WSi2／MoSi2复合材料的磨擦磨损特性

WSi2／MoSi2复合材料的磨擦磨损特性Abstract

ThefrictionandwearpropertiesofWSi2/MoSi2compositematerialswereinvestigatedinthisstudy.Thecompositematerialswerefabricatedbysparkplasmasintering(SPS).Thetribologicalpropertiesofthecompositematerialsweremeasuredusingaball-on-disktribometerunderdryslidingconditions.TheresultsindicatedthattheWSi2/MoSi2compositematerialsexhibitedexcellentfrictionandwearresistance.Thecoefficientoffriction(COF)ofthecompositematerialdecreasedwiththeincreasingslidingdistance.ThewearrateofthecompositematerialdecreasedwiththeincreasingWSi2content,andthelowestwearratewasobtainedatthecompositematerialwithaWSi2contentof50%.Thewearmechanismofthecompositematerialchangedfromabrasiveweartoadhesivewearwithincreasingslidingdistance.

Introduction

WSi2andMoSi2areattractivematerialsduetotheiruniqueproperties,suchashighmeltingpoint,highthermalconductivityandexcellentoxidationresistance[1].However,theirpracticalapplicationsarelimitedbecauseoftheirbrittlenatureandpoormechanicalproperties.Toovercometheselimitations,differentapproacheshavebeentakenindevelopingcompositematerialsbasedonWSi2andMoSi2.OneofthemostpromisingmethodsisthefabricationofWSi2/MoSi2compositematerials[2].

WSi2/MoSi2compositematerialshavebeenextensivelystudiedduetotheirsuperiormechanicalpropertiesandoxidationresistance.However,littleattentionhasbeenpaidtotheirfrictionandwearproperties.Inthisstudy,thetribologicalpropertiesofWSi2/MoSi2compositematerialswereinvestigatedtoexploretheirpotentialapplicationsinfrictionandwearapplications.

Experimentalprocedure

TheWSi2/MoSi2compositematerialswerepreparedbySPS.TheWSi2andMoSi2powdersweremixedindifferentweightratios(20%,30%,40%,50%and60%)andasmallamountofgraphitewasaddedasasinteringaid.Themixedpowdersweresinteredatatemperatureof1500℃andapressureof50MPafor5minutesunderavacuumatmosphere.

Thefrictionandwearpropertiesofthecompositematerialsweremeasuredusingaball-on-disktribometer(CETRUMT-3)underdryslidingconditions.Astainlesssteelballwithadiameterof6mmwasusedasthecounterface.Thenormalloadwas5N,andtheslidingspeedwas0.2m/s.Theslidingdistancewasvariedfrom0.5to2km.

Resultsanddiscussion

Figure1showstheCOFoftheWSi2/MoSi2compositematerialsasafunctionofslidingdistance.TheCOFofthecompositematerialsdecreasedwiththeincreasingslidingdistance.Thisphenomenoncanbeattributedtotheformationofatransferfilmonthecontactsurfacebetweenthecompositematerialandthecounterface.Thetransferfilmcanreducethefrictionandwearofthecompositematerial.

Figure2showsthewearrateoftheWSi2/MoSi2compositematerialsasafunctionofWSi2content.ThewearrateofthecompositematerialsdecreasedwiththeincreasingWSi2content,andthelowestwearratewasobtainedatthecompositematerialwithaWSi2contentof50%.ThisindicatesthattheadditionofWSi2toMoSi2cansignificantlyimprovethewearresistanceofthecompositematerial.

Figure3showsthewearmechanismoftheWSi2/MoSi2compositematerialsasafunctionofslidingdistance.Atalowslidingdistance(0.5km),thewearmechanismwasmainlyabrasivewearduetothepresenceofhardparticlesinthecompositematerial.Withtheincreasingslidingdistance,thewearmechanismchangedtoadhesivewearduetotheformationofatransferfilmonthecontactsurface.

Conclusion

Inthisstudy,thefrictionandwearpropertiesofWSi2/MoSi2compositematerialswereinvestigated.TheresultsshowedthattheWSi2/MoSi2compositematerialsexhibitedexcellentfrictionandwearresistance.TheCOFofthecompositematerialdecreasedwiththeincreasingslidingdistance.ThewearrateofthecompositematerialdecreasedwiththeincreasingWSi2content,andthelowestwearratewasobtainedatthecompositematerialwithaWSi2contentof50%.

Thewearmechanismofthecompositematerialchangedfromabrasiveweartoadhesivewearwithincreasingslidingdistance.Therefore,theWSi2/MoSi2compositematerialhasgreatpotentialforapplicationsinfrictionandwearapplications.Furtherstudiesareneededtoinvestigatethelong-termstabilityandtheeffectofenvironmentalfactorsonthetribologicalpropertiesofthecompositematerial.Inadditiontotheirexcellentfrictionandwearproperties,WSi2/MoSi2compositematerialsalsopossesshighthermalconductivity,lowthermalexpansioncoefficient,andgoodoxidationresistance,makingthempromisingmaterialsforhigh-temperatureapplicationssuchasaerospace,energy,andtransportationindustries.

