烷烃乳液润滑Si3N4陶瓷摩擦副的摩擦学特性研究

采用多种烷烃乳液以及添加剂对氮化硅陶瓷摩擦副进行润滑试验。试验结果表明:对于氮化硅陶瓷摩擦副来说,所有的烷烃都可以得到较好的润滑效果,摩擦因数最高的基础油也仅有0.13;相对于包含直链烷烃、支链烷烃和环状饱和烃的基础油和柴油,正构烷烃的摩擦因数更低,抗磨性能更好;润滑性能最佳的液体石蜡中添加极性添加剂氯化石蜡和油酸后,乳液的润滑性能变差,但加入有机硅乳液后则润滑性能大大提高,摩擦因数进一步降低为0.017。基于试验试剂的结构特征,得出对于水乳润滑剂来说,化学性质和分子结构与氮化硅陶瓷相似的有机物可以更好地在陶瓷摩擦副表面聚集从而起到更好的润滑效果的结论。     

Elastohydrodynamic properties of water in oil emulsions

Elastohydrodynamic (EHL) film thicknesses of emulsions have been measured in a rolling point contact using an optical interference method. Both water in oil and oil in water emulsions have been studied.For water in oil emulsions the experimental data suggest that EHL film thickness is almost independent of water concentration and also particle size distribution, although the bulk viscosity of the emulsions is heavily dependent upon these two variables. It is concluded that the EHL properties of such emulsions are determined almost entirely by the EHL properties of the pure oil.For oil in water emulsions, negligible EHL film formation was observed.     

Study on the Performance of Oil-in-Water Emulsions during Cold Rolling of Steel Strip

Lean oil-in-water (O/W) emulsions with oil concentrations of 2 to 5% are in general use in industrial rolling mills. The oil formulators and technologists aim to develop more efficient and cost effective O/W emulsions using hybrid emulsifiers and other chemicals. Different researchers have expressed different views on film forming and lubrication characteristics of O/W emulsions. The present authors have carried out a study to assess the film-forming characteristics and tribological performance of three commercially available O/W emulsions of different chemical compositions. Results of the present study indicate that the chemistry of the O/W emulsions plays an important role in their film-forming and tribological characteristics. Rolling emulsions of relatively low stability, high droplet size, and high saponification value are found to provide better lubrication and lower coefficient of friction. There is good correlation between the results of the present experiments and actual observations in industry.     

板带钢冷轧乳化液及润滑效果研究

针对冷轧无间隙原子钢(IF钢),配制了2种不同的乳化液,并将其与国内、国外商品级乳化液的冷轧实验进行对比。实验发现乳化油中基础油的选择对乳化液冷轧润滑效果的影响很大,当基础油含饱和脂肪酸高时乳化液润滑能力好,可以用乳化液皂化值来衡量乳化油冷轧润滑效果的优劣。一般皂化值高的乳化液可用来冷轧屈服强度较高、成形较困难的板带钢。使用乳化液冷轧后的表面形貌明显优于无润滑状态的轧后表面。在乳化液冷轧润滑过程中,当压下率较低时,轧件的表面质量有所改善,总压下率超过90%以后,轧件的表面质量又呈下降趋势。     

Quantitative estimation of wear amounts by real time measurement of wear debris in lubricating oil

A diagnostic technique that can estimate quantitatively wear amounts under lubricated condition was developed using our developed on-line particle counter. Wear tests were carried out by rubbing a bearing metal against a carbon steel in paraffin oil. The size and number of wear debris in the circulating oil could be measured in real time. The volume of each debris was calculated and, additionally, the total wear amount during a given duration was calculated by accumulating all debris volume. The wear amounts obtained by the quantitative estimation were fairly similar to the measured values of mass loss of the specimen.     

Lubrication of Aluminum Rolling by Oil-in-Water Emulsions

The dynamic concentration model for lubrication by oil-in-water emulsions proposed by Wilson el al. (1) is applied to strip rolling to derive a relatively simple equation for inlet film thickness. The predictions of the new model are supported by rolling experiments using emulsions as lubricants, where the film thickness is inferred from the surface roughness that is generated on the workpiece during rolling. The experiments also seem to suggest that the efficiency of oil droplet capture increases with increasing rolling speed.     

The effect of emulsifier concentration on the lubricating properties of oil-in-water emulsions

Although the use of oil-in-water (O/W) emulsions as metalworking fluids is widespread, the mechanisms of emulsion lubrication are not yet well understood. Several theories have been proposed but there is not a clear agreement about the effect of different operating conditions and emulsion properties on the lubricating performance of O/W emulsions. In the present study, the film forming ability of O/W emulsions as a function of emulsifier concentration is studied. The emulsifier content exerts a strong influence on all the emulsion properties, such as stability, droplet size distribution, surface and interfacial tension, wetting ability, etc., as well as on the lubricating behaviour, so it has been used to ascertain the relationship between all the properties involved. Three different emulsifiers—anionic, nonionic and cationic—were used at different concentrations in the design of lubricant O/W emulsions. Experimental results show that the work of adhesion of oil droplets on the metal surface is a valuable parameter to predict the ability of emulsions to form thick films in elastohydrodynamic (EHD) contacts. The influence of pH value of O/W emulsions on their lubricating behaviour is also verified. The overall conclusion is that the interactions between metal and oil droplets rule the mechanism of lubrication and that this interaction is primarily controlled by emulsifier concentration.     

