学科分类
/ 4
66 个结果
  • 简介:BulkZr55Al10Ni5Cu30metallicglassplateswithadimensionof85mm×35mm×4mmandacomplicatedplatewerefabricatedbyinjectingcastingmethodusingspongyzirconiumandindustrialpurityaluminum,nickelandcopperasrawmaterials.Itwasshownthattheholdingtimeofliquidmetalsatelevatedtemperatureshadagreatinfluenceontheoxygencontentoftheplatesduetothecontaminationresultingfromtheatmosphere.Increasingholdingtimeresultedintheincreaseofoxygencontentintheinjectedalloy.Theglasstransitiontemperaturesofthebulkmetallicglassplatesarehigherthanthatreportedintheliteratureandcrystallizationtemperatureislowerfortheonewithhigheroxygencontentatthesameheatingrate.Theextensionoftheundercooledliquidregion△Txreachingabout87Kis3Khigherthanthatpreviouslyreportedand26Khigherthanthatwithoxygencontentof0.076wtpctfortheonewithoxygencontentashighas0.065wtpct.Thereforetheoxygencontentofthealloyhasasignificantinfluenceontheglassformingabilityandthermalstabilityofbulkmetalglass.Itissuggestedthatdirectcorrelationbetweenhighglassformingabilityandlarge△Txisonlyvalidforawell-definedIowoxygenconcentrationorhastobereconsideredbyincorporatingoxygenasanadditionalalloyingelement.

  • 标签: 铝基合金 氧化行为 冷却 合金元素 ZR55AL10NI5CU30
  • 简介:Se89Zn2Te5In4和Se87Zn2Te5In6chalcogenide合金的作文依赖者微结构形态学变化被调查。玻璃质并且nanophase表面和这些合金的结构的形态学与扫描电子显微镜(SEM)和传播电子显微镜(TEM)的帮助被描述了,并且他们的元素的集中从精力被证实散X光检查光谱学(EDX)。试验性的结果证明Se89Zn2Te5In4合金的微观结构属于纯玻璃质的状态,当Se87Zn2Te5In6合金与nanophase结构时。

  • 标签: 纳米结构 微观结构 合金 硫系 透射电子显微镜 扫描电子显微镜
  • 简介:AUltrafineamorphousNiBalloywaspreparedviachemicalreductionmethod;ItsstructuresduringthecrystallizatioinprecesswascharacterizedbysuchtechniquesasDifferentialthermalanalysis(DTA),X-rayabsorptionfinestructure(XAFS)andX-raydiffraction(XRD),andcorrelatedtothecatalyticpropertiesforbenzenehydrogenation.ItwasfoundthatthecrystallizationofamorphousNiBalloywascarriedoutintwosteps,asindicatedbytwoexothermicpeakscenteredat598and652Krespectively.Duringthefirststep.twometastablecrystallinephases,i.e.,Ni3BandanoaocrstallineNiphase(Ni-richNiBalloy),wereformed.Furtherannealingathighertemperatureof652KmayresultinthedecompositionofcrystallineNi3BandaggregationofnanocrystallineNi,thebenzenehydrogenationisoptimizedaroundtheannealingtemperatureof623K.ItmostprobablyresultsfromthemaximumamountofactivesiteonnanocrystallineNiformedbythermaltreatmentatappropriateannealingtemperature.

  • 标签: 非晶合金 NIB 催化激活 退火结晶
  • 简介:Inthispaper,adrivingstressfiniteelementmethodofelastic-plasticlargedeformationbasedonimplicittimeintegratingalgorithmandaneight-chainmolecularnetworkmodelisusedforthenumericalsimulationofthesimplesheartestofpolycarbonate(PC)materials.Thesimulatedresultsarecomparedwithexperimentalones.Thestrainlocalizationpropagationfortheshearbanddeforma-tionforsimplesheardeformationisinvestigatednumerieaUy.TheeffectsofmicrostructureparametersinthemodelonstrainsofteningandorientationhardeningofthePCarediscussedindetail.

  • 标签: driving stress finite element method eight-chain
  • 简介:Tetrahedralamorphoushydrogenatedcarbon(ta-C:H)filmsonSi(lO0)substrateswerepreparedbyusingamagnetic-field-filterplasmastreamdepositionsystem.Sampleswithdifferentratiosofsp^3-bondtosp^2-bondwereobtainedbychangingthebiasvoltageappliedtothesubstrates.Theellipsometricspectraofvariouscarbonfilmsinthephotonenergyrangeof1.9-5.4eVweremeasured.Therefractiveindexnandtherelativesp^3CratioofthesefilmswereobtainedbysimulatingtheirellipsometricspectrausingtheForouhi-BloomermodelandbyusingtheBruggemaneffectivemediumapproximation,respectively.Thehaemocompatibilityoftheseta-C:Hfilmswasanalysedbyobservationofplateletadhesionandmeasurementofkineticclottingtime.Theresultsshowthatthesp^3Cfractionisdependentonthesubstratebiasvoltage,andthehaemocompatibilityisdependentontheratioofsp^3-bondtosp^2-bond.Agoodhaemocompatibilitymaterialofta-C:Hfilmswithasuitablesp^3Cfractioncanbepreparedbychangingthesubstratebiasvoltage.

