| How to reduce the economic losses caused by friction and wear through technical means has always been an important subject of tribology research.Therein,lubrication is currently the world's most effective method.With the continuous development of industrialization,mechanical equipments' requirements on lubricants quality are getting higher and higher.Adding excellent additives is an important means to improve the quality of lubricating oil.However,the traditional lubricant additives are mostly single functional additives.When facing with complex operating conditions,it is difficult to meet a variety of lubrication requirements.At the same time,the traditional lubricants contain elements like S,P which are harmful to the environment.Therefore,it is of great practical significance to study and develop environmentally friendly nano lubricant additives with excellent lubricating properties.In this paper,octavinyl polyhedral oligomeric silsesquioxane(vinylPOSS)nanohybrid materials were used as the matrix,the organic modification of alkyl mercaptan with different alkyl chain lengths were achieved by the click reaction.UV-vis spectrum revealed that its dispersion and stability in the liquid paraffin were greatly improved.Ultrathin MoS2 can be obtained by protein-induced exfoliation of bulk MoS2 powders under ultra-sonication,and the surface modification of inorganic ultrathin MoS2 on vinylPOSS nanohybrid materials was finally realized.The structure,composition and morphology of modified vinylPOSS were characterized by means of Fourier transformed infrared spectroscopy,XRD,UV-vis spectroscopy,1H nuclear magnetic resonance(1H NMR),scanning electron microscopy and transmission electron microscopy.The results demonstrated that the structure,composition and morphology have undergone positive changes after the surface modification.Besides,the dispersion stability of the modified vinylPOSS was studied by means of static observation and UV-vis spectroscopy.It was found that the modified vinylPOSS nanomaterials had good compatibility with the organic solvents.The effects of organic mercaptan modified vinylPOSS nanohybrids on the tribological performance improvements of liquid paraffin(LP)were investigated.It was found that organic mercaptan modified vinylPOSS nanohybrids have excellent tribological performance and can significantly improve the friction-reducing property of liquid paraffin at a lower concentration.Related mechanism:on the one hand,vinylPOSS nanohybrids can work as nano ball bearings which translate the sliding friction of pin with ceramic disk into rolling friction;On the other hand,vinylPOSS nanohybrids possess small size and large surface area,which can easily fill the micro-scratches and form lubrication film on the frictional surface in the friction process.By this way,the self-repairing of the abrasive surface is partially realized.Friction experiments of MoS2,vinylPOSS,MoS2-POSS nanocomposites indicated that MoS2-POSS nanocomposites can effectively improve the tribological properties of liquid paraffin,with a better friction-reduction and anti-wear abilities than MoS2 or vinylPOSS works alone.MoS2-POSS nanocomposites play a role in lubrication even at a lower concentration.According to the surface morphologies and element analysis results,the tribological mechanism was analyzed:The high load-carrying capacity of MoS2 nanosheets and the oil-soluble properties of vinylPOSS together with the easily formation of adsorbable oil films contribute to the excellent anti-friction and anti-wear properties of MoS2-POSS,giving full play to the two kinds of lubricant additives compound and synergistic effect. |
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