本站原创2004届硕士研究生学位论文摘 要
材料加工工程
论文题目:高强度高韧性贫铀合金(U-Nb-Zr)热处理工艺研究
StudyontheHeat-TreatmentofDuAlloys
WithHighStrenghandHighToughness
研究生姓名:郭洪
导师姓名:李冠兴院士
协助导师:任慧平教授
杨继先任永岗研究员
专业:材料加工工程
摘 要:
U-Nb-Zr合金作为动能穿甲弹的材料,要求具有高强度,高韧性的特点.为了获得最佳的性能搭配,就要从成分,工艺,组织,性能等各方面入手,对合金进行深入系统的研究.本论文以金相研究为重点,综合运用力学性能测试,X射线衍射,断口分析等手段,由纵向,横向两个方面比较分析热处理工艺和合金成分对组织和性能的影响,从而得出在"淬火+回火"热处理工艺条件下,U-Nb-Zr合金组织及性能的变化规律,并分析了Nb,Zr在合金中的作用.在此基础上,提出获得高强度,高韧性贫铀合金的成分范围和相应的加工及热处理工艺.
关 键 词:U-Nb-Zr合金热处理高强度,高韧性
ABSTRACT
Asamaterialfordynamicenergyprojectile,U-Nb-Zralloysshouldpossessthecharacteristicsofhighstrengthandhightoughness.Inordertoobtaintheoptimalprehensiveproperties,westudiedthealloysintheaspects:ponents,craft,microstructure,andmechanicalproperties.Inthecourseofresearch,theworkofmetallurgicalanalysiswasinthefirstplace.Meanwhile,themechanicalpropertiesweretested,thestructureofcrystallineanalyzed,themorphologyoffractureobserved.Byallthesemeans,theeffectsofheat-treatmentandponentsonpropertiesandstructurehebeenmadeout.Thus,therulesofpropertiesandstructure'sevolutionintheheat-treatment(quenching+tempering),areclear,andtherolesofNbandZrinthealloysaredrawnout.Onthebasisoftheseworks,therangeofponents,andthecraftofheat-treatmentandworkingareprovided.
Keywords:U-Nb-Zralloyheat-treatmenthighstrengthhightoughness
论文题目:薄板坯CSP连轧热力耦合有限元模拟
ThinSlabCSPThermalMechanicalCoupled
FemSimulationduringContinuousRolling
研究生姓名:李传瑞
导师姓名:王宝峰教授
专业:材料加工工程
摘 要:
薄板坯连铸连轧是20世纪80年代成功开发的一种全新的生产热轧板卷的工艺,是钢铁工业最重大的革命性技术之一.与传统热轧板带钢相比,薄板坯连铸连轧具有非常大的优越性.因此世界各国都给予极大关注,在冶金界产生极大反响.
典型的薄板坯连铸连轧技术包括CSP技术,ISP技术和FTSR技术.其中CSP技术应用最多.据统计,1997年世界有CSP生产线20条,占薄板坯连铸连轧线的70%,CSP生产的热轧板占世界钢产总量的5%.预计到2016年,CSP生产的热轧板占世界钢产总量的50%.可见CSP技术有很大的发展前景.
1997年,我国的广东珠江钢铁公司,河北的邯郸钢铁公司以及内蒙古的包头钢铁公司分别从德国的S引进3条CSP生产线,并相继建成投产,年生产能力在200万t/a.最近,我国的唐山钢铁公司,通化钢铁公司,马鞍山钢铁公司以及涟源钢铁公司等企业也计划建立薄板坯连铸连轧生产线.
薄板坯连铸连轧技术具有广阔的发展前景,因此研究与此相关的课题具有一定的必要性.
目前,由于计算方法与数值模拟理论的结合,极大的推动了轧制技术的发展.同时,也使得对钢材生产过程形,温度的计算机模拟成为可能.
本文是针对包头钢铁公司的CSP连轧生产工艺,借助Marc商用软件,采用热力耦合分析技术,建立大变形弹塑性有限元数学模型,分析薄板坯的连续轧制变形过程.包括以下内容.