  • 标签: 逼近性 碳膜 中子衍射 磁场 SEM
  • 简介:PECVD在玻璃底层上准备的非结晶的硅电影被退火的常规炉子并且快速的热退火(RTA)分别地使结晶。夫罗姆塞·拉曼系列,X光检查衍射和扫描电子显微镜,谷物尺寸在两种技术在850℃被使结晶,这被发现。RTA做的薄膜是光滑的并且完成式组织,薄膜由FA退火了有高度结构的混乱。大约30nm的一种平均谷物尺寸被两种技术获得。

  • 标签: 半导体技术 材料 PECVD 硅薄膜
  • 简介:Amorphoussiliconfilmsarepreparedatlowertemperatureof350℃bynewcatalyticchemicalvapordepositionmethod.Inthemethod,materialgases(SiH4andH2)aredecomposedbycatalyticreactionatgiventemperature,soa-Sifilmsaredepositedonsubstrates.Itisfoundthata-Sifilmswithhighqualitycanbeobtain,suchashighphotosensitivityof10^6,lowspindensityof2.5×10^16cm^-3.

  • 标签: 无定形硅片 气相化学沉积 生长率
  • 简介:MoleculardynamicssimulationwascarriedouttoinvestigatetheliquidandamorphousmicrostructuresofbinaryAgx-Rh(100-x)(x=25,50,75inatomfraction)alloys.SegregationfeatureofhomogeneousinteratomicbindingofAg-Rhliquidwasfoundandprobed,whichcanberetainedintoamorphoussolidsuponrapidcooling.Homogeneousbindingmayoccurwhenthedifferenceintheelementalatomicsizesislessthan10%.Theicosahedrainliquidbeforetheformationofamorphousstateexistinastablestateandthenetworkformedby1551-clustersinmoltenalloyswouldinhibitthecrystallizationanddiffusionofatoms.Ahigherdegreeof1551-clusterswillbefavorabletoformmetallicglasses.

  • 标签: 分子动力学 模拟 非晶形隔离 Ag-Rh合成 金属玻璃 液体结构
  • 简介:Sinceamorphousalloyshavewiderapplication,theycannotbefabricatedusingtheconventionalcoolingvelocity.ThebarmaterialplasmasprayingisadoptedtofabricateFebaseamorphousalloyinthisinvestigation.Thecrystallizationdegree,microstructure,micro-hardness,composition,crystallizationtemperatureoftheamorphousalloyandtheflyingrulesoftheatomizedparticlesintheprocessoftheplasmasprayaretested.Theresultsshowthatthealloypreparedhasthehighamorphousdegreeandhomogeneousmicrostructure,micro-hardnessandthecrystallizationtemperaturecanreach1187HVand531℃respectively.Theatomizationisverywellduringtheprocessofplasmaspraying;andthereishighthermalgradient,thecoolingvelocityreaches6.07×107K/s.

  • 标签: 非定形合金 棒材 等离子体喷射 焊接
  • 简介:Nitrogen-dopedamorphouscarbonthinfilmsaredepositedontheceramicsubstratescoatedwithTifilmbyusingdirectcurrentmagnetronsputteringtechniqueatN2andArgasmixtureatmosphereduringdeposition.Thefieldemissionpropertiesofthedepositedfilmshavebeeninvestigated.Thethresholdfieldaslowas5.93V/μmisobtainedandthemaximumcurrentdensityincreasesfrom4μA/cm2to20.67μA/cm2at10.67V/μmcomparingwithundopedamorphousfilm.Theresultsshowthatnitrogendopingplaysanimportantroleinfieldemissionofamorphouscarbonthinfilms.

  • 标签: Field EMISSION AMORPHOUS carbon MAGNETRON SPUTTERING
  • 简介:X-raydiffraction(XRD)anddifferentialscanningcalorimetry(DSC)wereemployedtoinvestigatetheinfluenceofNicontentonthecrystallizationofamorphousZr70Cu30-xNix(atomfrationin%)alloys,ExperimentalresultsshowthatwiththeNicontentincreasingtheactivationenergiesforcrystallizationofamorphousZr70Cu30-xNixalloysincreasecorrespondingly,indicatingthatthethermalstabilityisgreatlyimproved.AlltheDSCtracesofamorphousZr70Cu30-xNixalloysexhibittwoexothermicpeaks,suggestingthatthecrystallizationprocessviaadouble-stageticles,whilethesecondonecorrespondstotheprecipitaionofnano-scaleZr2Niphaseandcrystallizationofresidualamporphousphase,ThemechanismonthecrystallizationofamorphousZr70Cu30-xNixalloyswasdiscussed.

