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1、RareMetaletal./RareMetalMaterialsandEngineering,2011,40(3):0？？？-0？？？TaSi2OxidationProtectiveCoatingforSiCCoatedCarbon/CarbonCompositesRareMetal1,2,RareMetal2,RareMetal1,RareMetal1,RareMetal21RareMetalMaterialandEngineering,NorthwestInstituteforNonferrousMetalResea
2、rch,Xi’an710016,China;2RareMetalMaterialandEngineering,NorthwestInstituteforNonferrousMetalResearch,Xi’an710016,ChinaAbstract:Modemodemodemodemode..Keywords:raremetal;material;engineeringRareMetaletal./RareMetalMaterialsandEngineering,2011,40(3):0？？？-0？？？Carbon/ca
3、rbon(C/C)compositeshavebeenusedasattractivematerialsforhigh-temperatureapplications,suchasreentryshieldsofspacevehicles,aircraftbrakeandrocketnosesetc.Inaninertatmosphereorinvacuum,C/Ccompositesretaintheirstrength,modulusandothermechanicalpropertiestotemperaturesh
4、igherthanthosetoleratedbyothermaterials.However,themostimportanthigh-temperaturestructuralapplicationsforC/Ccompositesoccurinoxidizingenvironments,andthecarboninanyformwillreactwithoxygen,oxidizeattemperaturesaslowas723K[1].So,thebroaduseofC/Ccompositesashigh-temp
5、eraturestructuralmaterialsrequiresthedevelopmentofeffectiveoxidationprotection.ThecoatingtechnologyhasbeenconsideredastheeffectivewaytoprotectC/Ccomposites[1-8].1ExperimentSmallspecimens(10mm×10mm×10mm)usedassubstrateswerecutfrom2D-C/Ccompositeswithadensityof1.78g
6、/cm3.Thespecimenswerehand-polishedusing400gritsandpaper,thencleanedwithalcoholanddriedinair.Powdercompositionsinmassfractionforpackcementationprocesswereasfollows:75%-80%Si(45µm)and20%-25%graphite(45µm)forSiCcoating,60%-75%Si(45µm),20%-30%Ta(45µm)and5%-10%graphite
7、(45µm)forTaSi2coating.Thepackmixtureswereweighedandmixedbytumblinginaballmillupto10h.ThespecimenswerefirstlycoatedbySiCcoating,andtheoperationprocesswasasfollows.ThespecimensandpowdermixturesforSiCcoatingwereputinagraphitecrucible.Thecruciblewasplacedintoafurnace,
8、whichwasheatedinargonatmosphereto1873Kandheldatthetemperaturefor2h.Secondly,theSiC-coatedsamplesandthepowdermixturesforTaSi2coatingwereputinagraphitecru