1综合考虑了板坯与轧辊的接触换热,板坯与周围环境的对流辐射换热,机架间冷却水的冷却作用,塑性变形和摩擦而产生的热量等条件对温度变化的影响,计算了板坯内部的温度场,分析了板坯内的温度变化情况,得出其温度变化规律.
2计算变形区内等效应力场,等效应变场,等效应变速率场,分析了板坯内三者各自的变化情况.
3计算轧制过程中的轧制力,分析了轧制力的变化情况.
本文结合薄板的生产过程,对变形过程中的温度场以及力能参数进行研究,所得到的分布规律,可以为工业生产提供参考.
关 键 词:CSPMarc热力耦合有限元模拟
ABSTRACT
Thinslabcontinuouscastingrollingisanewtechniqueofhotrollingstripcurlproduct.Itisoneofthemostimportantrevolutionarytechnologies.Comparedwithtraditionalhotslabproduct,thistechnologyhaanyadvantages.Soalargenumberofcountriesshowgreatconcernaboutit.
TypicalthinslabcontinuouscastingrollingtechnologyincludesCSP,ISPandFTSR.YetCSPtechnologyisusedwidelynowadays.ItisreportedthattherearemorethantwentyCSPproductionlinesallovertheworld,accountingfor70percentofthinslabcontinuouscastingrollinglines.HotrollingstripproducedbyCSPaccountor5percentoftotalsteeloutput.ItiscalculatedthathotrollingstripproducedbyCSPwillamountto50percentoftotalsteeloutputby2016.
In1997,threeCSPlineswereintroducedfromSandwereputupindividuallyinZhuJiangironandsteelpany,HanDanironandsteelpanyandBaoTouironandsteelpany.Theyheputintousenow.Theirdesigncapacityamountsto200milliontonsannually.
Nowthatthinslabcontinuouscastingrollingisboomedrapidly,itisnecessarytoresearchsubjectaboutthat.
Therollingtechniquegetmuchfromthemutualdevelopmentofputationmethodsandmathematicalimitationwhichmakeitpossibletosimulatethedeformationandtemperatureevolutionintheprocess.
Inthisarticle,thesixpasseshotrollingprocessofthinslabwasstudiedwiththeaidoftwodimensionalelastic-plasticandthermal-mechanicalcoupledFEMusingmercialsoftwareMarc.Whatwereresearchedisaellows:
Thedistributionandchangeoftemperaturefieldinrollingprocesswereanalyzed.Inviewofboundaryconditionalinfluenceontemperature,somefactorssuchasthermalexchangebetweenrollingandrolledpiece,plasticdeformingquantityofheat,coolingflux,convectionandradiationheatexchangewereconsideredduringsimulation.Theparametersofrollingmechanicalpropertyduringdeformationsuchasequivalentstress,equivalentstrainandequivalentstrainratewereinvestigated.Theresultsshowedthatelastic-plasticandthermal-mechanicalcoupledFEMcouldcorrectlyreflectmetaldeformation.
Underthebackgroundofthedevelopmentofthinslabrollinginourcountry,thepresentedtemperatureandmechanicalpropertyparametersdistributionandruleayeupwithreferencetoindustrialproduction.
Keywords:CSPMarcheat-mechanicalcoupledFEMsimulation
论文题目:快淬AB5型贮氢合金电化学性能及其微观结构的研究
TheInvestigationsonElectrochemicalPerformancesand
MicrostructuresofRapidQuenchingAB5-typeHydrogenStorageAlloys
研究生姓名:王国清
导师姓名:张羊换教授
专业:材料加工工程
摘 要:
AB5型稀土系贮氢合金,作为Ni/MH电池负极材料已得到大量研究和广泛应用.为了提高Ni/MH电池的市场竞争力,降低贮氢合金的生产成本和提高合金的电化学性能成为贮氢合金研究的主要方向.目前研究的焦点是如何提高低钴,无钴贮氢合金的电化学循环稳定性.本文旨在通过合金成分的优化调整,同时结合适当的快淬工艺,改善低钴无钴贮氢合金的循环稳定性,制备出综合性能优异的贮氢合金电极材料.
