The Study On The Tribological Properties Of TiN And WS₂ Nanoparticles As Lubricant Additives

Wear is one of the three failure modes of materials and the lubrication failure causes about 80%failure of mechanical equipment.Therefore,reasonable lubrication plays an important role in reducing friction and wear and prolonging the service life of machine.With the development of nanotechnology,the nonmaterial has been widely used in the lubrication field.With special properties of large specific surface,high diffusivity and low melting point,the nanoparticle can not only improve the antiwear and friction reducing performance of lubricating oil,but also compensate and repair the worn surface.The friction and wear properties of titanium nitride?TiN?and tungsten sulfide?WS₂?nanoparticles as an additive have been investigated using a MRS-10 A four ball friction and wear machines under different nanoparticle content,load and composite ratios conditions.The wear surface morphology was analyzed using laser confocal scanning microscope,scanning electron microscopy and energy dispersive spectrometer.Moreover,the mechanism of wear reduction of two kinds of nanoparticles were explored in detail.The main conclusions are obtained as follows:?1?Using oleic acid,stearic acid,silane coupling agent and polyethylene glycol as the dispersants,the dispersions of TiN and WS₂ nanoparticles have been studied in the base oil.The result of two nanoparticles dispersing with oleic acid is the best,and the optimal content of dispersant is about 1wt%.?2?Two nanoparticles of TiN and WS₂ as additive can improve the friction reduction and wear resistance properties of lubricating oil significantly.With the two nanoparticles content increasing,the friction coefficient both increase a little,while,the wear scar diameter shows a trend of decline first and then rising.Furthermore,the optimal nanoparticles contents of TiN and WS₂ are 0.1wt%.With the load rising,the antifriction and antiwear performance of TiN and WS₂ nanoparticles can be improved efficiently,especially at 392N,the damage of worn surface is the slightest.It can be found contrastively that the TiN nanoparticle has better than WS₂ nanoparticle.?3?With the increase in mass ratio of TiN to WS₂ in composite TiN/WS₂ lubricant,the friction coefficient and the wear scar diameter both drop to a point and then increase.When the ratio of TiN/WS₂ is 1:1,the surface damage is the slightest and the composite TiN/WS₂ shows a good synergistic effect.?4?The nanoparticles additives exhibit favorable antiwear properties.The contrastive analysis results of worn surface morphology and element content indicates that the nanoparticles can play a role as tiny ball bearing and participate in tribochemical reaction,which can changes the sliding friction into rolling friction and repair the surface plows and micro-pitting..The performance of wear reduction from good to bad in turn is TiN/WS₂,TiN,WS₂ and the base oil.