玻璃外文文献加手工翻译

Microstructureandsolidparticleerosionofcarbonbasedmaterialsusedfortheprotectionofhighlyporouscarbon-carboncompositethermalinsulationR.I.BAXTER,R.D.RAWLINGSDepartmentofMaterials,ImperialCollegeofScience,TechnologyandMedicine,LondonSW72BP,UKMultiparticleerosiontestswereperformedoncandidatecoating(colloidalgraphitepaints)andcladding(densecarbonc—arboncompositesandgraphitefoil)materialsemployedtoprotectporouscarbon—carboncompositethermalinsulationinvacuumandinert-gasfurnacesthatutilizeinertgasquenching.ThedependenceoftheerosionrateontheangleofincidenceoftheerodentwasexaminedandrelatedtothemicrostructureandthemechanismsofmaterialremovalasobservedbySEM.Inaddition,theeffectofathinchemicalvapourdeposited(CVD)carbonlayerontopofacolloidalgraphitepaintcoatingandagraphitefoilcladwasinvestigated.Thecoatingandcladdingmaterialsdisplayedagreatererosionresistanceatallanglesofincidencecomparedtotheporouscarbon—carboncomposite.Ingeneral,thegreatesterosionratewasfoundatanangleofincidenceof90°,wheretheerodentstreamisperpendiculartotheerosionsurface,andbrittlefracturewasthepredominantmechanismofmaterialremoval.Theexceptionwasthegraphitefoilmaterialwhichdisplayedmaximumerosionatanangleofincidenceof60°.Forthismaterial,twomechanismswereeffective:disruptionofthegraphiteflakes,whicharemainlyheldtogetherbymechanicallocking,andaploughing-likemechanism.TheadditionofathinCVDcarbonlayertocolloidalgraphitepaintimprovedperformance,whereastheerosionresistanceofthegraphitefoilwasslightlydegradedastheCVDlayerwastoothintopreventtheploughing-likemechanism.1.IntroductionAclassofhighlyporouscarbon—carbon(C—C)composites,withlowdensitiesintherange0.1—0.4Mgm\3,areutilizedasthermalinsulationinvacuumandinert-gasfurnacesattemperaturesupto2800°C.Aconsequenceofthevacuum-mouldingprocessusedintheproductionofthecompositeisthatthediscontinuousfibresareorientatedintolayerstoformatwo-dimensionalplanarrandomstructure.Thevastmajorityofthevolumeofthecompositeconsistsofinterconnectedporesandthefibrenetworkisbondedattheintersectionsoffibresbydiscreteregionsofthecarbonmatrixasopposedtoacontinuousmatrix.Forthisreasonthesecompositesarealsoknownascarbonbondedcarbonfibre(CBCF).Asaresultofthehighporosityandthefibreorientation,thethermalconductivityperpendiculartothefibrelayerplanesislow,atypicalvalueforamaterialwithanominaldensityof0.20Mgm\3is0.24Wm\1K\1at2000°Cinvacuum.Investigationsintothemicrostructure[3,4],mechanicalproperties[2,5—9]andthermalproperties[10,11]ofthesematerialshavebeenreported.