本文主要应用熔炼法和真空快淬技术制备AB5型贮氢合金,用开口式三电极系统测试合金的电化学性能,用XRD分析了铸态及快淬态合金的相组成及相结构,用SEM和光学显微镜观察了铸态及快淬态合金的微观组织形貌,用TEM观察了铸态及快淬态合金的形貌并用SAD确定其晶态.全面研究了合金微观结构与其电化学性能的联系,得到如下一些主要结论:
1.综合研究了Mm(NiMnSiAl)4.3Co0.6-xFex(x等于0,0.2,0.4,0.6)系列铸态和快淬态合金的微观结构及电化学性能.结果表明,Fe替代Co导致合金的电化学容量下降,但不同程度的改善了合金的循环稳定性.Fe替代Co对快淬态合金循环寿命的提高比较显着,这主要是由于随Fe替代量的增加,快淬态合金的晶粒明显细化.快淬工艺可以极大地提高合金的循环寿命.
2.对铸态及快淬态低钴无钴LaxMm1-x(NiMnSiAlFe)4.7Co0.2(x等于0,1)和LaxMm1-x(NiMnSiAlFe)4.9(x等于0,1)两个系列铸态和快淬态合金的研究结果表明,La替代Mm使合金放电容量提高,其主要原因是合金中第二相的消失和晶胞体积的增大.
3.研究表明,通过以Fe替代Co,成分优化设计以及应用真空快淬工艺研制低钴无钴AB5型贮氢合金是可行的.实验发现两种成分的低钴无钴合金可以达到实用化需求.这两种合金成分是La(NiMnSiAlFe)4.7Co0.2和La(NiMnSiAlFe)4.9,活化次数为2次,最大放电容量分别为309.42mAh/g和304.47mAh/g,循环寿命分别为370和300次.
关 键 词:AB5型贮氢合金,低钴无钴,快淬,循环稳定性
ABSTRACT
AB5-typerare-earth-basedhydrogenstoragealloy,asthenegativeelectrodematerialoftheNi/MHbatteries,hasbeenextensivelyinvestigatedandwidelyapplied.InordertoexaltthepetitionabilityofNi-MHbatteriesintherechargeablebatterymarket,theinvestigationontheAB5-typehydrogenstoragealloyhasbeencarryingouttoenhancetheelectrochemicalperformancesandreducetheproductioncostofthealloy.Atpresent,theinvestigationfocusontheAB5-typehydrogenstoragealloyishowtoincreasethecyclestabilityofLow-CoandCo-freeelectrodealloy.Thisthesisintendstogetakindofhydrogenstoragealloywithgreatsyntheticalpropertiesthroughoptimizingthepositionandrightrapidquenchingtechnology.
AB5-typehydrogenstoragealloyswerepreparedbycastingandrapidquenching.Theelectrochemicalperformancesoftheexperimentalalloysweremeasuredbyanopentri-electrodesystem.Themicrostructuresoftheas-castandquenchedalloyswerestudiedsystematically:thephasestructureswereanalyzedbyXRD,themicrostructuresandmorphologieswereobservedbySEMandOpticicroscope,thecrystallinestateandmorphologiesweredeterminedbySADandTEM.Theinfluencesofrapidquenchingtechnologyonthemicrostructuresandelectrochemicalperformancesoftheexperimentalalloyswereresearchedindetail,andsomeimportantconclusionswereobtained.
1.Themicrostructuresandelectrochemicalperformancesoftheas-castandquenchedMm(NiMnSiAl)4.3Co0.6-xFex(x等于0,0.2,0.4,0.6)alloysweresyntheticallyinvestigated.TheresultsshowthatsubstitutionFeforColeadstodecreaseofthedischargecapacityandimproveofthecyclelifeofthealloystosomedegree.Especially,theeffectofsubstitutionFeforCoonthecyclelifeoftheas-quenchedalloysisoutstanding.ThisiainlyattributedtothegrainrefinementproducedbytheincreaseoftheamountofFecontent.Rapidquenchingcangreatlyimprovethecyclelifeofthealloy.
2.Theelectrochemicalperformancesandmicrostructuresoftheas-castandquenchedLow-CoandCo-freeLaxMm1-x(NiMnSiAlFe)4.7Co0.2(x等于0,1)andLaxMm1-x(NiMnSiAlFe)4.9(x等于0,1)electrodealloyswereresearchedandresultsshowthat,thesubstitutionLaforMmmakestheincreaseofthedischargecapacityofLow-CoandCo-freealloys.ThemainreasonisthatthesecondaryphasedisappearsandthelatticevolumeaugmentswhenLasubstitutesMmintheLow-CoandCo-freealloys.
