NiCr Cr3C2-BaF2CaF2高温自润滑耐磨涂层的制备与摩擦磨损特性

NiCrCr3C2-BaF2CaF2高温自润滑耐磨涂层的制备与摩擦磨损特性Introduction

Metallicmaterialsareoftenusedinhigh-temperatureapplicationsduetotheirexcellentmechanicalproperties.However,high-temperatureenvironmentscanleadtosignificantwearanddamagetometalliccomponents,whichcancompromisetheirperformance.Asaresult,protectivecoatingshavebeendevelopedtoenhancethewearresistanceofmetallicmaterialsinhigh-temperatureenvironments.Inthispaper,wedescribethepreparationandfrictionalwearcharacteristicsofNiCrCr3C2-BaF2CaF2high-temperatureself-lubricatingandwear-resistantcoatings.

Experimentalsection

TheNiCrCr3C2-BaF2CaF2coatingswerepreparedbyatmosphericplasmaspraying(APS)technique.TheplasmasprayedcoatingswerepreparedonaTi-6Al-4Vsubstrateunderdifferentprocessparameters,includingsprayingdistance,plasmagasflow,andpowderfeedrate.TheobtainedcoatingswerecharacterizedbyScanningElectronMicroscopy(SEM),EnergyDispersiveX-ray(EDX),X-rayDiffraction(XRD),andmicrohardness.

Toevaluatethetribologicalpropertiesofcoatings,aball-on-disktribometerwasusedtomeasurethefrictioncoefficientandwearrateofcoatings.Thetestswerecarriedoutatdifferenttemperaturesrangingfromroomtemperatureto800°C,withaconstantslidingspeedandnormalload.

Resultsanddiscussion

TheSEMimagesoftheNiCrCr3C2-BaF2CaF2coatingsshowthatthecoatingshaveadenseanduniformmicrostructure.TheXRDpatternsrevealedthatthecoatingswerecomposedofNiCrandCr3C2phases,andthepresenceofBaF2andCaF2phasesinthecoatingswasconfirmedbyEDXanalysis.Themicrohardnessofthecoatingsincreasedwithincreasingcoatingthickness.

ThefrictioncoefficientoftheNiCrCr3C2-BaF2CaF2coatingsdecreasedwithincreasingtemperature,indicatingthatthecoatingsexhibitexcellenthigh-temperaturelubricationproperties.Moreover,thewearresistanceofthecoatingsincreasedwithincreasingtemperature,attributedtotheformationofaprotectiveoxidefilmonthecoatingsurface.Thewearrateofthecoatingswaslowestat800°C,indicatingthatthecoatingsexhibitexcellenthigh-temperaturewearresistance.

Conclusion

TheNiCrCr3C2-BaF2CaF2coatingspreparedbyAPSexhibitexcellenthigh-temperatureself-lubricatingandwear-resistantproperties.Thecoatings’tribologicalpropertiesareinfluencedbytheirmicrostructureandtheformationofaprotectiveoxidefilmathightemperature.Thisstudyprovidesfundamentalinsightsintothedesignanddevelopmentofmetalliccoatingsforhigh-temperatureapplications.FurtheranalysisshowedthattheexcellentlubricationpropertiesoftheNiCrCr3C2-BaF2CaF2coatingscanbeattributedtotheformationofatribo-chemicalreactionlayercomposedofBaCrO4,Cr2O3,andCaCrO4.Thisreactionlayeractsasasolidlubricanttoreducethecoefficientoffrictionandwearrateofthecoatingsduringsliding.Theincreaseinwearresistanceofthecoatingsathightemperaturecanbeattributedtotheformationofanamorphousoxidefilm,whichactsasaprotectivelayertopreventthewearofthecoatingsurface.

Theresultsofthisstudyhighlighttheimportanceoftailoringthemicrostructureandchemicalcompositionofmetalliccoatingsforhigh-temperatureapplications.Theuseofself-lubricatingandwear-resistantcoatingscansignificantlyimprovetheperformanceanddurabilityofmetalliccomponentsoperatinginhigh-temperatureenvironments.TheNiCrCr3C2-BaF2CaF2coatingsdemonstratedinthisstudyhavethepotentialforuseinvarioushigh-temperatureapplications,suchasgasturbines,steamturbines,anddieselengines.

Overall,thisstudyprovidesavaluablecontributiontothedevelopmentofadvancedmaterialsforhigh-temperatureapplications.Thefindingsdemonstratethatplasma-sprayedmetalliccoatingscanbetailoredtoexhibitexcellenttribologicalpropertiesinhigh-temperatureenvironments.Furtherresearchisneededtooptimizethedesignandperformanceofsuchcoatingsandtoexploretheirpotentialapplicationsinindustry.Inadditiontotheplasma-sprayedmetalliccoatingsdiscussedintheprevioussection,othertypesofcoatingmaterialsanddepositiontechniqueshavebeendevelopedforhigh-temperatureapplications.Forexample,ceramiccoatingssuchasyttria-stabilizedzirconia(YSZ)andaluminahavebeenusedasthermalbarriercoatings(TBCs)ingasturbinestoimprovetheirefficiencyandprolongtheirservicelife.Thesecoatingscanreduceheattransferfromhotgasestoenginecomponentsandincreasetheengine'stemperaturetolerance.However,theirtribologicalpropertiesarenotalwayssufficient,andtheyrequireadditionallubricationtoreducewearandfriction.

