简介:2012上海第二十六届中国国际塑料橡胶工业展览会展会时间:2012年4月18—21日展会地点:上海新国际博览中心
简介:Si3N4/TiCnanocompositeceramicshavebeenfabricatedbyhotpressingtechniquewithAl2O3andY2O3asadditives.TheresultsshowedthatwelldispersedcompositepowderwascarriedoutbyaddingdispersantandadjustingpHvaluesofsuspensions.RemarkableincreaseinflexuralstrengthatroomtemperatureswasobtainedbyaddingnanoparticlesinSi3N4matrixwith10%(wtpct)ofnano-Si3N4and15%ofnano-TiC.Theflexuralstrength,fracturetoughnessandhardnesswere1025MPa,7.5MPa·1/2and15.6GPa,respectively.Themicrostructuresofmaterialswereanalyzedbyscanningelectronmicroscopy(SEM)andtransmissionelectronmicroscopy(TEM),whichindicatedthatTiCnanoparticlesdistributeinthematrixandatthegrainboundaries.Accordingtothefractureform,lowcontentsofnanoparticlescouldrefinematrixgrainsandleadtothecrackdeflectionaswellascrackpinning.Themultiplexmicrostructurewasformedbymixingnano-Si3N4particles.Thecracktrajectoriesexhibitedcrackdeflection,rod-likegrainbridgingandpull-out.
简介:以3种煤沥青为研究对象,采用元素分析、平均分子量、核磁共振氢谱(1H—NMR)以及红外光谱分别对其进行表征和分析,使用改进Brown-Ladner法对煤沥青的结构参数进行计算,并构建出各煤沥青的平均分子结构模型。结果表明,煤沥青的基本结构单元是稠环芳烃连接烷基侧链并含杂原子,结构单元之间形成缔合体,缔合数为5~9。3种煤沥青的烷基侧链都很短,且均不包含环烷烃。构建的分子模型为煤沥青提供了形象的化学结构,有助于从分子水平加深对其认识和研究。
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简介:Inthispaper,polycrystallinesiliconfilmsweredepositedbyelectroncyclotronresonanceplasma-enhancedchemicalvapordeposition(ECR-PECVD)usingSiH_4/ArandSiH_4/H_2gaseousmixture.EffectsofargonflowrateonthedepositionefficiencyandthefilmpropertywereinvestigatedbycomparingwithH_2.TheresultsindicatedthatthedepositionrateofusingArasdischargegaswas1.5-2timeshigherthanthatofusingH_2,whilethepreferredorientationsandthegrainsizesofthefilmswereanalogous.FilmcrystallinityincreasedwiththeincreaseofArflowrate.OptimizedflowratioofSiH_4toArwasobtainedasF(SiH_4):F(Ar)=10:70forthehighestdepositionrate.