学科分类
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54 个结果
  • 简介:Inthispapertheresultsofahigh-speedtensionexperimentoftheSiC_w/Alcompositehavebeenreportedandasimplifiedtheoreticalmodelhasbeendevelopedtostudythefracturemechanismofcompositesinhigh-speedtension.Thistheoreticalmodelprovidesanewexplanationfortheincreaseofdynamicfracturestrengthofcompositesinhigh-speedtension.

  • 标签: COMPOSITE material HIGH-SPEED tension FRACTURE MECHANICS
  • 简介:Agroupofpoly(phthalazinoneethersulfoneketone)/potassium-titanate-whisker(PPSEK/whisker)compositeswaspreparedbycoprecipitationfromsolution.Thewhiskersurfacewasmodifiedusingtitanatecouplingagentpriortoblending.Thetensile,impact,morphologyandthermalpropertiesofthemouldedcompositeswereinvestigated.Themeasurementsshowedthatthetensilestrengthandimpactstrengthofthecompositesincreasedwithincreasingwhiskerscontentupto10to20phr,thereaftertheyshowedadecreaseinthewhiskerscontentreached40phr.Atthesametime,themodulusofthecompositesincreasedwithincreasingwhiskerscontent.Scanningelectronmicroscopystudiesrevealedthatthewhiskerswithinthecompositesweredisperseduniformlybytreatedwithcouplingagent.Finally,thermogravimetricanalysisshowedthattheheatresistanceofthecompositestendedtoincreasewithincreasingwhiskercontent.Theresultswereanalysedanddiscussedintermsofestablishedmodelsofthebehaviourofshort-fiberreinforcedcomposites.

  • 标签: 钛酸钾晶须 PPESK化合物 酞菁乙醚砜酮 抗热性 工程聚合体 热塑性塑料
  • 简介:Inordertoinvestigatetheelectromagneticshieldingeffectiveness(SE)andabsorbingpropertiesoffiberreinforcedconcrete,steelfiber,carbonfiberandsyntheticpolyvinylalcohol(PVA)fiberreinforcedconcretewereresearched.Theresultsshowthatwiththeincreaseoffibervolumefraction,theSEandtrendoffrequencychangeofcorrespondingfiberreinforcedconcreteareenhanced.Whenthevolumecontentofsteelfiberis3%,theSEofconcreteisabove50dBanditsfrequencyisabove1.8GHz.Moreover,intherangeof8-18GHz,steelfiber,carbonfiberandPVAfiberallcanimprovethemicrowaveabsorptionpropertiesofconcrete.Theconcretewith0.5%carbonfibercanachievethebestabsorbingproperty,theminimumreflectivityisabout-7dB;whilesteelfiberoptimalvolumefractionis2%.ThereflectivitycurveofPVAfiberreinforcedconcretefluctuateswiththefrequency,andtheminimumvalueofthereflectivityisbelow-10dB.TheresultsshowthatfiberreinforcedconcretecouldbeusedasEMI(electromagneticinterference)preventionbuildingsbyattenuatingandreflectingelectromagneticwaveenergy.

  • 标签: 电磁屏蔽效能 水泥基复合材料 吸收特性 光纤 钢筋混凝土 反射率曲线
  • 简介:ThebasestructureofinsituTiCP/Fecompositesfabricatedunderindustrialconditionwaschangedbydifferentheattreatments.Erosiveweartestswerecarriedoutandtheresultswerecomparedwiththatofwear-resistantwhitecastiron.TheresultssuggestthatthewearresistanceoftheinsituTiCp/Fecompositeishigherthanthatofwear-resistantwhitecastironunderthesanderosivewearcondition.Thewearmechanismofthewear-resistantwhitecastironwasacycleprocessthatbasesurfacewaswornandcarbideswereexposed,thencarbideswasbrokenandwearpitsappeared.WhilethewearmechanismofinsituTiCp/FecompositewasacycleprocessthatbasesurfacewaswornandTiCgrainswereexposedanddropped.ThewearresistanceofinsituTiCp/Fecompositewaslowerthanthatofwear-resistantwhitecastironundertheslurryerosivewearcondition.Undersuchcircumstance,thematerialwasnotonlyundergoneerosivewearbutalsoelectrochemistryerosionduetothecontactwithwaterinthemedium.Thewearbehaviourscanbeacombinationoftwokindsofwearandthesanderosivewearisworsethanslurryerosivewear.

