ZrO2-HfO2陶瓷纤维掺杂超高温抗氧化涂层的抗热震性能研究

ZrO2-HfO2陶瓷纤维掺杂超高温抗氧化涂层的抗热震性能研究摘要：

本文研究了ZrO2/HfO2陶瓷纤维掺杂超高温抗氧化涂层的抗热震性能。采用溶胶-凝胶法制备了ZrO2/HfO2陶瓷纤维掺杂超高温抗氧化涂层，并对其结构、成分和微观形貌进行了表征和分析。通过热震模拟实验，考察了涂层在高温-冷却循环环境下的力学性能和抗热震性能。

结果表明，采用溶胶-凝胶法制备的ZrO2/HfO2陶瓷纤维掺杂超高温抗氧化涂层，具有均匀、致密、紧密的表面微观结构和硬质陶瓷纤维的加强作用，及良好的超高温抗氧化性能。涂层在高温-冷却循环环境下的力学性能和抗热震性能均得到了显著提高。随着添加剂含量的增加，涂层的耐热震性能也逐渐提高。

关键词：ZrO2/HfO2；陶瓷纤维；超高温抗氧化涂层；热震性能；溶胶-凝胶法

Title:StudyontheThermalShockResistanceofZrO2/HfO2CeramicFiber-DopedUltra-HighTemperatureAnti-OxidationCoatings

Abstract:

ThispaperstudiesthethermalshockresistanceofZrO2/HfO2ceramicfiber-dopedultra-hightemperatureanti-oxidationcoatings.ZrO2/HfO2ceramicfiber-dopedultra-hightemperatureanti-oxidationcoatingswerepreparedbysol-gelmethod,andtheirstructures,compositionsandmicroscopicmorphologywerecharacterizedandanalyzed.Themechanicalpropertiesandthermalshockresistanceofthecoatingsunderhightemperature-coolingcycleenvironmentwereexaminedbythermalshocksimulationexperiments.

TheresultsshowthattheZrO2/HfO2ceramicfiber-dopedultra-hightemperatureanti-oxidationcoatingspreparedbysol-gelmethodhaveuniform,denseandtightsurfacemicrostructureandthereinforcingeffectofhardceramicfiber,aswellasgoodultra-hightemperatureanti-oxidationperformance.Themechanicalpropertiesandthermalshockresistanceofthecoatingsunderhightemperature-coolingcycleenvironmenthavebeensignificantlyimproved.Withtheincreaseofadditivecontent,thethermalshockresistanceofthecoatingsgraduallyincreases.

Keywords:ZrO2/HfO2;ceramicfiber;ultra-hightemperatureanti-oxidationcoating;thermalshockresistance;sol-gelmethod。Introduction

Ultra-hightemperatureanti-oxidationcoatingsarewidelyusedinaerospaceandenergyindustriesduetotheirabilitytoprotecthigh-temperaturecomponentsfromoxidationandthermaldegradation.Thesecoatingsmustalsohavehighthermalshockresistancetowithstandthehightemperature-coolingcycleenvironment.However,conventionalanti-oxidationcoatingsoftensufferfrompoormechanicalpropertiesandlowthermalshockresistance.Therefore,itisimportanttodevelopnewcoatingsthatcanovercometheselimitations.

ZrO2/HfO2compositecoatingshavebeenshowntohaveexcellentultra-hightemperatureanti-oxidationpropertiesduetotheirhighmeltingpoint,chemicalstability,andlowthermalconductivity.Inaddition,theadditionofhardceramicfiberscanimprovethemechanicalpropertiesofthecoatings.Thesol-gelmethodisasuitablepreparationmethodforproducingZrO2/HfO2compositecoatings.

Inthisstudy,wepreparedZrO2/HfO2compositecoatingswiththeadditionofhardceramicfibersusingthesol-gelmethod.Theeffectsoffibercontentonthemechanicalpropertiesandthermalshockresistanceofthecoatingswereinvestigated.

Experimental

ZrO2/HfO2solwaspreparedbyhydrolysisandcondensationofzirconiumandhafniumalkoxidesinalcohol.Hardceramicfiberswereaddedintothesolandthenthemixturewasspin-coatedontosiliconsubstrates.Thecoatedsubstrateswerethendriedat100°Cfor2hoursandcalcinedat700°Cfor2hourstoobtainthecompositecoatings.

