简介:采用反应合成方法制备孔隙度为54.3%的高纯Ti3SiC2多孔材料,并研究其在400~1000°C下空气中的氧化行为。采用热重-差热分析法、扫描电镜、X射线衍射技术、能谱仪、拉曼光谱、BET比表面分析法和孔结构测试等研究Ti3SiC2多孔材料在氧化前后的氧化动力学、物相组成、微观形貌以及孔结构参数演变。结果表明:形成不同晶型TiO2氧化产物是影响Ti3SiC2多孔材料抗氧化性及孔结构稳定性的主要因素。由于氧化产物体积应力以及热应力的存在,因此,在400~1000°C试验过程中试样表面均出现开裂现象。其中,在400~600°C下形成的锐钛矿型TiO2会导致Ti3SiC2晶粒出现严重开裂,并引发快速氧化以及孔径和透气度的异常减小。600°C以上在氧化过程中主要形成金红石型TiO2,开裂现象得以缓解,但是氧化膜的外延生长大幅降低了Ti3SiC2多孔材料孔隙的连通性。
简介:BondingofAl2O3tocuisperformeddirectlyusingTifoilattemperatureof1273K.Themicrostructureofthejointinterfaceisinuestigatedthroughscanningelectronmicroscope(SEM),electron.probemicroanalysis(EPMA)andX-raydiffraction(XRD).theeffectoftheinitialtifoilthicknessonthereactionlayerthicknessandthejointStrengthareinvestigated.
简介:MoleculardynamicssimulationusingauniversalforcefieldhasbeenemployedtodeterminethediffusioncoefficientsofO2andNa2SO4vaporintoB2O3andSiCfrom700Kto1273K,respectively.Einsteindiffusionwasobservedina250~300pssimulation.ThediffusioncoefficientfortheO2rangefromabout9.279×10-9cm2/sforB2O3to2.275×10-10cm2/sforSiCataloadingof32moleculespersimulationbox,thatfortheNa2SO4vaporrangefromabout9.888×10-7cm2/sforB2O3to1.837×10-10cm2/sforSiCataloadingof8moleculespersimulationbox.EnvironmentpropertiesofC/SiCcompositewillbeincreasedviatheB2O3preventingthediffusionofO2andNa2SO4vaporintothepyrolyticinterphaseandcarbonfibers.
简介:MicrostructureandgrainboundarycharacterofhotpressedbinaryAl2O3(mullite,ZrO2)-SiCompositesandquaternaryAl2O3-mullite-ZrO2-SiCcompositewerestudiedbyelectronmicroscopyandmicroanalysis,ResultssuggestthatthereexistgrainboundarysolidsolutionsduetoelementaldiffusionnearSiCandmatrixoxidesgrainboundaries.
简介:TheAl2O3-SiCcompositepowderswerepreparedinargonatmosphereusingcoalgangueandcarbonaceousmaterials
简介:LowcementAl2O3-SiO2castableswaspreparedusingsupergradebauxite(w(Al2O3)>85%)asaggregate,brownfusedcorundum,siliconcarbide,Secar71CAcement,α-Al2O3micropowderandmicrosilicaasfinepowders.TheinfluenceofSiC(0,5wt%,10wt%,and15wt%)onresistancetoPbO-richslagwasinvestigatedbystaticcrucibleslagtest(1300℃for5h,inair).TheslagcorrosionmechanismofthecastableswasanalyzedbymeansofSEM,EDSandXRD.TheresultsshowthattheresistanceofAl2O3-SiO2castablestoPbO-richslagisimprovedobviouslybytheadditionofSiC.ThecorrosionmechanismofthePbO-richslagcanbediscribedasthatPbOintheslagreactswithSiO2andCaOinAl2O3-SiO2castables,forminglow-meltingcompounds(suchasPbO·SiO2and2PbO·SiO2).
简介:Inthisstudy,inordertoevaluatetheperformanceofhomogenizedbauxite,twoAl_2O_3-SiC-Ccastableswerepreparedusinghomogenizedbauxiteandbrownfusedcorundumasaggregates,respectively.5mass%andalusitewasintroducedintothetwocastablessoastoresearchtheeffectandmechanismofandalusiteinAl_2O_3-SiC-Ccastables.Theresultsshowedthat:(1)comparedwiththebrownfusedcorundumbasedcastables,thehomogenizedbauxitebasedcastableshadhighercoldstrengthafterheattreatment,butlowerhotmodulusofrupture;(2)additionof5mass%andalusitecouldenhancethecoldandhotmodulusofrupture,improvethethermalshockresistance,andoptimizethemicrostructureofspecimens;(3)themullitizationofandalusitewasnotobviousinthecastablesfiredat1100-1400℃.
简介:研究不同碳源下Al2O3-SiC-C铁钩料的性能。分别以球沥青、焦炭和炭黑为碳源,比较了常温下三者的显气孔率、抗折和抗压强度。结果表明,不同种类碳源将对试样的气孔率和抗折强度产生不同程度的影响。
简介:pH价值和Y2Y23-SiO2(Y-Si)泥浆>为Ti-6Al-4V投资扔的脸上衣的O3粉末和硅石大音阶的第五音被测量。Y-Si脸上衣系统做的壳的热行为被微分扫描热量计(DSC)调查,热gravimetric(TG)分析与集体spectrometry(MS)结合了,并且阶段转变被X光检查衍射(XRD)决定。热力量,剩余力量,线性扩大系数,和壳的穿的抵抗性能也被测试。微观结构和相互作用层的元素分发被分别地扫描电子显微镜(SEM)和精力散的分光计(版本)学习。microhardness测试者被申请microhardness。结果证明泥浆为至少60是稳定的?h。YZrO3的很小的数量低于1050被形成?普牯慭?楦汥?桴潥祲?畢?畯?敲?瑬?灡汰?畱污瑩瑡癩汥?潴愠眠摩牥挠慬獳漠?睴?楤敭獮潩慮?楤慬潴?牧癡瑩?桴潥楲獥?潆?慥档琠灹?景猠汯瑵潩獮眠?数晲牯?潨潬牧灡楨?敲潮浲污穩瑡潩?挠浯異吗??
简介:Toimprovetheharvestingofvisiblelightandreducetherecombinationofphotogeneratedelectronsandholes,Ti3+self-dopedTiO2nanoparticlesweresynthesizedandassembledintophotoanodeswithhighvisiblelightphotoelectrochemicalproperties.X-raydiffraction,transmissionelectronmicroscopy,X-rayphotoelectronspectra,electronresonancespectroscopyandenergydispersiveX-rayspectrawereusedtocharacterizethestructure,crystallinity,morphologyandotherpropertiesoftheobtainednanoparticles.UV–visiblediffusereflectancespectrashowedthattheTi3+self-dopedTiO2nanoparticleshadastrongabsorptionbetween400and800nm.Moreover,whenhydrothermaltreatmenttimewasprolongedto22h,theheterogeneousjunctionwasformedbetweentheanataseandrutileTiO2,wheretheanataseparticlesexposedhighlyactive{001}facets.Undervisiblelightirradiation,theTi3+self-dopedTiO2electrodeexhibitedanexcellentphotoelectrocatalyticdegradationofrhodamineB(RhB)andwatersplittingperformance.Intriguingly,byselectinganappropriatehydrothermaltime,thehighphotoconversionefficiencyof1.16%wasachieved.