Metalworking fluids from vegetable oils

The biodegradability of metalworking fluids has assumed very high priority. Biodegradable metalworking fluid formulations consist of vegetable oil, an emulsifier, co‐surfactant, fungicide and additives. Non‐edible vegetable oils such as neem, ricebran, and karanja oil are renewable, biodegradable and cheaper than synthetic fluids. Oleates and fatty‐acid amides of these oils have been used as emulsifiers to eliminate biohard emulsifiers. Additives are used to achieve a high level of performance. Metalworking soluble oil formulations were evaluated for physico‐chemical characteristics such as emulsion and thermal stability, copper‐strip corrosion, iron chip corrosion, deposit‐forming tendency on hot metal surfaces, and lubricity. Oil–water micro‐emulsions of these oils have higher stability. The emulsions were stable over a wide range of temperatures. Performance of formulations from all three oils are found at par with the ASTM specifications. Neem oil based formulation showed better characteristics than ricebran and karanja oil. Copyright © 2006 John Wiley & Sons, Ltd.     

油酸修饰纳米粒子的摩擦学性能比较

利用化学法合成了表面为油酸所修饰的PbS、PbO和ZnS纳米粒子,由于无机纳米粒子表面有一层由油酸组成的长链有机化合物,使得所修饰的PbS、PbO和ZnS纳米粒子在基础油中有良好的分散性,能够作为润滑油添加剂。用四球摩擦磨损试验机分别考察了它们作为润滑油添加剂的摩擦学行为,结果表明,无机纳米核的化学组成、大小,以及摩擦过程中所形成边界润滑膜的成膜机制对油酸修饰纳米粒子作为润滑油添加剂的摩擦学性能影响不大,所合成的油酸修饰PbS、PbO和ZnS纳米粒子作为润滑油添加剂都能够明显提高基础油的减摩抗磨性能。     

Tribological properties of diamond and SiO2 nanoparticles added in paraffin

This work studies the tribological properties of liquid paraffin to which diamond and SiO₂ nanoparticles, which were prepared by the surface modification method using oleic acid, had been added and observed by scanning electron microscopy (SEM) and infrared (IR) spectroscopy. Also, the dispersion capability and stability dispersivity of both modified nanoparticles in liquid paraffin were measured using a spectrophotometer. The measurements show the dispersion capacity and the dispersing stability of oleic acid-modified diamond and SiO₂ nanoparticles in liquid paraffin.The tribological properties are evaluated using a ball-on-ring wear tester. The results show that both nanoparticles as additives in liquid paraffin at a tiny concentration have better antiwear and antifriction properties than the pure paraffin oil. Also, SEM was used to observe the plowing of nanoscale grooves of worn surfaces by diamond and SiO₂ nanoparticles.     

液体石蜡的碳数分布和组分含量测定方法的研究

本文针对进口的液体石蜡样品,运用微分流系统和色谱质谱联用仪对样品进行定性和定量分析,测定液体石蜡样品的碳数分布和组分含量。     

Increased Film Thickness of Oil-in-Water (O/W) Emulsions at High Speed

The thickness of films formed by oil-in-water (O/W) emulsions under confined conditions can be tens of nanometers, which is much thicker than that formed by pure water. Film thickness can increase even more with limited lubricant supply, especially for O/W emulsions with a low oil percentage. The central film thickness of a 1% oil emulsion can increase to up to 2.4 times its initial value. In this paper, the film-forming behavior and mechanism driven by the competitive wetting behavior of oil and water are investigated and discussed.     

镁合金轧制乳化液的配方设计

为开发镁合金板带轧制用冷却润滑剂,对以10#变压器油、7#主轴油和聚乙二醇600 (PEG600)为基础油,以Span80、Tween80、十二烷基磺酸钠(SDS)为复合乳化剂,以十二醇和油酸作为油性剂的水包油型乳化液进行性能检测.结果表明:乳化液的稳定性主要受到表面活性剂种类与加入量的影响,以非离子和阴离子型表面活性剂复配的乳化剂为佳,适宜的加入量在10％左右;复配乳化剂制备的乳化液的稳定性和离水展着性均优于单独使用某一种乳化剂,随着乳化剂加入量的增加,乳化液的离水展着性明显增加,表面张力明显下降;十二醇油性剂有利于提高乳液的稳定性,油酸油性剂有利于提高乳液的离水展着性.     

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.     