3.TheinvestigationsshowthatitieasibletoprepareanddeveloptheLow-CoandCo-freeAB5-typehydrogenstoragealloysbysubstitutionFeforCo,ponentoptimizingdesignandusingrapidquenchingtechnology.TwokindsoftheLow-CoandCo-freealloyswhichcanattaintherequirementofthepracticalapplicationarediscovered.ThealloysareLa(NiMnSiAlFe)4.7Co0.2andLa(NiMnSiAlFe)4.9withtheactivationpropertyof2cycles,themaximumdischargecapacityof309.42mAh/gand304.47mAh/g,andthecyclelifeof370and300cyclesrespectively.
Keywords:AB5-typehydrogenstoragealloy,Low-CoandCo-free,rapidquenching,cyclestability
论文题目:热处理工艺及稀土元素对Ni-Mn-Ga磁性形状记忆合金性能的影响
InfluenceofHeatTreatmentProcessandRareEarthson
thePropertiesofNi-Mn-GaMagicShapeMemoryAlloys
研究生姓名:李雪梅
导师姓名:赵增祺教授
专业:材料加工工程
摘 要:
本文主要研究了不同热处理制度和稀土元素对Ni-Mn-Ga合金马氏体相变温度和磁感生应变的影响.利用交流磁化率测定仪测定合金的相变温度和居里温度,利用动态电阻应变仪和特斯拉计测定合金的磁感生应变,并利用XRD,SEM等实验技术研究了合金的相结构和微观结构.
对合金进行不同制度的热处理,研究其对合金性能的影响,并以此为据选用最佳的热处理工艺.研究结果表明:热处理制度不同,对合金引入的内应力不同,内应力越大,合金的相变温度越低,同时磁感生应变也越小.
对合金Ni52.5Mn23.5Ga24-XTbX(X等于0,0.1,0.2,0.4)和合金Ni52Mn24.7Ga23.3-XDyX(X等于0,0.1,
0.2,0.4)研究不同含量的稀土元素对合金性能的影响.稀土元素对合金晶体结构没有影响,添加稀土元素显着提高了合金的相变温度,使合金的相变热滞后稍有降低,同时对合金的居里温度影响不大,添加稀土元素合金的晶粒明显细化,改善了合金的机械性能.无外加应力作用下,添加稀土元素合金的磁感生应变值较低,但当外加应力与磁场作用方向相同时,添加稀土元素合金的磁感生应变值很高,最大可达0.3%以上.定向凝固试样的磁感生应变值比相应铸态试样的高,最大为0.85%.
关 键 词:Ni-Mn-Ga合金,热处理制度,稀土,相变温度,磁感生应变
ABSTRACT
Theeffectofdifferentheattreatmentprocessandrareearthonmartensitictransitionandmagic-field-inducedstraininNi-Mn-Gaalloysareinvestigated.MartensitictranormationtemperatureandtheCurietemperatureweredeterminedbymeansofacmagicsusceptibility.Ametalfoilstraingaugewasattachedonsampleormeasuringstrainsasafunctionofthemagicfieldatroomtemperature.CrystalstructurewasidentifiedbyX-raydiffractometerusingCuKαradiationatroomtemperature.Fracturesurfacesofthepressiontestspecimensandmicrographsofsamplewereobservedwithscanningelectronmicroscope(SEM).
Effectofvariouscontentsrareearthontranormationpropertiesandmagicpropertiesaswellaechanicalpropertiesofalloyswerestudied.TheresultsshowedthatrareearthhadlittleinfluenceonthecrystallinestructureandtheCurietemperatureandremarkableincreasedthetranormationtemperatureanddecreasedtemperaturehysteresis.SEMstudiesrevealedthatthemechanicalstrengthwasenhancedbyreducedsizesofgrains.Itwaoundthatmagic-field-inducedstrainwasreducedbyaddingrareearthwithoutpressurebutwasincreasedupto0.3%whenpressurewasexerted.Thestrainofdirectionsofpolycrystalwaslargerthanthatofcastspecimens.
