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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.

The purpose of this paper is to formulate heavy-duty lithium complex grease using low molecular weight poly tetra fluoro ethylene (PTFE) micro-particles as extreme pressure (EP) additive manufactured by E-beam scissoring and ultra-high speed grinding process of pre-sintered PTFE scrap.

Lithium complex grease is formulated with PTFE micro-particles, and optimum treat rate was studied by standard bench tests by ASTM D 2266 and IP-239 for tribological properties and compared with commercially available Molybdenum Di sulphide (Moly)-based lithium complex grease. The performance of the grease was further evaluated by a cyclic load test at varying speeds and loads to simulate the operational field conditions.

The lithium complex PTFE grease was manufactured using PTFE micro-particles as EP additive. The PTFE micro-particles dispersed in the lithium complex grease significantly improve the anti-wear performance and load bearing properties. Further, when the product was tested under a cyclic load conditions on standard tribological bench test against commercially available Moly lithium complex grease, shows stable anti-wear properties and reduced coefficient of friction.

The low molecular weight PTFE micro-particles, manufactured in the in-house electron beam (E-beam) and ultra-high speed micronizer facility from a pre-sintered PTFE scrap has been used as EP additive for grease applications for the first time. The results on the cyclic load tests indicate significant performance improvement in retaining the anti-wear and friction properties. Thus, value addition is done in formulating superior performance grease and evaluating under cyclic load conditions similar to field operating conditions and also in creating value added additives by converting the pre-sintered PTFE scarp which is environmental hazard due to poor biodegradability, creating a cyclic economy and a sustainable concept.

This paper aims to improve the tribological properties of lithium complex greases using nanoparticles to investigate the tribological behavior of single additives (nano-TiO₂ or nano-CeO₂) and composite additives (nano-TiO₂–CeO₂) in lithium complex greases and to analyze the mechanism of their influence using a variety of characterization tools.

The morphology and microstructure of the nanoparticles were characterized by scanning electron microscopy and an X-ray diffractometer. The tribological properties of different nanoparticles, as well as compounded nanoparticles as greases, were evaluated. Average friction coefficients and wear diameters were analyzed. Scanning electron microscopy and three-dimensional topography were used to analyze the surface topography of worn steel balls. The elements present on the worn steel balls’ surface were analyzed using energy-dispersive spectroscopy and X-ray photoelectron spectroscopy.

The results showed that the coefficient of friction (COF) of grease with all three nanoparticles added was low. The grease-containing composite nanoparticles exhibited a lower COF and superior anti-wear properties. The sample displayed its optimal tribological performance when the ratio of TiO₂ to CeO₂ was 6:4, resulting in a 30.5% reduction in the COF and a 29.2% decrease in wear spot diameter compared to the original grease. Additionally, the roughness of the worn spot surface and the maximum depth of the wear mark were significantly reduced.

The main innovation of this study is the first mixing of nano-TiO₂ and nano-CeO₂ with different sizes and properties as compound lithium grease additives to significantly enhance the anti-wear and friction reduction properties of this grease. The results of friction experiments with a single additive are used as a basis to explore the synergistic lubrication mechanism of the compounded nanoparticles. This innovative approach provides a new reference and direction for future research and development of grease additives.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-09-2023-0291/

The purpose of this paper is to report on the tribological properties of beef tallow grease and improvements therein through modification with special processing, polymeric compounds and additives.

Pure original beef tallow grease was used as a biological lubricating grease reference material for the tribological research. Beef tallow was modified and synthesized by adding special biological anti-oxidant additives, LZ anti-wear additives, waste polyethylene terephthalate (PET) polymer compounds and thermally processed graphite.

Rheometric measurements indicate that the beef tallow grease modification technology used in this study enables control of the synthesis process to produce lubricants with the required microstructure. Investigation results of the tribological properties of differently modified greases show that beef tallow synthesized with polymer additives efficiently operates together with anti-wear additives to reduce friction and wear. The grease compound with thermally processed graphite has good tribological properties at 300 N load levels. The critical load level of lubricating greases could be significantly increased through the use of anti-wear additives and thermally processed graphite.

Investigation results of the tribological properties of differently modified beef tallow greases show that beef tallow synthesized with polymer additives efficiently operates together with anti-wear additives to reduce friction and wear. The critical load level of lubricating beef tallow greases could be significantly increased using anti-wear additives and thermally processed graphite.

The purpose of this paper is to improve the properties of metal nanoparticles which are easy to agglomerate and hard to disperse evenly, thus limiting the application of metal nanoparticles in grease. A novel technology was proposed for modifying metal oxide to improve the dispersibility of nanoparticles.

SA-TiO2 nanoparticles were synthesized using an in-situ esterification method followed by surface modification with stearic acid. The microstructure of the nanoparticles was characterized by scanning electron microscope, transmission electron microscope and Fourier transform infrared spectroscopy and their thermal stability was evaluated by thermogravimetric analyzer. The tribological properties of the SA-TiO2 nanoparticles as additives in lithium grease were evaluated with a four-ball tester and TE77 reciprocating friction tester. The worn surfaces of the steel balls were investigated by EDS and XPS.

The prepared nanoparticles can be well dispersed in the lithium grease and possess much better tribological properties compared to traditional nanoparticles. The results indicated that the excellent tribological performance of SA-TiO2 was attributed to the chemical reaction film composing of Fe2O3, iron oxide and other organic compounds.

This paper provides a method to prevent the agglomeration of nano-TiO2 by surface modification with stearic acid. And the prepared nanoparticles can effectively improve the tribology performance of lithium grease.

