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The adverse effects of temperature on the lubricating properties of nano magnetorheological grease are reduced by applying of a magnetic field.

Nano magnetorheological grease was prepared via a thermal water bath with stirring. The lubricating properties of the grease were investigated at different temperatures. Then the lubricity of the prepared nano magnetorheological grease was investigated under the effect of thermomagnetic coupling.

As the temperature rises, the coefficient of friction of grease lubrication gradually increases, surface wear gradually increases and lubrication performance gradually decreases. Compared with grease, magnetorheological grease has a decreased coefficient of friction and enhanced lubrication effect under the action of a magnetic field at different temperatures.

A lubrication method using a magnetic field to reduce the effect of temperature is established, thereby providing new ideas for lubrication design under a wide range of temperature conditions.

A joint paper by G. L. HARTING, of Exxon Research and Engineering Company and T. C. WILSON, Exxon Company of USA present a joint paper at the National Lubricating Grease Institute annual general meeting.

The purpose of this paper is to study, analyze and present the lubricating mechanism and tribological properties of two types of oil‐based titanium complex grease containing Polytetrafluoroethylene (PTFE).

Two types of oil‐based sebacic acid/stearic acid titanium complex greases containing PTFE additive were synthesized using 3 L reaction vessel, and the base oils including neopentyl polyol ester and mixed oil of 650SN and neopentyl polyol (1:1.8). Friction‐reduction, antiwear, and load‐carrying properties of greases were evaluated using a four‐ball tester, and their dropping point and penetration were characterized using relevant ASTM standards. Morphologies of wear scar and chemical states of typical elements on worn surfaces were characterized by means of scanning electron microscope and X‐ray photoelectron spectroscopy, respectively.

Tribological results show that titanium complex grease containing PTFE had better friction‐reduction and antiwear properties than base grease. However, PTFE could not improve the load‐carrying capacity of base grease. Moreover, a synergistic effect between deposited film and adsorptive film contributes to good tribological properties of titanium complex grease.

Such a very useful lubricating material could be used in industrial applications including steel plants, power plants, packaging, and fertilizer industries.

The lubricating mechanism of titanium complex grease containing PTFE was proposed by tribochemical analysis of worn surfaces. The mechanism should become the direction of the theoretical and applied research of grease in the future.

Nanoparticles as the grease additives play an important role in anti-wear and friction-reducing property during the mechanical operation. To improve the lubrication action of grease, the tribological behavior of lithium-based greases with single (nanometer Al₂O₃ or nanometer ZnO) and composite additives (Al₂O₃–ZnO nanoparticles) were investigated in this paper.

The morphology and microstructure of nanoparticles were characterized by means of transmission electron microscope and X-ray diffraction. Tribological properties of different nanoparticles as additives in lithium-based greases were evaluated using a universal friction and wear testing machine. In addition, the friction coefficient (COF) and wear scar diameter were analyzed. The surface morphology and element overlay of the worn steel surface were analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), respectively.

The results show that the greases with nanometer Al₂O₃ or nanometer ZnO and the composite nanoparticles additives both exhibit lower COFs and wear scar diameters than those of base grease. And the grease with Al₂O₃–ZnO composite nanoparticles possesses much lower COF and shows much better wear resistance than greases with single additives. When the additives contents are 0.4 Wt.% Al₂O₃ and 0.6 Wt.% ZnO, the composite nanoparticles-based grease exhibits the lowest mean COF (0.04) and wear scar diameter (0.65 mm), which is about 160% and 28% lower than those of base grease, respectively.

The main innovative thought of this work lies in dealing with the grease using single or composite nanoparticles. And through a serial contrast experiments, the anti-wear and friction-reducing property with different nanoparticles additives in lithium grease are evaluated.

The purpose of this paper is to prepare a novel nano magnetic grease with favorable lubricating performance; to contrast the tribology performance of the magnetic grease with the original grease, and to find the lubricating mechanism of the magnetic grease.

The nano Fe₃O₄ magnetic fluids are added into the general urea grease to synthesize the nano magnetic grease. Tribology performance tests of the magnetic grease and the original grease are contrasted on a MMW‐1 four‐ball tester. Based on three kinds of effects caused by the nano magnetic fluids, the lubricating mechanism of the magnetic grease is discussed.

Nano magnetic grease with favorable lubricating performance can be synthesized by adding the nano Fe₃O₄ magnetic fluids into the general urea grease. The nano magnetic grease has better lubricating performance and more steady bearing capability than the original grease, and is especially available for the lubricating of equipment with high speed and heavy load. The performance improvement of the magnetic grease is owing to the interactions of three kinds of effects as follows: the viscosity increasing effect, the micro‐rolling effect, and the friction weakening effect, which are all caused by the nano magnetic fluids added into the grease.

The paper documents that the nano Fe₃O₄ magnetic fluids added into the urea grease to synthesize a novel nano magnetic grease has been proved to have quite favorable lubricating performance by the tribology experiments, and the lubricating mechanism of the magnetic grease is also discussed.

