简介:Inthisstudy,twokindsofWC–Cocoatingswithdifferentdecarburizationlevelsweredepositedbyhigh-velocityoxy-fuel(HVOF)sprayingusingtheultrafineWC–Cocompositepowderandcommercialmicronsizedpowder,respectively.Thehardnessandelasticmodulusweremeasuredonthetopsurfaceandcrosssectionsofthepreparedcoatingsbythenanoindentationmethod.Theresultsshowthattheultrafine-structuredcoatinghasmuchhigherdensityandinhibiteddecarburizationthantheconventionalcoating,whichthusresultsinhigherhardnessandelasticmodulusvaluesthanthemicronsizedcoating.Thewearresistanceofthermal-sprayedcermetcoatingsgreatlydependsonthecross-sectionalhardnessandelasticmoduluswhichreflectsthebondstrengthbetweensplatstosomeextent.Basedontheanalysis,abetterunderstandingofthemicrostructureandpropertiesincermetcoatingmaterialswasobtained.
简介:研究了立方碳化物Cr3C2、VC以及稀土La添加剂对WC-Co合金中WC晶粒形貌以及合金硬度与韧性的影响。为了强化烧结过程中WC晶粒生长的驱动力,采用具有高烧结活性的纳米W和纳米C为原料。为了获得合金中WC晶粒的三维形貌,采用扫描电镜直接观察合金烧结体的自然表面。结果表明,合金添加剂对WC晶粒形貌及其粒度分布特征以及合金的硬度与韧性有较大影响。由于均质三角棱柱形板状WC晶粒的形成,WC-10Co-0.6Cr3C2-0.06La2O3合金具有极佳的硬度与韧性组合。讨论了合金中WC晶粒形貌的调控机制以及合金中WC晶粒形貌特征对合金性能的影响。
简介:采用扫描电镜、能谱仪以及X射线衍射仪对具有WC+β(β为钴基粘结相)两相结构的WC-11Co-0.71Cr3C2-0.06RE(RE为含La、Ce、Pr、Nd的混合稀土)硬质合金烧结体表面进行观察与分析。结果表明,在烧结过程中合金中的La、Ce、Pr、Nd通过定向迁移与烧结炉内气氛中的S、O等杂质元素结合,在合金烧结体表面形成RE2S3(主)和RE2O2S(少量)弥散相。从合金中Cr3C2的热力学稳定性、Cr在Co中的溶解度特性以及稀土原子激发等3个方面,对稀土迁移活性的激发机制和稀土原子的定向迁移机制进行分析与讨论。
简介:这份报纸在极其细小的颗粒的WC-12%Co合金的磁性、机械的性质上处理codopedVC/Cr3C2和sintering温度的效果。结果证明在最佳的比例的做的VC/Cr3C2的synergistic行动提高坚硬和合金的横向的破裂力量(TRS),与更多的同类的微观结构。当合金是在1430点的sintered时?C并且与0.5%Cr3C2/0.2%VC,TRS到达3786MPa,坚硬是91.7HRA和比0.6m小的谷物尺寸。谷物生长上的数字分析在sintering过程期间证明在WC谷物边界并且Cr3C2溶解在公司上猛抛的两VC分阶段执行减少固体/液体的界面的精力,溶解和降水的过程极大地被延迟,WC谷物变粗被禁止。
简介:采用超音速火焰(HVOF)喷涂制备了一种新型的由纳米、亚微米、微米WC颗粒和CoCr合金组成的多尺度WC-10Co4Cr金属陶瓷涂层,对比了双峰和纳米结构WC-10Co4Cr涂层,在分析了涂层组织的基础上,研究了多尺度涂层的孔隙率、显微硬度、开裂韧性和抗空蚀性能,并分析了多尺度WC-10Co4Cr涂层的空蚀行为和机理。结果表明,HVOF喷涂制备的多尺度WC-10Co4Cr涂层具有≤0.32%的孔隙率和高的开裂韧性,涂层中未发现明显的纳米WC脱碳现象。与双峰与纳米结构涂层相比,多尺度WC-10Co4Cr涂层表现出最优异的抗空蚀性能,在淡水中的抗空蚀性能分别比双峰涂层和纳米结构涂层提高了大约28%和34%。多尺度WC-10Co4Cr涂层的优异抗空蚀性能归结于其独特的微纳米结构和优良的性能,能有效阻碍空蚀裂纹的形成和扩展。
简介:Theexchangecouplingattheferromagnetic/antiferromagnetic(FM/AFM)interfaceisinfluencedbyboththemagneticstructureandthecrystallinemicro-structure.Co/FeMn/Cothinfilmswith0.4nmPtspacerlayerinsertedintotheCo/FeMnandFeMn/Cointerfacerespectivelyweredepositedbymeansofmagnetronsputtering.ThetwointerfacesuponandbeneaththeFeMnlayershowdistinctbehaviorsbeforeandafterthePtspacerinserted.ThereisaremarkableshrinkoftheinterfacialuncompensatedspinswithintheFeMnbottominterfacialmonolayers,whereasarelaxationofthepinningstrengthoftheFeMninterfacialspinsalongtheout-of-planedirectionoccursatthetopinterface.XRDanalysisindicatesthePtlayerupontheFeMnlayerformsanfcc(002)texture,implyingthemagneticdiscrepancybetweenthetopandbottomFeMninterfaceshascrystallinestructuralorigins.
