学科分类
/ 8
158 个结果
  • 简介:Wehaveinvestigatedthephysicalproperties,includingthemorphology,texture,adhesionandchemicalquality,ofhigh-frequencychemicalvapourdepositeddiamondcoatingsonWC-6%Cosubstrates,whichwerepre-treatedbyatwo-stepetchingmethod.TheresultsindicatethattheincreasingCocontentfrom0.12to3.05%withintheetchingdepthof5μmcausedamorphologytransformationfromprismdiamondtospheruliticdiamond,andatexturetransformationfroma{111}orientationtoa{110}orientation.TheRamanspectrumshowsthatthespheruliticdiamondfilmcontainsmorenon-diamondphases(graphite,amorphouscarbonanddiamond-likecarbon,etc)andhaslowerchemicalqualitythandiamondfilmsonaWC-6%Cosubstrate.Thediamondcoatinggrainsizesbecameaboutfourtimessmallerwhenthedepositiontemperaturesonthesubstratesurfacewerereducedfrom1000to900℃.Comparedwithspheruliticdiamondfilms,theprismdiamondfilmsexhibitbetteradhesionontheWC-6%Cosubstrate.

  • 标签: 金刚石 化学汽相淀积 金刚石薄膜
  • 简介:物质的颗粒度大小及分布,直接联系着物质的性能和应用。过去,对常规10-20gm的炸药颗粒度研究较多,而对炸药颗粒度研究较少。与常规炸药相比,炸药存在许多特殊性,如颗粒间更易团聚不易分散、在溶剂里表现出不同于大颗粒的溶解性等,使测试变得更复杂。以TATB、BTF、HNS、RDX和HMX为对象,使用LS-230型激光粒度仪,对颗粒度测试过程中涉及的各种测试条件(如分散介质的选择、分散剂选择、超声时间的确定、光学模型设置、运行时间等)进行研究,获得各种炸药的最佳测试条件,形成基本完善的测试方法,并将测试结果与扫描电子显微镜及英国马尔文公司的Matersizer2000型激光粒度仪的测试结果进行比较。

  • 标签: 超细炸药 颗粒度 测试方法 光学模型 超声波振荡器
  • 简介:为研制具有较宽频带微波吸收性能的材料,采用机械合金化法制备CoxFe80-xSi20(x=0,6,10,14摩尔百分数)合金粉体,使用SEM、XRD和矢量网络分析仪等测试手段,研究了合金粉体微观结构及Co-Fe-Si合金微波吸收性能。结果表明:制备的合金粉末呈片状,主要由-Fe相组成;Co的添加使Co-Fe-Si合金出现两个微波吸收峰。在较高频段处的微波吸收峰值随Co的添加先增大后减小。在涂层厚度为1.8mm时,x=10的合金低频处的反射率最小值最小,合金吸波峰频率和峰值分别为6.2GHz和-14.8dB,合金在高频处吸波峰频率和峰值分别为18GHz和-8.8GHz,合金反射率低于-5dB的带宽达14GHz,具有良好的微波吸收宽频效应。

  • 标签: Co-Fe-Si合金 吸波材料 电磁参数 反射率
  • 简介:钨基合金由于具有高密度、高强度及高冲击韧性等优异性能而得到广泛应用。它在军事工业中主要用作穿甲弹、动能弹和导弹弹头。我单位对高密度钨基合金材料的研究已有多年历史,重点研究了添加Co,Mn,Cr等元素对钨基合金性能的影响,并研制出一系列密度和力学性能的钨基合金

  • 标签: 钨基合金 机械性能 真空热处理
  • 简介:COandformaldehyde(HCHO)oxidationreactionswereinvestigatedovermesoporousAg/Co3O4catalystspreparedbyone-pot(OP)andimpregnation(IM)methods.Itwasfoundthattheone-potmethodwassuperiortotheimpregnationmethodforsynthesizingAg/Co3O4catalystswithhighactivityforbothreactions.ItwasalsofoundthatthecatalyticbehaviorofmesoporousCo3O4andAg/Co3O4catalystsforthebothreactionswasdifferent.AndtheadditionofsilveronmesoporousCo3O4didnotalwaysenhancethecatalyticactivityoffinalcatalystforCOoxidationatroomtemperature(20C),butcouldsignificantlyimprovethecatalyticactivityoffinalcatalystforHCHOoxidationatlowtemperature(90C).Thehighsurfacearea,uniformporestructureandtheprettygooddispersiondegreeofthesilverparticleshouldberesponsiblefortheexcellentlow-temperatureCOoxidationactivity.However,forHCHOoxidation,theadditionofsilverplayedanimportantroleintheactivityenhancement.AndthesilverparticlesizeandthereducibilityofCo3O4shouldbeindispensableforthehighactivityofHCHOoxidationatlowtemperature.

