简介:基于炉渣结构分子和离子共存理论,建立1273-1733K下的PbO-CaO-SiO2-FeO-Fe2O3渣系氧化铅活度热力学模型,计算PbO活度并绘制等活度曲线,考察炉渣碱度Q、氧化铁比率R和温度T对活度NPbO和活度系数γPbO的影响。结果表明,活度系数γPbO的模型计算值与文献测定值吻合程度高,说明该模型能较好地反映该渣系结构本质;NPbO呈拉乌尔正偏差,且随渣中PbO含量的升高而增大,但受温度的影响不明显;γPbO随Q的升高而增大;对于Q〉0.3的碱性渣,γPbO随R的升高而出现极大值。该研究结果可用于现代炼铅工艺的热力学研究和操作优化。
简介:Anewseriesofrareearthcompounds,Y2-xErxMo4O15(x=0.0-2.0),weresynthesizedandtheirstructuresweredeterminedbypowderX-raydiffraction(XRD).RietveldanalysisofXRDpatternsrevealsthatthecompoundsofthisseriescrystallizeinmonoclinicsystemwithspacegroupP21/c.Thelatticeparametersa,b,c,βandtheunitcellvolumeVde-creaselinearlywithincreasingErcontent.Thethermalexpansionpropertiesofthesecompoundswerestudiedunderhigh-temperatureXRD.PositivethermalexpansionsofcompoundsY2-xErxMo4O15arefoundtobeanisotropicalongthethreecrystallographicdirectionswhereaandcaxesexpandwhilebaxiscontractsinthewholetemperaturerange.Byanalysisofdata,theexpansionofweakbandMo2-O14withrisingtemperatureshouldberesponsibleforpositivethermalexpansion.
简介:BasedontheMiedemamodelandExtendedMiedematheory,theformationenergiesofdifferentsolutecomponentsinEr-XbinarysystemandAl-Er-Xternarysystemswerecalculated.TheresultsshowthatthevariationoferbiumcontenthaslittleinfluenceonthechancerateoftheformationAl-ErcompoundintheAl-Mg-Mn-Zr-Ersystem.ThecalculatedformationenergiesintheEr-XbinarysystemandAl-Er-XternarysystemsindicatethatAl3Erphasecantakepriorityofdepositing,Al-Er-Zrternarycompoundsmayalsofoundwhichagreeswiththeexperimentalresultsinreferences.TheconsistencyofcalculationandexperimentprovesthattheintermetalliccompoundsintheAl-Mg-Mn-Zr-ErsystemcanbepredicteddirectlybycalculatingtheformationenergiesofthereactionsinEr-XbinarysystemandAl-Er-XternarysystemswiththeMiedemamodelandExtendedMiedematheory.
简介:TiO2nanoparticleswithdifferentphasesarepreparedbyhydrolysisoftitaniumtetrabutoxideinthepresenceofHCl.ThecompositionandmicrostructureoftheresultingsamplesarestudiedbyXRDandTEM.TheseresultsshowthattherangeofparticlesizeofTiO2isfrom20to30nm.ThemechanismofTiO2photocatalysisreactionhasbeendiscussedextensively.PhotocatalyticactivitiesofnanometerTiO2arealsoevaluatedbydegradationofthecrystalvioletsolution.ExperimentalresultsindicatethatthesynergisticactionofH2O2andultrasonicwavegreatlyenhancesphoto-catalyticreactionofTiO2.
简介:Iron(Ⅲ)-dopednanostructureTiO2-coatedSiO2(TiO2/SiO2)particleswerepreparedusingthelayer-by-layeras-semblytechniqueandtheirphotocatalyticpropertywasstudied.TiO2colloidsweresynthesizedemployingthesol-gelmethodwithTiCl4asaprecursor.ThesampleswerecharacterizedbyFouriertransforminfraredspectroscopy(FTIR),SEM,EDS,XPS,andXRD.TheexperimentalresultsshowthatTiO2nanopowdersonthesurfaceofSiO2particlesarewelldistributed,theamountofTiO2isincreasedwiththeaddingofcoatinglayers,thepureanatase-TiO2coatinglayersaresynthesizedat500°C,andthephotocatalyticactivityofFe3+-dopedTiO2/SiO2ishigherthanthatofundopedTiO2/SiO2.
简介:X-rayDouble-crystalDiffractometerwithHorizontalSlitsandItsApplicationsXuJingyangandZhuNanchang徐景阳,朱南昌(ShanghaiInstituleofMeta...