The purposes of this paper are to prepare the carbon nanotube (CNT) grease, to contrast the tribology properties of the CNT grease with the original grease and to find the lubricating mechanism of the CNT grease.

The CNTs (single-wall and multi-wall) are added into the polyalphaolefin oils (DURASYN_166) to form stable and homogeneous CNT grease with potential heat transfer, conductive and lubricative properties. The friction of this new type of CNT grease was determined by wear experiments under three conditions: dry friction, with the base oil grease and with the CNT grease.

The research is about the tribological properties of CNT greases; it shows better lubricating performance and wear resistance than the base oil grease. The performance improvement of CNT grease is owing to the unique hexagonal structure and the high thermal conductivity of CNTs.

The paper documents that CNTs can obviously improve the lubricating effect of grease, and the lubricating mechanism of the CNT grease is also discussed.

The paper aims to study comparatively the fretting behavior in gross slip regime of fretting both under grease lubrication and dry condition and to investigate the mechanism of palliation of fretting wear with grease lubrication.

All fretting tests were carried out on high‐temperature fretting devices with standard GCr15 bearing steel ball against 45 steel flat and against GCr15 bearing steel flat contact pairs. The wear scar was examined by optical microscope, surface profiler and the confocal laser scanning microscope as well as energy dispersive X‐ray spectroscopy.

Compared with dry condition, the coefficient of friction and wear are decreased drastically and wear occurs mainly at the early stage of fretting under grease lubrication. The palliation effect of grease lubrication is closely associated with the amount of oil separated from the grease, the low‐oxidation corrosion and high‐hardness white layer. However, the bubbles which expelled from the contact edges have little influence on fretting wear.

The tested greases do not contain any additives for preventing possible misinterpretations of the results, but it is necessary to investigate the influence of different lubricant additives added to grease on friction and wear at different fretting conditions.

The research reveals that the palliation effect of grease lubrication on fretting wear is related closely to the amount of oil separated from the grease. The bigger penetration and more susceptible greases, which are easier to separate from the base oil, should be taken into account for palliation of fretting wear.

The presented results help to understand the palliation mechanism of grease lubrication and could be useful for designers of engineering assembly for which fretting wear is an issue.

Modern technology is giving some new requirements for the lubricating grease, and there are also some weaknesses for the existing diurea grease, especially its lower anti‐shear stability. This paper aims to address this issue. In this work, in order to meet the new industrial requirements and improve the weaknesses of diurea grease, the tetraurea grease has been synthesized.

Tetraurea grease was synthesized by multi‐steps, characterized by FT‐IR, NMR, ESI‐MS. The properties were evaluated by the ASTM method, such as dropping point, penetration, oil separation and shear stability, as well as four‐ball machine experiment.

The result shows that tetraurea grease is indeed synthesized successfully and it has a better performance than the existing diurea grease, the main properties of it have been increased, such as high‐temperature performance, structural stability, anti‐shear stability and extreme pressure performance.

This enriches the kinds of polyurea grease. Enhanced lubricating grease performance would have better industrial prospects, and a larger application field than existing diurea grease.

The aim of this paper was to investigate the possibility of reusing frying oil, obtained during thermal treatment of food in fast-food restaurants for production of plastic greases.

In accordance with the proposed research concept, the used frying oil was to be the base oil of biodegradable plastic greases thickened with calcium 12-hydroxystearate and lithium 12-hydroxystearate. These studies included the determination of the effect of variable amounts of used oil component in the base oil on the properties of the resultant plastic greases.

It was found that the optimum amount of the component in the base oil is 10-15 per cent. Calcium and lithium greases prepared in such a way possess a quality to that of greases prepared with fresh rapeseed oil.

Higher concentrations of used frying oil in the base oil adversely affect the degree of thickening, thixotropic properties and dropping point of the grease, as well as, creating technological problems.

The investigations, beside their research goals have also a practical character – recycling waste material in place of its present method of disposal.

One of the least expensive material, and most commonly used to produce biodegradable lubricants are vegetable oils. In recent years, besides introducing biodegradable lubricating oils, increasing interest is observed in the use of plastic greases of high biodegradability. Now, it is possible to obtain such greases with additive of used frying oils. Biodegradable greases are used as lubrication of open gear, food production equipment, central lubrication system in cars and railway engineering.

Different percentages of calcium and lithium stearate greases were prepared using dimethyldi‐2‐ethyl‐1‐hexoxysilane and dimethyldi‐1‐dodecoxysilane as base oils by open kettle process and then were characterised. The performance of different greases has been studied by determining their apparent viscosity, consistency, dropping point, oxidation stability, anti‐wear characteristics and moisture resistance. These properties are compared with those of tetra‐2‐ethyl‐1‐hexoxysilane and polydimethylsiloxane greases. Lithium stearate thickened greases exhibit better lubrication and heat resistance properties than those of calcium stearate and can be used for extreme temperature conditions in the range between –70°C and +220°C for automotive ball joints, aircrafts, antifriction, ball bearings etc.