Performance properties of lithium greases with PTFE particles as additive: Controlling parameter- size or shape?

Kumar, Nikhil; Saini, Vinay; Bijwe, Jayashree

doi:10.1016/j.triboint.2020.106302

Cited by 44 publications

(27 citation statements)

References 24 publications

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“…The size of SLs also impacts the rheological and tribological properties of greases [13,26,27]. Niu and Qu [13] studied the effect of different sized graphite nanosheet of (Día 2, 3.5, 6 μm) in titanium complex grease and reported that the smaller-sized nanosheet of 2 μm benefitted most by showing 14% improvement in AF and 2% improvement in AW performance compared to the base grease.…”

Section: Introductionmentioning

confidence: 99%

Tribological Investigations of Nano and Micro-sized Graphite Particles as an Additive in Lithium-Based Grease

2020

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Graphite is a well-known solid lubricant (SL) additive widely used both as a standalone SL and also as additive in lubricating oils, greases, composites, etc. Size of the additive particles especially nano-particles (NPs) is a major attribute to the performance properties of a composite, oil, grease, etc. This paper highlights the influence of graphite particles of four sizes viz. 50 nm, 450 nm, 4 microns and 10 microns incorporated in the grease in identical amount (4 wt. %) on the anti-friction (AF), anti-wear (AW) and extreme-pressure (EP) performance. The results indicated that all sizes proved beneficial for all the selected properties. Higher the size of particles, lower was the improvement in performance. The particles were most effective as anti-friction additive (AFA) followed by anti-wear additive (AWA) and then extreme-pressure additive (EPA). The NPs exhibited highest improvement as AFA (57%), AWA (41%) and EPA (25%). Raman Spectroscopy proved the formation of exfoliated graphitic layer on the worn surface of balls. Furthermore, SEM micrograph with elemental mapping and XPS spectroscopy analysis proved supportive in comprehending the mechanisms responsible for improved tribo-performance.

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Section: Introductionmentioning

confidence: 99%

Tribological Investigations of Nano and Micro-sized Graphite Particles as an Additive in Lithium-Based Grease

2020

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“…Apart from pure carbon, polymer nanoparticles are also investigated as lubricant additives [96]. Kumar et al [69] synthesized lithium greases with PTFE nanoparticles as additives and revealed the enhanced friction reduction and wear resistance properties with the addition of PTFE nanoparticles. Moreover, the study implied that size and shape were two factors that affect the lubricating performance.…”

Section: Nanocarbon-based Lubricant Additivesmentioning

confidence: 99%

“…They indicated the formation of tribofilm containing CaCO 3 , CaO, Fe 2 O 3 , and some organic compounds. Kumar et al [69] found that the excellent tribological properties of PTFE were attributed to the formation of tribofilm of FeF2 on rubbing surfaces.…”

Section: Formation Of Tribofilmmentioning

confidence: 99%

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Nanolubricant additives: A review

et al. 2020

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Using nanoadditives in lubricants is one of the most effective ways to control friction and wear, which is of great significance for energy conservation, emission reduction, and environmental protection. With the scientific and technological development, great advances have been made in nanolubricant additives in the scientific research and industrial applications. This review summarizes the categories of nanolubricant additives and illustrates the tribological properties of these additives. Based on the component elements of nanomaterials, nanolubricant additives can be divided into three types: nanometal-based, nanocarbon-based, and nanocomposite-based additives. The dispersion stabilities of additives in lubricants are also discussed in the review systematically. Various affecting factors and effective dispersion methods have been investigated in detail. Moreover, the review summarizes the lubrication mechanisms of nanolubricant additives including tribofilm formation, micro-bearing effect, self-repair performance, and synergistic effect. In addition, the challenges and prospects of nanolubricant additives are proposed, which guides the design and synthesis of novel additives with significant lubrication and antiwear properties in the future.

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“…Furthermore, under the reciprocating friction motion, Mn 3 O 4 #G nanocomposites adhered to the surface of the wear scar area to form graphene islands. On the one hand, the presence of graphene islands can improve the strength of the tribofilm; this will increase the load-carrying capacity of the tribofilm [56,57]. On the other hand, interlaminar shearing occurs between graphene sheets, which will reduce the COF and improve the anti-friction properties.…”

Section: Mechanism Of Lubricationmentioning

confidence: 99%

Improvement of the lubrication properties of grease with Mn3O4/graphene (Mn3O4#G) nanocomposite additive

et al. 2020

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Although grease can effectively lubricate machines, lubrication failure may occur under high speed and heavy load conditions. In this study, Mn3O4/graphene nanocomposites (Mn3O4#G) were synthetized using a hydrothermal method as lubricant additives. The lubrication properties of compound grease with Mn3O4#G nanocomposite additive under heavy contact loads of 600–900 N (3.95–4.59 GPa) were investigated. First, the nanocomposites were dispersed into L-XBCEA 0 lithium grease via successive electromagnetic stirring, ultrasound vibration, and three-roll milling. Compound grease with additives of commercial graphene (Com#G) was also investigated for comparison. Tribological test results revealed that the trace amounts of Mn3O4#G (as low as 0.02 wt%) could reduce the coefficient of friction (COF) of grease significantly. When the concentration of Mn3O4#G was 0.1 wt%, the COF and wear depth were 43.5% and 86.1%, lower than those of pure graphene, respectively. In addition, under the effect of friction, the microstructure of graphene in Mn3O4#G nanocomposites tends to be ordered and normalized. Furthermore, most of the Mn3O4 transformed into Mn2O3 owing to the high temperature generated from friction. Using the Ar gas cluster ion beam sputtering method, the thickness of the tribofilm was estimated to be 25–34 nm. Finally, the improvement of the lubrication properties was attributed to the synergistic effect of the adsorbed tribofilm, i.e., the graphene island effect and the filling effect of Mn3O4#G.

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Performance properties of lithium greases with PTFE particles as additive: Controlling parameter- size or shape?

Cited by 44 publications

References 24 publications

Tribological Investigations of Nano and Micro-sized Graphite Particles as an Additive in Lithium-Based Grease

Tribological Investigations of Nano and Micro-sized Graphite Particles as an Additive in Lithium-Based Grease

Nanolubricant additives: A review

Improvement of the lubrication properties of grease with Mn3O4/graphene (Mn3O4#G) nanocomposite additive

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