Transmission Electron Microscopy of Boundary-Lubricated Bearing Surfaces. Part I: Mineral Oil Lubricant

Transmission electron microscopy (TEM) was performed on the near-surface material (depth <500 nm) of tapered roller bearing inner rings (cones) that were tested at two levels of boundary-lubricated conditions in mineral oil with no additives. Site-specific thinning of cross section cone surface sections for TEM analyses was conducted using the focused ion beam (FIB) milling technique. High-resolution structural and compositional characterization of near-surface material and surface layers was performed on an untested cone as well as cones tested at Λ～1.1 and 0.3. This approach revealed near-surface microstructural distortion and grain size gradients that were attributed to surface finishing operations during manufacture. The characteristics of oxide surface layers and micro-cracks on the tested bearing surfaces were evaluated and found to depend on lubrication conditions.     

矿物质润滑油添加剂对钢/铝锡合金摩擦副摩擦学性能的影响

利用销盘式磨损试验机研究了一种矿物质润滑油添加剂对钢/铝锡合金摩擦副摩擦学性能的影响,并考察了这种添加剂对实际工况下铝锡合金轴瓦的作用效果。采用AFM、SEM/EDS等仪器对摩擦副表面进行了分析。结果表明,矿物质添加剂在低载荷比高载荷条件下的减摩抗磨效果明显;试验时间越长,添加剂的作用越充分,圆盘表面的Al-Sn共晶体的分布越分散,减摩效果越明显;添加剂降低了摩擦表面的粗糙度,显著地提高了摩擦副的减摩抗磨性能,延长了使用寿命;添加剂作用后的摩擦表面发现了少量的Fe元素,并发现个别添加剂粒子和磨损粒子在铝锡合金表面的镶嵌和沉积,添加剂提高了其承载能力。     

The temperatures at scuffing and seizure in a four‐ball contact

The temperature of surface asperities affects lubricant‐surface tribochemical interactions. It is important to know the nature of this to identify ways of preventing scuffing and seizure under extreme‐pressure (EP) conditions. A new model for the determination of the temperature of contacting asperities is presented in this paper. It assumes the superposition of thermal processes occurring on the macroscale and thermal phenomena in the contact of asperity tips (microscale). Numerical results have been obtained for conditions of four‐ball testing of various lubricating oils — a mineral base oil with and without antiwear and EP additives. To calculate the scuffing and seizure temperatures, knowledge of the mechanical and physical properties of the test ball material (bearing steel) and lubricants, as well as the parameters describing the surface topography of the balls, was necessary. Friction coefficient curves were also needed; they were determined during four‐ball tests with a continuously increasing load. For the base oil with lubricating additives, the temperature of contacting surface asperities at the moment of scuffing initiation was calculated to be about 230°C and increased to over 1000°C at the highest loading of the four‐ball tribosystem. This suggests the possibility of tribochemical reactions of the lubricating additives with the steel surface, and diffusion of some elements, a modified surface layer having good antiseizure properties being produced. Such a layer prevents seizure of the tribosystem. For the base oil without lubricating additives, scuffing initiated at about 150°C and the temperature exceeded 1200°C at seizure. The temperature values obtained agree with results in the literature.     

二硫化钨发动机油的摩擦学性能研究

采用矿物油和合成油调配成半合成发动机油基础油,同时,通过表面化学修饰和吸附修饰表面改性超细二硫化钨颗粒,使其作为固体润滑添加剂稳定悬浮于基础油中,并加入一定量的功能添加剂,研制了一种二硫化钨发动机油。与国内外品牌发动机油进行摩擦学性能对比实验,发现该种发动机油的油膜强度分别是壳牌超凡喜力发动机油和国产长城发动机油的1.06倍和1.38倍,烧结载荷分别是它们的1.75倍和2.33倍,并且在392N、1450r/min、30min下长时间作用时,摩擦副的摩擦因数随时间的增长而减少,磨斑直径小,磨斑表面光滑,没有明显的犁沟出现。实验表明二硫化钨发动机油具有比国内外品牌发动机油更加优良的抗磨、减摩和极压性能。     