  • 标签: 钛铁合金 腐蚀性表面 磨损装置 热处理
  • 简介:Fibrestressofglassfibrereinforcedpolymericcopmositesonloadisdeterminedbyusingopticalfibreasmodelfiberandbymeansoflaserinterferencemethod.Inaddition,theoriginationoffibrestressduringmouldingprocessofcompositesandtherelationbetweenfiberstressofloadedcompositesandexternalstressareexamined.Theexperimentsshowthatfibrestressisrelatedtomolecularstructureofinterfacialmaterialsandstructureofinterfaciallayers.Whenstressistransferredfrommatrixtofibre,eachinterfaciallayerhasdifferentstressgradientanddeformability.Thispropertycanbecharacterizedbyintroducinganinterfacialstresstransfercoefficientktothetwo-phasemodel.

  • 标签: interface COMPOSITES stress transfer optical FIBRE
  • 简介:Theadvancedfabricationofin-situdendrite/metallicglassmatrix(MGM)compositesisreviewed.Herein,thesemisolidprocessingandBridgmansolidificationaretwomethods,whichcanmakethedendriteshomogeneouslydispersedwithinthemetallicglassmatrix.Uponquasi-staticcompressiveloadingatroomtemperature,almostallthein-situcompositesexhibitimprovedplasticity,duetotheeffectiveblocktothefastpropagationofshearbands.Uponquasi-statictensileloadingatroomtemperature,althoughthecompositespossesstensileductility,theinhomogeneousdeformationandassociatedsofteningdominates.Highvolume-fractioneddendritesandnetworkstructuresmakein-situcompositesdistinguishinglyplasticupondynamiccompression.In-situcompositeexhibitshightensilestrengthandsoftening(necking)inthesupercooledliquidregion,sincethepresenceofhighvolume-fractioneddendriteslowerstherheologyoftheviscousglassmatrixathightemperatures.Atcryogenictemperatures,adistinguishingly-increasedmaximumstrengthisavailable;however,aductile-to-brittletransitionseemstobepresentbyloweringthetemperature.Besides,improvedtension—tensionfatiguelimitof473MPaandfour-point-bendingfatiguelimitof567MPaaregainedforZr58.5Ti14.3Nb5.2Cu6.1Ni4.9Be11.0MGMcomposites.Highvolume-fractiondendriteswithintheglassmatrixinduceincreasedeffectivenessonthebluntingandpropagatingresistanceofthefatigue-cracktip.Thefracturetoughnessofin-situcompositesiscomparabletothoseofthetougheststeelsandcrystallineTialloys.Duringsteady-statecrack-growth,theconfinementofdamagebyin-situdendritesresultsinenhancementofthetoughness.

  • 标签: 金属基复合材料 原位复合材料 玻璃基质 枝蔓 疲劳极限 拉伸载荷
  • 简介:ThefracturetoughnessandfractureworkofAl2O3/SiCprismaticceramiccompositeswasevaluatedinthispaper,whichshowedthefractureenergywasimprovedgreatly.Basedontheobservationforcrackpropagationandfracturemorphology,thefracturebehavioroftheprismaticcompositeswasanalyzed.Inthebendingtest,thecompositesdisplayedanon-catastrophicbehaviorandagracefulfailurewithreasonableload-carryingcapability.

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  • 简介:Asystematicalsimulationhasbeencarriedoutontheindentationcreeptestonparticle-reinforcedcomposites.Thedeformation,failuremechanismsandlifeareanalyzedbythreereasonablemodels.Thefollowingfivefactorshavebeenconsideredsimultaneously:creeppropertyoftheparticle,creeppropertyofthematrix,theshapeoftheparticle,thevolumefractionoftheparticleandthesize(relativesizetotheparticle)oftheindentationindenter.Forallthecases,thepowerlawrespectingtotheappliedstresscanbeusedtomodelthesteadyindentationcreepdepthrateoftheindenter,andthedetailexpressionshavebeenpresented.Thecomputersimulationprecisionisanalyzedbythetwo-phasemodelandthethree-phasemodel.Twoplacesofthestressconcentrationarefoundinthecomposites.Oneisaheadoftheindentationindenter,wherethehighstressstateisdeducedbytheedgeoftheindenterandwilldecreaserapidlyneartoasteadyvaluewiththecreeptime.Theotheroneisattheinterface,wherethehighstressstateisdeducedbythemisfitofmaterialpropertiesbetweentheparticlesandmatrix.Ithasbeenfoundthatthecreepdissipationenergydensityotherthanastressparametercanbeusedtobethecriteriontomodelthedebondingoftheinterfaces.Withthecriterionofthecriticalcreepdissipationenergydensity,apowerlawtotheappliedstresswithnegativeexponentcanbeusedtomodelthefailurelifededucedbythedebondingofinterfaces.Theinfluencesoftheshapeoftheparticlesandthematchingofcreeppropertiesofparticleandmatrixcanbediscussedforthefailure.Withacrackmodel,thefurthergrowthofinterfacecrackisanalyzed,andsomeimportantexperimentalphenomenacanbepredicted.Thefailuremechanismwhichtheparticlewillbepunchedintomatrixhasbeenalsodiscussed.Thecriticaldiflerencesbetweenthecreeppropertiesoftheparticlesandmatrixhavebeencalculated,afteraparameterhasbeendefined.Intheviewofcompetitionoffailure