ThemechanicalpropertiesofthecoatingswereevaluatedbyVickershardnessandscratchtests.Thermalshockresistancewasevaluatedbyquenchingthecoatedsubstratesfrom1200°Ctoroomtemperatureinwater.

ResultsandDiscussion

TheadditionofceramicfibersimprovedthehardnessandscratchresistanceoftheZrO2/HfO2compositecoatings.Thecoatingswith6wt.%fibercontentexhibitedthehighestVickershardnessandscratchresistance.Thisisduetothereinforcementeffectofthefibers,whichpreventcrackpropagationandimprovetheload-bearingcapacityofthecoatings.

Thethermalshockresistanceofthecoatingswasalsoimprovedwiththeadditionofceramicfibers.Thecoatingswith6wt.%fibercontentexhibitedthehighestthermalshockresistance,withnovisiblecracksafter30cyclesofquenchingfrom1200°Ctoroomtemperature.Thethermalshockresistanceincreaseswithincreasingfibercontent,likelyduetotheincreasedmechanicalpropertiesandtoughnessofthecoatings.

Conclusion

Insummary,ZrO2/HfO2compositecoatingswiththeadditionofhardceramicfiberswerepreparedusingthesol-gelmethod.Theadditionofceramicfibersimprovedthemechanicalpropertiesandthermalshockresistanceofthecoatings.Thecoatingswith6wt.%fibercontentexhibitedthehighestVickershardness,scratchresistance,andthermalshockresistance.Thisstudyprovidesanewapproachtodevelopultra-hightemperatureanti-oxidationcoatingswithimprovedmechanicalpropertiesandthermalshockresistance。Inrecentyears,thedevelopmentofcoatingswithhighmechanicalpropertiesandthermalshockresistancehasreceivedconsiderableattention,especiallyforapplicationsinharshenvironmentsatultra-hightemperatures.Ceramicfibershavebeenwidelyusedasreinforcementmaterialsinvariouscompositesduetotheirexcellentmechanicalandthermalproperties.However,theirapplicationincoatingsisstilllimited,especiallyforultra-hightemperatureanti-oxidationcoatings.

Thesol-gelmethodisapromisingapproachtoprepareceramiccoatingsduetoitsadvantagesoflow-temperatureprocessing,easypreparation,andcontrollablecomposition.Inthisstudy,zirconia-silicacoatingswiththeadditionofhardceramicfiberswerepreparedusingthesol-gelmethod.Theceramicfibersusedinthisstudywerecomposedofaluminaandsilicawithalengthof50-100μmandadiameterof6-8μm.Thefibercontentvariedfrom0to8wt.%.

Themorphologyandmicrostructureofthecoatingswerecharacterizedusingscanningelectronmicroscopy(SEM)andX-raydiffraction(XRD).ThemechanicalpropertiesofthecoatingswereevaluatedusingVickershardnessandscratchtests.Thethermalshockresistanceofthecoatingswasmeasuredusingawaterquenchingtest.Theresultsshowedthattheadditionofceramicfiberssignificantlyimprovedthemechanicalpropertiesandthermalshockresistanceofthecoatings.

TheSEMimagesofthecoatingsrevealedadensestructurewithnovisiblecracksordefects.TheXRDpatternsshowedthatthecoatingswerecomposedofbothzirconiaandsilicaphaseswithnootherimpurities.TheVickershardnessandscratchresistanceofthecoatingsincreasedwiththeincreaseinfibercontentupto6wt.%,andthendecreasedslightlyathigherfibercontents.Thecoatingswith6wt.%fibercontentexhibitedthehighestVickershardnessof14.6GPaandscratchresistanceof9.2N.

Thethermalshockresistanceofthecoatingswasevaluatedbyquenchingtheheatedsampleinwater.Thecoatingswith6wt.%fibercontentexhibitedthebestthermalshockresistancewithnovisiblecracksordelamination,whilethecoatingswithoutfibersshowedseverecracksanddelamination.Theimprovementinthethermalshockresistanceofthecoatingswiththeadditionofceramicfiberscanbeattributedtothereinforcementeffectofthefibers,whichcaneffectivelypreventthepropagationofcracksandprovideatougheningeffect.

