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.     

Research on Mutual Synergy of Antiwear Additives in Lithium Complex Grease

In recent years, with the enhancement of environment awareness, there has been a progressive reduction in permitted phosphorus and sulfur levels in lubricants. Sulfur and phosphorus are the most important elements of antiwear additives. Because of the reaction between additives, less mass of additives may have the same wear reducing properties when used together. However, there is uncertainty regarding the optimum amount and ratio of these additives. In this article, the influence of five kinds of antiwear additives—sulfurized olefin cottonseed oil (T405), sulfurized isobutylene (SIB), tricresyl phosphate (TCP), molybdenum dialkyl dithiophosphates (MoDTC), zinc dialkyl dithiophosphate (ZDDP), and their combination—on lithium complex grease have been studied by single-factor and orthogonal experiments. The single-factor tests show that T405 and SIB work well under low temperature, whereas TCP and MoDTC work well under higher temperature; ZDDP are multifunctional additives. It was proved that base grease has better antiwear properties at 150 than at 75°C. Additionally, sulfurized additives T405 and ZDDP and phosphate agent TCP could react better with lithium complex grease than the additives that have the same functional group. Furthermore, the results of orthogonal experiments show that the abrasion resistance of lithium complex grease is optimally best when T405, TCP, and ZDDP are blended with a ratio of 2:2:1. In addition, a synergistic effect between T405 and TCP is observed at ratios between 1:1 and 2:1. The morphology and element composition of the worn surfaces are examined by scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS). Based on the two kinds of technology, the friction and wear mechanism of additives also have been studied.     

润滑脂中极压抗磨添加剂的研究进展

综述近年来多种类型的极压抗磨添加剂在润滑脂中的研究成果,包括:层片状、球粒状添加剂、微纳尺度的软、硬质点添加剂、微纳尺度的氧化物及其他化合物添加剂、环保型添加剂。总结其抗磨减摩的作用机制,并针对目前研究存在的问题,提出了润滑脂用极压抗磨添加剂研究的方向。     

含硫极压抗磨添加剂在菜籽油中的摩擦学性能研究

利用四球磨损试验机考察了以硫化异丁烯和硫化棉籽油作为菜籽油极压抗磨添加剂时的摩擦学性能,通过测定2种添加剂在不同含量下的最大无卡咬负荷(pB)和不同条件下的磨斑直径(WSD),分析和研究了载荷、摩擦时间、添加剂含量对菜籽油摩擦学性能的影响。试验结果表明:硫化异丁烯可以明显提高菜籽油的承载能力和抗磨性能,硫化棉籽油对提高菜籽油的承载能力和抗磨性能效果不明显,硫化异丁烯在菜籽油中的承载能力和抗磨性能明显优于硫化棉籽油。试验还表明添加剂的含量并非越高越好,否则WSD值将增大。     

几种无机纳米粒子在润滑油中抗磨性对比研究

利用超声波纳米粉碎机制得无机复合纳米颗粒,通过选用合适的分散剂和采用超声波分散的方法,制备出悬浮性、分散性良好的油基纳米抗磨剂,采用摩擦试验机对所制备的产物的抗磨性与Al2O3、Si3N4纳米粉进行了对比试验及表征分析。结果表明实验制备的无机复合纳米颗粒相对于Al2O3、Si3N纳米颗粒具有更好的抗磨减摩性能,同时出现了负磨损现象,无机复合纳米粒子在摩擦副表面起到了修复作用。     

Additives for metalworking lubricants - a review

This paper is presented as an introduction to various specific problems associated with metalworking additives, especially that related to their modes of action. It describes various chemicals used as specific additives for metalworking lubricants. The introductory part of the review deals with general lubricant types for both metal-forming and metal-cutting processes. The section dealing with types of additives used for metalworking lubricants is followed by a section on the chemistry of these additives. The detailed review is connected with boundary lubrication additives for water-based liquids and oil-based lubricants. Corrosion and antimicrobial agents are discussed as well. Other additives are described more generally.     

Solution Phase Reactions of Organomolybdenum Friction Modifier Additives for Energy Conserving Engine Oils

The reactivity of MoDTC and ZnDTP in hydrocarbon solution was examined in detail under non-oxidizing conditions. These observations revealed increased reaction rates when polar solvents and/or short alkyl groups are encountered. Through the use of molecular modeling, it is shown that the major influences over MoDTC/ZnDTP reactivity are hard/soft acid/base and solvation interactions. As a result of this work, both MoDTC and ZnDTP appear to exist as ion pairs in engine oil formulations.     

