不同试验条件下ZDDP在250N基础油中的摩擦性能试验研究

为开发低黏度指数改进剂含量的自动变速箱油,选择四球机研究ZDDP在250N基础油中摩擦性能,在不同的ZDDP添加量、负荷、时间、转速下进行试验,观察各试验条件对ZDDP摩擦性能的影响程度,同时采用正交试验方法分析4种因素对ZDDP的影响显著性。试验结果表明:在950 r/min时,ZDDP在296 N负荷下相比196 N和392 N具有更佳的减磨性能;在1 200 r/min时,随着ZDDP加量提高,磨斑直径下降较为缓慢;在1 450 r/min时,392 N负荷下添加ZDDP的基础油无法提供有效润滑,造成剧烈磨损。正交试验结果表明:在选定的试验因素和水平下,对磨斑直径影响的显著性由大到小依次为负荷、转速、添加剂添加量、时间,其中添加剂添加量和时间对磨斑直径变化绝对值影响接近。     

含纳米PTFE颗粒润滑脂的润滑性能研究

在四球摩擦磨损试验机上考察纳米PTFE颗粒作为添加剂对复合钛基润滑脂摩擦磨损性能的影响,采用扫描电子显微镜分析试验钢球磨斑的表面形貌,并利用X射线光电子能谱仪检测磨斑表面化学元素的组成及状态。结果表明,在一定添加量范围内,纳米PTFE可以改善复合钛基润滑脂的摩擦磨损性能,其中纳米PTFE质量分数为3%时,复合钛基润滑脂具有最佳的抗磨、减摩性能,可使摩擦因数、磨斑直径分别降低约25.4%和18.9%。纳米PTFE颗粒在钢球表面发生摩擦化学反应,生成了一层金属氟化物,有效地抑制了摩擦表面的黏着磨损和接触疲劳。     

N-酰基谷氨酸在矿物油中的摩擦学性能研究

分别在油酸和月桂酸分子中引入氮,合成了2种新型的含氮润滑油添加剂——N-油酰基谷氨酸和N-月桂酰基谷氨酸。利用四球摩擦磨损试验机考察了2种添加剂作为HVI350矿物基础油极压抗磨添加剂时的摩擦学性能,通过测定不同条件下的最大无卡咬负荷和磨斑直径及摩擦因数,分析和研究了载荷、摩擦时间、添加剂含量对矿物油最大无卡咬负荷和磨斑直径及摩擦因数的影响。试验结果表明:2种添加剂均可以明显提高基础油的承载能力和抗磨减摩性能,添加剂N-油酰基谷氨酸在矿物油中的承载能力明显优于N-月桂酰基谷氨酸,而N-月桂酰基谷氨酸对提高矿物基础油抗磨减摩性能的效果好于添加剂N-油酰基谷氨酸。试验还表明添加剂的含量并非越高越好,否则磨斑直径将增大。     

齿轮油GL-5润滑及压力性能的试验研究

通过对齿轮油GL-5的润滑性能研究,探讨其在接触区承受接触压力的变化。在四球试验机上开展20和100℃下GL-5的磨损试验研究,分析GL-5磨斑直径与负荷的变化规律,探讨其接触压力的行为特征。结果表明,温度对GL-5的润滑油性能有影响,温度从20℃升高到100℃时,其最大无卡咬负荷从1 236 N降低到981 N;接触压力与负荷呈先增加后降低的变化规律,当负荷超过最大无卡咬负荷时,接触压力急剧降低,对应的Streibeck量纲一特征参数显著增加;摩擦因数随负荷呈非线性增加,温度对GL-5摩擦因数的影响较小。若GL-5承受更高的接触压力,则需提高其承载能力。     

纳米石墨/聚丙烯酸乙酯复合乳液的合成及其润滑性能研究

采用自由基乳液聚合方法合成了纳米石墨／聚丙烯酸乙酯复合乳液，并用四球摩擦磨损试验机对其润滑性能进行了评估。结果表明，一定浓度的纳米石墨／聚丙烯酸乙酯复合乳液可有效提高水基液的承载能力，降低磨损量。采用IRMM对摩擦磨损试验后的钢球磨斑表面进行分析，结果表明：磨痕变浅，磨斑减小，有效降低了磨损。     

