PAO油和硅油调和基础油的特殊黏度变化规律

通过测定不同黏度的聚α-烯烃(PAOs)、硅油及其不同调和比例混合基础油在-50~50℃时的运动黏度,研究调和基础油的黏度随调和组分和温度的变化规律。结果表明,调和基础油的实测黏度远小于按国际通用黏度模型计算得到的黏度值;黏度相差较大的PAO油与硅油调和时,调和基础油的高低温运动黏度均在两调和组分的黏度之间变化;而黏度接近的PAO油与硅油调和时,在一定成分范围内,调和基础油的低温运动黏度低于两调和组分的黏度,其低温流动性更加优异。特定的PAO油与硅油能够相互用作低温降黏剂进一步改善润滑油的低温性能。通过引入分子间相互作用对这一现象进行了解释。     

聚α－烯烃基础油中抗氧剂Ｎ－苯基－α－萘胺的氧化动力学

模拟实际使用条件,研究抗氧剂N-苯基-α-萘胺（NPAN）在聚α-烯烃（PAO）基础油中的热氧化性能,结合FTIR技术分析200 ℃反应油样的结构组成,应用GC/MS评价抗氧剂N-苯基-α-萘胺（NPAN）的热氧化衰变程度。结果表明,在PAO热氧化衰变过程中,其运动黏度值的变化与抗氧剂的含量有良好的相关性,随着抗氧剂的大量消耗,基础油开始急剧氧化,出现氧化失效现象;NPAN的热氧化反应为拟一级反应,抗氧剂的热氧化动力学规律可以很好地预测抗氧剂随反应时间及温度的消耗量,进而反映润滑油的热氧化衰变情况,为润滑油状况实时监控和及时掌握换油周期提供依据。     

聚α-C14烯烃/酯类润滑油基础油合成和性能研究

将α-C_(14)烯烃先与马来酸酐进行无规共聚,再与季戊四醇进行酯化反应,制得一种新型的聚α-C_(14)烯烃/酯类润滑基础油。采用红外光谱、核磁共振谱~1H-NMR、热重分析仪、油品运动黏度测定仪、酸值测定仪对产物进行表征和性能测试。结果表明:随着马来酸酐用量增加,合成的基础油的运动黏度、热分解温度、酸值均先增大后减小,随着季戊四醇用量增加,合成的基础油的运动黏度、热分解温度先增大后减小,酸值逐渐降低;当马来酸酐与α-C_(14)烯烃质量比为1∶5.14,季戊四醇占α-C_(14)烯烃质量4.17%时,润滑基础油的黏度指数为114,酸值为0.082 mg/g(以KOH计),热分解温度大于249.3℃,40℃运动黏度为276.31 mm~2/s,100℃运动黏度为25.91 mm~2/s。因此,与AIP类润滑油相比,合成的基础油具有更好的低温流动性和耐高温稳定性,与传统的酯类润滑油相比具有较低的酸值,对器件腐蚀性较低。     

黏度指数改进剂对基础油性能的影响

用凝胶色谱测定乙丙共聚物(OCP)和氢化苯乙烯异戊二烯(SDC)黏度指数改进剂的分子量和分散度,用运动黏度测定法、高温高剪切表观黏度测定法测定OCP和SDC在4类基础油中的运动黏度和高温高剪切表观黏度,用柴油喷嘴测定法测定其100℃下的剪切稳定性,用冷启动模拟机法测定其-15℃与-20℃的低温动力黏度。结果表明:SDC分子量小于OCP,但分散度大于OCP,在相同基础油中其黏温性能、剪切稳定性优于OCP类;在4类基础油中,OCP和SDC的黏温特性表现为Ⅳ类Ⅲ类Ⅰ类,稠化特性表现为Ⅳ类Ⅰ类Ⅲ类Ⅱ类,剪切稳定性表现为Ⅳ类Ⅲ类Ⅱ类Ⅰ类;OCP和SDC稠化油的-15℃以及-20℃的低温动力黏度与基础油相当。     

离子液体催化合成高粘度指数基础油工艺研究

为制备高黏度指数合成基础油,以1-癸烯为齐聚原料、［Emim］Cl/AlCl3离子液体为催化剂合成聚a-烯烃基础油,考察［Emim］Cl/AlCl3摩尔比、催化剂用量、反应温度、反应时间和原料含水量对反应产物性能及收率的影响。结果表明,提高催化剂AlCl3:［Emim］Cl摩尔比或降低反应温度,合成润滑油的黏度增加;增加催化剂用量可提高产物黏度,但会增加异构化等副反应,降低产物黏度指数;反应原料中含水量变化对聚合度有重要影响,但黏度指数保持稳定。在AlCl3/［Emim］Cl摩尔比为2∶1,催化剂质量分数为10%,反应温度为60 ℃,反应时间4 h的条件下,合成油的100 ℃运动黏度在10.34 mm2/s以上,黏度指数高于143,适合作为柴油机多级润滑油基础油。     