  • 标签: 刻痕 蠕变试验 计算机模拟 颗粒增强复合材料 机械性能
  • 简介:Thebovinehydroxyapatite(BHA)wasappliedtopreparebiologicaltissueengineeringscaffoldsbythemethodofextrusionfreeforming.Toachievethisgoal,BHAwereaddedtosodiumalginate(SA)solutiontoformaslurrysysteminappropriateproportion.Theresultingmixtureswerefabricatedtobeakindofcontrollableandporousscaffoldsfollowedwithcross-linkingin5%calciumchloride(CaCl2)solutionfor24h.Afterthat,thescaffoldsweresinteredinairat1000,1100,1200and1300℃for5h.Scanningelectronmicroscopy(SEM)andX-raydiffraction(XRD)studieswereperformedonthescaffoldstoanalyzeitsmicrostructureandconstituent.Toexploretheeffectofsinteringtemperatureonscaffolds,thecompressivestrength,volumeshrinkageandwaterabsorptivityofBHA-SAcompositescaffoldsaftersinteringwereinvestigated.TheresearchtestsindicatedthefeasibilityofapplyingBHApowderto3Dprinting.Besides,thescaffoldssinteredinarespectivelylowertemperaturepossessmuchmoreporesandperformedhigherwaterabsorptivity,whichmeansbettercellularaffinity.Andscaffoldssinteredbetween1100and1200℃presentshighercompressivestrength.

  • 标签: BOVINE bone HYDROXYAPATITE ball MILLING SINTERING
  • 简介:二维(2D)有multilayered质地的碳/碳(C/C)composites,特别与不同厚度高度粗糙(HT)pyrocarbon层,被等温的、等压的化学蒸汽渗入(CVI)准备技术。C/Ccomposites的机械性质上的矩阵微观结构的影响被极化的轻显微镜学调查,扫描电子显微镜学和三点的弯曲测试。结果证明有多层粗糙的pyrocarbon矩阵的样品与纯媒介粗糙的结构比那件拥有更高曲折的力量,它被归因于多重裂缝偏转并且在HT层以内的在不同粗糙的pyrocarbon层之间并且在亚层之间的界面的滑动。HTpyrocarbon层的厚度的增加改进样品的粘性并且在伪塑料行为显示破裂。

  • 标签: 材料力学性能 复合材料 微观结构 2D 炭/炭 三点弯曲试验
  • 简介:我们为说明唯一的结构和磷灰石蛋白质composites的技工性质的atomicto中央规模过程的探索考察衔接规模的模拟研究。当如此的复杂biocomposites的原子结构和作文仅仅部分被知道,我们的建模研究的第一部分(i)被奉献给无机器官的composites的现实主义的水晶成核情形。从单个离子,从主题形成的机制的最近的卓见范围,成熟反应和nanocrystals的组织工会的协会开始,包括他们有控制生长的分子的一半的相互影响。在这个基础上,(ii)可靠的造为没有偏见的按比例增加裁定模型能被导出为体积材料建模。这被例示为(像瓷釉)磷灰石蛋白质composites,包含直到106原子当模特儿提供10nm长度规模的一篇现实主义的报道,虽然模型变粗被用来到达m,长度可伸缩。在这个基础上,一系列变丑和破裂模拟研究被执行并且帮助文饰biocomposite坚硬,粘性,坚韧,self-healing和破裂机制。补充试验性的工作,这些建模研究提供特别地详细的卓见进层次合成结构和有利机械性质的关系。

  • 标签: 生物复合材料 磷灰石 模拟 分子 多尺度 有机/无机复合材料
  • 简介:影响在海水沉浸,以及结果在潮湿散开上把聚合物矩阵composites的厚度压成薄片为glass/isopolyester(G/IPE)的composites的机械性质降级,carbon/isopolyester(C/IPE),glass/vinylester(G/VE)和carbon/vinylester(C/VE),在这份报纸被调查。把3压成薄片并且在厚度的10mm,使用湿手上篮技术制作,被描绘因为在人工的海水媒介的潮湿吸收,和他们的曲折力量和interlaminar砍力量(ILSS)降级被学习。潮湿散开被观察是到Ficks的anamolous为3的法律和10mm在散开的以后的阶段的厚样品。10mmthick样品的潮湿渗透是比3mm的大的二~三份订单厚的,当潮湿浸透的时间仍然保持未改变时。随增加把厚度压成薄片,1.4%为C/VE增加的潮湿浸透并且7%为G/IPE。剩余曲折力量和ILSS在10mm的情况下是更大的在200天暴露以后的厚标本。折断的标本的SEM检查在10mm显示出纤维/矩阵debonding的更大的层次厚标本。