基于柴油介电特性快速检测其润滑性的方法研究

在加氢精制柴油中添加不同量的抗磨剂,研究柴油介电特性与校正磨斑直径的相关性,结果表明,介电常数与校正磨斑直径的相关性是最好的。将介电常数与校正磨斑直径数据拟合,建立基于介电特性快速预测柴油润滑性能的模型。通过添加不同量抗磨剂对柴油模型计算值与测定值的比较,发现两者非常吻合,符合重复性要求。因此,可以通过对柴油介电常数的测定,来预测柴油的校正磨斑直径。     

聚四氟乙烯颗粒在复合钛基脂中的摩擦磨损性能研究

采用实验室制脂釜制备新戊基多元醇酯为基础油的钛基脂和含聚四氟乙烯颗粒的钛基脂,考察了复合钛基脂摩擦学特性,利用扫描电子显微镜和X射线电子能谱仪明察了钢球的磨斑表面形貌和主要元素的化学状态.结果表明,聚四氟乙烯降低了基础脂的摩擦系数和磨斑直径,但没有提高极压性能.钢球的磨损特征为轻微粘着磨损,其减摩抗磨机制为吸附膜和化学沉积膜协同作用的结果.     

硼酸盐超微粒子在水溶液中的原位合成及摩擦学性能研究

用简单方法原位合成了多种水溶液稳定的硼酸盐超微粒子。采用四球摩擦磨损试验机测定了其作为水基润滑剂的摩擦学性能,并用扫描电子显微镜(SEM)分析了其磨斑表面。结果表明,相同条件下,不同金属的硼酸盐超微粒子的烧结负荷基本接近,不含表面活性剂的硼酸盐超微粒子水溶液的最大无卡咬负荷(pB)较低,而烧结负荷(pD)较高,最高可达6 080 N,而含有表面活性剂的硼酸盐超微粒子水溶液的pB值可达700~1 300 N。含表面活性剂硼酸盐超微粒子水溶液与油酸三乙醇胺相比,前者摩擦因数和磨斑直径均低得多,但磨斑表面没有后者光滑,硼酸盐超微粒子虽然能降低摩擦磨损,但对表面有一定的擦伤作用。     

纳米碳酸钙颗粒作为钛基脂添加剂的摩擦学性能

采用四球摩擦磨损试验机研究纳米碳酸钙作为复合钛基脂添加剂的摩擦磨损性能，利用X射线光电子能谱仪分析试验后钢球磨斑表面主要元素的化学状态，用扫描电子显微镜观察钢球的磨斑表面形貌。结果表明：纳米碳酸钙作为复合钛基脂添加剂具有明显的减摩抗磨效果；其中纳米碳酸钙质量分数为时3%复合钛基脂具有佳的减摩抗磨效果，与纯钛基脂相比，可使平均摩擦因数降低14.9 %，磨斑直径降低35.1%。在添加纳米碳酸钙的复合钛基脂润滑下，钢球磨斑表面形成了由纳米碳酸钙分解生成的CaO、钛基脂分解生成的TiO2，以及Fe2O3、FeO等无机化合物成分组成的多孔状保护膜，这层保护膜阻止了摩擦表面的直接接触，起到了有效的减摩抗磨效果。     

不同极压抗磨剂在磨损条件下的膜特征

本文选择了磷酸三甲酚酯（ＴＣＰ）,硫代磷酸三苯酯（ＴＰＰＴ）和２－巯苯并噻唑（ＭＢＴ）三种酯类润滑油常用的极压抗磨剂进行四球磨损试验,并用俄歇电子能谱（ＡＥＳ）对磨损试验后得到的磨斑进行表面膜的表层和深层剥离分析,试验发现磨斑上的表面膜的组成和厚度与四球试验得到的润滑性能有良好的对应关系。     

Laboratory shearing tests for viscosity index improvers

The relative resistance of VI improvers to breakdown depends on internal structural parameters (chemical type, ratio of monomers, degree of branching) as well as on external factors (test type, duration, severity). Of the many bench tests available to screen shear stability, the 30 cycle CEC injector test is most commonly used for engine oils. Test duration, however, can significantly change the relative ranking of VI improver shear stability. While some polymers stabilise quickly, others continue to degrade when test duration is extended. Some polymers are also more susceptible to the severity of the shearing conditions encountered, e.g. in the FZG and the Tapered Bearing tests. It is therefore important to determine which test, and which set of conditions, will rank shear stability of different VI improver types in the same order as does the field.     

