固体添加剂和摩擦改进剂对锂基润滑脂性能的影响

针对常用复合锂基润滑脂存在的润滑极压抗磨性不足等问题,研究不同固体添加剂、摩擦改进剂对复合锂基润滑脂极压抗磨减摩性能的影响。结果表明,固体添加剂对复合锂基润滑脂极压抗磨性能影响较大,其中PTFE和二硫化钼组成的复配剂可使润滑脂得到优异的极压和抗磨性能;摩擦改进剂Priolube 3986复酯和硬脂酸复配具有协同作用,可明显增强润滑脂的抗磨减摩性能;固体添加剂和摩擦改进剂对润滑脂的润滑作用可以优势互补,全面提升润滑脂综合性能。     

极压锂基润滑脂的生产与应用

极压锂基润滑脂具有长寿命、多效能等特点,是现代润滑脂发展的方向。提高我国润滑脂的生产和使用水平,是我国研究和生产工作者的努力方向。我厂担负了为1700轧机提供极压锂基润滑脂的生产任务。几年来,在石油化工科学研究院和一机部广州机床研究所研制报告的基础上,我们对极压锂基润滑脂工业性生产的冷却、极压添加剂的选择及其产品的使用进行了一些探索,现介绍如下:     

固体添加剂、摩擦改进剂在锂基润滑脂中的应用研究

针对常用复合锂基润滑脂存在的润滑极压抗磨性不足等问题,研究不同固体添加剂、摩擦改进剂对复合锂基润滑脂极压抗磨减摩性能的影响。结果表明,固体添加剂对复合锂基润滑脂极压抗磨性能影响较大,其中PTFE和二硫化钼组成的复配剂可使润滑脂得到优异的极压和抗磨性能;摩擦改进剂Priolube 3986复酯和硬脂酸复配具有协同作用,可明显增强润滑脂的抗磨减摩性能;固体添加剂和摩擦改进剂对润滑脂的润滑作用可以优势互补,全面提升润滑脂综合性能。     

纳米添加剂对润滑脂防腐蚀性能的影响

试验研究了纳米粒子作为添加剂对润滑脂防腐蚀性能的影响.结果表明,国产铁路货车用轴承通用锂基润滑脂中加入适量的Cu或ZrO2纳米粒子能够提高润滑脂的防腐蚀性能,减少轴承的腐蚀及由此引起的提前失效.     

锂基润滑脂FE9寿命的影响因素探讨

介绍了滚动轴承润滑脂测试仪FE9的测试条件及测试润滑脂寿命的重要意义,并以锂基润滑脂为研究对象,探讨油分离度和极压抗磨性对润滑脂寿命的影响,试验结果表明:锂基润滑脂油分离度过大或过小都会影响润滑脂寿命,合理选择锂基润滑脂极压添加剂不仅可以提高润滑脂寿命,而且可以使轴承运转更平稳.     

钻井液污染润滑脂对牙轮钻头轴承摩擦学性能的影响

高温或冲击载荷会引起钻井液泄漏进入复合锂基润滑脂,从而影响牙轮钻头滑动轴承润滑及摩擦磨损性能。采用MCR102旋转流变仪对含有不同质量分数钻井液的复合锂基润滑脂进行流变性测试,并采用MDW-1型摩擦磨损试验机开展牙轮钻头滑动轴承模拟工况下轴承单元摩擦学实验,研究钻井液质量分数对轴承摩擦磨损性能的影响。结果表明:钻井液的污染将降低润滑脂的黏度,改变润滑脂的流变性能;钻井液的污染总体上增大了滑动轴承单元摩擦因数及摩擦因数波动幅度,同时加大轴承的磨损,且在高转速下,润滑脂中较低含量的钻井液就会使滑动轴承单元的摩擦磨损达到最大值;钻井液中的超细碳酸钙和重晶石颗粒引起的磨粒磨损和犁沟效应,可能导致滑动轴承快速失效。     

二硫化钨在高温锂基润滑脂中摩擦性能的研究

比较了二硫化钨作为高温固体润滑剂和二硫化钼在具体使用过程中的优缺点,研究了超细二硫化钨粉末(0．3～0．5μm)基本特性。以二硫化钨作为新型极压添加剂,制备出一种高滴点、抗高速、具有良好稳定性和优秀极压性的高温锂基润滑脂。试验结果表明,二硫化钨改善了锂基润滑脂的摩擦磨损性能,特别在高温条件下表现出良好的抗磨特性,并对其抗磨减摩机理作了初步的探讨。     

固体磨粒对密封轴承寿命及润滑脂的影响

讨论并分析了四种固体磨粒(铁、粉尘、二硫化钼及铜)对密封轴承寿命及锂基润滑脂失效的影响。提出了在125°C左右的高温和3000r/min的条件下,磨损失效行为主要受控于化学劣化。而在较低温度下则主要以磨粒磨损为主。还结合失效现象及磨损行为,探讨了在高温下固体磨损与轴承表面等作用而形成表面固体润滑膜及抑制润滑介质的可能性。     