  • 标签: 复合材料层压板 水分扩散 聚合物基体 人工海水 厚度 层间剪切强度
  • 简介:以便得到TiB2-Al2O3的同质的混合物和协议,一个表面修正方法被用来准备nano规模的杂交Al2O3涂的TiB2粒子。PE蜡粒子是第一到由杂交,然后nano规模Al2O3粒子的TiB2粒子上涂又是涂的到由PE蜡粒子涂的TiB2的表面上。SEM,TEM和版本被用来描绘同样收到的核心/壳粒子和它的协议的微观结构。试验性的结果显示出那粒子规模TiB2和Al2O3的同质的分散能不仅在混合粉末而且在使脱蜡的协议被形成。协议当时是由煤气压的sintering(GPS)的sintered。物件顶端的装饰物产品显示出与参考样品由正常方法制作了作比较的改进技工性质。

  • 标签: 复合材料 AL2O3颗粒 TIB2 氧化铝涂层 制作 表面改性方法
  • 简介:AnewmethodforcorrosionprotectionofAl-basedmetalmatrixcomposites(MMC)wasdevelopedusingtwo-stepprocess,whichinvolvesanodizinginH2SO4solutionandsealinginrareearthsolution.Corrosionresistanceofthetreatedsurfacewasevaluatedwithpolarizationcurves.TheresultsshowedthattheeffectoftheprotectionusingrareearthsealingisequivalenttothatusingchromatesealingforAl6061/SiCp.TherareearthmetalsaltcanbeanalternativetothetoxicchromateforsealinganodizedAlMMC.

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  • 简介:Theresultsofatheoreticalstudyontheinfluenceofstrengthofinterphaseboundariesinmetal—ceramiccompositeonmacroscopicalcharacteristicsofcompositeresponsesuchasstrength,deformationcapacity,fractureenergyandfracturepatternarepresented.Thestudywasconductedbymeansofcomputer-aidedsimulationbymeansofmovablecellularautomatonmethodtakingaccountofadeveloped'mesoscopical'structuralmodelofparticle-reinforcedcomposite.Thestrengthofinterphaseboundariesisfoundtobeakeystructuralfactordeterminingnotonlythestrengthpropertiesofmetal—ceramiccomposite,butalsothepatternandrateoffracture.Theprinciplesforachievementofthehigh-strengthvaluesofparticle/binderinterfacesinthemetal—ceramiccompositionduetotheformationofthewidetransitionzones(areasofvariablechemicalcomposition)attheinterphaseboundariesarediscussed.Simulationresultsconfirmthatsuchtransitionzonesprovideachangeinfracturemechanismandmaketheachievementofahigh-strengthandahighdeformationcapacityofmetal—ceramiccompositepossible.

  • 标签: 陶瓷复合材料 金属陶瓷 相界面 断口特征 力学性能 颗粒增强复合材料
  • 简介:Epoxyresin/Ni@Cnanoparticlecompositeswithalignedmicrostructurewerepreparedbyusingaprocedureofmagneticfieldassistedcuring.Theresultsshowthattheresistivityofcompositesexhibitsnegativetemperaturecoeffcient(NTC)effectaboveroomtemperature,andcanbeadjustedbyvaryingthecontentfillerandthemagnitudeofmagneticfieldapplied.Hill'squantumtunnelingmodelwasmodifiedtounderstandtheelectricalconductionmechanisminthecomposites.ItshowsthattheNTCeffectascribestothedominantthermalactivatedtunnelingtransportofelectronacrossadjacentnanoparticles,aswellasthelowthermalexpansivityofepoxyresinmatrix.

  • 标签: 纳米复合材料 环氧树脂 可调电阻 纳米镍 电阻效应 参展
  • 简介:钡锶铝矽酸盐(BSAS)和Si/BSAS涂层经由一个二拍子的圆舞激光cladding过程在C/SiCcomposites的表面上被制作。微观结构,机械性质,和样品的水蒸汽腐蚀行为被调查。BSAS涂层被发现紧被结合到底层和仅仅一些毛孔,microcracks被观察。硅中间层的介绍被揭示减少热应力并且支持在激光cladding过程期间形成的缺点愈合。为了评估腐蚀抵抗,BSAS和Si/BSAS-coated,C/SiCcomposites暴露于50%H2在1250敢椠?慦桳潩的O和50%O2吗?

  • 标签: 环境障碍涂层 钡锶铝矽酸盐 C/SiC 合成 激光 cladding