A study in EP activity evaluation of some new oil-soluble Mo-S complexes

0.5% (w/v) solutions of bis(1,5-diaryl-2,4-dithiomalonamido) dioxomolybdenum complexes in paraffin oil were found to reduce significantly wear and friction of the steel balls in a four-ball test. The additive, bis(1,5-di-p-methoxyphenul-2,4-dithiomalonamido) dioxomolybdenum (VI) afforded higher values of initial seizure load (ISL, 112 kgf), 2.5 second seizure delay load (2.5 s SDL, 126 kgf), weld load (WL, >500 kgf), flash temperature parameter (FTP, 296) and mean Hertz load (MHL, 84 kgf) as compared with the plain paraffin oil and a sulphur-phosphorus additive. The tribological end effects were studied by scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) techniques respectively.     

EP activity evaluation of some 2-phenyl-3-phenylimino-5-arylimino-1,2,4-thiadiazolidines

A four-ball test was conducted to evaluate the EP activity of 2-phenyl-3-phenylimino-5-arylimino-1,2,4-thiadiazolidines (0.5% w/v) in paraffin base oil using a 12.7-mm diameter steel ball specimen. 2-phenyl-3-phenylimino-5-p-chlorophenylimino-1,2,4-thiadiazolidine exhibited good activity in reducing wear scar diameter and friction coefficient values at higher loads and increasing the values of flash temperature parameter (FTP), mean Hertz load (MHL) and pressure wear index (PWI) as compared with commercially available sulphur-phosphorous reference additives. The wear surface tribochemistry and topography were investigated using scanning Auger electron spectroscopy and scanning electron microscopy techniques.     

Silicon Nitride Boundary Lubrication: Effect of Oxygenates

A ball-on-three-flat (BTF) wear tester was used to investigate the boundary lubricating characteristics of oxygenates on a commercial silicon nitride. A wide variety of oxygen-containing compounds were tested neat and/or at 1% by weight in a paraffin oil. Compounds containing hydroxyl functional groups were more effective compared to a base case of neat paraffin oil. Decreases of up to 58% in friction coefficient, and 95% in wear were obtained. In most cases, films were observed in and around the wear scar, suggesting chemical reactions had taken place in the contact.

Additional wear tests, conducted using neat shorter-chain linear primary alcohols, i.e., 6–10 carbons, demonstrated boundary lubrication protection, with longer chain length providing better antiwear performance. A study of several C₈ compounds with specific oxygen-containing functional groups (primary alcohol, secondary alcohols, acid, aldehyde, and ketone) demonstrated that the primary alcohol had the strongest boundary lubricating effect. Varying the amount of water in the alcohols had little effect on friction and wear, suggesting that the boundary lubrication effects observed were not merely due to dissolved water in these fluids, but some characteristic chemical interaction with the hydroxyl functional group of the alcohols and acids.     

点/线/面接触条件下喹唑啉酮胺润滑油添加剂的摩擦学性能

目前杂环化合物作为润滑油添加剂在机械润滑领域受到重视,但对无硫磷含氮杂环化合物在多种接触方式下的摩擦学性能的研究还不多。合成一种新型无硫磷喹唑啉酮胺润滑油添加剂并利用四球试验机、环块试验机和万能摩擦磨损试验机分别考察了点/线/面接触条件下其在液体石蜡中的摩擦学性能,再用光学显微镜、扫描电子显微镜和X射线光电子能谱仪对其摩擦表面进行分析。试验结果表明:油溶性喹唑啉酮胺在液体石蜡中能显著改善基础油的摩擦磨损状况,明显提高基础油的承载能力,表现出良好的摩擦学性能,其作用机理是其在摩擦过程中与金属表面发生了摩擦化学反应,生成了含氧化亚铁、有机氮化物和含氮金属配合物等的复合膜,有效地提高了液体石蜡的减摩抗磨性能。     

油酸修饰PbS纳米粒子的摩擦学性能剖析

合成了基础油中分散性良好的油酸（OA）修饰PbS纳米粒子，并用四球摩擦磨损试验机考察了其作为润滑油添加剂的摩擦学行为，结果表明，OA修饰PbS纳米粒子在较低的添加浓度下就具有良好的减摩和抗磨效果，未修饰PbS纳米粒子作为润滑油添加剂时有一定的减磨作用，而修饰剂油酸则具有一定的抗磨性能。     

在不同润滑油下齿轮锻造材料摩擦特性研究

采用销-盘摩擦副接触方式在不同流体润滑及载荷下,对齿轮锻造用SCr420H合金结构钢进行摩擦试验.采用齿轮油、石蜡油以及加工润滑油润滑.利用在不同润滑及载荷下随速度变化的摩擦因数变化曲线图分析摩擦材料表面摩擦特性.利用Stribeck曲线和摩擦表面形貌SEM照片分析在不同润滑油及载荷下的摩擦状态和摩擦行为.结果表明:SCr420H合金结构钢在最低动黏度的石蜡油润滑下摩擦因数最高,且随速度增大而减少;在齿轮油和加工润滑油润滑下,最低载荷时具有最高的摩擦因数,但摩擦因数随载荷增大而减少,速度对摩擦因数影响不大;在齿轮油和加工润滑油润滑下摩擦副处于流体润滑状态,在石蜡油润滑下显示临界润滑摩擦状态.