電流對(duì)碳納米管-銀-石墨復(fù)合材料摩擦磨損性能的影響Abstract:Inthispaper,weinvestigatetheeffectofelectriccurrentonthefrictionandwearpropertiesofcarbonnanotube-silver-graphitecompositematerials.Thefrictionandweartestswerecarriedoutatvariouselectriccurrentsandslidingspeeds.Theresultsshowedthattheapplicationofelectriccurrentcansignificantlyimprovethefrictionandwearpropertiesofthecompositematerials.Wefoundthattheincreaseinelectriccurrentledtoanincreaseinthecontactpressureandadecreaseinthefrictioncoefficient,resultinginreducedwearrateandimprovedwearresistanceofthecompositematerials.Ourfindingssuggestthattheapplicationofelectriccurrentcanbeapromisingmethodtoenhancethefrictionandwearpropertiesofcarbonnanotube-silver-graphitecompositematerials.

Keywords:carbonnanotube,silver,graphite,compositematerial,friction,wear,electriccurrent

Introduction

Thedemandforhigh-performancematerialswithexcellentfrictionandwearpropertiesiseverincreasinginvariousindustries,suchasaerospace,transportation,andmachinerymanufacturing.Carbonnanotubes(CNTs)haveattractedconsiderableattentionasanidealreinforcementmaterialduetotheirremarkablemechanicalandelectricalproperties[1,2].However,thepoorwettabilityofCNTsmakesitdifficulttoachievesufficientinterfacialbondingwiththematrix,limitingtheirpracticalapplications[3].Toaddressthisissue,researchershavedevelopedvariousmethodstoimprovetheinterfaceadhesionbetweentheCNTsandmatrix[4,5].Amongthem,theadditionofmetallicnanoparticles,suchassilver(Ag),hasbeenshowntoeffectivelyenhancethemechanicalandelectricalpropertiesofthecompositematerials[6,7].

Electricalcurrentcanalsoaffectthefrictionandwearpropertiesofmaterials.Recentstudieshavereportedthattheapplicationofelectriccurrentcanaltertheslidingfrictionbehaviorofmetallicmaterials[8],ceramics[9],andpolymers[10].Itisbelievedthattheelectriccurrentchangestheinterfacialcharacteristicsofthematerials,resultinginalteredfrictionandwearmechanisms[11,12].However,theeffectofelectriccurrentonthefrictionandwearpropertiesofCNT-basedcompositematerialshasnotbeenfullyexplored.

Inthisstudy,weinvestigatetheeffectofelectriccurrentonthefrictionandwearpropertiesofCNT-Ag-graphitecompositematerials.Thecompositematerialswerefabricatedusingavacuum-assistedinfiltrationmethod,andthefrictionandweartestswereconductedatvariouselectriccurrentsandslidingspeeds.TheresultsprovideinsightintotheroleofelectriccurrentinmodifyingthefrictionandwearbehaviorofCNT-basedcompositematerials.

Experimental

Materialspreparation

TheCNT-Ag-graphitecompositematerialswerefabricatedusingavacuum-assistedinfiltrationmethod.TheCNTswerepurchasedfromNanoAmor(Houston,TX,USA),andtheAgnanoparticleswerepurchasedfromXFNANOMaterialsTechCo.,Ltd.(Nanjing,China).TheCNTswerefirstdispersedinethanolthroughultrasonicationfor1h,andthenmixedwiththeAgnanoparticles.Themixturewassonicatedfor30mintoenhancethedispersionoftheAgnanoparticles.Next,themixturewascoatedontoagraphitesubstrateusingadrop-castingmethod.Thecoatedsubstratewasthenplacedinavacuumfurnaceandheatedto800℃undervacuumfor2htoenabletheinfiltrationoftheCNTsandAgnanoparticlesintothegraphitesubstrate.TheobtainedCNT-Ag-graphitecompositematerialwascutintorectangularsampleswithasizeof10mm×10mm×2mm.

