用摩擦模拟实验的方法,研究在二硫化钼锂基脂、铅基润滑脂和没有润滑脂的3种条件下普通N80膨胀管材料的摩擦性能,使用扫描电子显微镜对不同载荷下试样的磨损表面进行分析,并讨论不同润滑条件下的磨损机制。结果表明,润滑脂的加入可以显著降低膨胀过程中膨胀管材料的摩擦因数和磨损量,磨损机制也从原来的磨粒磨损变成黏着磨损,铅基润滑脂由于摩擦因数更低具有最好的润滑效果,可以显著提高膨胀管材料在膨胀过程中的耐磨性能。     

Tribological Performance of Halogen-Free Ionic Liquids as Lubricants of Hard Coatings and Ceramics

Ionic liquids are expected to be used as new high-performance lubricants because of their low volatility, high thermal stability, and high oxidation stability. It is well known that halogen-containing ionic liquids exhibit excellent lubricity for metals. However, there is a concern about the corrosiveness of ionic liquids caused by the formation of halides. The lubricity of halogen-free ionic liquids for metals is inferior to that of halogen-containing ionic liquids; however, they do not cause any remarkable corrosion effects. In this study, the lubricity of halogen-free ionic liquids—1-butyl-3-methylimidazolium tricyanomethanide ([BMIM] [TCC]) and 1-ethyl-3-methylimidazolium dicyanamide ([EMIM] [DCN])—for hard coatings and ceramics was evaluated using an SRV oscillating sliding tester. Ionic liquids exhibited excellent lubricity for sintered ceramics. It is supposed that the lubricity of ceramics depends on the chemical interaction between the surface and the ionic liquids. Ionic liquids exhibited different lubricating properties with each nitride coating. [EMIM] [DCN] exhibited a better wear reduction than [BMIM] [TCC] on CrN, and its friction coefficient was higher than that of [BMIM] [TCC]. DLC coatings with [EMIM] [DCN] exhibited better lubricity than with [BMIM] [TCC], and the combination of H-free DLC and [EMIM] [DCN] particularly showed excellent lubricity. XPS analysis showed that two kinds of nitrogen compounds were on the sliding surface of H-free DLC lubricated with [EMIM] [DCN].