Antiwear/extreme pressure performance of graphite and molybdenum disulphide combinations in lubricating greases

Antony, Jiju; Mittal, Bhavishya; Naithani, K. P.; Misra, Ajay; Bhatnagar, A. K.

doi:10.1016/0043-1648(94)90083-3

Cited by 26 publications

(13 citation statements)

References 7 publications

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“…Typical solid lubricant additives, such as MoS 2 and graphite, have been used in engine oil for many years because of their excellent antiwear capacity and endurance under extreme pressure [3,5,6]. Numerous reports on the tribological behaviors of MoS 2 and graphite have been published [7][8][9][10]. However, as a sustained topic of research and for economic reasons, there is a desire to explore additives that are more efficient and capable of providing better lubrication.…”

Section: Introductionmentioning

confidence: 98%

“…These studies examined the synergistic and antagonistic behaviors in various tribological properties in combinations of surface reactive additives [10,15,16]. Narayan [17] reported that a combination of nanoparticle and microparticle treatments for engines enhances fuel efficiency and engine life, and reduces exhaust emissions; the nanoparticles used in this study were chosen from a class of hard materials (alumina, silica, ceria, titania, diamond, cubic boron nitride, and molybdenum oxide), whereas the microparticles were chosen from a class of layer-structured materials (graphite, hexagonal boron nitride, magnesium silicates, and molybdenum disulfide).…”

Section: Introductionmentioning

confidence: 99%

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Tribological Characteristics of Combined Layered Phosphate and Silicate Additives in Mineral Oil

Chen

Zhang

et al. 2011

Tribol Lett

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A mixture containing a-Zr(HPO 4 ) 2 ÁH 2 O, a small particle layered-phosphate, and a-Na 2 Si 2 O 5 , a microparticle-layered silicate, is investigated for its potential as an additive in mineral oil. A four-ball tester is employed to measure the maximum non-seizure load, wear scar diameter, and friction coefficient of the combined additives. Friction and wear tests indicate that synergistic behavior exists between the two base materials; the load capacity, anti-wear, and friction reducing ability of the base oil are markedly increased when the combined materials are added. More important is the combined materials exhibit considerable advantage over typical lubricant additives, such as MoS 2 and graphite, presenting good application prospects as lubricant additives. The X-ray diffraction, scanning electron microscopy, and energydispersive X-ray spectroscopy results illustrate that the synergistic behavior of the combined material stems from the small a-ZrP particles confined in the valleys of the contacting surfaces that polish the wear surface, as well as the layered a-Na 2 Si 2 O 5 microparticles that effectively fill voids in the wear surface.

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Tribological Characteristics of Combined Layered Phosphate and Silicate Additives in Mineral Oil

Chen

Zhang

et al. 2011

Tribol Lett

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“…Researchers also have reported studies on the friction behavior and extreme pressure behavior of PTFE in lubricating greases (Aswath et al , 2007; Stolarski, 1976; Aswath et al , 2012; Chen, 2010; Stolarski and Olszewski, 1976; Figuo, 2012; Fan et al , 2014; Suresh et al , 2009; Trabelsi et al , 2016; Bagi and Aswath, 2015; Antony et al , 1994; Krawiec, 2011). Recently, Stolarski (1976), Stolarski and Olszewski (1976) studied the frictional mechanism of PTFE grease in journal bearing test rig.…”

Section: Introductionmentioning

confidence: 99%

Sustainable lubrication: low molecular weight PTFE micro-particles as extreme pressure additives for heavy duty grease applications

Gupta

Kumar

Prasad

2021

ILT

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Purpose 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. Design/methodology/approach 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. Findings 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. Originality/value 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.

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“…MoS2 has been used as a solid lubricant as well as an EP additive for greases in addition to other solid lubricants such as graphite, PTFE, and talc. The lamellar structures of the MoS2 and graphite particles are mainly responsible for their load bearing capabilities wherein the layers that are interconnected by weak Van der Waals forces are sheared and deposited onto the interacting surfaces thereby preventing the contact in between asperities and protecting the surface from further seizure, wear, and abrasion [5][6][7][8][9]. ZDDP has been widely used as an anti-wear (AW) additive and as a mild anti-oxidant as well [10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Friction and Wear in MoS2 and ZDDP/F-PTFE Greases under Spectrum Loading Conditions

Bagi

Aswath

2015

Lubricants

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Two different greases formulated using MoS2 and a combination of ZDDP and functionalized PTFE (F-PTFE) were examined under spectrum loading conditions where loads, frequency, and duration of the steps were treated as variables. Combination of ZDDP and F-PTFE were synergistic resulting in a significant reduction in the wear and friction under spectrum loading condition. Decreasing the time step during the ramp up and ramp down cycles resulted in larger wear for the grease containing MoS2 particles in comparison to ZDDP/F-PTFE in grease. The tribofilm formed on the surface was analyzed using various characterization techniques like SEM, EDS, and Stereo Optical Microscopy. Tribofilms from MoS2 additives had extensive amounts of abrasive and adhesive wear and showed the formation of MoS2 on the surface on the other hand the tribofilms from ZDDP/F-PTFE had smaller amounts of severe wear and exhibited patchy tribofilms of Zn-phosphates as well as sulfides of Zn and Fe.

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Antiwear/extreme pressure performance of graphite and molybdenum disulphide combinations in lubricating greases

Cited by 26 publications

References 7 publications

Tribological Characteristics of Combined Layered Phosphate and Silicate Additives in Mineral Oil

Tribological Characteristics of Combined Layered Phosphate and Silicate Additives in Mineral Oil

Sustainable lubrication: low molecular weight PTFE micro-particles as extreme pressure additives for heavy duty grease applications

Mechanism of Friction and Wear in MoS2 and ZDDP/F-PTFE Greases under Spectrum Loading Conditions

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