Tribological performances of hexagonal boron nitride nanosheets via surface modification with silane coupling agent

Hexagonal boron nitride (h-BN) is a promising lubricant additive for decreasing wear and friction. However, the poor dispersion stability and bulky size of h-BN restricted its lubrication application. In this paper, bulk h-BN was exfoliated into h-BN nanosheets (h-BNNSs), and then the self-made h-BNNSs were chemically modified with silane coupling agent via a facile and scalable reaction method. The morphology and structure of surface-functionalized h-BNNSs (m-BNNSs) were certified using a series of characterizations. Results revealed that h-BNNSs could be chemically well capped by surface modifier and the lipophilic groups were covalently attached to h-BNNSs surfaces. The m-BNNSs composite possessed long-term dispersion in liquid paraffin (LP). At the optimal adding content of 0.6 wt%, coefficient of friction and wear volume of m-BNNSs composite were decreased by about 31.9% and 53.8% compared with those of LP, respectively. Therefore, m-BNNSs composite as a lubricating oil additive has high research value and good prospects of lubrication applications.

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.

Effect of different preparation processes on tribological properties of graphene

Two processes of physical liquid phase stripping and chemical redox reduction were used to obtain graphene sheets. Fourier transform infrared spectroscopy and Raman spectroscopy test methods were used to compare and analyze the structure and disorder of graphene. The obtained graphene was modified with oleic acid and stearic acid. The dispersion stability of graphene as a lubricating oil additive was investigated by natural sedimentation method and spectrophotometry. The tribological properties of the graphene dispersion were investigated by a four-ball friction and wear tester. Scanning electron microscope and energy spectrometer were used to characterize and analyze the microscopic morphology and composition of the worn surface. The results showed that the modified liquid phase stripping graphene demonstrated the best anti-wear and anti-friction properties of the dispersion, the lowest friction coefficient is 0.0677, and the average friction coefficient is reduced by about 26%.

Mechanical synthesis of chemically bonded phosphorus–graphene hybrid as high-temperature lubricating oil additive

Red phosphorus (P) was covalently attached to graphene nanosheets (Gr) using high-energy ball-milling under a nitrogen atmosphere.

Anti-wear Mechanism Analysis of Nano-CaCO3 Additives

In this paper, the wear test was carried on with cylinder piston by the wear test device, receiving the results of the piston ring wear and abrasive characteristics by monitoring the wear process, the thesis analysis and put forward the nano-CaCO3 lubricating oil additive anti wear mechanism by the ferrography analysis technology, and provide the technical reference for the relevant measures to reduce wear and the friction, and provide reference value for further study on the related theories of reducing wear and reducing friction.