中红外光谱法快速测定航空润滑油50—1—4Ф的运动粘度

对11个不同基础油含量的50—1—4Ф润滑油样品（标准油）和从现场采集的28个在用50—1—4Ф润滑油样品（在用油）进行傅立叶变换中红外光谱分析。选择1465cm。作为测定其运动粘度的特征峰,分别对标准油和在用油样品的运动粘度和相应红外光谱的特征峰处的吸光度进行了相关性分析,给出了回归方程。用另外20个新油样品较正了标准油的回归方程。结果表明,利用傅立叶变换中红外光谱法测定未用及在用50—1—49Ф润滑油的运动粘度是可行的,测定结果是可靠的。     

几种纳米固体润滑添加剂热稳定性及其对基础油黏度的影响

采用综合热分析仪测试纳米铜、镍、锡和SiO2粉以及超细蛇纹石粉的差热分析曲线,研究了常用固体润滑添加剂的热稳定性,并用平氏毛细管黏度法研究了含不同质量分数纳米金属Cu-Ni-Sn粉、纳米SiO2粉和超细蛇纹石粉对基础油黏度及黏度指数的影响.结果表明:纳米铜、镍、锡和SiO2粉以及超细蛇纹石粉等几种固体润滑添加剂的热学性质比较稳定,在200 ℃以前不发生氧化现象,其对基础油的黏度和黏度指数没有影响,具备作为润滑油添加剂的条件.     

酯类航空润滑油基础油热氧化衰变规律分析

对不同温度和反应条件下的癸二酸二-2-乙基己酯（DHS）基础油理化指标进行考察,并采用GC/MS现代分析手段测定油样结构组成,探讨酯类航空润滑油基础油的热氧化衰变规律,从分子水平揭示酯类航空润滑油基础油高温衰变后颜色、黏度和酸值变化的原因。试验结果表明：空气、氧气和抗氧剂N-苯基-α-萘胺（NPAN）对DHS黏度高温衰变影响较小,这是因为油品分子链在高温作用下既发生裂解使黏度低,也会相互聚合使黏度增大;氧气的存在会与自由基生成醇、醛和酸等含氧化合物,使油样酸值急剧增大,添加NPAN后极大地抑制了酸值升高,油样酸值的突变温度升高,表明NPAN在酯类基础油中发挥了较好的抗氧化效果。     

高温条件下发动机油配方组份对油品高温黏度及成焦倾向的影响

采用曲轴箱成焦性能试验仪对加氢基础油和聚ɑ烯烃(PAO)基础油、含有不同添加剂的基础油、发动机油进行试验,检测试样的成焦量、100℃运动黏度,分析添加剂及基础油在高温条件下的黏度变化和成焦倾向,并进行烘箱静置对比试验。试验结果表明:250N基础油、20W-50成品油、PAO8基础油3种油样中,250N的成焦量上升较快,纯基础油100℃运动黏度总体呈上升趋势,20W-50成品油100℃运动黏度先下降最低达15.8%然后上升;二烷基二硫代磷酸锌(T203)是含添加剂基础油中成焦主要来源,其次是黏度指数改进剂,其他添加剂影响较小;以PAO为基础油的试样较250 N基础油成焦量明显下降,合成磺酸钙清净剂对250N基础油清净效果较PAO更好;黏度指数改进剂、复合剂、聚异丁烯丁二酰亚胺分散剂对油品100℃运动黏度变化影响较大,烘箱高温静置试验表明:乙丙共聚物黏指剂、酚型抗氧化剂使油品烘箱试验后100℃运动黏度下降。     

润滑油黏度下降引起的烃类压缩机故障分析及措施

通过对K-5001低压溶剂回收压缩机轴瓦磨损原因进行分析,发现润滑油中有烃类气体溶解,导致润滑油运动黏度下降严重。为减少烃类气体在润滑油的溶解,选择合成基础油,根据压缩机工况以及轴瓦处最小许用黏度,确定润滑油黏度范围,最后选择一种适合烃类压缩机的合成机油。实际运行结果表明,烃类气体对该润滑油的黏度影响较小,润滑油能够满足设备工况要求。     

On-line acoustic viscometry in oil condition monitoring

The paper describes the theoretical standpoints of developing magnetoelastic viscometers and a concept of viscosity measurement. The magnetoelastic viscometer has shown the readings close to the capillary viscometer. Testing of the oils with PMMA viscosity-index improvers by viscometers has indicated changes in rheological properties observed in the non-Newtonian behavior of the oils. With increase in content or molecular weight of the improver, the non-Newtonian behavior of the oil appeared at lower frequencies of viscosity measurements.     

