Preparation Of Modified Graphite Oxide And Investigation Of Its Tribological Properties In Liquid Paraffin

Friction and wear are the main cause of the loss of materials and energy. Consumption of more than a third of world primary energy is caused by the friction and wear. Reducing the energy loss caused by friction and wear is imminent. It is reported that nanoparticles have good lubricating properties and can play a role in anti-friction and anti-wear. As the starting material of large-scale preparation of graphene, graphite oxide has excellent physicochemical properties and it is of contemporary significance to study its and derivative's tribological properties.In this paper, graphite oxide was prepared via the improved Hummers method and further modified using two organic silane molecules of different alkyl chain length. The structure and morphology of silane-modified graphite oxide was characterized by means of Fourier transformed infrared spectroscopy, XRD, UV spectroscopy, scanning electron microscopy. The results demonstrate the remarkable changes in the structure and morphology of graphite oxide after modification. The friction properties of modified graphite oxide as additives in liquid paraffin were tested based on four-ball method. It was found that modified graphite oxide has excellent friction properties at low concentrations and can significantly improve the anti-friction property of base oil. Besides, frictional performance of modified graphite oxide with different chain length differs from each other, corresponding to the differences in dispersity. The mechanism is presumed and analyzed:on one hand, silane-modified graphite oxide can stably dispersed in the base oil and easily enter into the metal contact region due to its small size; on the other hand, shedding or curling of graphite oxide from the alkyl chain occur under the shear and compressive stress and fill the pits of metal contact region, thus reducing friction and wear.Polyaniline and polyaniline-graphite oxide composite was prepared via the pressure assisted method. Rod-like polyaniline with different properties was obtained by changing the preparation procedure. In the four-ball machine, the effect of composite's and polyaniline's concentration on the friction properties as well as preparation procedure was explored. It was found that polyaniline and its composites can reduce the friction well. The tribological mechanism was analyzed preliminarily:firstly, nano-rod polyaniline play a role in lubricating as rolling micro-bears. Secondly, the synergy between polyaniline and graphite oxide in lubrication was observed. The rolling of polyaniline on the surface of graphite oxide makes the delamination of graphite oxide easier, thus reducing the friction and wear.