简介:基于国外定向凝固氧化物/氧化物共晶复合陶瓷的晶体生长动力学行为的研究成果,阐述其动力学机制,分析动力学因素对微观结构形态的影响,探讨晶体生长热力学、动力学行为与微观结构形态之间的关系,同时结合以燃烧合成、快速凝固技术制备的新型高强韧A12O3/ZrO2(Y2O3)共晶复合陶瓷,探讨共晶复合陶瓷在快速凝固条件下的晶体生长动力学行为。结合定向凝固与快速凝固两种晶体生长机制,得知过冷度、凝固界面前沿的温度梯度是影响晶体生长方式的重要因素,且受二者决定的凝固速率(即晶体生长速率)则决定材料的最终微观结构与形态。
简介:对C12-35/10型发电组出力提高15MW可行性进行了技术分析并提出了相关的改造方案.
简介:MeltspinningtechnologywasusedtopreparetheMg2Ni-type(Mg24Ni10Cu2)100–xNdx(x=0,5,10,15,20)alloysinordertoobtainananocrystallineandamorphousstructure.TheeffectsofNdcontentandspinningrateonthestructuresandelectrochemicalhydrogenstorageperformancesofthealloyswereinvestigated.ThestructurecharacterizationsofX-raydiffraction(XRD),transmissionelectronmicroscopy(TEM)andscanningelectronmicroscopy(SEM)linkedwithenergydispersivespectroscopy(EDS)revealedthattheas-spunNd-freealloydisplayedanentirenanocrystallinestructure,whereastheas-spunNd-addedalloysheldananocrystallineandamorphousstructureandthedegreeofamorphizationvisiblyincreasedwiththerisingofNdcontentandspinningrate,suggestingthattheadditionofNdfacilitatedtheglassformingoftheMg2Ni-typealloy.TheelectrochemicalmeasurementsindicatedthattheadditionofNdandmeltspinningimprovedtheelectrochemicalhydrogenstorageperformancesofthealloyssignificantly.Thedischargecapacitiesoftheas-castandspunalloysexhibitedmaximumvalueswhenNdcontentwasx=10,whichwere86.4,200.5,266.3,402.5and452.8mAh/gcorrespondingtothespinningrateof0(As-castwasdefinedasthespinningrateof0m/s),10,20,30and40m/s,respectively.Thecyclestability(S20,thecapacitymaintainrateat20thcycle)oftheas-castalloyalwaysrosewiththeincreasingofNdcontent,andthoseoftheas-spunalloysexhibitedthemaximumvaluesforNdcontentx=10,whichwere77.9%,83.4%89.2%and89.7%,correspondingtothespinningrateof10,20,30and40m/s,respectively.
简介:ThesurfaceofacommercialY3Al5O12:Ce3+phosphorwasmodifiedby99%NH4F+CH3COOHsolutioninasupersonicbathwithwatertemperatureof80oCfor4h.Thescanningelectronmicroscopy(SEM)resultsshowedthattheedgeangleswerenotassharpastheunmodifiedparticlesandtheflatsurfacesturnedroughwithmanymicro-structurescovered.Positronlifetimemeasurementsquantitativelyshowedthatsurfacedefectswereremovedawaybymorethan50%.Asaresult,thephotoluminescencedeterminationsshowedthatthebackscatterlosswasreducedby4.2%andtheemissionpowerwasenhancedby5.6%afterthesurfacemodification.Theconversionefficiencywasgreatlyimprovedfrom47.3%to51.1%,aspresentedbythefluorescenceimages.Therefore,itwouldbegreatlyhelpfulfortheimprovementofefficiency,transparencyandstabilityofpc-LED.Moreover,thismethodwassignificantlysuitableformassproductionduetoitseasyoperationandlowcost.
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简介:采用电磁感应悬浮炉制备La0.55Pr0.05Nd0.15Mg0.25Ni3.5-xCoxAl0.25(x=0,0.1,0.2,0.3,0.4)系列合金,研究Co含量对合金的相结构、吸放氢性能和电化学性能的影响。研究结果表明,该系列合金主要由LaNi5、Nd2Ni7相组成。当Co含量大于0.2时,合金中出现La2Ni7相。压强-吸氢量-温度(Pressure-Content-Temprature)测试显示在303K温度下,合金具有良好的吸氢性能,当x=0.4时合金的最大吸氢量为1.29(质量分数,%)。电化学测试表明:随x值变化,合金电极的最大放电容量分别为340.0(x=0.0)、346.6(x=0.1)、370.0(x=0.2)、320.0(x=0.3)和346.6(mA.h)/g(x=0.4);随Co含量增加,合金电极容量保持率不断增加,高倍率放电性能先增加后减小,循环伏安曲线、氢在合金体中的扩散系数D共同反映了合金电极的动力学特性。