(1997Chapman&HallCBCFisusedinfurnacesemployedinhightechnologyapplicationssuchassingle-crystalgrowing(forexample,siliconorgalliumarsenide)ormetalheattreatment.Theheattreatmentofmetals,suchastoolsteels,isincreasinglycarriedoutinfurnacesthatutilizegasquenching(typicallynitrogenisused)[12,13].Thegasquenchmaybeusedtoreducetheturnaroundtimeofbatchprocessesorasanintegralpartoftheheat-treatmentregime.Theadvantageofgasquenchingduringheattreatment,asopposedtoanoilquench,isthatthecoolingratecanbecontrolled;therefore,itispossibletoreducewarpingandcrackinginthecomponent.Duringgasquenching,parti-culatemattermaybecomeentrainedinthegasflows,andimpingementwiththeinsulationmayresultinmaterialremoval.Inthechallengingenvironmentofgasquenching,thereisarequirementforerosionprotectionoftheCBCFbytheuseofhigherdensitycarbon-basedcoatingandcladdingmaterials.Generally,ductileandbrittlematerialsexhibitdifferenterosioncharacteristics;ofparticularinterestistheirrelationshipbetweentheerosionrateandtheangleofincidence[15].Ductilematerialstendtodisplaymaximumerosionatglancinganglesofimpact,approximately30°formetals,andmaterialremovalisthoughttooccurbyamicromachiningmechanismwithacontributionofdeformationwearathigherangles.Ontheotherhand,forbrittlematerials,maximumerosionisfoundwheretheerodentstreamisperpendiculartotheerosionsurface,andmaterialremovaltypicallyresultsfromtheformationofHertzianorlateralcracks.Althoughitisaconvenientapproachtoidealizematerialserosionbehaviourinthismanner,itisanoversimplification,becauseerosionisfoundtodependonotherfactors,includingtheerosionconditions,suchaserodentpar-ticlesizeandshape,aswellasthedetailsofthemicrostructureofthetargetmaterial.Thispaperisconcernedwiththeexaminationofthemicrostructureandtheefectivenessinimprovingtheerosionresistanceofseveralcandidatecoatingsandcladdings.Theresultspresentedinvolvethesteadystateerosionrateasafunctionofimpingementangleunderdefinedconditions.Theoverallaimofthisworkistorelatethemicrostructuretotheerosiondatabymeansofamechanisticapproach.materialsincludedtheFiberMaterialsInc.C3composite],whichisresinimpregnated,andtheToyoTansoG3470.Inaddition,ahigh-densitycarbon—carboncompositewasproducedbyemployingCVDoveraperiodof800htoinfiltratea5mmthicksectionoftheCBCFsubstratetoadensityof1Mgm\3.TheCVDprocessusednaturalgasasthecarbonprecursorandnitrogenasthecarriergas.Thedensificationwascarriedoutatapproximately1100°Cunderareduced.2.Experimentalprocedure2.1.MaterialsTheCBCFusedasthesubstratewasastandardcommercialmaterial(density0.18Mgm\3)manufacturedbyCalcarbLtd.ThecoatingandcladdingmaterialswereappliedtothexyplaneoftheCBCFsubstrate(seetheschematicdiagramofCBCFstructureinFig.1);thexyplaneisperpendiculartothedirectionofminimumthermalconductivityandhenceismostlikelytobetheexposedsurfaceoftheinsulationinafurnace.Thecoatingandcladdingmaterialsexam-inedinthispaperwereallcarbonbasedandtheyarelistedinTableI.ThecoatingmaterialsaredefinedasthosethatbondindependentlytotheCBCFsubstrate,whereasthecladdingsarebondedbymeansofacar-bonizingcement.CalcoatandCalcoatMarecolloidalgraphitepaintcoatingsthatwereappliedtotheCBCFsubstratebybrushing.Thematerialwassubsequentlyheattreatedat900°Cinnitrogentocarbonizetheresinconstituentofthecolloid.Higherdensitycarbon—carboncomposites('1.3Mgm\3)usedascladdingpressureof5kPa.