  • 标签: MESOPOROUS materials Co3O4 AG CO OXIDATION
  • 简介:Dopantsanddefectsareimportantinsemiconductorandmagneticdevices.Strategiesforcontrollingdopinganddefectshavebeenthefocusofsemiconductorphysicsresearchduringthepastdecadesandremaincriticaleventoday.Co-dopingisapromisingstrategythatcanbeusedforeffectivelytuningthedopantpopulations,electronicproperties,andmagneticproperties.Itcanenhancethesolubilityofdopantsandimprovethestabilityofdesireddefects.Duringthepast20years,significantexperimentalandtheoreticaleffortshavebeendevotedtostudyingthecharacteristicsofco-doping.Inthisarticle,wefirstreviewthehistoricaldevelopmentofco-doping.Then,wereviewavarietyofresearchperformedonco-doping,basedonthecompensatingnatureofco-dopants.Finally,wereviewtheeffectsofcontaminationandsurfactantsthatcanexplainthegeneralmechanismsofco-doping.

  • 标签: co-doping fully compensated PARTIALLY compensated non-compensated
  • 简介:制备了几种CU-CO尖晶石,并用于催化CO2加氢合成低碳醇反应。结果表明,Cu-Co尖晶石是一种极具潜力的催化剂前驱体,具有出色的C2+醇合成能力。但是,当在该催化剂中加入KOH时,这种能力下降。XRD表征表明,KOH的加入破坏了CU-Co合金的生成。一些结果被讨论。更多还原

  • 标签: Cu-Co催化剂 CO2加氢 低碳醇合成
  • 简介:Ba1.0Co0.7Fe0.2Nb0.1O3-δ(BCFN)oxidewithperovskitecubicstructurewassynthesizedbysolidstatereactionmethod.CO2corrosionofBCFNmembranewasinvestigatedbyX-raydiffraction(XRD),scanningelectronmicroscopy(SEM),diffusereflectanceinfraredFouriertransformedspectroscopy(DRIFT)andX-rayabsorptionfinestructurespectroscopy(XAFS).Cobalt(Co)K-edgeabsorptionspectraofBCFNannealedinCO2revealthattheoxidationstatesofCoinallthesampleswerelargerthan+3andtheydecreasedwiththeincreaseofcalcinationtime.At800℃,1%CO2introducedintoHecouldspeedupthereductionofCocationsincomparisonwithpureHe.Inaddition,sulfateionsinthebulkofBCFNmembranepreferredtomigratetothesurfaceunderCO2calcinationandformmonoclinicBa(CO3)0.9(SO4)0.1besidesorthorhombicwitherite.Moreover,SEMresultsindicatethatthenucleationandgrowthofcarbonatesgrainsstartedatthegrainboundaryofthemembrane.

  • 标签: 钙钛矿型氧化物 CO2 氧化态 组织演变 退火 X射线吸收精细结构
  • 简介:在这份报纸,活跃光学和合作焦点,分割的镜子的试验性的系统被造。第一,分割的镜子的支持结构被设计,为分割的镜子的试验性的系统满足要求被模拟验证。在这个系统,大散焦并且倾斜/付小费给分割的镜子的错误被观察密度调整并且基于等斜的干扰理论干扰穗形成对照直到defocus并且倾斜/付小费给错误在Shack-Hartmann的侦探范围。然后,Shack-Hartmann被用来测量他们,他们被致动器调整。致动器被活跃光学控制为分割的镜子的好合作焦点认识到靠近环的调整和维护。并且干扰穗被利用验证Shack-Hartmann的侦探精确。在分割的镜子调整的合作焦点以后,倾斜/付小费给剩余表面错误比RMS好;defocus剩余表面错误比RMS好。