  • 标签: ZrCuNi合金 非晶形合金 结晶作用 X射线衍射
  • 简介:Thisworkaimedtoresearchthestructuremodelsofamorphousmaterials.Fiveamorphousandparacrystallinesamples(naturalorartificial)wereinvestigatedvia29Si/27Alnuclearmagneticresonance(NMR)andfieldemissionscanningelectronmicroscopy/energydispersivespectroscopy(FE-SEM/EDS).TheresultsofNMRshowedtheresonancesofdifferentspecimens:-93.2ppm,-101.8ppm,-111.8ppmfornaturalpozzolanaopalshale(POS).ThesepeakswereassignedtotheQ2(2OH),Q3(OH)/Q4(1Al)andQ4respectively.Theresultsof27AlMASNMRindicatedthatAlsubstitutedforSisiteintetrahedralexistinginthePOS,whiletheAl/Siatomicratioinopalwaslow(around0.04).Forthealkali-silicate-hydrategel,therewereatleastthreeresolvedsignalsassignedtoQ0andQ1,respectively.Forthefusedsilicaglasspowder,thereweretheprimarysignalscenteredaboutattherangefrom-107to-137ppm,whichwereassignedtoQ4units.Inaddition,thepeaksataround-98and-108ppmwerecorrespondingtoQ3(1OH)andQ4unitsexistinginaerogelsilicastructure.

  • 标签: AMORPHOUS and paracrystalline SILICA the structure
  • 简介:Wepresentintegrated-opticbuildingblocksandfunctionalphotonicdevicesbasedonamorphoussiliconon-insulatortechnology.Efficientdeep-etchedfiber-to-chipgratingcouplers,low-losssingle-modephotonicwirewaveguides,andcompactpowersplittersarepresented.Basedonthesub-μmphotonicwires,2×2Mach–Zehnderinterferometersandadd/dropmicroringresonators(MRRs)withlowdevicefootprintsandhighfinesseupto200wererealizedandstudied.Compactpolarizationrotatorsandsplitterswith≥10dBpolarizationextinctionratiowerefabricatedforthepolarizationmanagementon-chip.Thetuningandtrimmingcapabilitiesofthematerialplatformaredemonstratedwithefficientmicroheatersandapermanentdevicetrimmingmethod,whichenabledtherealizationofenergy-efficientphotoniccircuits.Wavelengthmultiplexersintheformofcascadedfilterbanksand4×4routersbasedonMRRswitchesarepresented.Fabricationimperfectionswereanalyzedandpermanentlycorrectedbyanaccuratelaser-trimmingmethod,thusenablingeight-channelmultiplexerswithrecordlowmetricsofsub-mWstaticpowerconsumptionand≤1°Ctemperatureoverhead.Thehighqualityofthefunctionaldevices,thehightuningefficiency,andtheexcellenttrimmingcapabilitiesdemonstratethepotentialtorealizelow-cost,denselyintegrated,andultralow-power3D-stackedphotoniccircuitsontopofCMOSmicroelectronics.

  • 标签:
  • 简介:Depositionofamorphousparticles,asaprevalentproblemparticularlyinthespraydryingoffruitandvegetablejuices,isduetolow-molecular-weightsugarsandisstronglydependentontheconditionoftheparticlesuponcollisionwiththedryerwall.Thispaperinvestigatestheconditionoftheamorphousparticlesimpactingthewallatdifferentdryingconditionswiththeaimofelucidatingthedepositionmechanismandphysicalphenomenainthedryingchamber.Amodelsucrose-maltodextrinsolutionwasusedtorepresentthelow-molecular-weightsugar.Particledepositswerecollectedonsamplingplatesplacedinsidethedryerforanalysesofmoisturecontent,particlerigidity(usingSEM)andsizedistribution.Moisturecontentwasadoptedasageneralindicatorofstickiness.Productparticlescollectedatthebottomoftheexperimentaldryerwerefoundtohavehighermoisturethanparticledepositsonsamplersinsidethedryer.Moisturecontentprofileinthedryershowsthatapartfromtheatomizerregion,whereparticlesarerelativelywet,particledepositsatotherregionsexhibitsimilarlowermoisturecontent.Atthehighesttemperatureadoptedintheexperiments,particlesbecamerubberysuggestingliquid-bridgeformationasthedominantdepositionmechanism.Furtheranalysisonparticlessizedistributionrevealsaparticlesegregationmechanismwherebysmallerparticlesfollowpreferentiallytothecentralairstreamwhilelargerparticlestendtore-circulateinthechamber,aspredictedinpastCFDsimulation.ThefindingsfromthisworkwillformthebasisandprovidevalidatingdataforfurthermodelingofwalldepositionofamorphousparticlesinspraydryingusingCFD.

  • 标签: POWDER handling AMORPHOUS PARTICLES DEPOSITION Particle