Synergistic lubricating effect of graphene/ionic liquid composite material used as an additive

We prepared a graphene/ionic liquid(G/IL)composite material by the hybridization of G and an IL for use as a lubricating oil additive.The friction coefficient and wear volume of a base oil containing 0.04 wt%of the G/IL composite was reduced by 45%and 90%,respectively.Furthermore,the base oil containing the G/IL composite exhibited better lubricating properties than the base oil containing G,IL,or a mixture of IL and G at the same mass fraction.A synergistic lubrication mechanism was also revealed.The G/IL composite was adsorbed and deposited on the wear surface,forming a more ordered protective film and a unique tribochemical reaction film during rubbing.Therefore,the G/IL composite exhibited the synergistic lubricating effects of G and IL,which significantly improved the lubricating performance of the base oil.This study also suggested a way to limit the out-of-plane puckering of G at the macroscale.

The Effect and Mechanism of Nano-Cu Lubricating Additives on the Electroless Deposited Ni-W-P Coating

The coating and deposition process with excellent anti wear and suitable for industrial application were developed, and the optimum bath composition and process were obtained by studying the influence of the bath composition, temperature and pH value on the deposition rate and the plating solution stability. Moreover, the tribological properties of nano-Cu lubricating additives and electroless deposited Ni-W-P coating as well as their synergistic effect are researched using ring-block abrasion testing machine and energy dispersive spectrometer. Research results show that Ni-W-P alloy coating and nano-Cu lubricating additive have excellent synergistic effect, e g, the wear resistance of Ni-W-P alloy coating （with heat treatment and the oil with nano-Cu additives） has increased hundreds times than 45 steel as the metal substrate with the basic oil, and zero wear is achieved, which breaks through the bottleneck of previous separate research of the above-mentioned two aspects.

Influence of Silver Contents on the Tribological Properties of Ni-Based Self-Lubricating Coatings by Atmospheric Plasma Spraying

The NiCrAlY-Mo-Ag composite coatings were prepared by atmospheric plasma spraying. The tribological properties of the composite coatings were investigated from 25 to 900 ℃ in details. The tribo-layer formed on the worn surface of the composite coatings and influenced the tribological properties at different temperatures. The addition of silver could effectively decrease the friction coefficient and wear rate of the coatings at the wide range of temperature. The rubbing process could form the nickel molybdate and promote the formation of silver molybdate within the worn surfaces at high temperature. The synergistic lubricating effects of nickel molybdate and silver molybdate are attributed to the improvement of the tribological properties of coatings at high temperature.

Construction of ternary PEG200-based DESs lubrication systems via tailoring tribo-chemistry

Designing novel lubricants with easily customized structures,devisable compositions,and simple and economic synthesis over traditional lubricants is critical to fulfilling complex applications,prolonging machine lifetime,and saving energy.Deep eutectic solvents(DESs),which show tunable composition,adjustable structure,easy fabrication,and environmental friendliness,are promising candidates for variable and complicated lubricants applications.To promote the use of DESs as lubricants,a series of PEG200-based DESs with active heteroatoms were fabricated to tailor the tribological performance via tribo-chemistry.Thereinto,PEG200/boric acid(BA)DES shows optimal lubrication performance by forming tribo-chemical reaction film composited of B2O3,iron oxides,and FeOOH,and PEG200/thiourea(TU)DES displays abrasive wear-reducing property by producing FeS tribo-chemical film.Given the excellent abrasive wear-resistance of PEG200/TU DES and friction reduction of PEG200/BA DES,ternary PEG200/BA/TU DESs,composited of PEG200/TU DES and PEG200/BA DES,are first exploited.The ternary DESs possess superior wettability and thermal stability,which render them potential lubricants.Tribological tests of the ternary DESs demonstrate that synergistic lubrication is achieved by forming a transfer film consisting of FexBy,BN,B2O3,and FeS.Wherein FexBy,BN,and B2O3 increase load bearing of the film,and FeS mitigates severe abrasive wear.The proposed design philosophy of novel DESs as lubricants opens up a unique realm that is unattainable by traditional DESs lubrication mechanisms and provides a platform to design next-generation DESs lubrication systems.

Improvement of the lubrication properties of grease with Mn_(3)O_(4)/graphene (Mn_(3)O_(4)#G) nanocomposite additive

Although grease can effectively lubricate machines,lubrication failure may occur under high speed and heavy load conditions.In this study,Mn_(3)O_(4)/graphene nanocomposites(Mn_(3)O_(4)#G)were synthetized using a hydrothermal method as lubricant additives.The lubrication properties of compound grease with Mn_(3)O_(4)#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 Mn_(3)O_(4)#G(as low as 0.02 wt%)could reduce the coefficient of friction(COF)of grease significantly.When the concentration of Mn_(3)O_(4)#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 Mn_(3)O_(4)#G nanocomposites tends to be ordered and normalized.Furthermore,most of the Mn_(3)O_(4) transformed into Mn_(2)O_(3) 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 Mn_(3)O_(4)#G.