简介:从SiCp/Al复合材料性能分析着手,讨论了预置件法、焊接法和粘接法等在空间遥感器研制中常用的联接方法的优缺点,提出了在高体积分数(体分)SiCp/Al复合材料上直接加工螺纹,并加装钢丝螺套的方法来改善螺纹联接性能。对在某高体分SiCp/Al复合材料上加工的M4、M5螺纹进行了拉伸测试,结果表明:加装钢丝螺套前,复合材料螺纹有被拉脱现象;加装钢丝螺套后,M4螺纹、螺杆在3000~4000N被拉断;M5螺纹、螺杆在8000~9000N被拉断,测试后两种规格的螺纹状态良好,可以满足实际应用对该材料拉伸强度的要求,其已应用于工程项目中。
简介:我们学习分子的氧的绑定到一(5,0)单身者原文如此围了nanotube,借助于密度功能的计算。在SiCNT表面上的地点的硅和碳原子的等边六角形的中心是为O2分子的最稳定的吸附地点,与一个有约束力的精力?38.22eV和1.698的平均SiO有约束力的距离?。我们也与abinitio测试了O2adsorbedSiCNT/CNT的稳定性在房间温度被执行了的分子的动力学模拟。而且,单个围的碳nanotubes上的O2的吸附被调查了。我们的第一原则的计算预言硅碳化物nanotubes的O2吸附的能力比碳nanotubes的好一些。这可能为煤气的察觉和精力存储有潜力。
简介:在传统的利用化爆和二级轻气炮作为驱动源的状态方程阻抗匹配实验中,为了考核不同标准材料的可信度,采用了标准材料交叉检验技术。即依次利用这些标准材料作为测量某个待测材料测量雨贡纽线的标准材料,通过比较待测材料雨贡纽线数据的一致性实现对这些标准材料的检验。2004年在神光-Ⅱ装置上完成的二倍频激光Al-Cu和Cu-A1阻抗匹配实验,是一种交叉实验。这两类实验不仅铝、铜二者互为标准材料和待测材料,而且实验包含了正反阻抗匹配两种类型:铝-铜正阻抗匹配实验中冲击波由低阻抗铝进入高阻抗待测材料铜,铜-铝反阻抗匹配实验中冲击波由高阻抗铜进入低阻抗待测材料铝中。
简介:Theapplicabilityandlimitationofseveralquadraticstrengththeorieswereinvestigatedwithrespectto2D-C/SiCand2.5D-C/SiCcomposites.Akindofdamage-basedfailurecriterion,referredtoasD-criterion,isproposedfornonlinearceramiccomposites.Meanwhile,thenewlydevelopedcriterionispreliminarilyvalidatedundertension-shearcombinedloadings.ThepredictionshowsthatthefailureenvelopegivenbyD-criterionislowerthanthatfromTsai–HillandHoffmancriteria.Thisrevealsthatthedamage-basedcriterionisreasonableforevaluationofdamage-dominatedfailurestrength.
简介:Basedonthethermodynamictheory,anorthotropicdamageconstitutivemodelwasdevelopedtodescribethenonlinearmechanicalbehaviorofC/SiCcomposites.Thediferentnonlinearkinematicandisotropichardeningfunctionswereadoptedtodescribeaccuratelythedamageevolutionprocesses.Thedamagevariablesweredefinedwiththedamagedmodulusandtheinitialundamagedmodulusonenergyequivalenceprinciple.Theinitialorthotropyanddamagecouplingwerepresentedinthedamageyieldfunction.Tensileandin-planeshearloadingandunloadingtestswereperformed,andagoodagreementbetweenthemodelandtheexperimentalresultswasachieved.
简介:ThecorrelationbetweenphasestructuresandsurfaceacidityofAl2O3supportscalcinedatdifferenttemperaturesandthecatalyticperformanceofNi/Al2O3catalystsintheproductionofsyntheticnaturalgas(SNG)viaCOmethanationwassystematicallyinvestigated.Aseriesof10wt%NiO/Al2O3catalystswerepreparedbytheconventionalimpregnationmethod,andthephasestructuresandsurfaceacidityofAl2O3supportswereadjustedbycalciningthecommercialγ-Al2O3atdifferenttemperatures(600–1200C).COmethanationreactionwascarriedoutinthetemperaturerangeof300–600Catdifferentweighthourlyspacevelocities(WHSV=30000and120000mL·g-1h-1)andpressures(0.1and3.0MPa).ItwasfoundthathighcalcinationtemperaturenotonlyledtothegrowthinNiparticlesize,butalsoweakenedtheinteractionbetweenNinanoparticlesandAl2O3supportsduetotherapiddecreaseofthespecificsurfaceareaandacidityofAl2O3supports.Interestingly,NicatalystssupportedonAl2O3calcinedat1200C(Ni/Al2O3-1200)exhibitedthebestcatalyticactivityforCOmethanationunderdifferentreactionconditions.LifetimereactiontestsalsoindicatedthatNi/Al2O3-1200wasthemostactiveandstablecatalystcomparedwiththeotherthreecatalysts,whosesupportswerecalcinedatlowertemperatures(600,800and1000C).ThesefindingswouldthereforebehelpfultodevelopNi/Al2O3methanationcatalystforSNGproduction.