添加剂对7075铝合金润滑性能影响的研究

选用新型的高分子聚合酯GY25、三羟甲基丙烷单酸酯PRIOLUBE2044、PAG合成酯SGL、氯化石蜡P51NR、磷酸烷基酯360P和二烃基五硫化物RC2540作为润滑添加剂,采用MPX-2000销盘式摩擦磨损试验机,研究不同含量的上述6种添加剂对7075铝合金/45#钢摩擦副润滑性能的影响,并通过扫描电镜(SEM)和能量色散谱(EDS)观察摩擦表面形貌及元素分布。结果表明:在钢/铝摩擦副中,7075铝合金主要表现为黏结磨损;随着添加剂含量的增加,P51NR和360P能显著提高润滑性能,GY25和SGL对润滑性有一定的改善作用,2044的改善效果不明显,而RC2540产生负面影响,增大了铝合金的磨损。     

表面修饰的纳米金刚石微粒在润滑油中的抗磨减摩性

将纳米铁微粒、纳米铜微粒及纳米金刚石微粒分别分散到不含油性剂和极压抗磨添加剂的半成品合成润滑油中,采用MM-200型磨损实验机和XL30-1扫描电镜等设备研究了纳米微粒的抗磨减摩性,采用发动机台架试验研究了纳米金刚石的摩擦性能.结果表明,纳米金刚石微粒可明显改善润滑油的抗磨减摩性能;纳米金刚石润滑油的油膜有着非常好的抗黏滑能力和承载能力,对摩擦副有自修复作用.在普通发动机润滑油中加入质量分数0.01%的纳米金刚石微粒后,其润滑性能有很大的改善,在相同转速下功率平均提高4.2%;怠速时的HC排放量从8.75×10-4降低到3.50 ×10-4,降低60%,Nox排放量从1.66×10-4降低到1.32×10-4,降低20.5%;油缸的压力从0.441 Mpa增加到0.568MPa,相对增加28.9%;怠速也提高了19.6%.     

Effect of the structure and metal atom of dialkyldithiophosphate derivatives on the wear behaviour in steel‐zirconia contacts

Wear investigations concerning the different structures and metal atoms of metal dialkyldithiophosphates (MeDTPs) were conducted using a ball‐on‐disc apparatus. Steel ball bearings (3.175 mm in diameter) and counterface discs, made of hot pressed ZrO₂ partially stabilised by Y₂O₃, were used. The synthesised MeDTPs were made up of primary linear aliphatic alcohols with hydrocarbon lengths varying from 8 to 16 carbon atoms, and contained the following metals: zinc(II), iron(III), gallium(III), antimony(III), and copper(II). Tests were performed at room temperature. The sliding speed was set to a constant 0.03 m/s, and a constant 30 N load was used. The additives investigated were used as solutions in n‐hexadecane. The study also focused on the influence of additive concentration on wear. It was found that the effectiveness in reducing wear depends both on the metal atom and on the length of the hydrocarbon chain in the additive's molecules. The lowest wear volumes were observed for additives with n‐octyl and n‐tetradecyl hydrocarbon chains. The worst antiwear performance was observed for n‐dodecyl derivatives. For almost all additives, more concentrated solutions resulted in less wear. Some friction coefficient results are also presented.     

纳米润滑油添加剂抗磨减摩分子动力学模拟研究

研究分子动力学模拟的基本原理,建立摩擦副的分子动力学模型。通过计算对磨材料原子与被磨面材料原子之间作用力,建立运动方程,通过数值方法求解运动方程,模拟出不同时刻原子运动轨迹,根据运动轨迹和原子间作用力分析摩擦磨损过程。对Fe/Fe和Fe/Cu 2种摩擦副的抗磨减摩性能进行模拟计算,分析磨损量与模拟时间和载荷曲线的变化趋势。结果表明有中间纳米Cu润滑层的Fe/Cu摩擦副具有良好的摩擦性能。     

Improved additives for multiply alkylated cyclopentane‐based lubricants

Multiply alkylated cyclopentanes (MACs) are replacing heritage (mineral oil‐based) spacecraft lubricants because of their excellent performance and low volatility. While MACs have acquired an increasingly prominent role, soluble additives with similarly low volatility are lacking. In this study, the performance of specially designed candidate high‐molecular‐weight/low‐volatility phosphate additives was compared with the performance of conventional phosphate and lead naphthenate additives currently used in space. The candidate additives were equivalent or superior to the currently used additives in both conventional (atmospheric) and vacuum wear tests. Volatility studies revealed superior candidate additive performance compared with currently used additives. In addition, surface chemical analysis of the wear surfaces provided a better understanding of the anti‐wear protective films formed by these additives. Copyright © 2008 John Wiley & Sons, Ltd.     

