| Friction and wear are the main causes of energy waste and material loss,and lubrication is an effective way to reduce friction and wear.In addition to its own small size characteristics,nanomaterials also have excellent friction reduction and anti-wear properties and harmless combustion products,which have attracted widespread attention in the field of lubricant additives,of which nano-diamond,as an ultra-hard,zero-dimensional carbon material,is a potential high-quality lubricant additive.However,the agglomeration problem of nanodiamond in lubricants severely limits its application as a lubricant additive.Considering that polyaniline is a polymer material with both lubrication and certain high temperature stability,this thesis proposes to use flexible polyaniline coated with nano-diamond to investigate the effect of polyaniline(PANi)on the dispersion of nano-diamond(ND)and the effect of PANi/ND nanocomposite additive on the friction and wear performance of lubricating oil and the related mechanism,which is expected to obtain the development of a composite nanolubricating oil additive with flexible-rigid synergy and has important scientific research significance and practical value for the development and application of new lubricating oil additives under complex working conditions.Firstly,based on the strong interaction between aniline cation and nano-diamond,and through the in-situ polymerization process,the dispersion of nano-diamond in polyaniline matrix was achieved,and then the effective and stable dispersion of polyaniline-coated nanodiamond composite particles in lubricating oil was achieved with the aid of ultrasound and the lipophilic property of polyaniline itself.The influence laws of additive content,nano-diamond particle size,polyaniline structure and doping acid type on the friction and wear performance of polyaniline/nano-diamond composites were investigated separately,mainly including the following:(1)Polyaniline/nano-diamond composites were prepared using hydrochloric acid as the doping acid,and the friction and wear performance of the composites with different additions of polyaniline/nano-diamond was investigated in base oil HVI-5 and refined oil CD40,respectively.It was found that the introduction of polyaniline/nano-diamond composites could effectively improve the friction and wear reduction performance of lubricants,and the composite additives showed significant differences in the improvement of friction and wear reduction effect of base oil HVI-5 and refined oil CD40.For base oil HVI-5,the composite material with 2 wt.% addition exhibits the best friction reduction and anti-wear performance;for refined oil CD40,the composite material with 1 wt.% addition exhibits the best friction reduction effect,while the composite material with 3 wt.% addition exhibits the best anti-wear performance.(2)The effect of diamond particle size and morphological differences on the structure of the composite and its frictional wear characteristics was investigated.Research shows that different particle size and shape of the lubricant additive package are on the base oil HVI-5,refined oil CD40 has a certain effect of anti-friction and anti-wear.For the base oil system,the ND particle size is within a certain range(<300 nm),the additive has good anti-wear performance and the introduction of lamellar diamond will improve the anti-wear performance to a certain extent;while for the refined oil CD40,the ND below 100 nm has better anti-wear properties,and the ND particle size is too large(>200 nm)will significantly reduce the antiwear properties of the composite.Among them,the composite materials of PANi/ND30-50 and PANi/ND60-100 have the best comprehensive anti-friction and anti-wear effects.(3)The polyaniline/nano-diamond composites were treated with carbonization,and the effects of the degree of carbon accumulation on the surface and the degree of polymer dissociation on the friction and wear reduction performance of the composite lubricant additives were investigated.It is shown that the differences in surface polymer structure significantly affect the anti-friction and anti-wear effects of the composites,where the best anti-friction effect of the products is achieved at a carbonization temperature of 1100 °C and the best anti-friction performance is achieved at a carbonization temperature of 200 °C.(4)It was shown that the nano-diamond dispersion in the organic acid-doped polyaniline/nano-diamond composites was poor,and the anti-wear properties of the corresponding composites decreased significantly,indicating that the anti-wear properties of the composites were mainly determined by the nano-diamond dispersion,while the anti-friction properties of the organic acid-doped composites were enhanced,indicating that the introduction of the organic acid flexible group contributed to the anti-friction properties of the polyaniline/nano-diamond composite particles The improvement of the anti-friction properties of the composites was shown. |
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