简介:(1-x)La_(0.67)Ca_(0.33)MnO_3/Cr_2O_3(LCMO)+xCr_2O_3composites被一个新液相方法综合。XRD和SEM大小表明在LCMO结构和LCMO的晶格常数可溶的很少Cr_2O_3几乎没变化,当大多数Cr_2O_3在谷物边界或在LCMO谷物的表面上是分布式的时。Inresistivity对温度大小,金属--绝缘体转变被观察什么时候x<0.20。抵抗力增加和金属--绝缘体转变温度与Cr_2O_3的增加的内容减少。一个随机的电阻器网络(KRN)模型被使用,到模仿混合样品的运输性质。模拟结果同意试验性的观察。结果证明方法为理解maganite的composites的电子运输是合理的。
简介:Aseriesofflexiblepoly(m-phenyleneisophthalamide)(PMIA)-basedcompositeswithdifferentsizesandmassfractionsofhexagonalboronnitride(hBN)weresuccessfullymanufacturedforthefirsttimeviathecastingtechnique.TheeffectsofmodifiedhBNparticlesonmicrostructure,mechanicalproperties,dielectricpropertiesandthermalconductivitiesoffabricatedcompositeswereinvestigated.TheresultsindicatethatmodifiedhBNparticlesmanifestgoodcompatibilitywiththePMIAmatrix.TheYoung'smodulusandTheat-resistanceindexofPMIA-basedcompositesareincreasedwithincreasingthemassfractionofhBNparticles.Duetoadditionalthermalconductivepathsandnetworksformedbynano-sizedhBNparticles,theK-m/n-hBN-30compositedisplaysthethermalconductivityof0.94W·m^-1·K^-1higherthanthatoftheK-m-hBN-30composite(0.86W·m^-1·K^-1),andmorethan4timeshigherthanthatofneatPMIA.Moreover,theobtainedPMIA-basedcompositesalsoshowlowdielectricconstantandidealdielectricloss.Owingtotheexcellentcomprehensiveperformance,hBN/PMIAcompositespresentpotentialapplicationsinthebroadfieldofelectronicmaterials.
简介:Tomeettheincreasingdemandforadvancedmaterialscapableofoperationover2000℃forfuturethermalprotectionsystemsapplication,C/C—ZrC—SiCcompositeswerefabricatedbyreactivemeltinfiltration(RMI)withZr,Simixedpowdersasrawmaterials.ThestructuralevolutionandformationmechanismoftheC/C—ZrC-SiCcompositeswerediscussed,andthemechanicalpropertyoftheas-preparedmaterialwasinvestigatedbycompressiontest.TheresultsshowedthataftertheRMIprocess,aspecialstructurewithZrC-SiCmulti-coatingasouterlayerandZrC-SiC-PyCceramicsasinnermatrixwasformed.ZrCandSiCrichareaswereformedinthecompositesandonthecoatingsurfaceduetotheformationofZr-SiintermetalliccompoundsintheRMIprocess.MechanicaltestsshowedthattheaveragecompressionstrengthoftheC/C-ZrC-SiCcompositeswas133.86MPa,andthecarbonfibersinthecompositeswerenotseriouslydamagedaftertheRMIprocess.
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简介:TheinteractionbetweenZn-AleutecticalloyandAl2O3p/6061Alcompositesinthevacuumfurnacewasinvestigated.Greatattentionhasbeenpaidtotheelementsdiffusion,themicrostructureandformationoftheinterfacebetweenZn-AIeutecticalloyandAl2O3p/6061Alcomposites.ExperimentalresultsshowthatZn-AleutecticalloyhasagoodwettingabilitytoAl2O3p/6061Alcompositesandthewettingangledecreaseswithincreasingthetemperatureinvacuum.Aftertheinteraction,aninteractionlayerformsbetweenZn-AIalloyandAl2O3p/6061Alcomposites.Thephasesintheinteractionlayermainlyconsistofα-Al(Zn),Al2O3andCuZn5resultedfromthediffusionofelementsfromtheZn-Alalloy.SeveralporositiesdistributeintheregionneartheinterfaceoftheZn-Alalloy/interactionlayer.TheamountofshrinkagevoidsintheinteractinglayerisrelevanttothepenetrationofZnelementintoAl2O3p/6061Alcompositeswhichisafunctionoftemperature.SoitisnecessarytolowerheatingtemperatureinordertolimittheZnpenetration.