Development of a statistical method to formulate high‐VI hydraulic oils

Mobile hydraulic equipment is often subjected to a wide range of operating temperatures, and so must be lubricated with oils with a high viscosity index (VI) in order to maximise efficiency. Formulating high‐VI hydraulic oils is a complex task that requires testing numerous intermediate blends in order to achieve the desired viscosity at both low and high temperatures. With the introduction of the ASTM D 6080 hydraulic oil classification, which defines a separate grade at low and high temperature for high‐VI oils, and further includes VI and viscosity measurements after the sonic shear test, formulating high‐VI hydraulic oils has become even more complex. In order to determine the most effective VI improver to meet a given set of viscosity requirements, a large statistically designed experiment has been carried out. Empirical equations have been obtained that can be used to model the blending efficiency of VI improvers at different temperatures and to estimate their shear stability. This paper shows how the results obtained for 42 hydraulic oils have been used to develop a computer program aimed at facilitating the formulation of high‐VI hydraulic oils.     

The Effect of Lubricant Viscosity and Composition on Engine Friction and Bearing Wear

This paper investigates the effect of lubricant composition on engine friction and connecting-rod bearing wear. Special attention has been given to polymer-thickened (VI improved) oils since these oils are characterized by shear-dependent viscosity and a simultaneous occurrence of viscous and elastic properties. The variables investigated in this study included lubricant viscosity, polymer type, and concentration.

Two sets of engine studies were conducted, one to determine engine friction, the other to measure connecting-rod bearing wear, using irradiated bearings. For Newtonian fluids, the engine friction and wear response can be predicted from classical lubrication theory—that is, (a) friction decreases with increaing viscosity until a viscosity is reached where friction is a minimum; beyond this viscosity, further increases in viscosity result in increased friction. (b) Bearing wear decreases with increasing viscosity, but as a step function, not linearly, and the transition viscosity (of the step) corresponds to the viscosity which gives a minimum engine friction.

The addition of polymeric VI improvers (non-Newtonian fluids) to mineral oil base stocks reduces engine friction and lowers bearing wear—the amount of friction and wear reduction depending on the polymer type and concentration. This paper demonstrates that polymer-thickened oils actually give better bearing wear performance than their comparable mineral oil counterparts despite the fact that they have a lower apparent viscosity at high rates of shear. In addition, it appears that temporary viscosity loss is not the sale cause of the reduced engine friction of polymer-thickened oils.     

一种二甲醚专用润滑性改进剂的性能研究

采用四球机和高频往复试验机研究了一种二甲醚(DME)专用润滑性改进剂在不同基础试验液体中的润滑特性,考察了其与醚的互溶性能及对金属的腐蚀性能,并与其它润滑性改进剂进行了对比,从而为DME发动机选择合适的燃料润滑改进剂提供了依据。结果表明:该DME专用润滑性改进剂添加量少,润滑效果显著,与DME相容性好,没有腐蚀性。     

Antiwear Properties of Phosphorous-Containing Compounds in Vegetable Oils

Antiwear properties of vegetable oils were investigated under boundary lubrication conditions using the four-ball wear test (ADTM D 4172). Additive-free vegetable oils exhibit similar antiwear properties, which are superior to those of additive-free mineral oils. Phosphorus-containing compounds such as zinc bis(dialkyldithiophosphate) and dialkyl phosphonates improve the antiwear properties of vegetable oils. The effect of the additives on wear reduction was found to depend on the peroxide value of the base oil. It is considered that peroxides decompose the antiwear additives to less active forms. The formation of peroxides by the autooxidation of vegetable oils was observed even at room temperature. Sunflower oil exhibits good oxidation stability, which may promise success in various applications.     

