简介:以葡萄糖和硅溶胶混合溶液为前驱体,采用碳热还原法在多孔SiC陶瓷表面生长SiC纳米线膜层,制备纳米复合陶瓷膜.使用X射线衍射、光学显微镜、扫描电镜、孔径分析仪等对样品的物相、形貌和孔径特征进行了分析.结果表明,在1 450 ℃反应6 h,微米孔径SiC的表面生长出了分布比较均匀的SiC纳米线膜层,纳米复合陶瓷膜具有窄分布的亚微米孔径.
简介:LowcostsiliconcarbonnanometerpowderwassynthesizedbycarbothermalreductionmethodwithnanometerSiO2andcarbonasrawmaterial.Itssynthesisthermodynamicswerediscussed.TheinfluenceofLaonTG-DSCcurvewasalsoanalyzed.ItindicatedthatthesynthesisprocessofSiCpowderhadtwosteps.InthefirststeptwomedialproductionsofSiOgandCOgformed,andinthesecondstep,β-SiCwasfinallysynthesized.After0.3%Laadded,atthefirststep,theinitiatoryformingtemperatureofproducingSiO(g)andCO(g)declinedfrom1351.4to1250.9℃,andthethermalactivationenergydecreasedfrom223.6to34.7J·g-1;atthesecondsteptheinitiatoryformingtemperatureofsynthesizingβ-SiCpowderdeclinedfrom1526.5to1357.8℃,andthethermalactivationenergydecreasedfrom693.7to295.7J·g-1.WithoutLaadded,thebestsynthesistechnologyforβ-SiCpowderwas1550℃for120min,averagepowderdiameterwasbiggerabout150nm.WithLaadded,thebestsynthesistechnologywas1500℃for120min,averagepowderdiameterwasabout100nm.
简介:利用CVI法,在两种不同类型的国产SiC纤维束中引入(PyC/SiC)4或(PyC/SiC)8多层界面,并进一步致密化,制备含不同纤维种类和界面类型的SiCf/SiCMini复合材料。研究纤维种类和界面类型对SiCf/SiCMini复合材料力学性能和断裂机制的影响。结果表明:致密化的SiCf/SiCMini复合材料已形成一个整体,在纤维和基体连接处可观察到明显的界面层,且界面厚度均匀;A/(PyC/SiC)4/SiC、B/(PyC/SiC)4/SiC、A/(PyC/SiC)8/SiC三种SiCf/SiCMini复合材料的最大拉伸强度分别达到466,350和330MPa,最终拉伸应变分别达到0.519%,0.219%和0.330%;拉伸断口均有纤维拔出,且随纤维种类或界面类型不同,纤维拔出长度和断口形貌有所差异。其中A/(PyC/SiC)4/SiC以ModelⅡ断裂机制发生断裂,B/(PyC/SiC)4/SiC和A/(PyC/SiC)8/SiC以ModelⅠ断裂机制发生断裂。
简介:SiCwhiskerswith'rosarybead'morphologyweresynthesizedusingsuitablesiliconsourceandcarbonsourcethroughsolidreactionatthetemperatureabove1537K.ThediameterandlengthoftheSiCwhiskerswereabout0.1-1.0μmand20-100μm,respectively.Thelargestdiameteroftheirenlargedendsofthewhiskerswasabout0.2-1.0μm,anditgraduallyandsmoothlydecreasedtothesizeoftheplainpartofthewhiskers.TheresultsofX-raydiffractionanalysisshowthatthecrystallinestructureoftheobtainedSiCwhiskersisβ-SiC.ItisconsideredthattheSiCwhiskersgrowviaavapor-solidmechanism.
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:交流UPS的主要功能,是为电力系统中的各种变配电设备、监控用计算机等提供高质量的不间断电源。本文重点介绍了常时逆变器供电方式的UPS电路结构,并将电路中功率模块内的半导体元件全部置换成SiC半导体元件。全SiC功率模块用于SiC-UPS时,电力变换损耗约减小30%,轻载时的运转效率达到90%以上,而且可靠性高。
简介:CurrentlytheservicelifeofCDQshaftsinChinaismainlyrestrictedbythepropertiesoftheinclinedfluebricks.Inthiswork,basedonthesystematicanalysisofthedamagemechanismofinclinedfluerefractories,highperformancemullite-SiCbricksweredeveloped.Thebrickswereproducedbycorundum,andalusite,SiCandotherhighpurityrawmaterials.Metalsiliconandaluminaultramicropowderwereaddedtoformdispersionmulti-phasestructure,fortifyingthematrixandimprovingthemicrostructure.Theproductshaveexcellentpropertiessuchaslowporosity,highdensity,goodwearresistance,highrefractorinessunderload,andgoodthermalshockresistance.Theproductscanreplacetheordinarymullite-SiCbricksandobtainagoodservicelife.
简介:Moleculardynamics(MD)simulationswereperformedtoinvestigateF+continuouslybombardingSiCsurfaceswithenergiesof100eVatdifferentincidentanglesat300K.Thesimulatedresultsshowthatthesteady-stateuptakeofFatomsincreaseswithincreasingincidentangle.Withthesteady-stateetchingestablished,aSi-C-Freactivelayerisformed.ItisfoundthattheetchingyieldofSiisgreaterthanthatofC.IntheF-containingreactionlayer,theSiFspeciesisdominantwithincidentangleslessthan30o.Forallincidentangles,theCFspeciesisdominantoverCF2andCF3.
简介:ASiC/2024compositewasmadebysemisolidcasting.ThewettingbetweenSiCandAlmatrixisimprovedbytreatingSiCparticlesatahightemperature,coatingK2ZrF6,andaddingMgtotheAlmelt,AneffectivewaytoremovethegasaroundSiCparticleswasalsofound.Microstructureswereobservedunderopticalmicroscope(OM)andscanningelectronmicroscopy(SEM).TheresultsshowthatSiCparticlesandAlmatrixarewellbondedandnogapsorcavitiesaroundtheparticlesareobserved.SiCparticlesdistributehomogeneouslyintheAlmatrix.TheexistenceofSiCparticlesresultsintheincreaseofwearresistanceandstrength.