Study On Synthesis And Performance Of Lubricant Additives With A Green Anti-wear And Friction-reduction Molecular Structure

With the increasing awareness of environmental protection in the world,the requirements of lubricant additives are becoming more and more stringent.Environmental friendly lubricant additives have become a heated research in this field.In order to quickly and efficiently screen out the potential green friction-reducing and anti-wear additives without phosphorus,three kinds of lubricant additives were designed and synthesized,which are hydrazide,2-aminobenzoxazole and Schiff base copper complexes modified MWCNTs.The tribological properties in three kinds of ester base oils(DE,TMPTO and TMT)were evaluated by UMT-3 microtribometer,and the worn surface morphology was observed.The possibility of2-aminobenzoxazole compounds as friction reducing and anti-wear additives in ester base oils under low load was analyzed.The tribological properties of modified MWCNTs and GO were compared,and the mechanism of friction reduction and anti-wear was discussed.The tribological similarity of hydrazide group and phosphate group was evaluated,the Co MFA or Co MSIA model was established,and the synergistic problem between the molecular structural similarity of lubricant additives and base oil and tribological performance was discussed,so as to provide more scientific basis for QSTR application.The main results are as follows:1.11 N',N'-hydrazides were prepared by Grignard method,carboxylation,hydrazidation and nucleophilic substitution reaction for the first time and N',N'-hydrazide were characterized by ¹HNMR,FT-IR and MS spectrum.2.31 hydrazides were selected as isosteres and other analogs when 5 phosphate was used as templates by an isosteric exchange from phosphate group(PO₄)to hydrazide group(CONHN).Their tribological properties of the lubricant modified with 1%hydrazide or phosphate additives were tested under 98N load in 3 oils,respectively.About 40%of the isosteres showed an acceptable deviation of±5%relative to the template.The phosphate template molecules and hydrazide isosteres have better tribological properties in TMT than TMPTO or DE.Especially,most of the other hydrazide analogs have better anti-wear property because of the same CONHN group as the isostere.Co MFA and Co MSIA models were used to discuss the dependency of molecular structure.The models show that the higher the structural similarity between the base oil and the additive,the more synergy the molecular force field in a lubricant,which may ameliorate the anti-wear or friction-reduction properties.Surface analysis of the worn disc specimen also shows similarity between a template and an isostere by SEM,EDS and Raman spectra.3.Ten kinds of 2-aminobenzoxazole compounds were synthesized.The tribological test was carried out under 30N load,and the three-dimensional morphology of the worn surface of disc was observed by white light interferometer.The result show that the wear spot diameter and average friction coefficient of2-aminobenzoxazole additive in TMT are lower than those in TMPTO and DE,and the additive A9(N,N-diethyl-2-aminobenzoxazole),which is the one with the least wear,is expected to become a excellent green lubricant additive under a low load.4.Four kinds of diamine glycidyl Schiff base copper(?)complexes were synthesized to modify the acidified MWCNTs.The micro morphology of the four modified MWCNTs was observed by TEM.It is found that the O-phenylenediamine glycidyl Schiff base copper complexes modified the acidified MWCNTs are well dispersed,the defects of easy winding and aggregation of the MWCNTs are improved,and the modification effect is the best.5.Tribological experiments of four Schiff base copper complexes modified MWCNTs were carried out as additives in ester base oil,respectively.Their three-dimensional morphology of the worn surface was also observed and the mechanism of friction reduction and anti-wear was discussed.The results show that the WSD of 4 modified MWCNTs in TMT is smaller than those in TMPTO and DE,but there is no obvious advantage compared with GO.By contrast,the WSD of modified MWCNTs in TMPTO is significantly smaller than that in GO,which shows better antiwear performance than that in GO.After adding a-MWCNTs+add4 in TMPTO,the wear marks on the worn surface of the disc become rare and shallow,and the morphology of the worn surface is improved due to the"filling"and"isolation"effects of the modified MWCNTs between the rubbing pairs.