基础油复配复合锂基脂的制备及性能研究

为提高复合锂基脂的高温性能,以500SN矿物油和甲基苯基硅油为复合基础油,以12-羟基硬脂酸、癸二酸、一水氢氧化锂等为稠化剂原料制备复合锂基润滑脂,考察基础油含量、种类及复配比对润滑脂性能的影响。确定润滑脂的最佳配方,并对润滑脂进行热分析和扫描电镜测试和四球摩擦试验。结果表明:当基础油质量分数为86%时,所制备润滑脂综合性能更优;甲基苯基硅油所制备的润滑脂综合性能明显优于矿物油润滑脂;矿物油与甲基苯基硅油复配比例为4∶6时,所制备润滑脂具有较高的滴点;热分析、扫描电镜测试和四球摩擦试验均证明所制润滑脂高温性能良好、减摩抗磨性能优良。     

导电复合锂基润滑脂润滑的制备及性能研究

以聚α烯烃(PAO)为基础油,以复合锂皂为稠化剂,并添加抗氧、极压和导电添加剂,制备一种导电复合锂基润滑脂,用高速往复摩擦磨损试验机和表面电阻测定仪测定其润滑性能和导电性能,并与国外商用润滑脂和国产导电润滑脂进行比较。通过光学显微镜观察磨斑表面发现,自制的复合锂基脂润滑的表面光滑平整,其润滑性能优于其他2种润滑脂;体积电阻测量结果表明,复合锂基脂的体积电阻率要远远小于国外商用润滑脂和国产导电脂,说明其导电性也要优于其他2种润滑脂。研究表明,选用的有机导电介质不但降低了体积电阻,而且形成的摩擦保护膜也提高了其润滑性能。     

The Importance of Variable Speeds under Extreme Pressure Loading in Molybdenum Disulfide Greases Using Four-Ball Wear Tests

There is recent concern regarding grease behavior in extreme pressure applications. The research described here is aimed at providing good friction and wear performance while optimizing rotational speeds under extreme loading conditions. A design of experiment (DOE) was used to analyze molybdenum disulfide (MoS₂) greases and their importance in reducing wear under extreme loading and various speeds conditions (schedule 1 and schedule 2 speeds). The lamellar structure of MoS₂ provides very good weld protection by forming a layer that can be easily sheared under the applications of extreme pressures. An extreme load of 785 N was used in conjunction with different schedules of various rotational speeds to examine lithium-based grease with and without MoS₂ for an equal number of revolutions. A four-ball wear tester was utilized to run a large number of experiments randomly selected by the DOE software. The grease was heated to 75°C and the wear scar diameters were collected at the end of each test.

The results indicated that wear was largely dependent on the speed condition under extreme pressure loading, and thus a lower MoS₂ concentration is needed to improve the wear resistance of lithium-based greases. The response surface diagram showed that the developed molybdenum disulfide greases exhibited both extreme pressure as well as good wear properties under various rotational speeds when compared to steady-state speed. It is believed that MoS₂ greases under schedule 1 speeds perform better and provide an antiwear film that can resist extreme pressure loadings.     

The tribological behaviors of some rare earth complexes as lubricating additives Part 1. An investigation of the friction-reducing behaviors and an XPS study of the tribochemical characteristics

Several rare earth coordination compounds of 8-hydroxyquinoline and of di-n-hexadecyldithiophosphate were synthesized. The burnished films of these coordination compounds on a GCr15 bearing steel (SAE 52100 steel) disc were prepared. The friction-reducing behaviors of the burnished films were evaluated on a DF-PM friction tester. The friction-reducing behaviors of these complexes as additives in a lithium grease were examined on an SRV fretting wear tester. The binding energies of some typical elements in the complexes before and after friction were determined on an X-ray photoelectron spectrometer. It was found that these coordination compounds could form a quite complete burnished film on a GCr15 bearing steel surface. The lowest friction coefficient was obtained with respect to the burnished film of neodymium di-n-hexadecyldithiophosphate (NdDDP), while a decreased friction coefficient was reached with respect to the burnished film of rare earth 8-hydroxyquinolinate, as compared with the non-burnished friction pairs. Besides, the SRV fretting wear test results revealed that NdDDP in lithium grease exhibited better antiwear and extreme pressure properties than zinc di-n-butyldithiophosphate (ZDDP), while the antiwear and extreme pressure performance of rare earth 8-hydroxyquinolinates is comparable to that of ZDDP. The related results will be published in a following part of this work. The XPS results indicated that tribochemical reactions were involved in the wear process of these coordination compounds as lubricants or as lubricating additives. Here in the first part of this work, the friction-reducing behaviors of the burnished films and of the additives in a lithium grease are dealt with, while the XPS study of the tribochemical characteristics of these complexes is also reported.     