硅烷偶联剂修饰纳米ZrO2润滑油添加剂的摩擦学性能研究

以氧氯化锆为原料制备纳米ZrO2并对其结构进行了表征;用硅烷偶联剂对其表面进行表面改性处理,使其具有良好的亲油性;用摩擦磨损试验机测定了所制备的纳米ZrO2作为20#机械油添加剂的摩擦磨损性能。结果表明所制备的ZrO2为粒径为10nm左右的球形颗粒,具有无定形晶体结构;纳米ZrO2作为添加剂可以显著提高20#机械油的抗磨减摩性能,当纳米ZrO2的添加量为0.1%(质量分数)时相应的磨斑直径最小、摩擦因数最低、磨损量最少。     

基础油组成对润滑脂抗磨性能的影响

采用液固吸附色谱、红外光谱和X射线荧光光谱对2种润滑脂基础油进行了分离和分析,用SRV摩擦性能实验考察基础油和润滑脂的抗磨性能。实验结果表明,增加基础油的芳烃和硫化物含量能够提高基础油的抗磨性能,基础油的抗磨性与润滑脂的抗磨性具有一致性,可以通过改变基础油的组成来改善润滑脂的抗磨性能。     

一种硫磷氮衍生物在菜籽油中的摩擦学研究

通过Mann ich合成了2种有机环胺的硫磷酸酯衍生物,在四球摩擦磨损试验机上研究了它们作为菜籽油添加剂的摩擦学性能。实验结果表明,该类化合物具有良好的极压抗磨性能,能提高菜籽油的极压抗磨性能。通过用X-射线光电子能谱(XPS)分析了钢球磨损表面典型元素的化学状态,显示在摩擦过程中,钢球表面形成了一层含硫、磷无机膜和含氮的有机膜。     

X-Ray Absorption Spectroscopy and Morphology Study on Antiwear Films Derived from ZDDP Under Different Sliding Frequencies

X-ray absorption near-edge structure (XANES) spectroscopy has been used to characterize the chemistry of antiwear (AW) films generated from mineral base oil containing a zinc dialkyl dithiophosphate additive. These films were formed on rubbed steel surfaces with a reciprocating boundary contact using different sliding frequencies. The phosphorus L-edge XANES spectra show that these films have slightly different chemical natures. Longer chain polyphosphates were present on the steel surface prepared at the higher sliding frequencies. The surface morphology of these films was investigated using atomic force microscopy. These images show that the surface morphology of the AW films changes with the sliding frequency. Round and bigger antiwear pads were formed at a lower frequency while higher frequencies resulted in thinner films and flattened surfaces. Nanomechanical properties of these antiwear films were investigated by nanoindentation measurement and the elastic moduli extracted from force–displacement (f–d) curves are similar for all antiwear films, 100 ± 10 GPa.     

可促进润滑油生物降解的新型润滑添加剂研究

设计并合成了N-油酰基丝氨酸添加剂,运用红外光谱表征了其结构,通过摩擦学和生物降解实验考察了其在HVI350矿物油中的摩擦学和生物降解性能,并探讨了其摩擦学和促进润滑油生物降解的作用机制.研究表明:N-油酰基丝氨酸能有效提高矿物基础油的减摩抗磨能力,并能显著提高矿物基础油的生物降解性能,是一种潜在的环境友好润滑添加剂.     

油溶性CuO纳米颗粒的抗磨性能研究

利用四球摩擦磨损实验机考察了油酸铜修饰CuO纳米颗粒作为润滑油添加剂的抗磨性能,并用扫描电子显微镜（SEM）和X-射线光电子能谱（XPS）等对钢球磨损表面进行了分析。摩擦磨损试验结果表明,当添加质量分数仅为0.025%时,油酸铜修饰CuO纳米颗粒作为润滑油添加剂即能够明显提高基础油的抗磨能力。SEM及XPS分析结果表明,油酸铜修饰CuO纳米颗粒作为润滑油添加剂在摩擦过程中形成了一层富含Cu2O和Fe2O3的化学反应膜,正是这层膜的存在使得其表现出良好的抗磨性能。     

Friction and wear behavior of AZ91D magnesium alloy against steel lubricated with N‐ and S‐containing organic borates

The friction reduction and antiwear properties of a range of nitrogen‐ and sulfur‐containing organic borates as oil additives in mineral oil were assessed using a Timken tester with a bearing steel ring against an AZ91D magnesium alloy block. X‐ray photoelectron spectrometry and scanning electron microscopy were employed to examine the boundary film formed on the surface of the magnesium alloy block. The results show that the borate additives were effective at reducing the wear of magnesium. The acting mechanism of borate, which acted as additive in the magnesium‐on‐steel tribological system, was proposed. Copyright © 2006 John Wiley & Sons, Ltd.     