Keywords:Ni-Mn-Gaalloy,heattreatmentprocess,rareearths,tranormation
temperature,magic-field-inducedstrain-曲线测量仪直接测量三组不同系列合金铸态及粉末样品在低磁场下的磁热效应,借助X-射线衍射分析技术,分析研究成分和高能球磨对合金磁热效应的影响及可能存在的原因.
对锰锗,锰锗硅,锰锗锑三种合金材料的研究发现,硅元素的加入使材料的居里温度下降,且材料的磁热效应也随硅元素含量的增加而下降,锑元素的加入使材料的居里温度升高,而材料的磁热效应随锑元素含量的增加而下降.
对于大量固态磁致冷材料的研究表明,目前还没有任何一种金属或合金在低磁场下,室温附近的磁热效应超过金属钆.因此,我们提出开发具有磁热效应的磁液体的方案.根据理论,当磁致冷材料颗粒达到一定粒度时,出现超顺磁性,并且可能放大材料的磁热效应.对经机械球磨后锰锗系列合金的研究表明,由于材料在球磨过程中受长时间,周期性机械力作用,而产生晶格扭曲,导致材料磁热效应的下降.为使合金粉末的磁热性能达到试验用样机磁液体的要求,我们用热处理的方法恢复合金粉末的晶格扭曲,使合金粉末的磁热效应回升.实验表明制定合适的热处理工艺可以使扭曲的晶格得到恢复,同时合金粉末的磁热效应也得到回升.
关 键 词:锰锗锑合金锰锗硅合金磁热效应热处理
ABSTRACT
Becauseoftheecologicalharmfulnessoffreons,thequestionofdevelopmentandproductionofsubstitutiverefrigerationdevicesoperatingintheroomtemperaturerangehasbeetopical.Magicrefrigerationtechnique,whoseprincipleofoperationusestothemagocaloriceffect,isbeingfocusofresearchintheworldforitshighefficiency,lessenergyandecologicalharmfulness.
Themagocaloriceffectoftheroomtemperaturemagicrefrigerationmaterials,suchasMn5Ge3,Mn5Ge3-xSbxandMn5Ge3-xSixalloys,atlowmagicfieldof1.3Teslawerestudiedinthepresentpaper.First,thecastingandpowderofMn5Ge3,Mn5Ge3-xSbxandMn5Ge3-xSixalloyswerepreparedusinghighfrequencyvacuumlevitationfurnaceandaplaaryballmill.,Secondthemagocaloriceffectsofthealloysweremeasureddirectlybyusingtheself-made-curvemeasurementdevicesatthefieldof1.3Tesla.Last,thepossiblecausesofthepositionchangeandballmillingaffectthemagocaloriceffectsofthealloyswereanalyzedbyXRDmethod.
Asresearchshows,themagocaloriceffectandCuricetemperatureofMn5Ge3-xSbxandMn5Ge3-xSixalloysvarieswiththeconsisteryofSi,Sbrespectively.Studyofpowderedalloysshowsthatmagicmaterialsresultsindistortedcrystallatticewithlongtimeandrecurrenteffectofmechanicalforce.Becauseofthereasons,themagocaloriceffectsofmaterialsdecreaseswiththedecreasesofsizedpowder.Thedistortionofcrystallatticehasbeenrecoveredbyusingheattreatment.Themagocaloriceffectofalloypowderisimprovedbytheproperheattreatment.
Keywords:Mn5Ge3-xSbxMn5Ge3-xSixmagocaloriceffectheattreatment
论文题目:310乙字钢轧制过程实验研究及三维有限元模拟
ExperimentalResearchand3DFEMSimulationon310ZshapeSteel
研究生姓名:苏光
导师姓名:陈林教授
协助导师:王秉义教授级高工
专业:材料加工工程
摘 要:
310乙字钢是铁路货车车厢的重要结构件.从技术角度讲,310乙字钢变形复杂,生产技术难度大,孔型设计要求高.包钢轨梁厂生产的310乙字钢一直采用现有的孔型系统,在轧制过程中存在腿部在孔型中充不满,造成腿部尺寸短尺的技术难题.
