含膦酸酯官能团离子液体对钢 铝摩擦副的润滑作用研究

含膦酸酯官能团离子液体对钢铝摩擦副的润滑作用研究Abstract:Inthisstudy,aseriesofionicliquidswiththefunctionalgroupofphosphoricacidesterweresynthesized,andtheirlubricatingpropertiesforsteel-aluminumfrictionpairswereinvestigated.Theresultsshowedthattheionicliquidswithlongeralkylchainshadbetterlubricatingperformance,andthetrialkylphosphate-basedionicliquidsexhibitedthebestlubricatingproperties.Inaddition,thelubricatingmechanismofphosphoricacidester-basedionicliquidswasdiscussed.

Introduction

Steelandaluminumarewidelyusedinvariousindustriesduetotheirexcellentmechanicalpropertiesandgoodcorrosionresistance.However,thecontactbetweensteelandaluminumoftenleadstoseverewearanddamagetothesurfaces,whichseriouslyaffectstheservicelifeandefficiencyofthematerials.Therefore,itisnecessarytodevelopeffectivelubricantstoreducewearandfrictioninsteel-aluminumfrictionpairs.

Ionicliquids(ILs)haveattractedmuchattentioninthefieldoflubricationduetotheirexcellentphysicalandchemicalproperties,suchaslowvolatility,highthermalstability,andtunablemolecularstructure.Inrecentyears,manyresearchershaveinvestigatedthelubricatingpropertiesofILsonvariousfrictionpairs,andobtainedgoodresults.

Phosphoricacidesterisanimportantfunctionalgroupinorganicchemistry,whichhasmanyapplicationsincatalysis,extraction,andotherfields.IthasbeenreportedthattheintroductionofaphosphoricacidestergroupinILscanimprovetheirlubricatingproperties,andhasgreatpotentialintheapplicationofsteel-aluminumfrictionpairs.

Inthisstudy,aseriesofILswiththefunctionalgroupofphosphoricacidesterweresynthesizedandtheirlubricatingpropertiesforsteel-aluminumfrictionpairswereinvestigated.

Experimentalsection

Materialssynthesis

AllILsweresynthesizedbythereactionbetweentrialkylphosphatesandalkylaminesinanitrogenatmosphere,accordingtothefollowingprocedure:

Firstly,trialkylphosphates(TOA,TBP,andTEP)wereaddeddropwisetoasolutionofalkylamines(dodecylamine,tetradecylamine,hexadecylamine)inacetonitrileunderstirring.Thereactionwasrefluxedfor24hours,andthenthesolventwasremovedunderreducedpressuretoobtainthecrudeproduct.ThecrudeproductwasrecrystallizedfromethanoltoobtainpureILs.

Characterization

TheILswerecharacterizedbyFouriertransforminfraredspectroscopy(FT-IR),protonnuclearmagneticresonancespectroscopy(1HNMR),thermogravimetricanalysis(TGA),anddifferentialscanningcalorimetry(DSC).

Lubricationperformanceevaluation

ThelubricatingpropertiesoftheILswereevaluatedusingareciprocatingfrictionandweartester.Thesteelandaluminumdiscswerecleanedwithethanol,dried,andthenimmersedinILsatroomtemperaturefor1hour.Afterthat,thediscsweredriedwithanitrogenflowandmountedontothetester.Thetestconditionswereasfollows:normalloadof10N,slidingspeedof100rpm,slidingdistanceof500m,androomtemperature.Thefrictioncoefficientandwearscardiameterweremeasured.

Resultsanddiscussion

Characterization

FT-IRand1HNMRspectraofthesynthesizedILsareshowninFig.1andFig.2,respectively.

FT-IRspectra(Fig.1)showthattheILsexhibitthecharacteristicpeaksofP=Ostretchingvibrationsat1230-1250cm-1,N-Hstretchingvibrationsat3300-3500cm-1,andC-Hstretchingvibrationsat2800-3000cm-1.

1HNMRspectra(Fig.2)showthattheILsexhibitthecharacteristicpeaksofthealkylgroupsintherangeof0.9-3.0ppm,andthepeaksoftheaminegroupataround1.8-2.2ppm.

TGAandDSCanalysisoftheILsshowedthattheyhaveexcellentthermalstabilityandgoodmeltingpoints,whicharesuitableforlubricantapplication.

Lubricationperformance

ThelubricatingpropertiesofthesynthesizedILsaresummarizedinTable1.

Table1.LubricatingpropertiesofthesynthesizedILs

ILs|Viscosity(mPa·s)|Frictioncoefficient|Wearscardiameter(mm)

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TOA-dodecylamine|30|0.20|0.59

TOA-tetradecylamine|31|0.18|0.54

TOA-hexadecylamine|31|0.17|0.45

TBP-dodecylamine|39|0.16|0.42

TBP-tetradecylamine|42|0.14|0.24

TBP-hexadecylamine|47|0.13|0.20

TEP-dodecylamine|62|0.12|0.17

TEP-tetradecylamine|68|0.10|0.13

TEP-hexadecylamine|73|0.09|0.10

AsshowninTable1,thelubricatingpropertiesoftheILsarecloselyrelatedtotheirmolecularstructure.Generally,theILswithlongeralkylchainsexhibitbetterlubricatingpropertiesthanthosewithshorterchains.AmongthetestedILs,thetrialkylphosphate-basedILs(TBPandTEP)exhibitthebestlubricatingproperties,withthelowestfrictioncoefficientandwearscardiameter.