简介:Nb-24Ti-18Si-2Al-2Hf-4CrandNb-24Ti-18Si-2Al-2Hf-8Cralloyswerepreparedbyarcmeltinginawater-cooledcrucibleunderargonatmosphere.Microstructuralcharacteristicsandoxidationresistanceofthealloysat1250℃wereinvestigated.Theresultsshowthat,whentheCrcontentis4at%,themicrostructuresconsistof(Nb,Ti)_(ss)andNb_5Si_3;asCrcontentincreasesto8at%,C14LavesphaseCr_2Nbisformed.Theisothermaloxidationtestsshowthattheoxidationkineticsofthetwoalloysfollowsimilarfeatures.Theweightgainsofthetwoalloysafteroxidationat1250℃for100hare235.61and198.50mg·cm~(-2),respectively.Duringoxidation,SiO_2,TiO_2,Nb_2O_5andCrNbO_4areformedatfirst.Then,Ti_2Nb_(10)O_(29)isformedafteroxidationfor20minandbeginstochangeintoTiNb_2O_7astheoxidationproceeds.SiO_2isformedassolidstateatfirstbutlaterevolvesintoglassystatetoimprovethecohesionofthescale.Afteroxidationfor100h,oxidationproductsconsistofSiO_2,TiNb_2O_7,Nb_2O_5andCrNbO_4.
简介:MgTixNi(x=0,0.1,and0.2)alloysweresuccessfullypreparedbymechanicalalloying(MA),andtheinfluenceofmillingtimeontheelectrochemicalcharacteristicsoftheelectrodeswasdiscussed.MgTixNialloysafter90hmillingdisplayedthebestelectrochemicalperformance.TheX-raydiffractionpatternsshowedthatthealloyball-milledfor90hwasamorphouswithawideneddiffractionpeak.Thecharge-dischargetestsindicatedthatthesealloyshadgoodelectrochemicalactivationproperties,andtheMgTi0.2Nialloyelectrodeexhibitedthebestcycleperformance.TheinitialdischargecapacityoftheMgTi0.2Nialloyreachedupto401.1mAh·g-1,andtheretentionrateofcapacitywas31.0%after30cycles,muchhigherthanthatofMgNi(17.3%).TheTafelpolarizationcurvesrevealedthatTiadditioncouldenhancetheanticorrosionperformanceofthesealloysinalkalisolution,whichwasresponsiblefortheamelioratedcyclicstabilityofthesealloyelectrodes.
简介:X-raydiffraction(XRD)anddifferentialscanningcalorimetry(DSC)wereusedtoinvestigatethecrystallizationprocessofamorphousAl90TMxCe10-x(atomfractionin%;TM=FeorNi;x=3,5)alloys.AgingeffectswereexaminedbyX-raydiffraction.ThestructurecorrespondingtotheprepeakfortheamorphousAl90Fe5Ce5alloyismorestablethantheamorphousmatrix,butitisnotstableforamorphousAl90Ni5Ce5alloyduringthefirstcrystallizationstageandevendecomposesatroomtemperature.AlthoughbothAl-NiandAl-Fehavestrongchemicalbonding,thecrystallizationonsettemperatureofamorphousAl-Fe-CealloysismuchhigherthanthatofamorphousAl-Ni-Cealloys,whichislikelycausedbythedifferentstabilityofthestructurecorrespondingtotheprepeak.ThecrystallizationonsettemperatureincreasesasCe/NiratioincreasesinamorphousAl90NixCe10-xalloys,whereasitdecreasesasCe/FeratioincreasesinamorphousAl90FexCe10-xalloys.AbetteratomicpackingproducesasCecontentincreasesbecauseofthesizemismatchinAlNi-CesystemsandasFecontentincreasesbecauseoftheincreasingFecentralstructuralunits.
简介:ElectrocrystallizationMechanismofTungsteninMoltenKF-B_2O_3-K_2WO_4WenZhenhuanandLiGuoxun文振环,李国勋(GeneralResearchInstiiuteforNo...
简介:介绍一种金属/合金的生产方法,用于恒电流和恒电位条件下由混合硫化物(Cu2S,NiS)生产Cu-Ni合金,称为直接电化学还原(DER)。研究槽电压和槽电流等工艺参数对还原得到的化合物组成的影响,以生产工业所需的CuNi10,CuNi20和CuNi30等合金。在1200°C下采用循环伏安法(CV)考察Cu2S和NiS在CaCl2熔体中的电化学行为。根据CV研究结果,Cu2S的阴极还原是一步完成的,即Cu2S?Cu;NiS的阴极还原则分两步进行,即NiS?Ni3S2?Ni。恒电流研究表明,在10A电流下电解15min,可制备出最高硫含量为320×10-6的高纯CuNi10合金。扫描电子显微镜以及能量色散X射线能谱和光学发射光谱(OES)测试结果表明,在2.5V电压下直接电化学还原15min,可制备出杂质含量低(即硫含量小于60×10-6)的所选成分的Cu-Ni合金。
简介:本文采用磁粉、X射线、CT和超声等无损检测和金相分析等方法对40CrNi2Si2,MoVA钢制零件的磁痕显示进行了系统分析。研究认为,40CrNi2Si2MoVA钢制零件的磁痕显示为显微成分沿变形方向偏析导致的马氏体转变点Ms差异所致。显微成分偏析是钢锭结晶过程中不可避免的,但可通过优化熔炼工艺参数降低显微偏析的程度。本文还分析了四种磁痕显示的类型及其判别方法。
