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简介:Theyolk-shellLaMnO3perovskitemicrosphereswerefabricatedbyanovel,simpleandmildsofttemplateapproach.Aseriesoftemplate-P123concentrations(0-6.12mmol·L^-1)wereemployedtooptimizethemostcompletespheres.WhentheconcentrationofP123is3.0mmol·L^-1,theobtainedyolk-shellmicrosphereswithadiameterof200-700nmwereconstructedbynanoparticles.Thepossibleformationmechanismoftheyolk-shellmicrosphereswasrevealedstepbystepviaXRD,SEM,TEM,EDSandHRTEM.MoleculesofP123weresuitablymixedwithsolventsfordoubleshelledvesiclesthroughself-assembly,whichinteractedwithmetalcomplexestoformP123-metalvesicles.AftertheremovalofP123andcitricacidbycalcinationat700℃,theyolk-shellLaMnO3microsphereswiththrough-channelswereobtained.Through-channelsonthesurfacewereduetocitricacidandthesolidcorewasattributedtotheshrinkofinnervesicles.Preparedyolk-shellmicrospheresamplespossessedalargersurfaceareaandahighermaximumNOconversionvalueof78%at314℃forNOoxidation,comparedwithsampleswithouttheyolk-shellstructure.
简介:Thewidthandspacingofadiabaticshearbands(ASBs)intheserratedchipsgeneratedduringhighspeedorthogonalcuttingof30CrNi3MoVstructuralsteelweremeasuredbyopticalmicroscopy(OM),thetemperatureriseintheshearbandwasestimated.ThemicrostructuresoftheASBswerealsocharacterizedbySEMandTEM.TheresultsshowthatthewidthandspacingofASBsdecreasewiththeincreaseofthecuttingspeed.ThefurtherobservationsshowthatthemicrostructurebetweenthematrixandthecenteroftheASBgraduallychanges,andthatthemartensiticphasetransformation,carbideprecipitationandrecrystallizationmayoccurintheASB.
简介:60%whitecorundumusedforaggregate,5%aluminiumpowderforfixedadditionsand35%variousadditivesformatrixwerepreparedforspecimens1#,2#,3#.Theyweremixeduniformlywiththesuitableresinasabinderandpressedunderpressureof315tonforgingpress,thendriedat200℃for24h.Effectsofvariousadditiveson1500℃×2hcreeppropertiesofAl3CONreinforcedcorundumcompositewereresearched.Theexperimenalresultsshowthatcreepcoeffi-cientsofspecimens1#,2#,3#at1500℃×2hare1.4×10-4,-9.4×10-4,-22.6×10-4,respectively.CrushingstrengthoftheslideplateaddedwithsuitableadditiveAafterfiredat1500℃×3hreachesto225MPa,thecreeprateispositiveallthetimefrom0%to0.014%at1500℃for2h.Themicro-structureresultanalysisshowsthatreinforcedphasesofAl3CONfibercompositehavebeenformedafterfiredwithAlpowderincokeathightemperaturesforspecimen1#,andthestrengthofthecompositeisincreased.Thehotmodulusofruptureisupto59MPaat1400℃andtheRULisobvi-ouslyhigherthanthatat1700℃.ItsservicelifeistwotimesasthatofAl2O3?Cslideplatewhenusedintheprocessofpouringsteel.Themechanismofcreeprateresistanceofthecompositescanbedis-coveredbymeansofSEMandEDAXanalysis.ItisconcludedthattheactiveAl3CONandAl2O3multiphasesthatwereformedbyN2ingas,C,AlandAl2O3insidethematrixofthecompositesduringin-situreaction,whichgivesthecompositesoutstandingcreeprateresistanceforthedensezonere-sultingfromAl3CONoxidationthatinhibitscontractionatthehightemperature.Besides,thematrixwillturnintothemultiphasewithhighrefractoriness,NcontentanditsAl3CONreinforcedfiberwillfurtherincreaseaccordingly.Inaddition,Al3CONformedbyAl2O3andC,AlinthematrixwithN2ingaswillinhibitthecreeprateandalsogreatlyimprovethecreeprateresistanceofthecomposites.
简介:对开发物理蒸汽免职(PVD)涂层为他们的优秀机械性质和腐蚀抵抗作为一组有希望的保护的涂层识别了的multilayered或nanolayered有许多兴趣。在这研究,multilayeredCrN/Cr2有不同bilayer时期的O3涂层()被弧离子plating(AIP)与纯氮和纯氧的其他的空气从一个Cr目标在擦亮的高速度钢底层上综合技术。结果表明multilayered涂层的微观结构,形态学和性质被bilayer时期强烈影响()。在multilayeredCrN/Cr2O3涂层:锋利的和模糊的。与减少价值,,宏粒子密度逐渐地减少了涂层microhardness,粘合剂力量并且穿首先稍微增加,然后减少或作为bilayer时期仍然保持稳定的抵抗<590nm。multilayeredCrN/Cr2有590nm的bilayer时期的O3涂层拥有了最好的全面性质,也就是最高的microhardness,最强壮的粘附,并且最低穿率。
简介:Ca_3Co_2O_6,Na和Ni的电子结构做了模型被被基于的Camhride连续全部的精力包裹(CASTEP)的量化学药品软件学习,在密度函数理论(DFT)和伪潜力上。优点(Z)的电子传导性,seebeckcoefficient,热传导性和图被计算。精力乐队结构在做semiconductors.Na的模型shoivs由于代理杂质揭示杂质层次的形式p类型半导体的特性,而是做Ni的模型是n-typesemiconductor。计算结果证明做的模型的电的传导性比的高非--做的模型,当Seebeck系数和做的模型的热电导率是比非做的那些低的时。因为大增加,电的电导率,做Na的模型的Z被提高,热电的性质被改进。作为Seebeck系数的大衰落,在另一方面,Ni-的Z做了模型不到的非--做的模型。
简介:采用溶胶-凝胶法制备了不同Zn含量掺杂的SrTiO3光催化剂(Zn-SrTiO3),通过X射线衍射(XRD)、扫描电子镜显微(SEM)和荧光光谱(PL)对其进行了表征,用亚甲基蓝(MB)光催化降解实验评价了其光催化活性。结果表明,SrTiO3经Zn掺杂后仍然保持了钙钛矿结构,Zn2+进入SrTiO3晶格对Sr2+进行了替位掺杂,导致晶格畸变;热处理温度升高,样品发生热团聚;适量的Zn掺杂,能有效降低光生电子和空穴的复合几率,提高SrTiO3的光催化活性;当掺杂量n(Zn):n(Sr)=1.5:100,热处理温度900℃时制备的样品光催化活性达95.5%,明显优于同等条件下纯SrTiO3活性58.5%,样品具有较高的光催化活性和良好的稳定性。