Effect of palm oil methyl ester and its emulsions on lubricant degradation and engine component wear

This paper presents the results of experimental work carried out to evaluate the effect of palm oil methyl ester also known as palm oil diesel (POD) and its emulsions, as alternative fuels, on unmodified indirect‐injection diesel engine wear and lubricant oil deterioration compared with ordinary diesel (OD). A constant 2500 rpm engine setting at half throttle was maintained throughout the wear debris and lubricant oil analysis period for 20 h for each fuel system. Samples of lubricant oil were collected through a one‐way valve connected to the crankcase sump at intervals of 4 h. The first sample was collected immediately after the engine had warmed up. The same lubricating oil, a conventional SAE 30, was used for all experiments. A multi‐element oil analyser was used to measure metal wear debris and lubricating oil additive depletion for the used lubricating oil. An ISL automatic houillon viscometer (ASTM D 445) and potentiometric titration (ASTM D 2896) were used to measure the viscosity and total base number, respectively. The lubricant oil analysis results for POD, OD, and their emulsions containing 10% water by volume were compared. Very promising results were obtained. The accumulation of metal wear debris in crankcase oil samples was lower with POD and its emulsion compared with the OD fuel. The addition of 10% water (by volume) to POD showed a promising tendency for wear resistance.     

Viscosity–pressure–temperature behaviour of mineral and synthetic oils

A new high‐pressure viscometer that can measure viscosity at pressures up to 0.8 GPa has been developed in the authors' laboratory. The ‘modulus equation’ has been used to compare the behaviour of mineral and synthetic lubricants. Among the oils investigated there was one ester that biodegraded rapidly both before and after ageing in a long‐term test‐rig operation. To facilitate a comparison or application of the results to other oils, an analysis of the correlation between the viscosity—pressure coefficient and the kinematic viscosity measured at atmospheric pressure has been provided. A prediction of lubricant film thickness based on high‐pressure viscosity data is compared with film thickness measurements in a roller bearing.     

Rheological properties of high‐viscosity‐index mineral base oils for automotive engine lubricants

Viscosity‐pressure‐temperature relations for paraffinic mineral base oils at pressures up to 0.7 GPa and temperatures between 30 and 90°C were determined using a falling‐ball‐type viscometer. The oils used were solvent refined oils, hydrocracked oils, and an oil produced by a wax isomerisation process. The viscosity at pressures higher than those possible with the viscometer was then derived by applying a simplified solution to the traction curves determined using an elastohydrodynamic disc‐on‐ball tester. When the measured viscosity and the calculated viscosity were plotted against pressure, for the oils with a viscosity index higher than 120 the viscosity derived from traction measurements followed the curve extrapolated to the high‐pressure region using either the Yasutomi or Roelands equations (the parameters for which were obtained using the viscometer). However, the calculated viscosity for the lower‐viscosity‐index oils deviated upwards from the extrapolated curve.     

Evaluation of the low-temperature performance of engine lubricants using the scanning brookfield viscometer

When subject to low-temperature conditions, the paraffins in a lubricant come out of solution to form structures that can impair oil flow. The size of the paraffinic crystals, and the strength of the three-dimensional network they form, depend on physical parameters, such as temperature, cooling rate and soaking time, as well as on the chemical nature of the wax and of other components in the oil. To evaluate the ability of lubricants to flow under low-temperature conditions, a number of test methods have been developed, from the simple pour-point test (ASTM D-97), to very sophisticated tests such as the MRV TP-1 (ASTM D-4864). In the early 1980s, a new technique, using the scanning Brookfield viscometer (ASTM D-5133), was developed. This method has progressively gained acceptance by industry and is now part of the ILSAC GF-2 specification. The scanning Brookfield technique provides a new approach to continuous measurement of the viscosity of engine lubricants at very low shear rates, with decreasing temperature. It is said to be unique in its ability to identify oils which develop gel structures at low temperature. After presenting background information on the scanning Brookfield viscometer, this paper examines its use with modern engine lubricants, and its ability to evaluate the effect of pour-point depressants on the low-temperature performance of engine lubricants.     