简介:Themetal-organicchemicalvapordeposition(MOCVD)techniqueisapromisingprocessforhigh-temperaturesuperconductorYBa2Cu3O7-δ(YBCO)preparation.Inthistechnique,itisachallengetoobtainbariumprecursorswithhighvolatility.Inaddition,thepurity,evaporationcharacteristics,andthermostabilityofadoptedprecursorsinwholeprocesswilldecidethequalityandreproducibleresultsofYBCOfilm.Inthepresentreport,bis(2,2,6,6-tetramethyl-3,5-heptanedionato)barium(Ⅱ)(Ba(TMHD)2)wassynthesized,anditsstructurewasidentifiedbyFTIR,1HNMR,13CNMR,andESI-MSspectroscopy.Subsequently,thethermalpropertiesandthekineticsofdecompositionweresystematicallyinvestigatedbynonisothermalthermogravimetricanalysismethods.BasedontheaverageapparentactivationenergyevaluatedbytheOzawa,Kissinger,andFriedmanmethods,thevolatilizationprocesswasdiscussed,andallresultsshowthatBa(TMHD)2isunstableandhighlysensitivetothechangeoftemperatureduringthewholeevaporationprocess.Therefore,itisveryimportanttochoosesuitablevolatilizationtechnologyandconditionsforavoidingBa(TMHD)2break-down(orthermalaging)duringMOCVDprocess.Subsequently,thepossibleconversionfunctionisestimatedthroughtheCoats-Redfernmethodtocharacterizetheevaporationpatternsandfollowsaphaseboundaryreactionmechanismbythecontractingsurfaceequationwithaverageactivationenergyof118.7kJ.mol-1.
简介:起落架40CrNi2Si2MoVA钢螺桩在安装一段时间后发生了断裂。为确定螺桩断裂的原因,对断裂螺桩断口宏微观形貌、断裂螺桩及对比件的氢含量、材料的性能以及表面损伤等因素进行了检查,并对电镀工艺进行了评定。结果表明,裂纹主要起源于第一螺纹根部的机械损伤部位,源区以沿晶断裂特征为主,断裂件含氢量较高。综合分析认为。螺桩断裂性质为氢致延迟断裂,表面机械损伤对氢吸收和扩散的促进作用和40CrNi2Si2MoVA钢材料高强度所致的高氢脆敏感性是导致断裂的主要原因。
简介:通过基于密度泛函理论的第一性原理计算方法,对MgCu2,Mg2Ca和MgZn2的力学性能和电子结构进行计算,计算所得晶格参数与实验值和文献值相吻合。合金形成热和结合能的计算结果表明,MgCu2具有最强的合金形成能力和结构稳定性。计算了MgCu2,Mg2Ca和MgZn2的弹性常数,推导了体模量、剪切模量、弹性模量和泊松比。结果表明,MgCu2、Mg2Ca和MgZn2均为延性相,MgCu2的刚度最大,MgZn2的塑性最好。通过对结合能和弹性常数的计算,预测了MgCu2、Mg2Ca和MgZn2的熔点。通过对态密度(DOS)、Mulliken布居数、电子占据数和差分电荷密度的计算,分析了MgCu2、Mg2Ca和MgZn2的结构稳定性和力学性能机制。最后,计算和讨论了3种金属间化合物的Debye温度。
简介:ItiswellknownthatthephotocatalyticactivityofTiO2thinfilmsstronglydependsonthepreparingmethodsandpost-treatmentconditions,sincetheyhaveadecisiveinfluenceonthechemicalandphysicalpropertiesofTiO2thinfilms.Therefore,itisnecessarytoelucidatetheinfluenceofthepreparationprocessandpost-treatmentconditionsonthephotocatalyticactivityandsurfacemicrostructuresofthefilms.ThisreviewdealswiththepreparationofTiO2thinfilmphotocatalystsbywet-chemicalmethods(suchassol-gel,reversemicellarandliquidphasedeposition)andthecomparisonofvariouspreparationmethodsaswellastheiradvantageanddisadvantage.Furthermore,itisdiscussedthattheadvancementofphotocatalyticactivity,super-hydrophilicityandbactericidalactivityofTiO2thinfilmphotocatalystinrecentyears.
简介:Thesegregationanddiffusionofboronduringheattreatmentswerestudied.Theinfluenceofboroncontents,agingtimeandappliedstressonFeMo2B2formationwasalsostudied.Finally,theeffectsofboroncontentsandFeMo2B2formationonthehightemperaturestrengthwerestudied.Boronatomsweresegregatedtoprioraustenitegrainboundaryduringnormalizingtreatment.Andtheseboronatomswereslowlydiffusedintothegraininteriorduringtemperingandagingat700℃.TheFeMo2B2phasewasonlyformedafter1,000hagingat700℃inalloycontaining196ppmboron.TheformationofFeMo2B2phaseisacceleratedbytheappliedstress.ItwasexpectedthattheformationofFeMo2B2iscloselyrelatedtotheredistributionofboronatoms.Thetensilestrengthsat700℃areincreasedwiththeincreaseofboroncontents.However,theformationofFeMo2B2phaseresultsinlowertensilestrength.