载电条件下铬青铜／纯铜摩擦副摩擦磨损性能研究

载电条件下铬青铜／纯铜摩擦副摩擦磨损性能研究Abstract:Thefrictionandwearpropertiesofchromebronze/purecopperfrictionpairsunderchargedconditionswerestudiedinthispaper.Theresultsshowthatthechargedconditionshaveasignificanteffectonthefrictionandwearpropertiesofthefrictionpairs.Thefrictionandwearpropertiesarerelatedtothechargedensity,contactpressureandslidingspeed.Underchargedconditions,thefrictioncoefficientofchromebronze/purecopperfrictionpairsdecreaseswiththeincreaseofchargedensityorslidingspeed.Thewearrateofcopperincreaseswiththeincreaseofchargedensity,whilethewearrateofchromebronzedecreaseswiththeincreaseofchargedensity.Thewearmechanismunderchargedconditionsisdifferentfromthatunderunchargedconditions,mainlyincludingmicro-cutting,micro-plowing,micro-cracking,andelectrochemicalcorrosion.

Keywords:chargedconditions,chromebronze,purecopper,friction,wear

Introduction

Asoneofthemostcommonlyusedfrictionpairs,copperalloy/copperfrictionpairsarewidelyusedinindustrialfieldssuchasmachinetoolmanufacturingandaerospacemanufacturing.Intheactualworkingstate,thefrictionpairsareofteninachargedstateduetotheinfluenceofexternalelectromagneticfieldsortheinternalstructureofthefrictionpairsthemselves.Therefore,itisofpracticalsignificancetostudythefrictionandwearpropertiesofcopperalloy/copperfrictionpairsunderchargedconditions.

Experimental

Inthispaper,chromebronzewasusedasthecopperalloy,andpurecopperwasusedasthecoppermaterial.Thespecimenswerepreparedbycuttingthematerialsintotheshapeofaring.Theouterdiameterofthespecimenswas50mm,theinnerdiameterwas10mm,andthethicknesswas10mm.ThesurfaceroughnessofthespecimenswasRa=0.4μm.Theexperimentalparameterswereasfollows:appliedvoltage0-400V,contactpressure1-5MPa,slidingspeed0.1-1m/s,reciprocatingstroke30mm,andtesttime1800s.

Resultsandanalysis

Thefrictioncoefficientandwearrateofthefrictionpairsunderchargedconditionsweremeasured,andtheresultsareshowninFigure1andFigure2,respectively.ItcanbeseenfromFigure1thatthefrictioncoefficientofthefrictionpairsdecreaseswiththeincreaseofchargedensityorslidingspeed.ItcanbeseenfromFigure2thatthewearrateofcopperincreaseswiththeincreaseofchargedensity,whilethewearrateofchromebronzedecreaseswiththeincreaseofchargedensity.

Figure1Frictioncoefficientunderchargedconditions

Figure2Wearrateunderchargedconditions

Thewearmorphologyofcopperandchromebronzeunderchargedconditionswasobservedbyscanningelectronmicroscopy(SEM),andtheresultsareshowninFigure3andFigure4,respectively.ItcanbeseenfromFigure3thatthewearmorphologyofcopperunderchargedconditionsismainlymicro-cuttingandmicro-plowing,andthereisasmallamountofmicro-crackingandelectrochemicalcorrosion.ItcanbeseenfromFigure4thatthewearmorphologyofchromebronzeunderchargedconditionsismainlymicro-cuttingandmicro-plowing,andthereisasmallamountofelectrochemicalcorrosion.

Figure3SEMimagesofwearmorphologyofcopperunderchargedconditions

Figure4SEMimagesofwearmorphologyofchromebronzeunderchargedconditions

Conclusion

Thechargedconditionshaveasignificanteffectonthefrictionandwearpropertiesofchromebronze/purecopperfrictionpairs.Thefrictionandwearpropertiesarerelatedtothechargedensity,contactpressure,andslidingspeed.Underchargedconditions,thefrictioncoefficientofchromebronze/purecopperfrictionpairsdecreaseswiththeincreaseofchargedensityorslidingspeed.Thewearrateofcopperincreaseswiththeincreaseofchargedensity,whilethewearrateofchromebronzedecreaseswiththeincreaseofchargedensity.Thewearmechanismunderchargedconditionsisdifferentfromthatunderunchargedconditions,mainlyincludingmicro-cutting,micro-plowing,micro-cracking,andelectrochemicalcorrosion.Inadditiontotheexperimentalresults,theoreticalanalysisanddiscussionarealsoneededtounderstandtheunderlyingmechanismsoftheobservedphenomena.Thedecreaseinfrictioncoefficientwithincreasingchargedensityorslidingspeedcanbeexplainedbytheinfluenceoftheelectricfieldonthecontactpressure,whichleadstoareductionintherealcontactareaandthusthefrictionforce.Theincreaseinwearrateofcopperwithincreasingchargedensitycanbeattributedtotheelectrochemicalcorrosioncausedbytheaccumulationofelectricchargesandtheformationofelectricmicro-arcs,whichcancauselocalheatingandchemicalreactions,leadingtomaterialloss.Thedecreaseinwearrateofchromebronzewithincreasingchargedensitymaybeduetotheformationofaprotectiveoxidelayeronthesurfaceofthealloy,whichcanresistthecorrosiveeffectoftheelectricfieldandreducewear.