The viscosity of dimethyl ether

Dimethyl ether (DME) has been recognised as an excellent fuel for diesel engines for over one decade now. Engines fuelled by DME emit virtually no particulate matter even at low NO_x levels. This is only possible in the case of diesel oil operation if expensive and efficient lowering particles and NO_x traps are installed.The most significant problem encountered when engines are fuelled with DME is that the injection equipment breaks down prematurely due to extensive wear. This tribology issue can be explained by the very low lubricity and viscosity of DME. Recently, laboratory methods have appeared capable of measuring these properties of DME. The development of this is rendered difficult because DME has to be pressurised to remain in the liquid state and it dissolves most of the commercially available elastomers.This paper deals fundamentally with the measurement of the viscosity of DME and extends the discussion to the difficulty of viscosity establishing of very thin fluids. The main issue here is that it is not easy to calibrate the viscometers in the very low viscosity range corresponding to about one-fifth of that of water. The result is that the low viscosity is measured at high Reynolds numbers so that the outcome has to be corrected by various factors. The validity of these can be discussed especially when they exceed a few percent of the apparent viscosity.The volatile fuel viscometer (VFVM) developed at DTU is presented. By enclosing a standard glass capillary viscometer in a glass tube it is possible to measure the viscosity of fluids at pressures below 15 bars. The kinematic viscosity of DME was established at 0.184 cSt @ 25 °C at the vapour pressure of the fluid at that temperature. The measurements were made at reasonable Reynolds numbers so the correction factors are negligible indicating a high accuracy of the method.Other pressurised viscometers have appeared since the development of the VFVM. These predict a 5–19% higher viscosity for DME than the VFVM. It seems that the causes for these differences are a too high Reynolds number and/or an influence of the gas used for pressurisation in these methods. The results of the VFVM are consolidated by measurements of the viscosities of propane and butane: these agree with the outcome of measurements using a quartz crystal microbalance (QCM) a method that is supposedly less sensible than the Reynolds number.     

基础油的性能检测及其在工业润滑油液中的应用技术

介绍浓硫酸显色法、加热法、烘干法、放置法、理化测试法、仪器分析法等6种基础油不同性能的常规测试法,并对基础油的应用技术进行讨论;指出在润滑油调配时尽量选用黏度中心值或范围接近的基础油,优先选用性能贡献率较大的基础油,新基础油和新型添加剂的合理配伍将是今后润滑油液调配的关键技术。     

以汽油和甲醇为燃料时小型二冲程发动机摩擦特性比较

采用往复振动机模拟小型二冲程发动机运转工况，实验研究汽油和甲醇为燃料时发动机气缸和活塞环间的摩擦特性，并比较分别使用润滑油新油、润滑油老化油、润滑油新油和老化油的混合油作为润滑油时气缸和活塞环间的摩擦特性。结果表明，以甲醇为燃料时的摩擦因数和磨损量均小于以汽油为燃料时的摩擦因数和磨损量，特别是使用添加了润滑油新油的燃料时的摩擦因数和磨损量最小。通过黏度和热重（TG）分析，探讨甲醇燃料改善气缸和活塞环间的摩擦特性的原因，结果表明，甲醇燃料具有较高的黏度和较低的摩擦因数，因而以甲醇为燃料时可以降低磨损     

用旋转粘度计法研究非牛顿流体的流变性能

本文主要介绍在5个不同减阻剂浓度(0 mg/L,100 mg/L,200 mg/L,300 mg/L,400 mg/L)和不同温度(15℃,20℃,25℃)下,用旋转粘度计法测定减阻剂样品在7m in内,剪切速率从0~183.45/s下,研究0号柴油及加入减阻剂后的流变性能。一般情况下,幂律模型适合于大部分非牛顿流体。加剂后的柴油溶液,与空白柴油相比较,稠度都有不同程度的提高。在低剪切速率下,大多数实验结果表现为牛顿流体流变行为,但D-41(块)溶液例外,浓度为300mg/L的15℃和20℃及浓度为400mg/L的25℃表现出假塑性流动行为。浓度与粘度的线性关系用关系和指数关系相对于乘幂关系拟合程度较高,而用乘幂关系拟合程度较低。粘度与温度间服从于阿累尼乌斯方程。     

Demonstrating Improved Fuel Economy Using Subsystem Specific Lubricants on a Modified Diesel Engine

Fuel economy performance in modern internal combustion engines is of increasing importance to lubricant formulators due to regulations targeting global greenhouse gas emissions. Engines typically employ a single lubricant, with a common sump, to service all components. As a result, base oil and additive selection for fuel economy performance is a compromise among competing demands for different engine subsystems. Opportunities for significant fuel economy improvement through targeted formulation of lubricants for specific engine subsystems are presented, with specific emphasis on segregating the lubricant supplies for the valve train and the power cylinder subsystems. A working prototype was developed in a lab environment by modifying a commercially available twin-cylinder diesel engine. Motored valve train and whole-engine fired test results were obtained and compared to model data. Fuel economy benefits were demonstrated using market representative heavy-duty diesel lubricants, including mineral oil and polyalphaolefin (PAO) blends. The fuel economy benefits of a dual-loop lubricant system are demonstrated through significant viscosity reduction in the power cylinder subsystem, achieving overall engine friction reductions of up to 8% for the investigated operating condition. Results suggest that additional gains may be realized through targeted base oil and additive formulation. Implications for incorporation in larger diesel engines are also considered.