(NotethattheCVDofcarbonintheinteriorofaporousmediumissometimestermedchemicalvapourinfiltration,CVI.)AnothercladdingmaterialwasgraphitefoilwhichwasproducedbyToyoTansobycompressingexfoliatedgraphiteflakesinarollingoperation[23].Thefoilisflexibleinnatureandispredominantlyheldtogetherbymechanicallocking,asnobinderisused.FurthersampleswereproducedbysubjectingtheCalcoatcoatingandthegraphitefoiltoaCVDtreatment(samplesdesig-nated#CVDinTableI)foraperiodof75hundertheconditionsdescribedabove.Amoreextensivedescrip-tionofthematerialswillbeforthcominginthedis-cussiononthemicrostructures.2.2.ErosiontestingMultiparticleerosiontestswereperformedonagas-blasttyperig,asdescribedbyCarteretal.[24].Inthisapparatustheerodentparticlesentertherigviaanapertureinthebaseofanopenhopper.Aventurifittedinthesystemallowstheparticlestobeentrainedinthecompressedairflow.Afterpassingthroughanozzlewithan8mminternaldiameter,theparticlesstrikethetargetatastand-ofdistanceof40mm.Thetargetspecimenshadnominaldimensions25mm;12.5mm;5mm.TheerodentusedwasangularequiaxedsilicasandobtainedfromHepworthMineralsandChemicalsLtd,Redhill,UK.Theerodentwassievedtoparticlesizesbetween150and300lm,themeansize(byweight)was230lmwhichwasfoundbyalaserdifrac-tionmethod(Mastersizer1005,MalvernInstrumentsLtd,Malvern,UK).Thevelocityoftheparticleswas6ms\1,foundbythestreakingcameratechniqueatthepositionofthetarget.Thismethodinvolvedexpo-singthefilmforaknownlengthoftimeandmeasuringthelengthofthelinethattheparticleproducesonthefilm.Erosiontestswerecarriedoutatanglesof30°,45°,60°,75°and90°.Generally,thesampleswereimpactedbyafixedmassoferodent,thencleanedandreweighed.Thisprocesswasrepeatedandtheaccumulatedmasslossplottedagainsttheaccumulatedmassoferodent.Theerosionrate,expressedintermsofmassremovedperunitmassoferodent,wascalculatedfromthegradientoftheseplots.However,inthecaseofthelow-densityCBCFsubstratematerial,whichwasinvestigatedforcomparisonpurposes,asignificantmassoferodentpenetratedandwasretainedwithintheporousstructureofthecomposite.Whencalculatingtheerosionrate,themassofthispenetratederodentmustbetakenintoaccountandthereforetheerosionratewasfoundinthefollowingmanner.Eachsamplereceivedonlyasingledoseoferodent.Thetotalmasschangeofeachsample,*¼,isequaltothemassofcompositepressureof5kPa.