简介:TheCW-CO2laserdrivengasreactionwasappliedtopreparenano-sizedSiCpowder,SiH4andC2H4ofhighpurties,asstartingmaterials,weremixedtacertainrationandintroducedintotheresactioncell.Thegasesflewacrossthelaserbeamorthogonallyandthuswereheatedbylaserbeam.Thenano-sizedSiCultrafinepowderwswereformedthroughthermicgasreation.Thefinalproductivityofthisprocesswas97%,Theobtainedpowderswerecharacterizedandanalyzed.ChemicalanalysisrevealedthattheSiCcontentwas95.38wt%,Oxygen,theprimaryimpurity,weighted1.32%whiletraceimpurities,suchascalcium,magnesiumandothermetals,wereonly0.03%,XRD,XPSandTEMindicatedthatthpowderparticleswerenearlysphericalandnotagglomerated.Theparticlesizerangedfrom10nmto25nmwithanaverageof15nm,Theparticlestredtobenoncrystalline.
简介:ThediamondfilmshavebeendepositedbythehotfilamentCVDmethodonmolybdenumsubstratesfromthemixturereactantgasofacetoneandhy-drogen.Thesurfacemorphologiesoftheobtaineddiamondfilmsundervariousde-positionconditionshavebeenobservedbyscanningelectronmicroscope(SEM).Theexperimentalresultsstronglyindicatethatthesurfacemorphologiesofthere-sultingfilmshavecloselyrelatedtothedepositionconditions,i.e.,reactionpres-sure.Formolybdenumsubstrates,underthelowerreactionpressurethesurfacemorphologiesofthegrainscomprisingtheresultingfilmsmainlydisplaythesmallsinglecrystalcubo-octahedronanddoublesmallcrystalcubo-octahedron;underthehigherreactionpressure,thesurfacemorphologiesmainlydisplaythelargecauliflower-like.TheseresultsshowthattherearevariouscrystalhabitsforCVDdiamondundervariousdepositionconditions.
简介:碳nanotubes(CNT)被综合由电加热催化化学药品使用乙炔的免职方法(CCVD)(C2H2)同样碳来源和氮(N2)被electroplating作为搬运人气体,和镍催化剂装载。电的加热方法,作为一个新方法,由使用它的传导性直接触电碳纤维。形态学和结构CNT被描绘由SEM和TEM,和碳的表面性质在CNT的生长前后的纤维被拉曼光谱学描绘。试验性的结果表演电加热方法是一个新方法生产CNT,和罐头成长在一短时间,结晶化度和表面的很多CNT平均雏晶碳的尺寸在CNT的生长以后增加的纤维上它。另外,当,装载催化剂的electroplating能也被使用装载方法的理想,能控制数字,由控制plating的镍粒子的形状,和分发预定。
简介:IntroductionIn2O3·Snfilmshavehightransparency(>95%)withinthevisiblespectralregion,lowresistivity(10-2—10-4ohm·cm)atroomtemperatureandsuperiorthermalstability.Thesefilmshavebeenappliedtosolarcells,electronicsandphotoelectronicsfields.Inrecentyears,organometallic-CVDmethodhasemergedasasuccessfulalternatetothephysicalmethodsandgeneralCVDforthegrowthofthesefilms.TheMO-CVDtech-
简介:Chemicalvapordeposition-tungsten(CVD-W)coatingcoveringthesurfaceoftheplasmafacingcomponent(PFC)isaneffectivemethodtoimplementthetungstenmaterialasplasmafacingmaterial(PFM)infusiondevices.ResidualthermalstressinCVD-Wcoatingduetothermalmismatchbetweencoatingandsubstratewassuccessfullysimulatedbyusingafiniteelementmethod(ANSYS10.0code).Thedepositionparametriceffects,i.e.,coatingthicknessanddepositiontemperature,andinterlayerwereinvestigatedtogetadescriptionoftheresidualthermalstressintheCVD-Wcoating-substratesystem.AndtheinfluenceofthesubstratematerialsonthegenerationofresidualthermalstressintheCVD-WcoatingwasanalyzedwithrespecttotheCVD-WcoatingapplicationasPFM.ThisanalysisisbeneficialforthepreparationandapplicationofCVD-Wcoating.
