The purpose of this study is to prepare graphene/FeOCl (G/FeOCl) heterojunctions via a microwave-pyrolysis approach and probe into the synergistic lubrication of G with FeOCl in liquid paraffin (LP). The morphology and chemical composition of specimens were analysed by utilizing scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) techniques. The tribological property of G/FeOCl was determined, and the interaction between the G/FeOCl heterojunction and friction pair was carried out through simulation calculations. The results indicated that neither G nor FeOCl significantly improved the lubrication performance of LP. However, together with FeOCl, G as lubrication additives greatly improved the lubrication performance of LP. Under the load of 1.648 GPa, the mean friction coefficient and wear scar diameter of LP containing 0.20 wt% G/FeOCl were 66.1% and 44.7% inferior to those of pure LP, respectively. Scanning electron microscopy (SEM) and elemental mapping analyses of worn scars revealed the formation of G/FeOCl layer tribofilms that prevent direct contact between metals. In addition, the high interfacial energy between graphene and FeOCl calculated based on first-principles density functional theory (DFT) further confirmed that graphene and FeOCl simultaneously form friction films with wear resistance and wear reduction effect at the friction interface, which is consistent with the experimental results. This study, therefore, provides a pathway for low-friction lubricants by deploying G/FeOCl two-dimensional material systems.

A novel carbon sphere (CS)@metallographic molybdenum disulfide (1 T-MoS2) hybrid was prepared by a straightforward one-step hydrothermal method and its synergistic effect on the tribology of polyethylene glycol 200 (PEG200) was reported. Systematical characterizations exhibited 1 T-MoS2 sheets were evenly anchored on the CS surface. Tribological results showed the friction coefficient of pure PEG200 oil decreased by 43% with adding 0.3125 wt% CS@ 1 T-MoS2. Optical images showed the diameters of wear marks were significantly reduced from 1860 mu m for neat base oil to 880 mu m for CS@ 1 T-MoS2. It was believed that the synergy between CS and 1 T-MoS2 played the crucial role in the friction reducing and anti-wear. Therefore, this work provides a facile approach to preparing lubricating additives by decorating 1 T-MoS2 on CS.

In our research described in this paper 1T Phase Molybdenum Disulfide/Polyethylene Glycol (200) (1T-MoS2/PEG) was studied as a lubricant for steel-steel contact with the goal of minimizing or eliminating galling. The morphology and structures of 1T-MoS2 were analyzed by various techniques, such as scanning electron microscopy (SEM), X-ray diffraction spectroscopy (XRD), and X-ray photoelectron spectroscopy (XPS). In addition, the friction performance of oleic acid (OA) modified 1T-MoS2 as a lubricants additive for PEG was investigated. The results of the friction test indicated that the average friction coefficient and wear scar diameter of PEG containing 0.1875 wt% 1T-MoS2 were 14.30% and 46.90% less than those of pure PEG, respectively. However, those of 0.1875 wt% 1T-MoS2/PEG modified by OA as lubrication additives were 47.83% and 56.79% lower than those of pure PEG. 1T-MoS2 nanoparticles can not only fill the inherent grooves on the surface of the steel ball, but also form a friction lowering film on the friction interface, thus reducing friction and wear, which was seen from the results of scanning electron microscopy (SEM) and element mapping of the wear scar. This study, most importantly, provides a foundation for the use of 1T-MoS2/PEG and OA/1T-MoS2/PEG as effective lubricants to reduce the friction problems in the mechanical industry.