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关于电化学方面论文例文,与医学学位文湖北,硕士学位文的通知相关毕业论文范文
本论文是一篇关于电化学方面毕业论文范文,关于医学学位文湖北,硕士学位文的通知相关毕业论文格式模板范文。免费优秀的关于电化学及合金及控制工程方面论文范文资料,适合电化学论文写作的大学硕士及本科毕业论文开题报告范文和学术职称论文参考文献下载。
enshortdistanceorderingdomain,whichmicrostructureeffectsonthefollowingagingbehaviorgreatly.Thetransformationsequencewithagingmaybeα-Fe→orderingdomain→bccCucluster→transitionphase→ε-Custablephase,ε-Cuphasewasnotfoundinthisexperiment,hence,thedrasticstrengtheningeffectmaybeconformingresultoforderingdomainandbccCucluster.Keywords:copper,highpuritysteel,solution,aging
论文题目:氧化钐,氧化钆二元稀土掺杂氧化铈基固体电解质的制备与电性能研究
PreparationandElectronicPropertiesofCeO2Based
SolidElectrolyteDopedWithSm2O3,Gd2O3
研究生姓名:赵永旺
导师姓名:安胜利教授
协助导师:宋希文讲师
专业:材料加工工程
摘 要:
固体氧化物燃料电池(SOFC)以Y2O3稳定ZrO2(YSZ)作为固体电解质,需在1000℃左右的高温下运行.高温带来了电极烧结,密封困难等一系列问题.于是,降低SOFC运行温度已成一种必然趋势,其中一条途径便是寻找在低温下具有较高离子电导率的固体电解质材料.掺杂CeO2在500-700℃下具有较高的离子电导率,是一种最具希望替代YSZ而成为中温固体氧化物燃料电池的固体电解质材料.
采用化学共沉淀法制备了氧化钐,氧化钆二元稀土掺杂氧化铈纳米粉体.研究了pH值对Ce(OH)4水分散体系Zeta电位和沉降高度的影响,当pH等于7时,体系的Zeta电位为0,也就是体系的等电点(IEP)为7,当pH等于10时,Zeta电位达最大值-18.5mV,沉降高度最大19ml.利用DTA/TG热分析和XRD对Ce(OH)4的热分解行为进行了研究,Ce(OH)4在200℃左右时开始分解.利用XRD,TEM和BET等现代物理测试方法对氧化铈纳米粉体的物相,颗粒度,分散性,颗粒形貌和比表面积等性能进行了表征,650℃焙烧的粉体呈现出良好的结晶状态,为立方萤石结构,粉体的比表面积在56.134-27.354m2/g之间,平均颗粒直径为14nm-30nm,呈良好的分散状态.
研究了成型压力对素坯及烧结体密度的影响.当成型压力大于46.31MPa时,粉体中的团聚体开始破碎,成型压力为400MPa时,烧结体的密度最大.烧结实验研究表明,随温度的升高,线收缩率与密度都是增大的,试样的气孔率是降低的.等温烧结实验表明,当烧结温度达到1500℃时,试样的相对密度为96.8%,随温度进一步升高,密度基本不变.
利用交流阻抗法测试了材料的电导率.结果表明,随成型压力的增加,电导率先增大后减小,成型压力为400MPa时,电导率达最大值.电导率随烧结温度的升高而增大,烧结温度为1500℃,电导率是最高的.(CeO2)0.8(Sm2O3)0.08(Gd2O3)0.02固体电解质的电导率明显高于(CeO2)0.8(Sm2O3)0.1及(CeO2)0.8(Gd2O3)0.1固体电解质的电导率.
关 键 词:氧化铈,纳米粉体,固体电解质,电导率
ABSTRACT
Yttria-stabilizedZirconia(YSZ)hasbeenusedasanelectrolyteforsolidoxidefuelcell(SOFC).TheYSZ-basedfuelcellsrequireoperatingaround1000℃,leadingtosomeproblems,suchasthermalstress,reactionbetweentheponentsandsinteringoftheelectrode.Oneapproachtooveringtheselimitationsistouseanelectrolytethattheoxygen-ionconductivityissignificantlyhigherthanthatofYSZatlowertemperature(below700℃).Oneofthepromisingalternativesisdoped-ceriabasedelectrolyte.
TheSm2O3,Gd2O3dopedCeO2nano-powdersweresynthesizedbyacoprecipitationmethod.TheZetapotentialandsedimentationvolumeofCe(OH)4aqueousdispersionsatdifferentpHvaluesweremeasured.Theisoelectricpoint(IEP)ofCe(OH)4suspensionsis7.0.Themaximumpotentialvalueof-18.5mVandthemaxinumsedimentationvolumeof19mlarereachedatpH等于10.TheevolutionbehavioroftheCe(OH)4driedpowdersintheheatingprocesswascharacterizedbyDTA/TGandXRD.TheresultsindicatethatCe(OH)4deposetoCeO2atatemperaturearound200℃andformscubicfluoritestructureceriabelow650℃.Thephase,particleshapes,particlesizeandspecificsurfaceareaofthedopedceriapowderswerecharacterizedbyXRD,TEMandBET.Theresultsshowthatdopedceriapowderscalcinedat650℃haveacubicfluoritestructure,anaveragesizeof14to30nm,andahighdispersionbehaviours.
Thepowderwasuniaxiallypressedinasteeldieatthepressureof12to1000Mpa.Theagglomeratesinthepowderscanbebrokenunderaconditionofthehigherpressurethan46.31MPa.Thedensityofsinteredbodyisthebiggestwhenthepressureis400MPa.ThelinearShrinkageanddensityincreasewithimprovingthesinteringtemperature.Therelativedensityofthespecimensinteredat1500℃is96.8%,anditchangesslightlywiththefurtherincreasingofsinteringtemperature.
TheionicconductivityofdopedCeriaelectrolytesweremeasuredbythea.cimpedancespectroscopytechnique.Theeffectofshapingpressureandsinteringtemperatureontheionicconductivitywerestudied.Initially,theionicconductivity,whichhasamaximumvalueatashapingpressureof400MPa,isincreasingwiththeincreaseoftheshapingpressure,thenisdecreasingwiththefurtherimprovementofshapingpressure.Theionicconductivityincreaseswiththeincreaseofthesinteringtemperature.Thehighestconductivityofelectrolytesinteredat1500℃isobtained.TheconductivityofSm0.16Gd0.04Ce0.8O1.9electrolyteis0.103Scm-1at900℃.
Keywords:Ceria,nano-powders,solidelectrolyte,electronicconductivity0.04%稀土,钢中RE/S≈1.4时,夹杂物的变质达到最佳效果,当稀土加入量达到0.06%时,效果反而下降.
本次实验进一步表明,虽然钙与稀土一样在钢中具有很强的脱氧,脱硫的能力,但稀土更能彻底地变性硫化物夹杂.先用钙处理尽量减少钢中的[S]含量,再加入少量稀土,则是彻底变质钢中夹杂物,提高钢的洁净度的有效办法.因此,很好地应用这种方法研究开发洁净钢是很有发展前景的.
关 键 词:稀土钙洁净钢夹杂物变质
ABSTRACT
TheapplicationandstudystatusofRareEarthandCalciuminsteelhasbeenbrieflydiscussedinthispaper,andthepropertiesofRareEarthandCalcium,theactionmechanismsinsteelofthemandtheadditionmethodsofaddingintosteelofthemhavebeensummarizedindetail.
Theeffectofpoundtreatme
关于电化学方面论文例文,与医学学位文湖北,硕士学位文的通知相关毕业论文范文参考文献资料：