简介:A60%Fe/Al2O3catalystwaspreparedbytheco-precipitationmethod.ItwasreducedbyH2toproducemetallicFe,whichwasthensulfidedbyCS2toFe0.96SandFe3S4orphosphidedbytriphenylphosphine(PPh3)inliquidphasestoFe2PandFeP.Itwasfoundthattheironsulfides(Fe0.96SandFe3S4)exhibitedthelowactivityforthehydrodesulfurization(HDS)reactions.TheHDSactivitywasalsolowontheFe(metal)/Al2O3andFe2P/Al2O3catalystssincetheywereconvertedintoFe0.96SandFe3S4duringtheHDSreactions.Incontrast,theFeP/Al2O3wasfoundtobestableandactivefortheHDSreactions.Inparticular,FeP/Al2O3possessedsignificantlysmallerFePparticlesthanFeP/C,leadingtothesignificanthigherHDSactivityofFeP/Al2O3thanFeP/C.
简介:Thispaperreportsthattheetchingmorphologyofdislocationsin8°off-axis4H-SiCepilayerisobservedbyusingascanningelectronicmicroscope.Itisfoundthatdifferenttypesofdislocationscorrespondwithdifferentdensitiesandbasalplanedislcation(BPD)arrayandthreadingedgedislocation(TED)pileupgroupliealongsomecertaincrystaldirectionsintheepilayer.Itisconcludedthattheelasticenergyofthreadingscrewdislocations(TSDs)ishighestandTEDsislowestamongthesedislocations,sothedensityofTSDsislowerthanTEDs.TheBPDscanconverttoTEDsbutTSDscanonlypropagateintotheepilyerinspiteofthehigherelasticenergythanTEDs.ThereasonoftheformofBPDsarrayinepilayeristhatthebigstepalongthebasalplanecausedbyfacedefectsblockedtheupstreamatoms,andTEDspileupgroupisthatthedislocationsslideisblockedbydislocationgroupsinepilayer.
简介:Wepresentnumericalcalculationoftheimpactofelectron-electroninteractiononthebehaviorofdensityofstatesandopticalpropertiesofBeO,SiCandBoron-Nitridenanotubesandsheets.Hubbardmodelhamiltonianisappliedtodescribethedynamicsofelectronsonthelatticestructureofthesescompounds.TheexcitationspectrumofthesysteminthepresenceoflocalelectronicinteractionshasbeenfoundusingmeanSeldapproach.WefindthebandgapwidthinbothopticalabsorptionanddensityofstatesreduceswithlocalHubbardelectronicinteractionparameter.Theabsorptionspectraexhibitstheremarkablepeaks,mainlyowingtothedivergencebehaviorofdensityofstatesandexcitoniceffects.AlsowecompareopticalabsorptionfrequencybehaviorofBeO,SiCandBoron-Nitridenanotubeswitheachother.FurthermoreweinvestigatetheopticalpropertiesofBeOandSiCsheets.Anovelfeatureofopticalconductivityofthesestructuresisthedecreaseoffrequencygapintheopticalspectrumduetoelectronicinteraction.
简介:与飘移散开(DD)的联合使用模型,试验性的测量参数和小信号的正弦曲线不变的分析,我们为4H-SiC提取Y参数埋葬隧道的金属氧化物半导体域效果晶体管(BCMOSFET)。输出电线走火水流获得G,梅森的不变的U分别地在普通来源的配置f(T)和摆动f(最大)的最大的频率为外推的统一水流获得频率被计算。这里f(T)=800MHz和f(最大)=5GHz为4H-SiCBCMOSFET被提取,当地效果活动性到达它的山峰时,珍视87cm(2)/Vs什么时候V-GS=4.5V。模拟结果清楚地证明4H-SiCBCMOSFET和地效果活动性的典型频率是优异的,由于新奇结构,与常规MOSFET相比。