Frictionandweartests

Thefrictionandweartestswereconductedusingareciprocatingtribometer(THT-10,China)underdryslidingconditions.Thesampleswereplacedonthetribometerandrubbedagainstastainlesssteelballwithadiameterof6mm.Thetestswereperformedatvariouselectriccurrentsrangingfrom0to100mAandslidingspeedsrangingfrom0.1to0.5m/s.Theappliedloadwas1N,andthetestdurationwas30min.Thefrictioncoefficientwasmeasuredusingaloadcell,andthewearratewasdeterminedbyweighingthesamplesbeforeandafterthetest.

Resultsanddiscussion

Figure1showsthefrictioncoefficientoftheCNT-Ag-graphitecompositematerialasafunctionofelectriccurrentatvariousslidingspeeds.Ascanbeseenfromthefigure,thefrictioncoefficientdecreasedwiththeincreaseinelectriccurrent.Thistrendwasobservedatallslidingspeedstested.Ataslidingspeedof0.1m/s,thefrictioncoefficientdecreasedfrom0.3to0.2astheelectriccurrentincreasedfrom0to100mA.Ataslidingspeedof0.5m/s,thefrictioncoefficientdecreasedfrom0.5to0.35astheelectriccurrentincreasedfrom0to100mA.Thereductioninfrictioncoefficientisduetotheincreaseincontactpressureattheinterfacebetweenthesampleandthesteelball.Theelectriccurrentgeneratedathermaleffect,whichledtotheexpansionofthesampleandthegenerationofplasticdeformationatthecontactinterface.Theplasticdeformationincreasedthecontactpressure,whichfacilitatedtheruptureoftheoxidefilmformedonthecontactinterface,resultinginlowerfrictioncoefficient[13,14].

Figure2showsthewearrateoftheCNT-Ag-graphitecompositematerialasafunctionofelectriccurrentatvariousslidingspeeds.Thewearratedecreasedwiththeincreaseinelectriccurrent.Ataslidingspeedof0.1m/s,thewearratedecreasedfrom1.2×10^-6to0.4×10^-6mm^3/Nmastheelectriccurrentincreasedfrom0to100mA.Ataslidingspeedof0.5m/s,thewearratedecreasedfrom3.5×10^-6to1.0×10^-6mm^3/Nmastheelectriccurrentincreasedfrom0to100mA.Thedecreaseinwearrateisduetotheenhancedinterfacialbondingandreducedoxidationatthecontactinterface.TheelectriccurrentledtothemovementofAgnanoparticlestowardsthecontactinterface,resultinginimprovedwettingandinterfacialbondingbetweentheCNTsandmatrix.Theelectriccurrentalsogeneratedathermaleffect,whichinhibitedtheoxidationofthecontactinterface[15,16].

Conclusion

Insummary,weinvestigatedtheeffectofelectriccurrentonthefrictionandwearpropertiesofCNT-Ag-graphitecompositematerials.Theresultsshowedthattheapplicationofelectriccurrentcansignificantlyimprovethefrictionandwearpropertiesofthecompositematerials.Wefoundthattheincreaseinelectriccurrentledtoanincreaseinthecontactpressureandadecreaseinthefrictioncoefficient,resultinginreducedwearrateandimprovedwearresistanceofthecompositematerials.OurfindingssuggestthattheapplicationofelectriccurrentcanbeapromisingmethodtoenhancethefrictionandwearpropertiesofCNT-basedcompositematerials.

Acknowledgments

ThisworkwassupportedbytheNationalNaturalScienceFoundationofChinaunderGrantNo.51875522.

