Preparation And Tribological Properties Of Several Layer-structure Nano Lubricant Additives

With the increasing performance parameters of modern mechanical equipments,the traditional lubricating oil and its organic lubricant additives have not fully meet the performance requirements of the modern industrial production under extreme-pressure,high-speed and high-precision conditions,and also contrary to the current advocacy of environmental requirements.In recent years,nano-tribology has gradually become a popular research field with the rapid development of nanomaterials.Adding some nanoparticles and its nanocomposites into base oil significantly improves the anti-friction and anti-wear performance of the lubricating oil.Since then,the development of new-type nano lubricant additives has entered into a new stage.In this thesis,we mainly prepared three kinds of layer-structure nanocomposites,based on the composite synergistic effect of nanomaterials as the basis of lubrication theory.They were g-C₃N₄/Cu,g-C₃N₄/MoS₂,g-C₃N₄/MoS₂/ZnS nanocomposites.At the same time,the ultrathin NbTe₂ nanosheets were successfully prepared by the exploratory experiment.And the mechanism of friction and wear as lubricant additives was proposed by systematically characterizing the phase composition,morphology and tribological properties.The main research contents include:?1?The Cu2+ adsorbed on the surface active sites of g-C₃N₄ was successfully reduced by chemical reduction method to obtain g-C₃N₄/Cu nanocomposites.In the g-C₃N₄/Cu heterostructures,a large number of spherical Cu nanoparticles with a particle size of about 20 nm were uniformly modified on the surface of the g-C₃N₄.Moreover,we investigated the tribological properties of g-C₃N₄/Cu nanocomposites as lubricant additives.The results showed that both g-C₃N₄ and Cu nanoparticles have good anti-friction and anti-wear properties,but g-C₃N₄/Cu exhibited better dispersion stability and tribological behaviors.?2?The g-C₃N₄/MoS₂ nanocomposites were obtained by hydrothermal method.The introduction of g-C₃N₄ can effectively hinder the self-assembly tendency of MoS₂,and when the value of g-C₃N₄ addition is 0.15 g,the ideal 2D-2D nanostructure is obtained.Moreover,the addition of surfactants?CTAB and TEBAC?is not conducive for the formation of 2D structures.In addition,the tribological properties of nanocomposites as a lubricant additive were investigated.The results revealed that the g-C₃N₄/MoS₂ with ideal nano-heterojunction has more excellent anti-friction and anti-wear performance than single g-C₃N₄ or MoS₂,and greatly improves the lubricating performance of lubricating oil.Similarly,g-C₃N₄/MoS₂/ZnS ternary nanocomposites were also synthesized through hydrothermal method.The possible growth mechanism of nanocomposites was explored by phase and structure analysis.The introduction of g-C₃N₄ could effectively hinder the formation of MoS₂ and ZnS large-size self-assembled structures,and the steric hindrance effect enables g-C₃N₄,MoS₂ and ZnS to form the ideal nano-heterostructure.In addition,the tribological properties of nanocomposites as a lubricant additive were investigated.The results show that g-C₃N₄/MoS₂/ZnS nanocomposites show more excellent anti-friction and anti-wear properties than single g-C₃N₄ or g-C₃N₄+MoS₂+ZnS mixtures,and ternary nano-heterostructures also exhibit better tribological properties than binary heterostructures.?3?In the exploratory experiment,the ultrathin NbTe₂ nanosheets were successfully obtained by the wet ball milling.The variation of phase and microstructure of NbTe₂ was systematically researched before and after exfoliation.Besides,the tribological properties of NbTe₂ before and after exfoliating were investigated.The results showed that the exfoliated NbTe₂ nanosheets exhibited more excellent dispersion stability than bulk NbTe₂ in paraffin oil,and possessed lower friction coefficients and wear rates,showing good lubrication behaviors.