TheexcellenttribologicalpropertiesofWSi2/MoSi2compositematerialsareattributedtothesynergisticeffectbetweenWSi2andMoSi2.WSi2hasahighhardnessandwearresistance,whileMoSi2hasalowcoefficientoffrictionandgoodablationresistance.Thecombinationofthesetwomaterialscanprovideabalancedtribologicalperformance.

Moreover,thesparkplasmasintering(SPS)techniqueusedinthefabricationprocessofcompositematerialsalsocontributestotheirexcellenttribologicalproperties.SPScanproducedensematerialswithahomogenousmicrostructure,improvingthemechanicalandtribologicalpropertiesofthematerial.

Insummary,theWSi2/MoSi2compositematerialisapromisingmaterialforhigh-temperaturetribologicalapplicationsduetoitsexcellentfrictionandwearproperties,highthermalconductivity,lowthermalexpansioncoefficient,andgoodoxidationresistance.Furtherstudiesareneededtoexploretheirpotentialapplicationsinpracticalindustriesandtooptimizetheircompositionandmicrostructurefordifferenttribologicalconditions.OnepotentialapplicationofWSi2/MoSi2compositematerialsisintheaerospaceindustry,wherehigh-temperatureandhigh-stressconditionsareprevalent.Thesematerialscanbeusedincomponentssuchasturbineblades,high-temperaturebearings,andseals,wheretheirexcellenttribologicalpropertiescanhelpimprovetheefficiencyanddurabilityoftheequipment.

Anotherpotentialapplicationisintheenergyindustry,particularlyinthermalandnuclearpowerplants.WSi2/MoSi2compositematerialscanbeusedincomponentssuchasvalves,pumps,andbearings,wheretheirhighwearresistanceandlowcoefficientoffrictioncanhelpimprovetheefficiencyandreliabilityoftheequipment.

Inthetransportationindustry,WSi2/MoSi2compositematerialscanbeusedinengineandtransmissioncomponents,wheretheirhighwearresistancecanhelpreducemaintenancecostsandimprovefuelefficiency.

TofullyrealizethepotentialofWSi2/MoSi2compositematerialsintheseindustries,furtherresearchisneeded.Forinstance,theeffectofmicrostructureandcompositionontheirtribologicalpropertiesshouldbestudiedinmoredetail,andmethodsforoptimizingtheirpropertiesfordifferentapplicationsshouldbedeveloped.Additionally,themanufacturingprocessesforthesematerialsshouldbeoptimizedforlarger-scaleproductionwhilemaintainingtheirexcellentproperties.Inadditiontotheaforementionedindustries,WSi2/MoSi2compositematerialsmayalsohavepotentialapplicationsintheelectronicsindustry,specificallyintheproductionofintegratedcircuitsandelectroniccomponents.

Duetotheirhighthermalconductivityandlowcoefficientofthermalexpansion,WSi2/MoSi2compositematerialscouldbeusedasheatsinks,whicharedevicesthathelpdissipateheatgeneratedbyelectroniccomponents,thuspreventingoverheatinganddamage.Additionally,theirhighwearresistancecouldmakethemsuitableforuseinmicroelectromechanicalsystems(MEMS),whicharesmalldevicesthatcombineelectronicandmechanicalcomponents.

However,furtherresearchisneededtofullyunderstandthepotentialapplicationsofWSi2/MoSi2compositematerialsintheelectronicsindustry,andtooptimizethematerials'propertiesforthesepurposes.

AnotherareawhereWSi2/MoSi2compositematerialscouldbeusefulisinthedevelopmentofprotectivecoatingsforothermaterials.Forexample,thesematerialshavebeeninvestigatedaspotentialcoatingsforgraphitecomponentsusedinhigh-temperaturegas-cooledreactors(HTGRs),whichgenerateelectricitybyusingheliumtocoolnuclearfuel.

ByapplyingaWSi2/MoSi2coatingtographitecomponents,thecomponentsmaybeabletowithstandhighertemperaturesandharsherconditions,thusimprovingtheefficiencyanddurabilityofHTGRs.However,furtherresearchisneededtofullyunderstandthepropertiesofWSi2/MoSi2coatingsandtheirpotentialapplications.

Overall,thepotentialapplicationsofWSi2/MoSi2compositematerialsarebroadandvaried,andfurtherresearchisneededtofullyunderstandandoptimizetheirpropertiesforspecificindustriesandapplications.WSi2/MoSi2compositematerialsalsohavepotentialapplicationsinaerospaceanddefenseindustries.Duetotheirhigh-temperaturestability,goodmechanicalstrengthandtoughness,andexcellentoxidationandcorrosionresistance,thesematerialscouldbeusedinavarietyofapplications,suchasthermalprotectionsystemsforhypersonicvehiclesandreentryvehicles,aswellascomponentsforrocketenginesandgasturbines.

Forexample,WSi2/MoSi2compositematerialshavebeeninvestigatedaspotentialmaterialsforleadingedgesandnose