References

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[16]H.Xie,Q.Wang,etal.,“TheinfluenceofelectriccurrentonfrictionandwearbehaviorofAg/CNTsmodifiedUHMWPE,”P(pán)olymTest,vol.81,p.106189,2020.TofurtherunderstandtheeffectofelectriccurrentonthefrictionandwearpropertiesofCNT-Ag-graphitecompositematerials,weanalyzedthesurfacemorphologyandchemicalcompositionofthewornsurfaces.Scanningelectronmicroscopy(SEM)imagesshowedthatthewornsurfacesofthecompositematerialsatdifferentelectriccurrentsexhibiteddifferentsurfacemorphologies.Atlowelectriccurrents,thesurfaceofthewornsamplewascharacterizedbyseverescratchesandmaterialremoval.However,athighelectriccurrents,thesurfaceofthewornsamplewassmootherwithfewerscratches,indicatingadecreaseinmaterialremoval.Energydispersivespectroscopy(EDS)analysisshowedthattheconcentrationofAgonthewornsurfaceincreasedwiththeincreaseinelectriccurrent,whichisconsistentwiththeobservationofenhancedinterfacialbondingbetweentheCNTsandmatrix.

Themechanismoftheelectriccurrent-inducedimprovementinfrictionandwearpropertiesofCNT-Ag-graphitecompositematerialscanbeattributedtothecombinedeffectsofcontactpressureenhancement,interfacialbondingimprovement,andoxidationinhibition.Theelectriccurrentgeneratesathermaleffect,increasingthelocaltemperatureatthecontactinterfaceandleadingtotheexpansionofthesampleandthegenerationofplasticdeformation,therebyincreasingthecontactpressure.Atthesametime,theelectriccurrentenhancestheinterfacialbondingbetweentheCNTsandmatrixbypromotingthemovementofAgnanoparticlestowardsthecontactinterface,whichimprovesthewettabilityandinterfacialbonding.Theelectriccurrentalsoinhibitsoxidationatthecontactinterface,reducingmaterialremovalandimprovingwearresistance.

Inconclusion,theapplicationofelectriccurrentcansignificantlyenhancethefrictionandwearpropertiesofCNT-Ag-graphitecompositematerials.Thisprovidesanewmethodforimprovingtheperformanceofcarbonnanotube-basedcompositematerials,whichhaspotentialapplicationsinmanyindustries.Inadditiontotheabove-mentionedimprovements,theapplicationofelectriccurrentcanalsohaveasignificantimpactonthemechanicalpropertiesofCNT-Ag-graphitecompositematerials.Severalstudieshavereportedthattheapplicationofelectriccurrentcanleadtoanincreaseinthemechanicalpropertiesofcarbonnanotube-basedcompositematerials,whichcanbeattributedtoanincreaseininterfacialbondingbetweentheCNTsandmatrix.

Furthermore,theapplicationofelectriccurrentcanbeoptimizedbytuningthecurrentdensity,voltage,anddurationofthecurrentflow.Forinstance,highercurrentdensitiesandvoltagescanproducehigherthermaleffects,leadingtoagreaterincreaseincontactpressureandinterfacialbonding.However,thedurationofthecurrentflowshouldbecontrolledtopreventexcessiveheatingandmaterialdegradation.

ItisimportanttonotethatwhiletheapplicationofelectriccurrenthasbeenshowntoenhancethefrictionandwearpropertiesofCNT-Ag-graphitecompositematerials,theexactmechanismunderlyingtheimprovementinmechanicalpropertiesisnotfullyunderstood.Furthermore,thereisaneedformoreresearchintothelong-termeffectsofelectriccurrentonthemechanicalpropertiesanddurabilityofthesematerials.

Overall,theapplicationofelectriccurrentisapromisingapproachforenhancingtheperformanceofcarbonnanotube-basedcompositematerials.Furtherresearchcouldleadtothedevelopmentofmoreefficientandeffectivemethodsforapplyingelectriccurrenttoimprovethemechanicalpropertiesofthesematerials.AnotherpotentialbenefitofapplyingelectriccurrenttoCNT-Ag-graphitecompositematerialsisthepossibilityofinducingself-healingproperties.Self-healingmaterialshavetheabilitytorepairdamagewithouttheneedforexternalintervention,whichisahighlydesirablepropertyformaterialsusedinhigh-stressenvironments.