  • 标签:
  • 简介:基于随机介质的谱分解理论,建立了二维多孔介质的观模型,发展了多孔介质传热问题的多松弛格子Boltzmann方法求解算法,模拟了恒定热流加载下含基体孔隙复合材料的传热过程,计算了碳化硅多孔材料的等效热导率。结果表明,多孔介质的传热过程与孔隙率、孔隙结构密切相关,孔隙率越大材料传热性能越差,等孔隙率条件下,多孔介质沿某一方向的等效热导率随该方向孔隙自相关长度的增加而变大。

  • 标签: 多孔介质 细观模拟 格子BOLTZMANN方法 等效热导率
  • 简介:CO2capturewithionicliquids(ILs)hasattractedmanyattentions,andmostworksfocusedonabsorptionabilityatambienttemperatures,whileseldomresearchwasconcernedatelevatedtemperatures.ThisnotonlylimitstheCO2absorptionapplicationatelevatedtemperature,butalsothedeterminationoftheoperationconditionoftheCO2desorptiongenerallyoccurringathighertemperature.ThisworkmainlyreportedCO2solubilitiesinILsatelevatedtemperaturesandrelatedpropertieswerealsoprovided.1-alkyl-3-methylimidazoliumbis(trifluoromethylsulfonyl)imide([CnMIm][Tf2N])ILswereselectedasphysicalabsorbentsforCO2captureinthisworkduetotheirrelativehigherCO2absorptioncapacitiesandgoodthermalstabilities.Thelong-termstabilitytestsshowedthat[CnMIm][Tf2N]isthermallystableat393.15Kforlongtime.CO2solubilitiesin[CnMIm][Tf2N]weresystematicallydeterminedattemperaturesfrom353.15Kto393.15K.ItdemonstratedthatCO2solubilityobviouslyincreaseswiththeincreaseofpressurewhileslightlydecreaseswithincreaseoftemperature.Asthelengthofalkylchainonthecationincreases,CO2solubilityinILsincreases.Additionally,thethermodynamicpropertiesincludingtheGibbsfreeenergy,enthalpy,andentropyofCO2werealsocalculated.

  • 标签:
  • 简介:Permanentmagnetscapableofreliablyoperatingathightemperaturesupto450?Carerequiredinadvancedpowersystemsforfutureaircrafts,vehicles,andships.ThoseoperatingtemperaturesarefarbeyondthecapabilityofNd–Fe–Bmagnets.PossessinghighCurietemperature,Sm–Cobasedmagnetsarestillveryimportantbecauseoftheirhightemperaturecapability,excellentthermalstability,andbettercorrosionresistance.Theextensiveresearchperformedaroundtheyear2000resultedinanewclassofSm2(Co,Fe,Cu,Zr)17-typemagnetscapableofoperatingathightemperaturesupto550?C.ThispapergivesasystematicreviewofthedevelopmentofSm–Copermanentmagnets,fromthecrystalstructuresandphasediagramstotheintrinsicmagneticproperties.AnemphasisisplacedonSm2(Co,Fe,Cu,Zr)17-typemagnetsforoperationattemperaturesfrom300?Cto550?C.Thethermalstabilityissues,includinginstantaneoustemperaturecoefficientsofmagneticproperties,arediscussedindetail.Thesignificanceofnanograinstructure,nanocrystalline,andnanocompositeSm–Comagnetmaterials,andprospectsoffuturerare-earthpermanentmagnetsarealsogiven.

  • 标签: Sm–Co Sm2(Co Fe Cu Zr)17 high-temperature MAGNETS NANOCOMPOSITE
  • 简介:Mixedalcoholisofgreatpromiseasoctaneimproverinautomotivefuel,andhopefultoreplacetheMTBEtoreducetheenvironmentalpollution,Inthisfield,alkali-promtedmolybdenum-basedcatalystshavebeengivenspecialinterestbecauseoftheirexcellentsulfur-toleranceforsynthesisofmixedalcoholfromCO+H2,Itwasreportedthatthecoblatisafavorablepromoterforenhancingalcoholproduction,especiallyforimprovingtheselectivityforC2+alcohol[1-3],moreover,stronginteractionbetweenConandMoisinfavorofmixedalcoholsynthesis[4].Recently,weprparedakindofK-Co-Moultrafineparticlesbysol-gelmethodanditshowsmuchsmallerparticlesizebuthigheractivtyandselectivitytowardalcoholformationthantheonepreparedbyconventionalmethod[5],TheaimofthepresentworkistoresearchthemicostructuresoftheMoandCospeciesintheK-Co-Mosamplespreparedbydifferentmethod.