简介:Throughournewly-developed'chemicalvapordepositionintegratedprocess(CVD-IP)'usingcarbondioxide(CO2)astherawmaterialandonlycarbonsourceintroduced,CO2couldbecatalyticallyactivatedandconvertedtoanewsolid-formproduct,i.e.,carbonnanotubes(CO2-derived)ataquitehighyield(thesingle-passcarbonyieldinthesolid-formcarbon-productproducedfromCO2catalyticcaptureandconversionwasmorethan30%atasingle-passcarbon-base).Forcomparison,whenonlypurecarbondioxidewasintroducedusingtheconventionalCVDmethodwithoutintegratedprocess,nosolid-formcarbon-materialproductcouldbeformed.IntheadditionofsaturatedsteamatroomtemperatureinthefeedforCVD,thereweremuchmoreend-openingcarbonnano-tubesproduced,ataslightlyhighercarbonyield.Theseinspiringworksopenedaremarkableandalternativenewapproachforcarbondioxidecatalyticcapturetosolid-formproduct,comparingwiththatofCO2sequestration(CCS)orCO2mineralization(solidification),etc.Asaresult,therewasmuchlessbodyvolumeandalmostnogreenhouseeffectforthissolid-formcarbon-materialthanthoseofprimitivecarbondioxide.
简介:Siliconnitridenanoparticlesweresynthesizedbyradio-frequency(RF)plasmachemicalvapordeposition(PCVD)usingsilicontetrachlorideandammoniaasprecursors,andargonascarriergas.Byassumingchemicalthermodynamicequilibriuminthesystem,acomputerprogrambasedonchemicalthermodynamicswasusedtocalculatethecompositionsofthesystematdifferentinitialconcentrationsandfinaltemperatures.Atfirst,fiveelementsandthirty-fourspecieswereconsidered.Theeffectsoftemperatures,andconcentrationsofammonia,hydrogenandnitrogenontheequilibriumcompositionswereanalyzed.Itwasfoundthattheoptimalreactiontemperaturerangeshouldbe1200to1500KtoobtainthehighestconversionandyieldofSi3N4.Theinletpositionofammoniashouldbelowerthanthatofsilicontetrachloride,andbothshouldbelocatedatthetailoftheplasmatorch.Thebestmoleratioofammoniatosilicontetrachloridewasfoundtobeabout6.Later,theinfluencesofwater(andoxygen)wereconsidered,and17additionalspecieswereincludedinthecomputations.ItwasfoundthatoxygenorwatercontentintherawmaterialsshouldbeaslowaspossibleinordertohavehighnitridecontentintheproducedSi3N4.Nitrogenorhydrogenmightbeusedtoreplacesomeorevenalltheargontoimprovetheyieldofsiliconnitrideandreducethecost.Theratioofammoniatosilicontetrachlorideshouldbehighenoughtoobtainhighconversion,butnotexcessivelyhightoreducetheoxygencontentduetotheexistenceofwaterinammonia.Thesimulatedresultswereverifiedbyexperiments.
简介:摘要金刚石具有许多优异的性能,但天然金刚石的价格也比较昂贵。金刚石薄膜的各种性质与天然金刚石几乎相同,具有非常广阔的工业前景。本文采用乙醇和氢气作为工作气源,利用微波等离子体化学气相沉积法,在较低的温度下制备了金刚石薄膜,并研究了乙醇浓度、反应气压对金刚石薄膜生长的影响。
简介:摘要目的综合评估β受体阻滞剂对慢性阻塞性肺疾病(COPD)合并心血管疾病(CVD)患者肺功能、急性加重再住院率及死亡率的影响。方法制订文献纳入标准及检索策略,计算机检索Pubmed、Medline等外文数据库及中国知网、万方等中文数据库等。收集研究β受体阻滞剂治疗COPD合并CVD患者对于肺功能改变、急性加重再住院率及死亡率等的相关文献,应用STATA 12.0软件进行meta分析。结果检索到文献4 733篇,经筛选最终纳入34篇,样本总量1 415 791例。meta分析结果显示,β受体阻滞剂对COPD患者肺功能无明显影响,治疗前后第1秒用力呼气容积占预计值百分比、第1秒用力呼气容积/用力肺活量变化量与对照组变化量的差值合并值WMD及其95%CI为0.97(0.10~1.84)、-0.14(-1.47~1.18)。同时可以降低死亡率(OR=0.65,95%CI:0.51~0.83)以及急性加重再住院率(OR=-0.64,95%CI:0.43~0.97)。结论β受体阻滞剂对COPD合并CVD肺功能无不良影响,不仅可以降低急性加重再住院风险,还可降低死亡风险。