In-situ intercalated pyrolytic graphene/serpentine hybrid as an efficient lubricant additive in paraffin oil

In this study, a novel lubricant additive hybridizing pyrolytic graphene and serpentine was reported for the first time to enhance the tribological performance of paraffin oil. The in situ produced pyrolytic graphene from pyrolysis of citric acid was observed to be intercalated into the interlayer of serpentine sheets. The structure, morphology and chemical composition of the composite lubricant additives were characterized by scanning electron microscope, X-ray diffractometer and Fourier transform infrared spectroscopy. In addition, the anti-wear and friction-reduction mechanisms of the hybrid lubricant additive, owing to its activity on the friction interface, were disclosed by exploring the morphology and component of the wear scar after friction. The tribological results revealed that introducing a small amount of pyrolytic graphene/serpentine lubricant additive (0.2 wt%) to the base oil could effectively reduce the friction coefficient (~87%) and wear loss (~71%) in comparison with neat paraffin oil. First-principles calculations based on density functional theory were further performed to uncover the lubrication mechanism of the hybrid. Therefore, the pyrolytic graphene/serpentine hybrid reported herein represents a new strategy to prepare high efficient lubricant additive.