Effect of microstructure on the fracture behavior of biomorphous silicon carbide ceramics.pdf

《Effect of microstructure on the fracture behavior of biomorphous silicon carbide ceramics.pdf》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。

1、JournaloftheEuropeanCeramicSociety22(2002)2697–2707www.elsevier.com/locate/jeurceramsocEffectofmicrostructureonthefracturebehaviorofbiomorphoussiliconcarbideceramicsPeterGreila,*,EvelinaVoglia,TobiasFeya,AlexanderBezolda,NadjaPopovskab,HelmutGerharda,HeinoSiebe

2、raaDepartmentofMaterialsScience(GlassandCeramics),UniversityofErlangen-Nuernberg,Martensstr.5,D-91058Erlangen,GermanybDepartmentofChemicalEngineering,UniversityofErlangen-Nuernberg,Egerlandstr.3,D-91058Erlangen,GermanyReceived7October2001;receivedinrevisedform

3、22February2002;accepted8March2002AbstractHighlyporouscellularsiliconcarbidewaspreparedfromnativepinewoodtissuebyvaporinfiltrationofSi,SiO,andCH3SiCl3intothecarbonizedtemplate.b-SiCatthebiocarbonsurfacefinallyresultedinacompleteconversionofthetemplateintoacellula

4、rsiliconcarbidematerial.Duetothedifferentreactionmechanisms,differentstrutmicrostructureswereobtained.ThestrengthofthebiomorphousSiCwasmeasuredunderbiaxialtensileloadingconditionsperpendiculartothecellelongation(in-planeloading).Anon-catastrophicstress-strainbeh

5、aviorwasobservedintheSiandCH3SiCl3derivedmaterialswhichshowedahighskeletonden-sityof53g/cm3.Extendendcellwallfracture(peeling)wasobservedintheSiderivedmaterialwheretheoriginalintercellularlamellawasretainedintheceramicmaterial.FEcalculationsofthestressdistribu

6、tioninarepresentativestructuremodelshowedsignificantlylowerlevelsoftensilestressinrectangularporearrays(earlywoodtissue)comparedtoellipsoidalpores(latewoodtissue).#2002ElsevierScienceLtd.Allrightsreserved.Keywords:BiomorphousSiCceramics;Microstructureandstrengt

7、h1.Introductionsionsfromnanometers(cellulosemicrofibrils)tothecentimeterlevel(woodtissue).2TheinherentvascularWoodsarecellularsolids,composedofmixedbio-transportationsystemofwoodwhichconsistsoflargepolymers(cellulosefibers,ligninandhemicelluloseasporechannels(ve

8、ssels)withadiameterof30–45mminmatrixmaterial),andwitharelativedensityrangingsoftwoodsand10–400mminhardwoodsprovidesfromlessthan0.05toalmost1.Extendedstructurerapidaccessforgaseouso