(NotethattheCVDofcarbonintheinteriorofaporousmediumissometimestermedchemicalvapourinfiltration,CVI.)AnothercladdingmaterialwasgraphitefoilwhichwasproducedbyToyoTansobycompressingexfoliatedgraphiteflakesinarollingoperation[23].Thefoilisflexibleinnatureandispredominantlyheldtogetherbymechanicallocking,asnobinderisused.FurthersampleswereproducedbysubjectingtheCalcoatcoatingandthegraphitefoiltoaCVDtreatment(samplesdesignated#CVDinTableI)foraperiodof75hundertheconditionsdescribedabove.Amoreextensivedescriptionofthematerialswillbeforthcominginthediscussiononthemicrostructures.2.3.MicrostructuralandsurfaceobservationsSamplesforopticalmicroscopywerevacuumimpregnatedwithresinandsubsequentlypolishedtoa1lmfinish.SamplesforSEMweremountedontoaluminiumtabsandexaminedatanacceleratingvoltageof20kV.Inthemajorityofcases,coatingwasnotrequiredduetothesufcientelectricalconductivityofthecarbonsamples;however,wherechargingofretainedsilicaerodentwasevidentintheerodedsamples,theywerespluttercoatedwithgold.3.Resultsanddiscussion3.1.MicrostructureThestructureofCBCFinsulationmaterialisshowninFig.1;theporositycontentofthisfibrenetworkisexceptionallyhighwith87%ofthevolumeofthecompositeconsistingofopenandinterconnectedpores.Theorientationofthefibresisevidentinthemicrographinwhichthefibresliepreferentiallyinxyplanes(i.e.perpendiculartothezdirection)butarerandomindirectionwithintheseplanes.ThethicknessoftheCalcoatcolloidalgraphitepaintcoatingisvariable,duetothebrushingmethodofapplication,butgenerallyisintherange40—60lm(Fig.2a).However,asaresultofthehighporositycontentandtheinterconnectednatureoftheporosityintheCBCFsubstrate,someofthepaintpenetratesuptoadepthof600lm(Fig.2b).CalcoatMconsistsofCalcoatcolloidalgraphitepaint,whichcontainssub-micrometrecarbonparticles,withtheadditionofcoarsercarbonparticlesandshortfibres((50lm).Thecoarsercarbonparticlesincreasetheviscosityofthepaintwhichresultsinathickersurfacecoating(80—200lm)byminimizingtheextentofpenetrationintotheinterioroftheporoussubstrate(Fig.2c).TheCalcoat#CVDisproducedbydepositingcarbonfromthegaseousphaseontotheCalcoatcoatingintheCVDfurnace.Thisprocessproducesalayerofdensepyrolyticcarbonabout5lmthickonthesurfaceofthepaintcoatingwithlittlepenetration(Fig.2d).TheFMIC3C—Ccompositeisproducedfrompolyacrylonitrile(PAN)precursorcarbonfibrecloth,whichisabout1.2mmthick[21].Theclothisimpregnatedwithphenolicresinbutitisevidentthattheresindoesnotadequatelypenetratethefibrebundles(Fig.3a).Largeplateletsofresin-basedcarbon(500lm;500lm;40lm)arefoundbetweenthelayersofwovencloth,ascanbeseenintheplansectionmicro-graphinFig.3b.Thismayresultfromtheuseofahigh-viscosityresinoralowimpregnationpressure.外文资料译文碳结构和固体颗粒侵蚀的保护高度多孔炭碳复合保温材料的使用材料系，英国皇家理工学院，技术和医学，伦敦SW72BP,英国多粒子侵蚀进行了测试备用涂料,(胶状石墨油漆)和电镀（密集的碳—亚邦复合材料和石墨信息）用来保护多孔碳材料—碳复合保温在真空和惰性气体熔炉,利用惰性气体淬火。依赖性侵蚀率的发生率的角度考察了从微观结构与机制的材料切除率作为SEM观察的结果。