  • 标签: K-Co-M样品 微结构 EXAFS实验
  • 简介:Co-electrolysisofCO2andH2Ousinghigh-temperaturesolidoxideelectrolysiscells(SOECs)intovaluablechemicalshasattractedgreatattentionsrecentlyduetothehighconversionandenergyefficiency,whichprovidesopportunitiesofreducingCO2emission,mitigatingglobalwarmingandstoringintermittentrenewableenergies.AsingleSOECtypicallyconsistsofanionconductingelectrolyte,ananodeandacathodewheretheco-electrolysisreactiontakesplace.Thehighoperatingtemperatureanddifficultactivatedcarbon-oxygendouble-bondofCO2putforwardstrictrequirementsforSOECcathode.Greateffortsarebeingdevotedtodevelopsuitablecathodematerialswithhighcatalyticactivityandexcellentlong-termstabilityforCO2/H2Oelectro-reduction.Thesofarcathodematerialdevelopmentisthekeypointofthisreviewandalternativestrategiesofhigh-performancecathodematerialpreparationisproposed.UnderstandingthemechanismofCO2/H2Oelectro-reductionisbeneficialtohighlyactivecathodedesignandoptimization.Thusthepossiblereactionmechanismisalsodiscussed.Especially,amethodincombinationwithelectrochemicalimpedancespectroscopy(EIS)measurement,distributionfunctionsofrelaxationtimes(DRT)calculation,complexnonlinearleastsquare(CNLS)fittingandoperandoambientpressureX-rayphotoelectronspectroscopy(APXPS)characterizationisintroducedtocorrectlydisclosethereactionmechanismofCO2/H2Oco-electrolysis.Finally,differentreactionmodesoftheCO2/H2OcoelectrolysisinSOECsaresummarizedtooffernewstrategiestoenhancetheCO2conversion.Otherwise,developingSOECsoperatingat300-600°CcanintegratetheelectrochemicalreductionandtheFischer-TropschreactiontoconverttheCO2/H2Ointomorevaluablechemicals,whichwillbeanewresearchdirectioninthefuture.

  • 标签:
  • 简介:硬质聚氨酯泡沫塑料是聚氨酯材料体系中最重要的品种之一,它是以聚氨酯树脂为基体,经发泡工艺制作而成的泡沫材料。由于硬质聚氨酯泡沫塑料在使用过程中有可能发生老化而导致其力学性能发生变化,因而老化性能的研究和贮存寿命的评估是硬质聚氨酯泡沫塑料的一个重要研究方向。

  • 标签: 硬质聚氨酯泡沫塑料 寿命评估 贮存寿命 WLF方程 老化性能 聚氨酯树脂
  • 简介:Therectificationratiooforganicmagneticco-oligomerdiodesisinvestigatedtheoreticallybychangingthemolecularlength.Theresultsrevealtwodistinctlengthdependencesoftherectificationratio:forashortmoleculardiode,thechargecurrentrectificationchangeslittlewiththeincreaseofmolecularlength,whilethespin-currentrectificationisweakenedsharplybythelength;foralongmoleculardiode,boththecharge-currentandspin-currentrectificationratiosincreasequicklywiththelength.Thetwokindsofdependenceswitchataspecificlengthaccompaniedwithaninversionoftherectifyingdirection.Themolecularortibalsandspin-resolvedtransmissionanalysisindicatethatthedominantmechanismofrectificationsuffersachangeatthisspecificlength,thatis,fromasymmetricshiftofmoleculareigenlevelstoasymmetricspatiallocalizationofwavefunctionsuponthereversalofbias.Thisworkdemonstratesafeasiblewaytocontroltherectificationinorganicco-oligomerspindiodesbyadjustingthemolecularlength.更多还原

  • 标签: 旋转整流器 分子长度 依赖性 有机共聚物 分子二极管 自旋电流