添加纳米Fe3O4 润滑剂磨损性能试验研究

采用化学共沉淀发制备了纳米级铁磁流体润滑剂，利用MMW-1万能摩擦磨损试验机，测定了添加纳米Fe3O4润滑剂在不同速度、添加量和载荷下的摩擦学性能，并对减摩抗磨机制进行了研究。结果表明，添加纳米Fe3O4粒子的润滑油表现出了良好的抗磨减摩性能，并能够显著改善基础油的承载能力，最大可以提高16．5％。其减摩抗磨机制为，由于纳米微粒大多为球状，能起到类似“球轴承”的作用，从而提高润滑性能；另外，由于纳米颗粒的增粘作用，从而提高承载能力。     

汽油机油配方对节能发动机试验的影响

介绍了汽油机油节能发动机试验的发展状况,讨论了油品配方对节能性能的影响。发动机试验表明,基础油、粘度指数改进剂及添加剂都是影响汽油机油节能性能的因素,在不同的发动机试验中基础油、粘度指数改进剂、抗氧抗腐剂、摩擦改性剂、清净剂、分散剂的影响存在不同的表现形式,在配方设计中要根据具体的发动机试验来确定。     

Tribological behaviour of an elastomer aged in different oils

This paper presents the influence of aging the nitrile rubber, the most popular seal material, in various base fluids on sliding friction and abrasive wear. The lubricants used are synthetic esters, natural esters, different types of mineral base oils, poly-α-olefins and very high viscosity index oils. Friction has been studied for two directions of motion with respect to lay on the elastomer sample by using the SRV Optimol test machine. These findings show that as compared to all other lubricant formulations, ageing the elastomer in polyol ester leads to the maximum reduction of friction coefficient especially in perpendicular sliding to the initial lay on the surface. The abrasive wear studies were carried out by using a two-body abrasive wear tester against dry and lubricated elastomer. It was interesting to note that two-body abrasive wear of elastomeric material was higher during rubbing in presence of the fluids as compared to that in dry condition. Further, aging the elastomer in these base fluids especially in ester base fluids, results in more abrasive wear.     

Tribological Properties of Vegetable Oils Modified by Reaction with Butanethiol

Corn, canola, and castor-lauric estolide oils were chemically modified by photochemical direct reaction of butanethiol with the double bonds on the hydrocarbon chains. The effect of chemical modifications on viscosity, viscosity index (VI), pour point (PP), cloud point (CP), oxidation stability (RPVOT), 4-ball anti-wear (AW), and extreme pressure (EP) were investigated. The sulfide modified (SM) corn and canola oils showed increased viscosity, increased RPVOT time (more than one order of magnitude), reduced PP (9?C18 °C), and reduced VI. The SM estolide displayed similar trends in VI and RPVOT but showed no change in viscosity or cold flow. The SM oils, along with commercial mono- and polysulfide additives were also investigated as additives, at 0.6% (w/w) S concentration, in corn and polyalphaolefin (PAO) base fluids. In both fluids, the additives resulted in minor changes of PP, CP, coefficient of friction, wear scar diameter (WSD), and weld point (WP). Only the commercial polysulfide EP additive displayed large WP increases in the fluids. The additives resulted in no change of oxidation stability of corn oil, but displayed big improvement in the oxidation stability of PAO (8 to 16-fold increase in RPVOT time). The difference in the effect of the additives on the oxidation stability of PAO versus corn oil was attributed to the difference in the reactive hydrogen contents in the two base fluids relative to those in the additives. An empirical equation, for correlating change in RPVOT time with change in bond dissociation energy of reactive protons before and after chemical modification, is proposed.     

The effect of chemical structure of basefluids on antiwear effectiveness of additives

The effect of the chemical structure of a lubricant on the complexity of friction and wear under boundary conditions is studied using a pin-on-disc machine and a four-ball wear tester. The two test units are used to compare the friction and wear characteristics of four hydrocarbon fluids. Three vegetable oils and three additives are also evaluated in the four-ball wear tester to demonstrate the importance of chemical structure of the base fluids and the additives on the effectiveness of the additives in controlling friction and wear.