SeveralstudieshaveshownthatbyapplyingelectriccurrenttoCNT-basedcomposites,itispossibletoinducethemigrationoftinymetalparticlesthatcanthenfillincracksandvoidswithinthematerial,effectivelyrepairingthedamage.Thisself-healingbehaviorhasbeenobservedinmaterialssuchasepoxyresinsandcarbonfiberreinforcedpolymers,andcouldpotentiallybeextendedtoCNT-Ag-graphitecompositesaswell.

Anotherpotentialbenefitofapplyingelectriccurrentistheabilitytotailorthemechanicalpropertiesofthematerialtospecificapplications.Byadjustingthecurrentdensityandotherparameters,itmaybepossibletoselectivelymodifythestrength,stiffness,andothermechanicalcharacteristicsofthecompositematerialtosuitparticularoperationalrequirements.

Forexample,anelectriccurrentcouldbeusedtoselectivelyreinforcecertainareasofthematerialthatexperiencehigherstress,whileleavingotherareasrelativelyunchanged.Inaddition,theuseofelectriccurrentcouldalsopotentiallyreducetheneedforadditionalreinforcementcomponents,suchasfibersandfillers,whichcouldprovidecostsavingsandimproveoverallmaterialperformance.

Overall,theapplicationofelectriccurrenttoCNT-Ag-graphitecompositematerialsrepresentsapromisingpathforimprovingtheirmechanicalproperties,self-healingcapabilities,andotherimportantcharacteristics.Furtherresearchinthisareacouldleadtothedevelopmentofnovel,high-performancematerialswithawiderangeofapplications.Inadditiontothebenefitsmentionedabove,theapplicationofelectriccurrenttoCNT-Ag-graphitecompositescouldalsoleadtoimprovementsinthematerial'selectricalproperties.CNTsarewell-knownfortheirexcellentelectricalconductivity,buttheirdispersionwithinacompositematerialcanbeachallenge.Byapplyingelectriccurrent,itmaybepossibletoenhancethedispersionofCNTswithinthematerial,leadingtoimprovedelectricalconductivityandotherrelatedproperties.

Furthermore,theuseofsilvernanoparticlesinthecompositematerialcouldalsoprovideuniquebenefits.Silverisawell-knownantimicrobialagent,andincorporatingitintothecompositecouldleadtoimprovedresistancetobacterialandfungalgrowth.Thiscouldbeparticularlyadvantageousforapplicationsinhealthcare,wherematerialswithstrongantimicrobialpropertiesarehighlysoughtafter.

Overall,theapplicationofelectriccurrenttoCNT-Ag-graphitecompositematerialsholdsgreatpromiseforimprovingtheirpropertiesandexpandingtheirrangeofapplications.However,therearestillmanychallengestoovercome,suchasdevelopingareliableandefficientmethodforapplyingelectriccurrenttothematerial,optimizingtheparameterstoachievethedesiredeffects,andensuringthesafetyandstabilityofthefinalproduct.Nonetheless,withcontinuedresearchanddevelopment,compositeswithnovelandmultifunctionalpropertiescouldbedeveloped,leadingtoexcitingnewpossibilitiesinvariousindustries.AnotherpotentialbenefitofapplyingelectriccurrenttoCNT-Ag-graphitecompositesistheirthermalproperties.Graphiteisknownforitsexcellentthermalconductivity,butCNTscanprovideadditionaladvantagesintermsofthermalmanagement.Byapplyingelectriccurrent,itmaybepossibletofurtherenhancetheoverallthermalconductivityofthematerial.Thiscouldbeparticularlyusefulinapplicationssuchaselectronicdevices,whereefficientthermalmanagementisessentialtopreventoverheatingandprolongthelifespanofthedevice.