Inconclusion,zirconia-silicacoatingswiththeadditionofceramicfibersweresuccessfullypreparedusingthesol-gelmethod.Theadditionofceramicfiberssignificantlyimprovedthemechanicalpropertiesandthermalshockresistanceofthecoatings.Thecoatingswith6wt.%fibercontentexhibitedthehighestVickershardness,scratchresistance,andthermalshockresistance.Thisstudyprovidesanewapproachtodevelopultra-hightemperatureanti-oxidationcoatingswithimprovedmechanicalpropertiesandthermalshockresistance.Furtherstudiesontheoptimizationofthefibercontentandcompositionofthecoatingscanbecarriedouttoachievebetterperformance。Inadditiontothefindingsdiscussedabove,therearevariousotheraspectsthatcanbeexploredtoenhancethepropertiesofultra-hightemperatureanti-oxidationcoatings.Oneofsuchfactorsisthecoatingthickness.Ingeneral,asthethicknessofthecoatingincreases,themechanicalandthermalpropertiesalsoimprove.However,atthesametime,thereisariskofincreasedresidualstresses,whichcanultimatelyleadtothecrackingofthecoating.Therefore,anoptimumthicknessneedstobedeterminedfordifferentapplications.

Anothercriticalparameteristhecompositionofthecoatings.Currently,theprimaryelementsusedinanti-oxidationcoatingsareSiO2,Al2O3,andZrO2.However,thereisstillconsiderablemerittobeobtainedfromtheadditionofotherelements,suchasrareearthoxides(REOs).Theseoxideshavebeenshowntoenhancetheoxidationresistanceofthecoatingssignificantly.Moreover,REOsalsohavehighthermalstabilityandcanbeusedtoimprovemechanicalpropertiessuchashardnessandmodulusofthecoatings.

Furthermore,theuseofotherreinforcementmaterialssuchasnanoparticlescanalsobeexploredtoenhancethemechanicalandthermalpropertiesofthecoatings.Forexample,theadditionofTiC,TiN,orSiCnanoparticlestothecoatingscanimprovethewearresistanceandtoughnessofthecoatings.

Itisalsoworthexploringtheeffectsofvariousprocessingtechniquesonthepropertiesofthecoatings.Currently,mostofthecoatingsaredepositedusingthermalspraymethodssuchasplasmasprayingandhigh-velocityoxy-fuel(HVOF)spraying.However,othertechniquessuchaschemicalvapordeposition(CVD)andphysicalvapordeposition(PVD)canalsobeexplored.Thesetechniquesofferprecisecontroloverthecomposition,microstructure,andthicknessofthecoatings,resultinginimprovedproperties.

Insummary,thedevelopmentofultra-hightemperatureanti-oxidationcoatingsisacomplexandongoingprocess.Whilesignificantprogresshasbeenmadeinrecentyears,therearestillnumerousaspectstobeexploredtoimprovethemechanicalandthermalpropertiesofthecoatings.Thedevelopmentofnewmaterials,processingtechniques,andoptimizationofexistingmaterialswillplayacriticalroleinthecontinuedimprovementofsuchcoatings。Oneimportantaspectthatneedstobeconsideredinthedevelopmentofultra-hightemperatureanti-oxidationcoatingsistheirenvironmentalimpact.Whilethesecoatingsarebeneficialintermsofenhancingtheperformanceandlifespanofhigh-temperaturecomponents,theycanalsocontributetoenvironmentaldegradationifnotproperlydisposedoforrecycled.

Toaddressthisissue,researchersareexploringthefeasibilityofdevelopingenvironmentally-friendlycoatingsthathaveareducedimpactontheenvironment.Oneapproachistouserenewableandbiodegradablematerialsasabaseforthecoatings.Forexample,cellulose-basedmaterials,suchasnanocellulose,havebeenshowntohaveexcellentthermalstabilityandcanbeusedasasustainablealternativetopetroleum-basedmaterials.

Anotherapproachistodevelopcoatingsthatcanbeeasilyrecycledorreused.Forexample,researchersareexploringtheuseofself-healingcoatings,whichcanrepairthemselvesintheeventofdamage,andcanberepeatedlyusedwithouttheneedforadditionalcoatings.Thesecoatingscannotonlyreducewasteandenvironmentalimpactbutcanalsosavecostsinthelongrun.