二烷基二硫代氨基甲酸锑在聚α-烯烃中的摩擦性能及其摩擦化学作用机制的研究

合成了2种二烷基二硫代氨基甲酸锑,并经红外、核磁对其分子结构予以确认。研究了它们的热稳定性,系统地考察了其在聚α-烯烃（PAO）中不同含量、不同载荷下的摩擦学性能。探讨了二烷基二硫代氨基甲酸锑的抗磨作用机制。结果表明,二烷基二硫代氨基甲酸锑盐的热分解温度较高,热稳定较好,具有良好的极压抗磨性能。EDS分析表明,2种添加剂存在的润滑条件下,钢球磨斑表面上存在着S、Fe、Sb等元素。XPS分析表明,S元素以硫酸亚铁及少量的FeS形式存在,Sb元素以Sb2O3形式存在,而N元素则以复杂的吸附膜形式存在,这些因素一同起极压抗磨作用。     

2-烷基硫甲基噻吩系列添加剂对菜籽油磨擦学性能的影响

利用四球摩擦磨损试验机考察了噻吩及实验室合成的2－烷基硫甲基噻吩对菜籽油摩擦学性能的影响，用X射线光电子能谱仪（XPS）和扫描电子显微镜（SEM）观察分析了磨损表面的形貌和元素存在状态。用差示扫描量热法（DSC）评价了合成添加剂对菜籽油氧化稳定性的影响，结果表明：2－烷基硫甲基噻吩系列化合物大大提高了菜籽油的承载能力，但加剧了钢－钢摩擦副的磨损。含上述添加剂的菜籽油在摩擦副表面发生摩擦化学反应，生成菜籽油和添加剂共同作用所产生的边界润滑膜，从而改变了菜籽油的润滑性能，2－烷基硫甲基噻吩可明显改善菜籽油的抗氧化性能。     

Friction Reduction and Antiwear Capacity of Engine Oil Blends Containing Zinc Dialkyl Dithiophosphate and Molybdenum-Complex Additives

The efficacy of oil blends containing zinc dialkyl dithiophosphate (ZnDTP) and molybdenum (Mo)-complex additives to improve the tribological properties of boundary-lubricated steel surfaces was investigated experimentally. The performance of oil blends containing three different types of Mo-complex additives of varying Mo and S contents with or without primary/secondary ZnDTP additions were investigated at 100°C. The formation of antiwear tribofilms was detected in situ by observing the friction force and contact voltage responses. Wear volume and surface topography measurements obtained from surface profilometry and scanning electron microscopy studies were used to quantify the antiwear capacity of the formed tribofilms. The tribological properties are interpreted in terms of the tribofilm chemical composition studied by X-ray photoelectron spectroscopy. The results demonstrate that blending the base oil only with the Mo-compound additives did not improve the friction characteristics. However, an optimum mixture of Mo complexes and ZnDTP additive provided sufficient amounts of S and Mo for the formation of antiwear tribofilms containing low-shear strength MoS ₂ that reduces sliding friction. In addition, the formation of a glassy phosphate phase due to the synergistic effect of the ZnDTP additive enhances the wear resistance of the tribofilm. This study shows that ZnDTP- and Mo-containing additives incorporated in oil blends at optimum proportions improve significantly the tribological properties of boundary-lubricated steel surfaces sliding at elevated temperatures.     

羟基硅酸盐/纳米铜复合添加剂摩擦学性能研究

由羟基硅酸镁和纳米铜粉体按质量比1∶1组成复合添加剂,利用MJ-800型四球摩擦磨损试验机考察复合粉体、硅酸盐粉体和纳米铜分别作为N68基础油添加剂的摩擦学性能,借助JSM3010型扫描电子显微镜及EDS测试分析钢球磨痕的表面形貌和成分组成,研究了添加剂的作用机制.结果表明:添加剂的引入明显改善了基础油的摩擦学性能,添加剂粒子通过吸附、填充、微滚珠以及熔融铺展作用降低钢球磨损,并对磨损表面进行一定的修复;硅酸盐粉体和纳米铜表现出良好的协同抗磨效应,复合添加剂的极压抗磨性能优于硅酸盐粉体或纳米铜单独作为添加剂.     