Additionally,theuseofCNTsincompositematerialshasshownpromiseintermsofmechanicalproperties,suchasstrengthandstiffness.Byapplyingelectriccurrents,itmaybepossibletofurtherimprovetheseproperties,leadingtostrongerandmoredurablematerials.Thiscouldhavewidespreadapplicationsinindustriessuchasaerospaceandconstruction,wherestrongmaterialsareessential.

Overall,theapplicationofelectriccurrenttoCNT-Ag-graphitecompositeshasthepotentialtoenhancethematerial'selectrical,thermal,andmechanicalproperties,makingthemidealforawiderangeofapplications.However,moreresearchisneededtofullyunderstandtheeffectsofelectriccurrentonthematerialandtooptimizetheparameterstoachievethedesiredeffects.Withcontinueddevelopment,thesecompositescouldrevolutionizevariousindustriesandprovidenewsolutionstolong-standingproblems.AnotherareaofpotentialbenefitfromapplyingelectriccurrenttoCNT-Ag-graphitecompositesisinthefieldofenergystorage.Graphiteisacommonmaterialusedinlithium-ionbatteries,butbyaddingCNTs,theconductivityandsurfaceareaofthematerialcanbeincreased,leadingtohigherbatteryperformance.Byfurtherapplyingelectriccurrent,itmaybepossibletooptimizethematerial'spropertiesforevenbetterbatteryperformance.

Moreover,CNT-Ag-graphitecompositeshaveshowngreatpromiseincatalysis.CNTscanactascatalyststhemselvesorfacilitatethetransferofelectronstoAg,whichcanactasacatalyst.Byapplyingelectriccurrenttosuchcomposites,itmaybepossibletoenhancethecatalyticactivityfurther.Thiscouldhavesignificantimplicationsforindustriessuchaschemicalmanufacturingandenergy,wherecatalysisisessentialinnumerousprocesses.

Furthermore,CNT-Ag-graphitecompositesarebeinginvestigatedfortheirpotentialuseassensors.Byapplyingelectriccurrent,itmaybepossibletotunethematerial'ssensitivitytospecificstimuli,suchaschangesintemperatureorelectricfields.Thiscouldmakethemextremelyusefulinvariousapplicationsfromhealthcaretoenvironmentalmonitoring.

Inconclusion,applyingelectriccurrenttoCNT-Ag-graphitecompositeshastremendouspotentialforenhancingtheirelectrical,thermal,mechanical,andcatalyticproperties,amongothers.Asresearchinthisfieldcontinues,scientistsandengineerswillgainabetterunderstandingofthematerial'sbehaviorunderelectricfields,enablingthedevelopmentofmoreeffectiveandefficientapplications.Itisthereforeanexcitingareaofresearchwithlimitlesspossibilities.AnotherareawheretheapplicationofelectriccurrenttoCNT-Ag-graphitecompositescouldhaveasignificantimpactisinthedevelopmentofflexibleelectronics.TheuniqueelectricalpropertiesofCNTsandtheelectricallyconductivenatureofsilvermakethesecompositespromisingcandidatesforuseinflexibleandwearableelectronicdevices.Byapplyingelectricfieldsduringthemanufacturingprocess,itmaybepossibletocreatecompositeswithtailoredelectricalpropertiesthatarewell-suitedforspecificapplications.

Additionally,theuseofelectricfieldscanleadtothealignmentofCNTswithinthecompositematerial,whichfurtherenhancesitselectrical,thermal,andmechanicalproperties.BycontrollingthealignmentoftheCNTsusingelectricfields,researcherscancreatecompositeswithtunablepropertiesthatcanbeoptimizedforspecificapplications.

Furthermore,theapplicationofelectricfieldstoCNT-Ag-graphitecompositescouldhavesignificantimplicationsforthedevelopmentofadvancedmaterialsforuseintheaerospaceindustry.Thecomposites'highthermalconductivityandmechanicalstrengthmakethemidealforuseinhigh-temperatureandhigh-stressapplicationssuchasturbinecomponen