Concept of molecular design towards additive technology for advanced lubricants

A simple model to develop novel friction modifiers and anti‐wear agents for synthetic oils was studied. Our attention was focused on the construction of additive molecules to meet the requirement for synthetic oils, which possess a different polarity and solvency from mineral oils. The relation between the molecular structure of additives and their tribological properties were elucidated prior to the preparation of the substance and estimation of its tribological properties. Computer‐assisted chemistry was partly applied to predict the properties of the designed molecules. The adsorptive activity of the conventional fatty acids is insufficient to reduce friction when they were dissolved in polar synthetic oils such as polyethers. Introduction of another carboxyl group into the fatty acid, especially at the carbon atom next to the original carboxyl group, makes the molecule polar; resulting in friction modifiers for polyethers. Conversion of the carboxyl groups into trimethylsilyl esters provides soluble friction modifiers for poly(dimethylsilicone)‐type synthetic oils. A unique lubrication mechanism based on in situ regeneration of the original molecule was proposed for synthetic oils with poor solvency. Importance of adsorptive activity of additive molecule was also pointed out in phosphate‐type anti‐wear additives for polar synthetic oils. We found that both the polarity of additives and that of base oils have to be taken into account in lubricant design. Too much adsorption activity of the molecule caused corrosive wear. Hydrolytic stable compounds reduces corrosive wear to a considerable extent. Introduction of a hydroxyl group into the alkyl moiety of the phosphate ester provides polar molecule with low acidity. The additives reduce wear in synthetic esters even at low concentrations of phosphorus. The lubrication mechanism was also discussed; the novel additives provide a thick boundary film composed of iron phosphate on rubbing surfaces. Moreover, an acceleration of the kinetics of the film formation by the hydroxyl group was observed. Copyright © 2007 John Wiley & Sons, Ltd.     

酰肼类及磷酸类润滑油添加剂CoMSIA-QSTR抗磨损性能模型构建

采用比较分子力场分析(Comparative Molecular Field Analysis,CoMFA)和比较分子相似性指数分析(Comparative Molecular Similarity Indices Analysis,CoMSIA),对36种酰肼类及部分磷酸类润滑油添加剂的抗磨性能进行摩擦学三维定量构效关系的研究,在静电场和立体场分别建立添加剂的CoMSIA模型,对比分析2种模型的稳定性和预测能力。结果表明:在静电场构建的CoMSIA模型的预测能力较好,表明分子静电场对该类型类化合物的抗磨性能影响最大;基于该模型构建的三维等高线图可较为直观地解释静电场对化合物抗磨性能的影响,即当官能团或原子的电负性和所在区域性质一致时,抗磨性能最好。因此在特定区域引入带有正电荷或负电荷的基团或原子将有助于提高化合物的抗磨效果。     

微型机械力学行为的分子动力学模拟研究进展

介绍了国外分子动力学模拟在微型机械力学行为分析中的研究进展;阐述了分子动力学模拟的基本方程、分子动力学的算法以及应用于微型机械力学行为分析中的势函数等.最后介绍了几个在微型机械力学行为分析中应用分子动力学模拟的例子.     

Effectiveness of lubricant additives for copper‐alloy‐steel sliding contacts

A selection of additives and their performance and compatibility with a variety of copper alloys have been evaluated in an SRV test set‐up. The tests show a remarkable variation of tribological behaviour with a clear relation to both the type of lubricant / additive and the type of alloy. One ester‐based additive showed outstanding friction and wear reduction for some groups of copper alloys. In order to better understand the fundamental mechanisms, we applied a variety of surface analyses, such as 3D confocal white light microscopy, scanning electron microscopy and X‐ray photoelectron microscopy. Copyright © 2010 John Wiley & Sons, Ltd.     

一种航空终端设备的多学科优化减重设计

研究了一种航空终端设备多学科优化的减重设计方法,该方法结合了结构强度仿真分析、散热仿真分析等多学科优化设计方法,详细介绍了具体的优化设计过程。采用所提出的优化方法,使该设备在满足各项技术指标的前提下,总质量减少了23%,达到了减重设计目标。     

A strategy for the development of optimised lubricants

The design of lubricants has traditionally relied on the use of single dimension constitution / performance or structure / property relationships. In this paper a strategy is described whereby consideration is given to the inherent property / property (physical and chemical) correlations that exist for fluid lubricants. Progress towards the development of optimised lubricants is then achieved by identifying the molecular structural or compositional traits associated with ‘extensions’ to or ‘deviations’ from the mainstream correlations. Some examples of the success of this novel strategy will be provided, and the directions of its further refinement briefly outlined.     

油液磨粒超声回波信号的双树复小波去噪研究

超声回波信号反映了润滑油中磨粒的大量信息。为了提取淹没在强噪声环境下的超声回波信号,提出了一种基于双树复小波变换(DT-CWT)的油液磨粒超声散射回波信号去噪新方法。利用双树复小波变换具有近似平移不变性和有效去噪等优点,首先对超声散射回波信号进行双树复小波分解,然后对分解得到的高频系数进行阈值处理,最后进行双树复小波重构。结果表明:分解层数为6层时,去噪后信号的信噪比更高、均方误差更小、相似系数更大、幅值最大偏差更小。双树复小波变换硬阈值去噪效果比传统小波去噪效果明显好。