文档名：大气等离子喷涂制备Yb2Si2O7环境障涂层1350～1500℃水蒸气下的腐蚀行为
摘要：为了深入了解双硅酸镱(Yb2Si2O7)环境障涂层水蒸气腐蚀机理,采用大气等离子喷涂技术制备全包覆Si/Yb2Si2O7双层环境障涂层,水蒸气腐蚀实验(1350～1500℃,90%H2O/10%O2,体积分数,200h)后对不同阶段和不同温度的样品进行表征以分析腐蚀行为和腐蚀机理.结果表明:在1350～1500℃范围内腐蚀200h,Yb2Si2O7层整体结构完整,热生长氧化物层生长速率较慢且符合线性增长,对SiC基体具有良好的保护作用,涂层没有发生剥落失效.在不同温度下,水蒸气腐蚀机理不同,不仅有SiO2的挥发,还会发生"自修复"反应,同时Al(OH)3的污染也会影响腐蚀行为.
Abstract：IntroductionSiC-basedceramicmatrixcomposites(SiC-CMCs)canmeetbothoftheseconditionsforexcellenthigh-temperaturestrengthandoxidationresistancesimultaneously,makingthemhighlypromisinglightweightstructuralmaterialsforfutureaerospaceengineapplications.SidioxidegeneratesvolatileSi(OH)4compoundswhenreactingwithwatermoleculesinthehigh-temperatureenvironmentofanengineinwhichthereexistswaterandoxygencorrosion.Withtheprogressofthereaction,theSiCsubstrateiscontinuouslylost,resultinginasharpdeclineinthephysicalandchemicalpropertiesofCMCs.Therefore,environmentalbarriercoatings(EBCs)areneededtobecoatedontheCMCssurfacetopreventthematerialsfrombeingdamagedbycorrosivemediasuchaswatervaporandimprovetheservicelifeofSiC-CMCs.Si/Yb2Si2O7EBCsisformedbyarelativelymaturecontrollablepreparationmethod,anditsresistancetowatervaporcorrosionisakeytotherelatedresearch.Jianetal.foundthatYb2Si2O7coatinghadanexcellentphasestabilityunderthewatervaporcorrosionat1300℃.Thegrowthofthermallygrownoxides(TGO)waseffectivelycontrolled.Theoxidationweightgainrateofthecoatedsamplewaslowerthanthatoftheuncoatedsample,thusindicatingthatYb2Si2O7topcoatcouldhaveanexcellentcorrosionresistance.Zhangetal.observeda"self-healing"reactionofYb2Si2O7topcoatinthewatervaporcorrosionat1350℃,andthegrowthoftheTGOlayershowedapositivelinearrelationshipwithtime,andtheoverallstructureofthecoatingwasbasicallyintact.Ridleyetal.reportedthatafterYb2Si2O7topcoatwassubjectedtowatervaporcorrosionat1400℃,aporousYb2SiO5layerwasformed,thethicknessandporesizeincreasedwithtime,andadistinctlayeredstructureappearedinthereactionlayersinthehigh-speedarea,i.e.,aporousYb2SiO5layer,adenseYb2SiO5layer,andahighlyporousYb2O3layer.Theexistenceofthedenselayerhinderedtheinwarddiffusionofwatervaporandoxygen,reducingthetotalthicknessofthereactionlayerandeffectivelyprotectingSiCsubstrate.Inthispaper,agradientstructureyttriumsilicate-basedenvironmentalbarriercoatingwaspreparedfortheimprovementofhigh-performanceaero-enginethermalprotectioncoatingmaterial.Inaddition,thecontinuouswatervapordamagebehaviorandcorrosionmechanismat1350-1500℃werealsoinvestigated.MethodsSiCcompositesampleswerecuttoacubeof10mm×10mm×10mm.Sibondcoat(～50μm)andYb2Si2O7topcoat(～200μm)bothweredepositedbyanairplasmaspraytechniqueinanairplasmaspraysystem.Thesesampleswereannealedinvacuumat1300℃for2hbeforethecorrosiontest.Theequipmentusedforcontinuouswatervaporexposurewasaself-designedexperimentalplatform.Andthecoatingsampleswereplacedinaflowing90%(involume)H2O-10%O2underanatmosphericpressure.Fortheexperiments,thefurnacetemperaturewassetatdifferenttemperatures(i.e.,1350,1400,1450℃and1450℃),respectively.Thetensampleswerepreparedinazirconiacrucible.Finally,thesamplewasremovedfromthefurnacetubeateachtemperaturefordifferentdurations(i.e.,50,100,150hand200h).ThecompositionphasesonthesurfaceofthesampleswereanalyzedbyamodelXD-3X-raydiffractomter(XRD,AerisCo.,theNetherlands).ThemicrostructureofthesamplecrosssectionandthethicknessoftheTGOlayerinsecondaryelectron(SE)andbackscatteredelectron(BSE)imagesweredeterminedbyamodelMIRA3emission-scanningelectronmicroscopy(SEM,TescanCo.,CzechRepublic).TheelementdistributionandproportionwerecharacterizedbyanenergydispersiveX-rayspectroscope(EDS).ResultsanddiscussionAfter200hwatervaporcorrosion,thecoatingsatdifferenttemperaturesshowdifferentresults.At1350℃,thecoatingshowsatransformationfromYb2Si2O7phasetoYb2SiO5phase,aswellassomeholesappearduetothevolatilizationofSi(OH)4.Thecoefficientofthermalexpansion(CTE)mismatchresultsina"fragmented"layeronthetopofthecoating.At1400℃,a"self-healing"reactionoccursinthecoatings.TheproportionofYb2Si2O7phaseincreasesslightly,andsometransversecracksheal.The"self-healing"reactionisrelatedtoSi(OH)4concentration.Also,Yb2O3phaseappears,andsomecracksoccurduetotheCTEmismatch.At1450℃,ablackphase(i.e.,Yb3Al5O12)appearsonthetopofthecoatings.GaseousAl(OH)3diffusesintothecoating,andadarkmullitephaseforms.The"self-healing"reactionstillexistsat1450℃.At1500℃,manytransversecracksappearonthetopofthecoatings,the"self-healing"reactionisinhibited,Yb2O3phaseappearsatthecoatinginterface,andmanycracksandholesoccurinsidethecoating.ThecoatingmassgainandTGOgrowtharelinearlyrelatedtothecorrosiontimeat<1500℃,buttheyarenotrelatedtothecorrosiontimeat1500℃.ConclusionsAfter200hcontinuouswatervaporcorrosionat1350-1500℃,Yb2Si2O7topcoatexhibitedanexcellentphasestability,andTGOlayergrewataslowrate.ThisindicatedthatSi/Yb2Si2O7bi-layerEBCscouldhaveagoodcorrosionresistance,andthepreparationprocessofthefullycoveredsamplecouldreflecttheprotectiveeffectofthecoatingontheSiCsubstrate.Thecorrosionmechanismsweredifferentatdifferentstartingtemperatures.At1350℃,thereactionvolumeofYb2Si2O7andwatervapordecreasedtogeneratecracks,andtheCTEmismatchoftheproductYb2SiO5ledtocrackexpansion.At1400℃and1450℃,the"self-healing"reactiongraduallyplayedadominantrole,andthenewphasegeneratedbythepenetrationofAl(OH)3ledtosomeholesinthecoating.At1500℃,watervapordiffusedtoSi/Yb2Si2O7coatinterfaceinthelaterstageofcorrosionandreactedtoproduceYb2O3phase,resultinginchannelcracksattheTGOlayerinterface.
作者：柯希嘉 王长亮Author：KEXijia WANGChangliang
作者单位：中国航发北京航空材料研究院,中国航空发动机集团航空材料先进腐蚀与防护重点实验室,北京100095
刊名：硅酸盐学报 ISTICEIPKU
Journal：JournaloftheChineseCeramicSociety
年，卷(期)：2024, 52(7)
分类号：V254.2
关键词：双硅酸镱 环境障涂层 水蒸气腐蚀 等离子喷涂
Keywords：ytterbiumdisilicate environmentalbarriercoating watervaporcorrosion atmosphereplasmaspray
机标分类号：TG174TB323TQ174.75
在线出版日期：2024年7月24日
基金项目：中国科学技术协会青年人才托举工程项目大气等离子喷涂制备Yb2Si2O7环境障涂层1350～1500℃水蒸气下的腐蚀行为[
期刊论文] 硅酸盐学报--2024, 52(7)柯希嘉 王长亮为了深入了解双硅酸镱(Yb2Si2O7)环境障涂层水蒸气腐蚀机理,采用大气等离子喷涂技术制备全包覆Si/Yb2Si2O7双层环境障涂层,水蒸气腐蚀实验(1350～1500℃,90%H2O/10%O2,体积分数,200h)后对不同阶段和不同温度的样品进行...参考文献和引证文献
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