为了分析研究310乙字钢在孔型中的变形规律及孔型设计对产品质量的影响,本文采用了轧制实验和有限元模拟两种方法进行研究.
本文针对孔型系统,将孔型缩小为实际尺寸的1/5,利用实验轧机轧制铅试样的实验方法,研究了孔型形状参数,道次压下量等因素对310乙字钢成型的影响,为改变孔型系统,提高产品质量提供了解决的方向.实验结果表明:增长短腿水平投影长度有助于短腿的伸长.同时,实验室轧制的过程也为有限元模拟提供了计算策略.
在轧制实验的同时,采用显式有限元软件ANSYS/LS-DYNA,对310乙字钢的轧制过程进行弹塑性有限元模拟,研究了950Ⅱ孔轧制变形过程中各道次轧件断面节点的x,y方向的流动规律.同时在模拟过程中,采用了多种方案进行模拟,对各种计算结果进行相互的比较,其变形规律与实验室模拟结果是一致的,从而可以得出应用有限元软件进行轧制过程的实验模拟是可靠的.
运用数值模拟方法,采用不同的孔型系统方案,模拟分析了采用连铸坯料轧制310乙字钢的可行性.通过比较结果,选用最优的方案(即D轧制方案)进行工业试验,从而减少了实验室试验的环节,缩短了产品开发的步骤,降低了产品研制的成本,提高了产品的市场竞争力.
为了使ANSYS有限元软件能够具有在分析310乙字钢轧制过程中的通用性,本文在ANSYS软件的基础上,采用APDL和UIDL相结合进行了二次开发,编写了适用于现场工程技术人员使用的310乙字钢模拟分析程序.
关 键 词:型钢轧制实验有限元模拟ANSYS二次开发
ABSTRACT
310Zshapesteelistheimportantsectionofthecarriageinthelorry.Intheviewoftechnique,310Zshapesteelrollinghastheplexdeformation,therollingtechniqueisverydifficultyandtherollpassdesignhasthehighrequest.Forthe310Zshapesteelrolling,theplantofrailandbeamofBaoGanghasusedthecurrentrollpass.Duringtherolling,thesectionoftheleghasnotpermeatedtherollpass.Sotheshapeoflegwasnotveryperfection.
Inordertostudytheruleofthedeformationintherollpassandtheeffectoftherolldesigntothequalityoftheproduct,twokindsofmethodsi.e.experimentalrollingandFEMsimulationareusedinprofoundresearchworks.
Therollingexperimentswereperformedintherollingmilloflaboratorywithlead,therollpassscaleis1:5accordingtotheactualsizeof310Zshapesteel.Theeffectofrollingdesignandthereductiontothemoldingofthe310Zshapeisthetopicoftheresearchworks.Wecanconcludethattheshorterlegwillincreasewhenthelengthoftheprojectionoftheshorterleg.TheresultswilloffertheaspectforincreasingthequalityoftheproductandcalculationstrategyforFEMsimulation.
Meanwhile,thedynamicexplicitelastic-plasticelementmethodsimulationofthe310ZshapesteelrollingprocessunderthesamerollingconditionwasperformedwiththeFEMsoftwareANSYS/LS-DYNA.TheflowingruleofthemetalwiththexandydirectioncanbereceivedafterstudyingthedeformationoftheZshapesteelinthe950Ⅱ.Someschemeofsimulationwillbeadoptedintheresearch.Hinganalyzedtheresults,thedeformedruleinthesimulationaccordswiththeresultofthelabexperimental.AnditwillprovethatthemethodofFEMintherollingisreasonable.
TheFEMmethodwillbeexertedtoanalyzethefeasibilityofrollingthe310Zshapesteelonbaseofthecontinuouslycastingbillet.Afterinvestigatingtheresults,theoptimizationscheme(theDscheme)canbeadoptedtocarrythroughtheindustrialexperimentation.Thiethodcancutdownthelabexperimentation,soitwilldepressthecostofexploitingthenewproductandenhancethepetitivecapabilityofthemanufactureinthemarket.
InordertousetheANSYEMsoftwaretosimulatethe310Zshapesteelroll,onthebasisofANSYS,theresearchadoptstheAPDLandUIDLtomakeaprogramfortheengineerswhoworkinthelocationoftheproduction.
