The
present investigation demonstrates a green and scalable chemical
approach to prepare aminoborate-functionalized reduced graphene oxide
(rGO-AmB) for aqueous lubricants. The chemical, structural, crystalline,
and morphological features of rGO-AmB are probed by XPS, FTIR, Raman,
XRD, and HRTEM measurements. The spectroscopic analyses revealed the
multiple interaction pathways between rGO and AmB. rGO-AmB exhibited
long-term dispersion stability and improved the thermal conductivity
of water by 68%. The thermal conductivity increased with increasing
concentration of rGO-AmB and temperature. rGO-AmB as an additive to
water (0.2%) enhanced the tribological properties of a steel tribopair
under the boundary lubrication regime by the significant reduction
in friction (70%) and wear (68%). The tribo-induced gradual deposition
of an rGO-AmB-based thin film facilitated the interfacial sliding
between the steel tribopair and protected it from the wear. The ultralow
thickness, excellent dispersibility in water, high thermal conductivity,
intrinsic low frictional properties, and good affinity toward the
tribo-interfaces make rGO-AmB a potential candidate for aqueous lubricants.
In the present study, lubricating grease was developed with paraffin oil and 12-lithium hydroxy stearate metal soap as a thickening agent. MoS2 nanosheets were synthesized by hydrothermal method and functionalized with 1-octadecanethiol (i.e., MoS2-ODT). The MoS2 and MoS2-ODT nanosheets were dispersed in the grease with different concentrations to evaluate its tribological performance. Tribological results unveiled that the addition of MoS2 nanosheets in grease appreciably reduced the coefficient of friction and mean wear volume of tribo-interfaces as compared with pure grease. Energy dispersive spectroscopy (EDS) spectrum revealed the deposition of MoS2 on the worn surface and confirmed a thin tribo-film which protects steel tribo-pair against wear.
The present work addresses the use of synergistic blends of two different types of nanomaterials (spherical particles and lamellar sheets) as additives for coconut oil‐based grease formulation to provide the energy‐efficient and sustainable alternative to conventional grease. The spherical SiO2 nanoparticles are separately blended with 2D lamellar sheets of MoS2 and graphene oxide (GO) in variable ratio and probed their synergistic effects for enhancement of physicochemical and lubrication properties. The SiO2 nanoparticles, MoS2, and GO nanosheets are prepared by modified sol–gel, hydrothermal reduction, and Hummer's methods, respectively. The 0.05 wt% nanomaterials blends of MoS2/SiO2 (30:70) and GO/SiO2 (50:50) as optimised doses furnished the maximum reduction in the friction and wear. The combination of rolling friction and low shear properties using the synergistic blend of the spherical nanoparticles (SiO2) and nanosheets (MoS2 and GO) showed significant improvement in tribological properties. The optimised blends of nanoadditives, that is, MoS2/SiO2 and GO/SiO2 conserved the energy by 20% and 19%, respectively. These findings suggest that the use of synergistic blends of variable nanomaterials to vegetable oil‐based lubricants can pave a direction for new generation lubricant formulation, where environmental sustainability and energy conservation are on prime importance.
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