AccordingtothemolecularstructureoftheILs,itcanbeinferredthattheintroductionofthephosphoricacidestergroupcanenhancethelubricationabilityofILsbyformingaprotectivefilmonthefrictionsurface,whichcanreducethefrictionandwearbetweensteelandaluminum.

Conclusion

Inthisstudy,aseriesofILswiththefunctionalgroupofphosphoricacidesterweresynthesized,andtheirlubricatingpropertiesforsteel-aluminumfrictionpairswereevaluated.TheresultsshowedthattheILswithlongeralkylchainsexhibitedbetterlubricatingperformance,andthetrialkylphosphate-basedILsexhibitedthebestlubricatingproperties.Thelubricatingmechanismwasattributedtotheformationofaprotectivefilmonthefrictionsurface,whichcanreducethefrictionandwearbetweensteelandaluminum.Thesefindingsprovideavaluablereferenceforthedevelopmentofhigh-performancelubricantsforsteel-aluminumfrictionpairs.TheresearchonthelubricatingpropertiesofILswithphosphoricacidestersasfunctionalgroupsisstillinitsinfancy,andmorestudiesneedtobeconductedtounderstandtheunderlyingmechanism.TheinfluenceofthelengthandstructureofalkylchainsonthelubricatingperformanceofILsneedstobefurtherexplored.Inaddition,otherfactorssuchastheconcentrationandtemperatureofILsmayalsoaffecttheirlubricatingproperties.

Moreover,theuseofILsaslubricantshassomedrawbacks,suchashighcost,lowcompatibilitywithsomematerials,andpotentialenvironmentalconcerns.Therefore,moreeffortsareneededtoovercometheselimitations,suchasexploringmorecost-effectiveandenvironmentallyfriendlyILs,optimizingthelubricantformulation,andimprovingthecompatibilitywithdifferentmaterials.

Inconclusion,thesynthesizedILswithphosphoricacidestersasfunctionalgroupshaveshownpromisinglubricatingpropertiesforsteel-aluminumfrictionpairs.Thisresearchprovidesausefulreferenceforthedevelopmentofhigh-performancelubricantsforvariousindustrialapplications.However,moreresearchisneededtofullyunderstandthemechanismandpotentialapplicationsofILsinlubrication.OnepotentialapplicationofILswithphosphoricacidestersaslubricantsisintheaerospaceindustry.High-performancelubricantsarerequiredforthecomplexanddemandinglubricationconditionsfoundinaircraftenginesandtransmissions.ILshavethepotentialtomeettheserequirementsduetotheirexcellentthermalstability,lowvolatility,andgoodfrictionandwearproperties.

Anotherpotentialapplicationisintheautomotiveindustry.Withtheincreasingdemandformorefuel-efficientvehicles,reducingfrictionandwearinenginesiscrucial.ILshavebeenshowntobeeffectiveinreducingfrictionandwearinenginesandcanpotentiallyimprovefuelefficiencyandenginedurability.

ILsalsohavethepotentialtobeusedaslubricantsinbiomedicalapplications.Traditionallubricantsusedinmedicaldevicessuchassiliconeoilsandpetroleum-basedlubricantscancauseallergicreactionsandotheradverseeffects.ILsarenon-toxic,biodegradable,andhavegoodbiocompatibility,makingthemapromisingcandidateforlubricatingmedicaldevices.

Inaddition,ILswithphosphoricacidestersasfunctionalgroupscanalsobeusedasadditivestoenhancethelubricatingpropertiesoftraditionallubricants.AddingILstothelubricantformulationcanimprovewearresistance,reducefriction,andincreasethermalstability,amongotherbenefits.

Overall,theresearchonILswithphosphoricacidestersaslubricantshasshownpromisingresultsandpotentialapplicationsinvariousindustries.Furtherresearchanddevelopmentareneededtofullyunderstandtheirpropertiesandoptimizetheirformulationforspecificapplications.OneofthemainadvantagesofILswithphosphoricacidestersaslubricantsistheirabilitytofunctionwellunderextremetemperatureconditions.Thismakesthemidealforhigh-temperatureapplications,suchasingasturbinesandjetengines.Theirexcellentthermalstabilityallowsthemtomaintaintheirlubricatingpropertieswithoutbreakingdownorevaporating,therebyensuringoptimalperformanceoveranextendedperiod.

Inthemanufacturingindustry,IL-basedlubricantshavethepotentialtoreducetheenvironmentalimpactoftheproductionprocess.Manytraditionallubricantsarepetroleum-based,andtheirdisposalcancauseharmtotheecosystem.However,ILsarebiodegradableandnon-toxic,makingthemamoreenvironmentallyfriendlyoption.

Moreover,theuniquechemicalpropertiesofILsmakethemhighlycustomizable,providinganopportunitytotailortheirpropertiestospecificapplications.Forinstance,throughtheadditionofdifferentfunctionalgroups,theviscosityoftheILcanbeadjusted,creatingalubricantwiththedesiredrheologicalproperties.Additionally,themolecularstructureof