此外,效果很薄的化学气象沉积(CVD)碳层上的油漆涂料和胶体石墨石墨铝箔复合进行了检验。涂层和熔覆材料显示一个更大的抗侵蚀对所有角度的发病率比多孔碳复合材料。一般来说,最大的侵蚀速率是发现一个90度的入射角°，从流的垂直于表面的侵蚀和脆性断裂是优势机制的材料切除。唯一的例外是石墨箔材料显示角度为最大侵蚀角度为60°的发生率。对于这种材料,两种机制是有效的:破坏石墨薄片，这主要是由机械性的锁在一起，和像耕田一样的机制。除了薄层胶体CVD碳石墨涂料性能的改善，而腐蚀能力的石墨铝箔略退化为CVD层太瘦了防止像耕田一样的机制。1介绍一个类的多孔碳(C-C)复合材料与低密度范围0.1—0.4mg/m3，运用在真空和惰性保温炉在高温下到2800°C。结果真空成型工艺生产中所使用的复合材料纤维的成层不连续导向,形成一个二维平面随机结构。绝大多数的成交量复合由互联网和光纤网络是保税交叉运用离散区域的纤维碳矩阵而不是一个连续的矩阵。由于这个原因,这些复合材料也被称为碳保税碳纤维(CBCF)。由于高孔隙度和纤维取向、导热系数垂直于纤维层比较低,一个典型的有用的材料有表面密度0.20mg/m3是0.24wm/1k/1℃的真空中2000℃。调查显微组织、力学性能和热性能，这些材料被运用。(1997年查普曼大厅CBCF用于炉采用高技术应用,如单晶增长(例如,硅或砷化镓)或金属热处理。这个金属的热处理，如工具钢,越来越开展的熔炉,利用气体淬火(通常是氮是使用)气体淬火可以降低周转期的间歇过程或作为一个整体的一部分,热处理制度。天然气的优势淬火热处理中，相对于一个油淬火,冷却速度是可以控制的；因此，它有可能减少对变形和开裂的组件。在气体淬火、可吸入颗粒物可能成为吸引气体流,以及撞击与绝缘可能导致材料被切除。在充满挑战的环境下的气体淬火,有一个要求CBCF侵蚀的保护使用更高密度的碳基涂层和熔覆材料。通常,韧性和脆性材料具有不同的侵蚀特点。特别有趣的是他们之间关系的侵蚀率和入射角。韧性材料往往表现出最大的侵蚀在瞬间角度的影响,大约30°的金属。另一方面,脆性材料，最大侵蚀是很清楚的,从流垂直于表面的侵蚀,材料切除率通常结果是形成或横向裂缝，尽管这是一个方便的方法来优化的材料腐蚀以这样的方式进行腐蚀,它是一种简化,因为侵蚀是发现依赖于其他因素,包括侵蚀条件，如从指向形状和大小,以及微观结构的细节目标材料。本文关注的是测定的显微组织及有效改善耐蚀性的几个备用涂料和推。给出的结果包括稳态侵蚀率作为函数的角度定义的条件下的冲击。整体目标的进程都是与显微组织侵蚀现象的数据相关的，通过一个机械的方法材料包括纤维材料有限公司。这是树脂浸渍和随后的吸化学气相沉积(CVD)。此外,一个高密度碳复合材料由使用CVD在一段800h渗透到5毫米厚的部分CBCF衬底一个密度的3m/mg。心血管疾病过程使用天然气,作为碳和氮的前身为载体气体。致密化将在大约1100°C在缩水。2实验过程这个CBCF用作基体上的商业材料(密度0.18mg/m3),公司生产的涂层和熔覆材料,应用在xy平面上的CBCF基质;xy平面方向垂直,最小导热系数,因此是最有可能被暴露在表面的绝缘的熔炉中。涂层和熔覆材料测定——在本文中都是碳基及它们在表面涂层材料，是指那些性能自行以CBCF衬底,就像推保税通过一辆车——波兰特水泥。石墨油漆涂料,也应用于以CBCF衬底的。随后的材料热处理900°C碳氮树脂。组成的胶，密度高碳-碳复合材料作熔覆压力5kPa(注意,多粒子中碳的多孔介质内部的是有时被称为化学蒸气渗透)。另一个熔覆材料是石墨箔制作是通过压缩剥落石墨薄片在滚动来操作的。石墨具有灵活的性质的,主要是由机械锁在一起,因为没有使用额度的话。进一步的样本产生不利涂料和石墨衬多粒子(样本指定CVD的试样)，在一段75h上面描述的条件下。2.1侵蚀测试多粒子侵蚀测试进行气体——爆炸类型测定,被描述为卡特。在这个装置从粒子进入通过孔径钻机在基地的一个开放的环境。文丘里安装在系统允许粒子传递压缩空气中流动。在通过一个喷嘴内部直径着一个8毫米,粒子袭击的目标的一个站点的40mm的距离。目标标本表面尺度25mm、12.5mm、5mm。从使用的角度晶粒得到硅砂矿物质，运用于化工厂。从筛的是粒子大小在150nm到300nm之间、平均大小(重量)是230mg/m。发现由激光的方法。粒子的速度是按年代算的,发现的表面摄像技术在这个方位。这个方法涉及各行各业，即为已知的时间长度测量线的长度,粒子的产生光影。侵蚀试验角度在30°、45°、60°角,长度在75nm和90nm。通常,这些样品是一个固定的角度控制质量的,然后再清洗和再称重。这个过程被重复和累积的质量损失从多次的循环中记录。根据这些实验的梯度，这个侵蚀率,在数量上表现为大规模被切除。然而,为了进行比较研究，在低密度的情况下CBCF基体材料,,从一个重要的角度渗透,是保留在多孔结构的复合材料。当计算其腐蚀率、大规模的从渗透时，必须被考虑的。因此侵蚀率以下列方式被发现，每个示例只获得了从单剂量，总质量变化的每一份样本。另一个包覆材料石墨箔控制是通过压缩剥落石墨薄片在滚动操作。2.2微观结构和表面的观察样本用于光学显微镜真空浸渍树脂和随后抛光。扫描电镜样品,安装在选项卡并检查了铝在加速电压20千伏。在大多数情况下,不需要涂料由于碳样品的电导率;但是,充电的状态从硅胶中显侵蚀样本。3结果和讨论CBCF绝缘材料的结构,孔隙度的内容的网络是异常高的，达87%的复合构成的开放和互联的基础。纤维的方向是显而易见的显微纤维，优先在xy平面(即垂直于z方向)但方向随意在这些空间运用。厚度的胶状石墨油漆涂料是可变的,由于筛选方法的应用,但通常介于40lm。然而,由于高孔隙率的原因和相互联系的本质在CBCF基质孔隙度,一些油漆渗透到深度600lm。胶状石墨油漆,其中包含微碳粒子,加上较粗的碳颗粒和短纤维((50lm)。碳颗粒较粗的增加的粘度涂料,结果在一个较厚的表面涂层(80-200lm)，通过最小化的程度渗透多孔基体的内部。这个多粒子是由把碳从气态阶段到涂层在CVD炉。这个过程可以产生一层致密热解碳约5lm厚表面的油漆涂料,具有小的部分C3C-CFMI的复合是由聚丙烯腈(PAN)前体碳纤维布,它是大约1.2毫米厚。布是用酚醛树脂浸渍,但很明显,树脂不能充分穿透光纤束。大型块状的碳(500lm)被发现的各层之间,可以看到在该计划部分微型图。碳结构和固体颗粒侵蚀的保护高度多孔炭碳复合保温材料的使用就是这样。