简介:TheCurietemperatureof(Nd1-xPrx)2Fe14CoyBcompounds(x=0,0.2,…,1.0andy=O,2,4,6,14)hasbeendeterminedwithACinitialsusceptibilitymeasurement.ItwasfoundthatthevariationsofCurietempera-turewithxisnotlinearfory=0and14,whereasitislinearforothervaluesofy.Thelatticeconstantsof(Nd1-xPrx)2Fet14BweredeterminedbyusingX-raydiffraction.Thelatticeexpansionwasmostlyalongthecaxis,whereasthatalongthea-axisremainedpracticallyzeroforthewholeseries.ItissuggestedthatPratomsmayshowsitepreferenceinR2M14Bcompounds(M=FeorCo).DuetothesubstitutionofCoforFe.thetendencyofsitepreferenceofPrbecomeslesspronounced,whichmaybeattributedtothedecreaseofdiffer-enceofcrystalelectricfield(CEF)actingonthetworareearthsiteswiththeintroductionofCoorFe.Incon-trasttothatofthePratoms,thesitepreferenceofCoiu(Nd(1-x)Prx)2Fe(14-y)CoyBcompoundsdoesnotdependonthecompositionoftherareearthsublattice(R=NdorPr).
简介:Aseriesoftheelectrochemicalandlong-termcorrosiontestswascarriedoutina3.5wt%Na2SO4solutiononthermal-sprayedWC-17CoandWC-10Co-4Crcermetcoatingsinordertoexaminetheeffectofcompositionofbindermaterialsonthecorrosionbehavior.TheresultsrevealthattheoverallcorrosionresistanceoftheWC-17CocoatingisinferiortothatoftheWC–Co–CrcoatingsduetothecorrosionofbindermaterialswhichinduceWCparticlestofalloff.CoOandWO3oxidefilmsformonthesurfaceofWC-17CocoatinginNa2SO4solutionelectrochemicalcorrosionprocess,whichwillprotectthecoatingintheprocessofcorrosion.Cr2O3oxidefilmformedontheWC-10Co-4Crcoatingsurfacehasastronghinderedroletocorrosion.ThecorrosionmechanismofWC-17CocoatinginNa2SO4solutionisentirecorrosionofComatrix,whileitisfilm-holecorrosionmechanismforWC-10Co-4Crcoating.
简介:Low-CoLa1.8Ti0.2MgNi8.9Co0.1alloyswerepreparedbymagneticlevitationmeltingfollowedbyannealingtreatment.TheeffectofannealingonthehydrogenstoragepropertiesofthealloyswasinvestigatedsystematicallybyX-raydiffraction(XRD),pressure-compositionisotherm(PCI),andelectrochemicalmeasurements.TheresultsshowthatallsamplescontainLaNi5andLaMg2Ni9phases.LaCo5phaseappearsat1,000℃.Theenthalpychangeofallhydridesiscloseto-30.6kJ·mol-1H2ofLaNi5compound.Annealingnotonlyincreaseshydrogencapacityandimprovescyclingstabilitybutalsodecreasesplateaupressureat800and900℃.Afterannealing,thecontractionofcellvolumeandtheincreaseofhydridestabilitycausethehighratedischargeabilitytoreduceslightly.Theoptimumalloyisfoundtobeoneannealedat900℃,withitshydrogencapacityreachingupto1.53wt%,anddischargecapacityremaining225.1mAh·g-1after140charge–dischargecycles.
简介:TheTm-Ni-Coalloyfilmshavebeenpreparedbythesweeppotentialdepositiontechnique.ThesurfaceappearanceofTm-Ni-Coalloyfilmswassilver,smoothandadhesive.ThesurfacesofTm-Ni-Coalloyfilmsobservedbyscanningelectronmicroscope(SEM)wereuniform,adhesiveandcompact.Thesizesofmetallicgrainswereabout80-100nm,100-200amorphousasprovenbytheX-raydiffraction(XRD).
简介:磁性的元素Fe,公司和Ni的线性热扩大(CLE)的系数用与MATLAB计算相结合的理论模型从试验性的信息被估计。模型参数能精确地被决定,并且估计的数据在对试验性的结果的好同意。便于评价,热扩大的理论被使用把CLE分开成它的无磁性、磁性的部件。对CLE的无磁性的贡献的计算基于MnBi/NdFeB混血儿的修改Grc性质结合的磁铁都逐渐地减少,当混合磁铁的密度几乎线性地改善时。在293-398的一个温度范围?K,混合磁铁的coercivity温度系数从0.59逐渐地改善?%比较。建模和频率与二低角落频率认为压力消除阀门是一个秒顺序系统是合理的试验性的结果表演。PID控制,死了的乐队赔偿控制和鷸?鷸??