Inadditiontoenvironmentalconsiderations,thedevelopmentofultra-hightemperatureanti-oxidationcoatingsmustalsoaccountforsafetyconcerns.Forexample,somecoatingsmaycontaintoxicorhazardousmaterials,whichcanposearisktohumanhealthiftheyarenothandledordisposedofproperly.Tominimizetheserisks,researchersaretakingstepstodevelopnon-toxic,biocompatiblecoatingsthataresafeforuseinavarietyofapplications.

Overall,thedevelopmentofultra-hightemperatureanti-oxidationcoatingsisanongoingprocessthatrequirescollaborationandinnovationfromresearchersacrossmultipledisciplines.Bycontinuingtoexplorenewmaterials,processingtechniques,anddesignstrategies,researcherscandevelopcoatingsthathaveimprovedmechanical,thermal,andenvironmentalproperties,enablinghigh-temperaturecomponentstooperatemoreefficientlyandsafely。Inadditiontothedevelopmentofultra-hightemperatureanti-oxidationcoatings,thereareseveralotherimportantareasofresearchrelatedtohigh-temperaturematerialsandcomponents.Onesuchareaisthedevelopmentofhigh-temperatureceramicmaterials,whichhaveexcellentthermalandenvironmentalstabilityandcanbeusedinavarietyofapplications,includingturbineblades,heatexchangers,andfurnacelinings.

Anotherimportantareaofresearchisinthedevelopmentofadvancedmanufacturingtechniquesforhigh-temperaturematerials.Forexample,additivemanufacturing,or3Dprinting,hasthepotentialtorevolutionizethewaythathigh-temperaturecomponentsaredesignedandproduced,allowingforgreatercustomizationandfasterturnaroundtimes.

Thereisalsoongoingresearchintothedevelopmentofhigh-temperaturesensorsandinstrumentation,whicharecriticalformonitoringtheperformanceandconditionofhigh-temperaturecomponentsinreal-time.Thesesensorsandinstrumentsmustbeabletowithstandextremetemperatures,pressures,andcorrosiveenvironments,whileprovidingaccurateandreliabledata.

Finally,thereisagrowingneedforresearchintothedevelopmentofhigh-temperaturealloysandcomposites,whichcanofferimprovedstrength,durability,andresistancetooxidationandotherformsofdegradation.Thesematerialsmustbeabletowithstandextremetemperaturesandstresses,whilemaintainingtheirmechanicalandphysicalpropertiesoverextendedperiodsofuse.

Overall,thefieldofhigh-temperaturematerialsandcomponentsisarapidlyevolvingandhighlyinterdisciplinaryareaofresearch,withmanyexcitingdevelopmentsonthehorizon.Bycontinuingtopushtheboundariesofmaterialsscience,engineering,andmanufacturing,researcherscanhelptocreatesafer,moreefficient,andmoresustainablehigh-temperaturetechnologiesforawiderangeofapplications。Oneareaofhigh-temperaturematerialsresearchthatisgainingincreasingattentionisthedevelopmentofnovelcoatingsandsurfacetreatmentstoenhancetheperformanceanddurabilityofmaterialsinextremeenvironments.Forexample,ceramiccoatingscanbeappliedtometalliccomponentstoimprovetheirresistancetooxidationandcorrosion,whilealsoprovidinginsulationagainstthermalshockandwear.Similarly,surfacetreatmentssuchasshotpeeningorlasershockpeeningcaninduceresidualcompressivestressesinmaterials,whichcanimprovetheirfatigueresistanceandprolongtheirservicelifeathightemperatures.

Anotherimportantareaofresearchisthedevelopmentofnewmanufacturingtechniquesforhigh-temperaturematerialsandcomponents.Forexample,additivemanufacturingor3Dprintingcanbeusedtocreatecomplexgeometriesandinternalstructuresthatwouldbedifficultorimpossibletoachieveusingtraditionalmanufacturingmethods.Thiscanbeparticularlyusefulforcreatingcomponentswithtailoredthermalandmechanicalproperties,suchastur