Keywords:sectionsteel,rollingexperiment,FEM,simulation,ANSYS,re-development
论文题目:热变形Nd-Fe-B稀土永磁材料组织和织构的研究
StudyonMicrostructureandMagicTextureofHot-deformed
NdFeBRareEarthPermanentMags
研究生姓名:计云萍
导师姓名:任慧平教授
专业:材料加工工程
摘 要:
本文研究了热变形Nd-Fe-B稀土永磁材料的铸锭组织和热变形过程中组织与织构的变化.合金在真空中频感应炉冶炼,随后进行不同工艺的热变形及热处理.然后观察显微组织,采用X射线衍射的方法分析织构的变化.结果表明:Nd-Fe-B合金铸锭中Nd2Fe14B相生长成片状晶,若干个彼此近似平行排列的片状晶组成一个片状晶团/s的热压变形工艺下,得到以(006)晶面的衍射峰为主峰的织构,即(006)织构,随形变量的增大,(006)织构进一步增强.初始织构对热变形Nd-Fe-B永磁的磁织构影响当试样的初始织构不显着时,热轧变形后永的磁织构增强当试样有非常发达的初始织构时,热轧变形后的永的磁织构减弱ThemicrostructureofNd-Fe-Bingotandtheinfluenceofhot-deformationonmicrostructureandmagictextureofNd-Fe-Bpermanentmagicalloyswerestudied.Thealloyswereeltedinvacuumintermediate-frequencyinductionfurnace,thenthesampleswerehotdeformedandcarriedthroughheattreatment.MicrostructurewasobservedandtexturewasanalyzedbyX-raydiffraction.ResultsshowthatthegrowthofNd2Fe14Bgrainsduringsolidificationisinsheet-likepatternandseveralnearlyparallellatheormagroupofsheet.Hot-pressingdeformationrefinesthegrainsandwiththeincrementofdeformationratio,theNd2Fe14BgrainsarefurtherrefinedandNd-richphaseisinwell-proportioneddistributionalongthecrystalboundary.Nd-richphaseduringhot-pressingdeformationisinliquidstateanditplaysalubricantroleinhot-pressingdeformationinordertomakeNd2Fe14Bgrainsrotateandmovebeneficially.Heattreatmentimprovesthecrystalboundarymicrostructure.(006)textureisobtainedbyhot-pressingdeformationat700℃withadeformationrateof10-4～10-3/sand,withtheincrementofdeformationratio,(006)textureiurtherstrengthened.Inaddition,theinitialtextureofNd-Fe-Bingotisveryimportanttoformmagictextureduringhot-deformation.Hot-rollingdeformationmayincreasethemagictextureofNd-Fe-Bmagswhentheinitialtextureisnotverypronounced.Conversely,aningotwithawell-developedinitialtexturemayheitagictexturedecreasedbyrolling.
Keywords:Nd-Fe-B,rareearthpermanentmags,hotdeformation,texture
论文题目:热变形钕铁硼永磁材料加工处理工艺对组织和磁性能的影响
EffectofCureTechniqueonMicrostructureand
MagicPropertiesofHot-DeformationNdFeBMags
研究生姓名:王晓军
导师姓名:李文学教授
专业:材料加工工程
摘 要:
本文主要研究NdFeB永磁材料热压变形的可行性及加工处理工艺对NdFeB永磁材料显微组织和磁性能的影响.分析了化学成分,铸锭组织,热变形量,热形变温度和热处理对NdFeB永磁材料显微组织和磁性能的影响.结果表明:NdFeB永磁材料铸锭组织为柱状晶.在热压时,随着热变形量的增加,NdFeB永磁材料的晶粒变得细小,显微组织得到改善,磁性能提高.获得NdFeB永磁材料最佳磁性能的热形变温度与Nd含量有关,随Nd含量的提高,热形变温度降低.通过热处理,使Nd2Fe14B晶粒长大,主相Nd2Fe14B体积百分数增加,NdFeB永磁材料的磁性能得到提高.