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简介:hydroxyapatite(哈)涂层在对待H2O2的碳/碳(C/C)上被完成通过热水地对待和在超声的水下面在一个氨答案加热扔的CaHPO4涂层的正式就职合成洗澡。然后,这哈涂层被放在一个NH4F答案并且热水地再对待制作氟化的hydroxyapatite(联邦住房管理局)为在353,373,393和413K的24h的涂层分别地。结构,形态学和HA和联邦住房管理局涂层的化学作文被SEM,XRD,版本和FTIR描绘,并且粘着性和这些联邦住房管理局涂层的化学稳定性被擦伤测试和沉浸测试分别地检验。结果证明同样准备的联邦住房管理局涂层包含了像针或像条纹的晶体,与那些不同HA涂层。作为加氟作用温度玫瑰,FHA涂层的粘着性首先在在353和393K之间的温度从34.8~40.9N增加了,然后在413K减少了到24.2N,当FHA涂层的溶解率稳定地减少了时。为FHA涂层的性质变化的原因被分析涂层的形态学,作文和结构建议。
简介:Si_3N_4-Si_2N_2Ocomposites被液相sintering(LPS)与非结晶的缩放nano的氮化矽粉末制作。Si_2N_2O阶段被in-situreaction2Si_3N_4(s)+1.5O_2(g)=3Si_2N_2O+N_2(g)产生直到在体积的60percent的Si_2N_2O阶段的内容在1650t的sintering温度被获得并且当sintering温度增加了或减少时,减少了,显示反应是可逆的。集体损失,相对密度和平均谷物尺寸与增加sintering温度增加了。当sintering温度在1700degC下面时,Theaverage谷物尺寸是不到500nm。Thesintering过程包含复杂结晶化和阶段转变:非结晶的氮化矽->equiaxialalpha-Si_3N_4->equiaxial->Si_3N_4->杆--相似Si_2N_2O->像针的beta-Si_3N_4。小回合--塑造的beta-Si_3N_4粒子在Si_2N_2O谷物被骗诱,界定差错的高密度位于在1650degC的sintering温度的Si_2N_2O谷物的中间。坚韧在1600degCto7.2MPa从3.5Mpa中心点m~(1/2)增加了在1800degC的中心点m~(1/2)。坚硬在1600degC象21.5GPa(Vickers)一样高。
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简介:Inpursuingexcellentsupercapacitorelectrodes,wedesignedaseriesofM0S2/C0S2compositesconsistingofflower-likedMoS2andoctahedron-shapedCoS2throughafacileone-stephydrothermalmethodandinvestigatedtheelectrochemicalperformanceofthesampleswithvarioushydrothermaltime.Duetothecouplingoftwometalspeciesandabigamountofwell-developedCoS2andMoS2,theresultsindicatedthattheMoS2/CoS2compositeselectrodesexhibitedthebestelectrochemicalperfor-mancewithalargespecificcapacitanceof490F/gat2mV/sor400F/gat10A/gamongallsamplesasthehydrothermaltimereached48h(MCS48).Furthermore,theretentionofMCS48is93.1%after10000cyclesat10A/g,whichmanifeststheexcellentcyclingstability.TheoutstandingelectrochemicalperformanceofMCS48indicatesthatitcouldbeaverypromisingandnovelenergystoragematerialforsupercapacitorsinthefuture.
简介:AseriesofCd1-xZnxS/K2La2Ti3O10compositesweresynthesizedviaasimpleco-precipitationmethod.ThepreparedsampleswerecharacterizedbyX-raydiffraction(XRD),scanningelectronmicroscopy(SEM),X-rayenergydispersivespectroscopy(EDX),ultraviolet-visiblediffusereflection(UV-Vis),X-rayphotoelectronspectroscopy(XPS)andphotoluminescence(PL)measurements.ThecompositestructuresconsistedofCd1-xZnxSnanoparticlesevenlydistributedonthesurfaceofK2La2Ti3O10.TheabsorptionedgeofK2La2Ti3O10shiftedtothevisiblelightregionuponintroductionoftheCd1-xZnxSnanoparticles.Thephotocatalyticactivitiesofthecatalystswereevaluatedbyhydrogenproductionundervisiblelightirradiation.ThepreparedCd0.8Zn0.2S(30wt%)/K2La2Ti3O10exhibitedhigherphotocatalyticactivity,evolving6.92mmol/gH2undervisiblelightirradiationfor3h.ThepromotedphotocatalyticactivityofthecompositeswasattributedtothesynergisticeffectbetweenCd1-xZnxSandK2La2Ti3O10,whichresultedinenhancedseparationofphotogeneratedelectronsandholes.