简介:WehavecalculatedtheelectronicstructuresofCo2FeAl1-xSix(101)surfaceusingfirst-principlesmethodbasedonthedensityfunctionaltheory.Becauseofthesurfaceeffect,theminorityspinbandgapattheFermileveldisappearsatthesurfaceofbulkCo2FeAl1-xSix.However,beneaththesurface,theminorityspingapopensattheFermilevel,whichindicatesthattheelectronicstructuresofCo2FeAl1-xSix(101)be-comeclosetothatofbulkphase.Accordingly,theCo2FeAl1-xSix(101)surfaceisacompositetri-layerstructurethatcorrespondstotheweakeningofhalf-metallicpropertyinCo2FeAl1-xSixfilms.Eventhough,thespinpolarizationofCo2FeAl1-xSix(101)surfaceisstilllargerthanthatofCo2FeAlorCo2FeSimaterials,makingCo2FeAl1-xSixapromisingspintronicsmaterial.
简介:1IntroductionThestructureandelectrochemicalpropertiesofnickelhydroxidehavebeenstudiedextensivelyduetoitsimportanceasactivematerialsinnickelbatterysystems[1].Afundamentalunderstandingoftheeffectsofmetallicadditivesandimpuritiesonthenickelhydroxideelectrochemistrycouldbeofgreatvaluetothebatteryiindustry[2].Thepracticalimportanceofnickelhydroxideelectrochemistryisnotlimitedtobatteryapplications.Nickelhydroxideelectrodesalsocanbeusedinwaterelectrolysis[3].Theuseofmetallicadditivestomanipulatetheelectr...
简介:AseriesofPr-CothinfilmsweredepositedontheSi(100)substrateswithCrunderlayerbymagnetronsputtering.Theeffectsofboththepost-annealingtemperatureandtheannealingtimeonthemicrostructureandmagneticpropertiesforthePr-Cofilmswerestudiedsystematically.Theas-depositedPr-Cothinfilmsaremostlyamorphousandtendtocrystallizeafterannealingattemperaturesabove600℃.Whentheannealingtimeisincreased,thefilmsshowacomplicatedstructurewithvariousphasesco-existing.Accordingly,theas-depositedfilmandlowtemperatureannealedfilmsaresoftmagnetsandfilmsannealedattemperaturesbeyond600℃tendtobehardmagnets.Whentheannealingtimeisincreasedfrom5minto2h,thefilmstransferfromhardmagnetstosoftagain.Thesampleannealedat600℃for10minshowsthelargestcoercivityof0.59T.
简介:AseriesofnovelAgCl/Ag2CO3heterostructuredphotocatalystswithdifferentAgClcontents(5wt%,10wt%,20wt%,and30wt%)werepreparedbyfacilecoprecipitationmethodatroomtemperature.TheresultingproductswerecharacterizedbypowderX-raydiffraction(XRD),scanningelectronmicroscopy(SEM),X-rayphotoelectronspectroscopy(XPS),andultraviolet–visiblediffusereflectancespectroscopy(UV–VisDRS),respectively.Thephotocatalyticactivityofthesampleswasevaluatedbyphotocatalyticdegradationofmethylorange(MO)underUVlightirradiation.WiththeoptimalAgClcontentof20wt%,theAgCl/Ag2CO3compositeexhibitsthegreatestenhancementinphotocatalyticdegradationefficiency.Itsfirst-orderreactionrateconstant(0.67h-1)is5.2timesfasterthanthatofAg2CO3(0.13h-1),and16.8timesfasterthanthatofAgCl(0.04h-1).TheformationofAgCl/Ag2CO3heterostructurecouldeffectivelysuppresstherecombinationofthephoto-generatedelectronandhole,resultinginanincreaseinphotocatalyticactivity.
简介:Thermodynamiccalculation,SEM(scanningelectronmicroscopy),TEM(transmissionelectronmicroscopy),XRD(X-raydiffraction),phaseextraction,andchemicalanalysiswereemployedtostudythephasestabilityandphaseprecipitationinanewNi-Cr-Cobasesuperalloyheat-treatedat704and760℃foralongtime.Theresultsshowthattheprecipitatesofthisnewalloyheat-treatedatstandardannealingconditionandheat-treatedat704and760℃foratimeupto2000hareγ′,MC,M23C6,andM6C,andηphaseformsatgrainboundariesandinmatrixofsamplesheat-treatedat760℃aswell.Themassfractionsofγ′(+η),MC,M23C6,andM6Cinallsampleshavenolargechangeswithanincreaseinagingtime,butγ′precipitatesgrowobviously.Theγ′-to-ηtransformationinthesamplesheat-treatedat760℃tookplacewithincreasingagingtime.TheηprecipitatesformaWidmanstattenpattemandtheγ′phaseshaveremeltedpartlyinthesamplesheat-treatedat760℃.Thealloymaintainsabettermicrostructuralstabilityduringprolongedagingat704℃,butaworsemicrostructuralstabilityduringprolongedagingat760℃.