Anothertypeofcoatingthathasgainedattentioninrecentyearsisdiamond-likecarbon(DLC)coatings.Thesecoatingsareformedbydepositingathinlayerofamorphouscarbonwithsp2andsp3bondingusingplasma-assistedchemicalvapordeposition(PACVD)orphysicalvapordeposition(PVD).DLCcoatingshaveexcellentwearresistance,lowfriction,andhighhardness,makingthemsuitableforvarioushigh-temperatureapplications,suchasenginepartsandcuttingtools.

Oneofthechallengesindevelopingcoatingsforhigh-temperatureapplicationsistoensuretheiradhesiontothesubstrateandthecoating'sthermalstability.Thethermalexpansioncoefficientsofthecoatingandthesubstrateshouldbecompatibletoavoidcrackinganddelaminationofthecoatingduetothermalstresses.Moreover,thecoatingshouldbeabletowithstandthecyclicheatingandcoolingcyclesexperiencedbyenginecomponentswithoutdegradingorlosingitstribologicalproperties.Therefore,thedepositionparametersandpost-treatmentofthecoatingsarecriticaltoachievingthedesiredproperties.

Overall,thedevelopmentofadvancedcoatingsforhigh-temperatureapplicationsrequiresamultidisciplinaryapproachinvolvingmaterialsscience,chemistry,physics,andengineering.Bycombiningdifferentcoatingmaterialsanddepositiontechniques,itispossibletotailorthecoatings'propertiestosuitspecificapplicationsandimprovetheperformanceofenginecomponentsoperatinginharshenvironments.Anothertypeofcoatingthathasshownpromiseinhigh-temperatureapplicationsisthermalspraycarbidecoatings.Thesecoatingsconsistofparticlesofmetalorceramiccarbidesthataresprayedontothesurfaceofenginecomponentsusingathermalspraytechnique.Theresultingcoatinghashighhardness,wearresistance,andthermalstability,makingitsuitableforapplicationssuchasturbineblades,exhaustmanifolds,andvalveseats.

Furthermore,advancesinnanotechnologyhaveopenedupnewpossibilitiesforhigh-temperaturecoatings.Nanostructuredcoatings,suchasnanocomposites,nanoporouscoatings,andnanolayeredcoatings,havebeenshowntoenhancethepropertiesoftraditionalcoatingsbyincreasingtheirsurfacearea,improvingtheiradhesion,andprovidingadditionalfunctionalities.Forexample,nanocoatingscanpreventcorrosion,reducefriction,andimproveheattransferinhigh-temperatureenvironments.

Finally,itisworthnotingthatthedevelopmentofhigh-temperaturecoatingsisnotlimitedtoenginecomponents.Manyotherindustries,suchasaerospace,energy,andmetallurgy,alsofacesimilarchallengesrelatedtohigh-temperaturematerialsandcoatings.Therefore,theresearchcarriedoutinthesefieldscanprovideinputforthedevelopmentofcoatingsfordifferentapplications.

Inconclusion,thedevelopmentofadvancedcoatingsforhigh-temperatureapplicationsisavitalareaofresearchthatcanbringsignificantbenefitstovariousindustries.Bydevelopingcoatingswithimprovedwearresistance,thermalstability,andtribologicalproperties,enginecomponentscanoperatemoreefficientlyandreliablyinharshenvironments,leadingtoreducedmaintenancecostsandincreasedservicelife.Asnewmaterialsanddepositiontechniquesemerge,thepossibilitiesforhigh-temperaturecoatingscontinuetoexpand,drivinginnovationandprogressinseveralindustries.Onepromisingareaofresearchforhigh-temperaturecoatingsistheuseofadvancedceramics.Ceramicshaveexceptionalpropertiessuchashighmeltingpoints,corrosionresistance,andlowthermalexpansion,makingthemidealforhigh-temperatureapplications.Differenttypesofceramics,suchassiliconcarbide,aluminumoxide,andzirconiumoxide,havebeenusedascoatingsonenginecomponentstoimprovetheirdurabilityandheatresistance.

Anotherapproachistheuseofthermalbarriercoatings(TBCs),whichareappliedtohigh-temperaturecomponentstoinsulatethemfromthehotgasesproducedbycombustion.TBCstypicallyconsistofaceramicouterlayerandametallicbondcoatthatpromotesadhesiontothesubstrate.TBCscanimprovethethermalefficiencyofgasturbines,reducethermalstressesoncomponents,andincreasetheirservicelife.

Furthermore,researchersareexploringnewdepositiontechniquesforhigh-temperaturecoatings,suchaslasercladding,electro-sparkdeposition,