Friction and wear behaviors of aluminum-on-steel under the lubrication of grease containing a complex of lanthanum dialkyldithiocarbamate and phenanthroline

A complex of lanthanum dialkyldithiocarbamate and phenanthroline was synthesized, and its lubricating and antiwear behaviors as an additive in lithium grease were evaluated using a Timken tester with a SAE52100 steel ring sliding under an A1 2024 block. As a comparison, the wear behavior of a steel-on-steel system under the lubrication of the same grease was also investigated under the same test conditions. The protective film formed on the rubbed surface of aluminum was investigated by both XPS and AES. Results of friction and wear tests indicate that this rare earth complex possess good antiwear ability for aluminum, and its antiwear and friction reduction properties for the aluminum-on-steel system is even superior to that for the steel-on-steel system. The results of AES and XPS analyses illustrate that the prepared La complex as an additive in lithium grease forms a protective film containing lanthanum oxide, aluminum sulphide, and an organic compound containing sulfur and nitrogen on the rubbed surface of aluminum.     

Tribological Behavior of Amorphous and Crystalline Overbased Calcium Sulfonate as Additives in Lithium Complex Grease

The aim of this study was to examine the tribological behavior of amorphous overbased calcium sulfonate (AOBCS) and crystalline overbased calcium sulfonate (COBCS, transformed from the AOBCS) as additives in lithium complex grease. The transformation product of the calcium carbonate polymorph from AOBCS was calcite, as determined by Fourier transform infrared spectroscopy. Tribological properties were evaluated by an oscillating reciprocating friction and wear tester and a four-ball tester. The results showed that the addition of COBCS can dramatically improve both the antiwear performance and the friction-reducing and load-carrying properties of the base grease. However, improvement of the tribological properties of the base grease by AOBCS was highly dependent on the concentrations added and the loads applied. The tribological properties of the base grease were improved more by the addition of COBCS than by the addition of AOBCS. X-ray photoelectron energy spectrometry and thermogravimetric analysis revealed that both AOBCS and COBCS underwent complicated tribochemical reactions in the base grease and that chemically reactive films consisting of CaCO₃, CaO, iron oxide and organic compounds were formed on the worn surfaces. Taken together with the results of the tribo-tests, we suggest that transformation of the calcium carbonate polymorphs was the main factor in improving the tribological properties of lithium complex grease. The transformation of calcium carbonate polymorphs can broaden the application of AOBCS as an extreme pressure/antiwear additive in greases under boundary lubrication conditions.     

S-N型润滑添加剂的合成及其摩擦学性能研究

合成一种新型环境友好型、无灰、非磷极压抗磨剂——含羟基二烷基二硫代氨基甲酸衍生物(DDCSD)。采用红外光谱仪对其结构进行表征,利用热分析仪考察其热稳定性,使用四球试验机及SRV考察其在复合锂基润滑脂中的摩擦学性能,并用扫描电子显微镜及X射线光电子能谱分析摩擦表面形貌及表面化学成分。结果表明,DDCSD具有良好的热稳定性,能有效提高基础脂的抗磨、减摩及极压性能,可作为多功能润滑油脂添加剂ZDDP的替代品。这是由于DDCSD在摩擦过程中发生化学吸附及摩擦化学反应,在金属表面上形成了一层具有抗磨减摩性能的边界润滑膜,从而起到抗磨减摩的作用。     

Technical note: Extreme‐pressure activity assessment of certain nitrogen and sulphur compounds in lithium‐based grease

In this paper we report on the preparation and extreme‐pressure (EP) activity assessment of certain substituted 1‐amino‐3‐aryl‐2,3‐dihydro‐2‐thioxo‐4,6‐(1H,5H)‐pyrimidinediones as additives in a lithium‐based grease. These additives significantly decreased the wear and friction and possessed the ability to increase load‐carrying capacities and weld loads. Two greases were prepared with the above additives, and both greases exhibited lower values of wear‐scar diameter at higher loads and higher values of weld load in the four‐ball test than the lithium‐based grease alone. The prepared greases also passed rust and corrosion, and oxidation tests.     

Physical and chemical mechanisms of influence of Cu-containing additives on grease properties

The mechanisms governing the influence of copper additives (powders, oxides, organic and inorganic salts, complex compounds) on tribological, rheological and basic physical properties of greases with various thickeners (lithium, complex lithium, complex aluminium and polyurea) are discussed. The copper plating effect was found to occur only under EP conditions. The physical and chemical patterns of copper-containing grease additives under antiwear and extreme pressure conditions are discussed together with rational application alternatives in friction couples of equipment and machinery.     

Synthetic aluminium complex grease: A tribological evaluation using a four‐ball test

This paper describes the preparation and performance evaluation of a synthetic aluminium complex grease. The aluminium complex grease was prepared in situ by reacting stearic acid and benzoic acid in the presence of a synthetic base oil, polyalphaolefin. The preparation of the soap (aluminium benzoate stearate hydroxide) was monitored using Fourier transform infrared. Two different extreme‐pressure additives blended with the prepared aluminium complex grease were evaluated for their extreme‐pressure activity in four‐ball and Timken tests. These greases exhibited higher Timken OK loads (60 lb), lower values of wear‐scar diameter at higher loads, and higher values of weld load in the four‐ball test than the aluminium complex grease without additive. The blended greases were also found to pass rust and corrosion, oxidation‐stability, and shear‐stability tests. The topography of the specimens after four‐ball testing was studied with scanning electron microscopy.     

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.