噻唑衍生物在菜籽油中的摩擦学性能研究

合成了两种噻唑衍生物，采用热重分析对其热稳定性进行了评价；利用四球摩擦磨损试验机考察了其在菜籽油中的摩擦学性能，并用扫描电子显微镜和x射线光电子能谱仪观察分析了磨斑表面的形貌和元素化学状态。结果表明：噻唑氨基甲酸衍生物添加剂可显著改善菜籽油的减摩抗磨性能和承载能力；含上述添加剂的菜籽油在摩擦过程中发生了摩擦化学反应，生成了含菜籽油甘油酯、有机硫化物、硫酸亚铁等组成的边界润滑膜，从而改善了菜籽油的摩擦学性能。     

Comparison of tribological characteristics between aluminum alloys and polytetrafluoroethylene composites journal bearings under mineral oil lubrication

This study examined the tribological behavior of journal bearings made from polytetrafluoroethylene (PTFE) composites and aluminum (Al) alloys. The PTFE composite journal bearings consisted of a steel backing with a thickness of 1.6 mm, a middle layer of sintered porous bronze with a thickness of 0.24～0.27 mm, and a surface layer of PTFE filled with fluorinated ethylene propylene (FEP) powder and carbon fibers with a thickness 0.06～0.14 mm. The other was an aluminum alloy journal bearing consisted of a steel backing with a thickness of 1.5 mm and a surface layer of an Al-6Sn-6Si alloy with a thickness 0.35～0.75 mm. A series of lubrication tests were performed using a journal bearing tester under various normal loads. The tribological properties for each journal bearing were evaluated by measuring the lubricant oil temperature and friction coefficient as a function of the applied normal load. In addition, the chemical compositions and microstructures of the journal bearing materials used in this study was analyzed by inductively coupled plasma (ICP), optical microscopy (OM), and scanning electron microscopy (SEM), respectively. The experimental results showed that the Al alloy journal bearings reduce the friction coefficient by 28 % compared to the PTFE composites bearings. In addition, the Al alloy journal bearing worked properly at the maximum load of ～ 8,000 N without adhesion. However, the PTFE composite journal bearings exhibited strong adhesion at the loads ranging from 6300 to 8000 N. This suggests that the Al alloy is a more promising material in journal bearings than PTFE composites.     

The tribological behaviour and mechanism of action of sulphur-containing borate esters in rape seed oil

Three sulphur-containing borate esters and one borate ester based on boric acid and n-octanol were synthesised. The antiwear and friction-reducing properties of these synthetic compounds as additives in rape seed oil were examined using a four-ball machine. The relationship between the additive structure and tribological properties was explored, and the lubrication mechanisms of the additives investigated. The worn surfaces of a steel ball lubricated with the additive-containing rape seed oil were analysed using X-ray photoelectron spectroscopy and scanning electron microscopy. The elemental compositions of, and distributions in, the worn steel surfaces were determined with an electron probe micro-analyser. It was found that sulphur-containing borate esters as additives in rape seed oil at appropriate concentrations can be effective in improving antiwear and friction-reducing behaviour. The rape seed oil base stock experiences competitive adsorption and tribochemical reactions with additives on the rubbing steel surface. The introduction of the active element sulphur into the borate ester additives functions to improve the tribological behaviour of the base stock by increasing the rate of formation of a protective layer on the rubbing steel surface. However, the tribological behaviour of the additives is not dependent on the number of sulphur atoms in the additive molecules, and further work is needed to investigate the possible dependence of this behaviour on the ratio of boron to sulphur in the additive molecules.     

应用动植物油脂研制可降解抗磨液压油

对回收的动植油脂进行改性处理和加入部分150SN基础油后,调制出可以作为生物降解液压油的基础油.通过对功能剂的研究,解决回收基础油的氧化安定性和与金属材料的配伍性问题,从而开发出粘度指数高,粘温性、低温流动性、极压抗磨性和水解安定性好的有灰和无灰抗磨液压油,并通过台架试验.     

基础油组成对内燃机油抗磨性能的影响

利用质谱技术对多个I类油(溶剂精制基础油)和II类油(加氢基础油)组成进行分析,通过四球机、SRV摩擦磨损试验机对不同基础油组成与油品抗磨性能之间的关系进行了研究.经过大量试验后,对试验结果进行统计和归纳,建立了基础油组成与油品抗磨性能的线性模型.结果表明:随基础油中链烷烃与少环环烷烃含量增加,油品抗磨性能有变差的趋势;随芳烃含量及基础油100 ℃黏度的增加,油品抗磨性能有变好趋势.