Thewearmechanismsobservedunderchargedconditions,suchasmicro-cutting,micro-plowing,micro-cracking,andelectrochemicalcorrosion,arealsoinfluencedbythechargedensity,contactpressure,andslidingspeed.Understandingthecomplexinterplaybetweenthesefactorsisimportantfordesigningandoptimizingtribologicalsystemsunderchargedconditions,suchasthoseencounteredinaerospaceorelectricalengineeringapplications.

Overall,thestudyofthefrictionandwearpropertiesofcopperalloy/copperfrictionpairsunderchargedconditionsisimportantforimprovingthedurabilityandreliabilityofthesematerialsinindustrialandengineeringsettings.Itprovidesinsightsintothefundamentalphysicsandchemistryoftribologicalprocesses,andcanguidethedevelopmentofnewmaterials,coatings,lubricants,andtechnologiesthatcanbetterwithstandthechallengesofchargedenvironments.Anotherimportantaspecttoconsiderwhenstudyingthefrictionandwearpropertiesofcopperalloy/copperfrictionpairsunderchargedconditionsistheeffectoftemperature.Theresistiveheatingcausedbytheelectricallychargedinterfacescanleadtoasignificantincreaseintemperature,whichcanfurtheraffectthefrictionandwearbehaviorofthematerials.Hightemperaturescanincreasetherateofchemicalreactionsandcorrosion,andcanalsocausethermalsofteningandmeltingofthematerials,leadingtoacceleratedwearandfailure.

Therefore,itisimportanttointegratetemperaturecontrolandmonitoringintotheexperimentalsetupwhenstudyingtribologicalprocessesunderchargedconditions.Thiscaninvolvetheuseofcoolingsystems,suchasheatsinks,orthemeasurementoftemperatureusingthermocouplesorinfraredcameras.

Furthermore,thelubricationconditionscanalsohaveasignificantimpactonthefrictionandwearbehaviorofmaterialsunderchargedconditions.Theuseofappropriatelubricantsorcoatingscanreducetheeffectsofelectrochemicalcorrosionandmitigatethedetrimentaleffectsofhightemperatureandcontactpressure.Moreover,theuseoflubricantsorcoatingsthatcangenerateatribofilmorprotectiveoxidelayercanfurtherenhancethetribologicalperformanceofthematerials.

Inconclusion,thestudyofthefrictionandwearpropertiesofcopperalloy/copperfrictionpairsunderchargedconditionsisacomplexandinterdisciplinaryresearchfieldthatencompassesphysics,chemistry,materialsscience,andengineering.Theinsightsgainedfromsuchstudiescanhelptoimprovethedurability,reliability,andsafetyoftribologicalsystemsoperatinginchargedenvironments,andcanalsocontributetothedevelopmentofadvancedmaterialsandtechnologiesforaerospace,electrical,andotherindustrialapplications.Anotherconsiderationwhenstudyingthefrictionandwearpropertiesofcopperalloy/copperfrictionpairsunderchargedconditionsistheeffectofsurfaceroughness.Surfaceroughnessplaysanimportantroleintribologicalprocesses,asitcaninfluencethecontactarea,contactpressure,andadhesionbetweenthematerials.Underchargedconditions,surfaceroughnesscanalsoaffectthedistributionandintensityofelectricalchargesandcurrentflow,leadingtochangesinthetriboelectriceffectandelectrochemicalreactions.Therefore,itisimportanttocarefullycontrolandanalyzethesurfaceroughnessofthematerialsusedintribologicalexperiments.

Inaddition,thetypeandconcentrationofimpuritiespresentinthematerialscanalsoaffecttheirfrictionandwearbehaviorunderchargedconditions.Impuritiescanalterthechemistryandmorphologyofthematerialsurface,affectingitsmechanicalandelectricalproperties.Furthermore,impuritiescanactassitesforelectrochemicalreactionsorcatalyzechemicalreactions,leadingtoacceleratedcorrosionordegradation.

Lastly,itisimportanttoconsidertheeffectsofagingordegradationonthefrictionandwearbehaviorofcopperalloy/copperfrictionpairsunderchargedconditions.Theexposureofmaterialstochargedenvironmentscanleadto