The purpose of this paper is to synthesize a kind of core-shell Ag@polyaniline (Ag@PAN) as a lubricant additive to improve the friction reduction and anti-wear abilities of lithium-based complex grease.

The core-shell Ag@PAN was prepared by a simple method and was introduced into the lithium-based complex grease. The typical properties of Ag@PAN were investigated by scanning electron microscopy (SEM), Fourier transforms infrared spectrometer and thermal gravimetric analyzer. The tribological properties were evaluated under different conditions. After the tribological test, the worn surface was analyzed by SEM and X-ray photoelectron spectroscopy to probe the lubrication mechanisms.

The prepared Ag@PAN could greatly improve the friction reduction and wear resistance of the friction pair under different conditions. The preferable tribological performances were mainly attributed to the synergism of various lubrication mechanisms including “mending effect,” “rolling effect” and lubricating protective film, and so on.

This study synthesizes a new kind of core-shell Ag@PAN as a lubricant additive, and it possesses preferable friction reduction and anti-wear abilities.

The mixture of attapulgite and bentonite was used as a thickener, and polyalphaolefin was used as the base oil to prepare the new lubricating grease. Some solid particles such as Polytetrafluoroethene (PTFE), MoS2, nano-calcium carbonate and graphite were added in the new lubricating grease as anti-wear additives to investigate the tribological sensitivity.

The new lubricating grease was evaluated by optimol-SRV reciprocating friction and wear tester, and the wear volumes were determined using a MicroXAM-3D. At the same time, the dropping point and the cone penetration were investigated and analyzed. The tribological properties of the new lubricating grease and the sensitivity of some solid lubricating additives to the new lubricating base grease were investigated; pure organic-bentonite and pure organic-attapulgite base grease were used as contrast.

The new lubricating grease based on the surface-modified bentonite/attapulgite clay base grease was synthesized with a relatively high dropping point, and the mass ratio is 25/75 bentonite/attapulgite clay base grease, having a better tribological performance. MoS2 was used as an anti-wear additive that has good tribological sensitivity to the new lubricating base grease.

The main innovative thought of this work lies in the mixture of attapulgite and bentonite used as thickener. A relevant report is not available at present.

This study aims to reduce the harm of industrial lubricants to consumers. Composite aluminum-based grease (CAG) was prepared, and medical-grade montmorillonite (M-MMT) was used to improve the antiwear performance of the prepared grease.

The influence of the additive (M-MMT) on the tribological performance is mainly investigated using a ball-disc wear tester, and the wear scar surface about the disc was characterized by white light interferometer and electrochemical workstation. Moreover, the cell viability test was used to evaluate the safety of the grease.

The results indicated that for the grease containing 1.5% M-MMT, the average coefficient of friction was reduced by about 46% compared with the CAG, the wear volume of the disc reduced by about 74%. Moreover, CAG and 1.5% M-MMT-containing CAG were proved safety by means of the cell viability test.

The integral properties of CAG can be improved with the medical-grade materials as the additives, while ensuring the safety.

The purpose of this study is to reduce the use of Zinc dialkyl dithiophosphates (ZDDP) and improve the frictional properties and thermal oxidation stability of Perfluoropolyether (PFPE) grease by adding antioxidant additives. The addition of antioxidants can reduce the consumption of ZDDP as an antioxidant, thus improving the anti-wear efficiency of ZDDP and reducing the excess phosphorus element in the grease.

In this study, an antioxidant with good comprehensive performance was selected from several antioxidants by tribological tests and high-temperature tests. Then, the effect of its combination additive with ZDDP on PFPE grease was investigated. The anti-wear property, anti-friction property, thermal oxidation stability and extreme pressure property of greases containing different proportions of ZDDP and antioxidant were tested by four-ball tester and synchronous thermal analyzer (STA). The effects of additives on properties of grease were analyzed by SEM, EDS, LSCM, XPS and FT-IR.

The research shows that 2,6-Di-tert-butyl-4-methylphenol (BHT) can be used as an antioxidant in combined additives to reduce the antioxidant reactions of ZDDP, thus improving the anti-wear efficiency of ZDDP and further enhancing the anti-wear performance of the grease. Moreover, BHT and ZDDP have a synergistic effect on the high temperature performance of the PFPE grease due to their different antioxidant mechanisms.

In this paper, the problems related to PFPE grease are studied, which has a certain guiding effect on the industrial application of fluorine grease and the related formulation design.

In this paper, the properties of PFPE grease under different lubricating condition were studied. The synergistic lubrication effect of antioxidant and ZDDP are discussed. It provides experimental and theoretical support for reducing the content of ZDDP and improving the performance of additives.

This paper aims to develop a stable gel-type lubricant emulating commercial conditions. This encompassed rheological and tribological assessments, alongside field trials on the Medellín tram system.

The gel-type lubricant with graphite and aluminum powder is synthesized. Rheological tests, viscosity measurements and linear viscoelastic regime assessments are conducted. Subsequently, tribological analyses encompassing four-ball and twin disc methods are executed. Finally, real-world testing is performed on the Medellín tram system.

An achieved lubricant met the stipulated criteria, yielding innovative insights into the interaction of graphite and aluminum powder additives under varying tests.

Novel findings are unveiled regarding the interaction of graphite and aluminum powder additives in tribological, rheological and real-world trials. In addition, the wear behavior of polymers is observed, along with the potential utilization of such additives in tramway systems.