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1、西北工业大学硕士学位论文摘要AbstractBecauseofuniquemolecularstructureandproperties,suchashighaspectratio,largesurfacearea,remarkablemechanicalstrength,carbonnanotuhes(CNTs)hasbeenpaidwideattentionto.Thispaperdescribedbrieflyitspreparationmethods,growthmechanismsandpotentialapplications.The
2、growthofCNTsusingCVDwasconductedinthecool-wallheatingovenonthreesubstrates(monocrystallinesilicon,iron,graphite),twocatalysts(iron,nickle),twocatalystthickness(20nm,80nm),threedilutedgases(ammonia,hydrogen,nitrogen),threefluxratio(2/1,10/1,19/1),under700'Cand8500C,respectivel
3、y.SEMandTEMwereusedtoinvestigatethegrowthbehaviorsasafunctionofthecatalyst,substrate,growthtemperatureanddilutedgas.Themainresearchfindingswereasfollows:NickelhadahighercatalysisthanironinthegrowthofCNTs,andthethicknessofcatalystaffectedthediameterofCNTs.Comparedgraphiteandir
4、on,whenmonocrystallinesiliconwasusedasthesubstrate,CNTshadahigherpurity.Theinvolvedreasonwasthatmonocrystallinesiliconhadahighersmoothanduniformsurface.Thefluxratioofdilutedgaseswasholdas10/1,whichcouldresolvethecontradictionoftheasynchronismbetweentheproductandgrowthoftheato
5、miccarbon.ThedegreeofgraphitizationanddiameterofCNTsincreasedwithelevatedtemperature,whichshowedthathightemperatureimprovedthecatalysisofcatalyst,andwasatributedtouniformarrangementofatomiccarbon,andhinderedamorphouscarbon.AmmoniaplayedacriticalroleintheverticalalignmentofCNT
6、s,andthepossiblereasonwasthatin850Ctheatomichydrogendecomposedfromammoniareactedwithamorphouscarbontoformvolatileproductstokeepthemetalsurfaceclean,andmechanicalleaningagainstneighboringtubesestablishedamorphologyofverticalalignment.ThegrowthprocessofCNTsusingCVDwaspossiblyfo
7、llowedasthebased-growthmechanism.Theatomiccarbonprecipitatingfromthetopofthecatalystsgrew西北工业大学硕士学位论文摘要upward,butthecatalystsstillexistedinthebottomofCNTsduetothestrongadhesionbetweencatalystsandsubstrate.Keywords:Cool-wallCVD;CNTs;Catalyst;Substrate;Temperature;Dilutedgas;Fl
8、uxratio;Verticalalignment;Growthmechanism西北丁业大学硕L学位论文第一章绪论第一章绪论1991年