关 键 词:NdFeB永磁材料,铸锭组织,热变形,热处理,显微组织,磁性能
ABSTRACT
ThispaperstudiedthepossibilityofNdFeBmagshot-deformationtreatmentandtheeffectofcuretechniqueonmicrostructureandmagicpropertiesofNdFeBmags.Chemistryponent,ingotstructure,hot-deformationandheattreatmenteffectmicrostructureandmagicpropertiesofNdFeBmags.Experimentsshowedthatforthehot-deformedNdFeBmagsgrainsizedecreases,microstructureandmagicpropertiesimprovesashot-deformationincreases.Hot-deformedtemperatureofobtainedbestmagicpropertiesrelatescontentofNd,Hot-deformedtemperaturedecreasesascontentofNdincreases.Acrossheattreatment,Nd2Fe14Bcrystalgraingrowsup,magicpropertiesofNdFeBmagsincreasesasNd2Fe14Bvolumepercentenchances.
Keywords:NdFeBmags,ingotstructure,hot-deformation,heattreatment,microstructure,
magicproperties
论文题目:La1-xCaxMnO3纳米结构的制备及磁热效应的研究
PreparationandMagocaloricEffectofLa1-xCaxMnO3
Nanostructure
研究生姓名:赵辉荣
导师姓名:李保卫教授
协助导师:任永岗研究员
王正德副教授
专业:材料加工工程
摘 要:
室温磁致冷技术是一种新型致冷技术,因其潜在的优势而倍受科研工作者的关注.由于室温磁致冷技术具有无污染,低噪音,能耗小,体积小,易维护,寿命长等优点,国际上对室温磁致冷技术研发的投入非常大,我国对该技术已进行一定的研究.磁致冷技术的关键是磁致冷工质,其性能如何将直接影响制冷机的制冷性能和效益.近10年来由于La1-xCaxMnO3(LCMO)化合物具有居里温度可调,化学性能稳定,便宜,电阻率较高等优点,适合作为室温磁致冷材料而引起国内外广大研究工作者的广泛关注.本文针对La1-xCaxMnO3(LCMO)系致冷工质进行了研究.
本论文的研究工作主要包括室温纳米磁致冷材料La1-xCaxMnO3(x等于0.2,0.3,0.4,0.5)系化合物的制备,影响形状和大小的因素及其在低磁场(1.4T)下的磁热效应.
本论文采用水热共沉淀退火法制备了La1-xCaxMnO3(x等于0.2,0.3,0.4,0.5)系纳米结构,用X射线衍射仪确定产物为单相钙钛矿结构,无任何杂峰及第二相,用扫描电子显微镜与透射电子显微镜分析了产物的大小和形貌,发现水热温度对产物的形成起决定作用,随着温度的升高,产物由薄膜状向丝状转变,而溶液的碱度可控制产物的形貌和大小,当碱度为6.35mol/L,水热温度为240C时,La0.6Ca0.4MnO3的主要形貌为纳米丝并有少量纳米颗粒,纳米丝平均直径为40nm,最后测量了粉末样品在低磁场(1.4T)下的磁热效应,发现水热共沉淀退火法制备样品的最大绝热温度明显高于球磨法制备样品的最大绝热温变.
在低磁场(1.4T)下测量的La1-xCaxMnO3系纳米结构发现:绝热温度(ΔTad)的温度跨度有变宽的趋势,且不用水热共沉淀退火法制备的La1-xCaxMnO3系纳米结构的大小可为几十纳米,如果把形貌控制为大小一致的颗粒状,则可用它制备磁液体,使磁致冷样机热交换过程实现管道化,简化磁致冷样机的结构.
关 键 词:水热共沉淀退火法钙钛矿纳米结构磁热效应
ABSTRACT
Recentlycoolingtechnologyhasbeenusedineveryfieldssuchasindustry,agricultureetc.Increasingattentionhasbeenfocusedonlargemagocaloriceffectinthiaterialsbecausemagiccoolingtechnologyhasconsiderableadvantagessuchashighefficiency,non-pollution,goodchemicalstability,tunableTcandlowpriceinparisonwiththetraditionalvaporpressiontechnology.
WepreparednanostructuresamplesofformulaLa1-xCaxMnO3byhydrothermal-precipitationmethodandstudymagocaloriceffect(MCE)ofLa1-xCaxMnO3atlowmagicfieldinthispaper.
Inthiswork,nanostructuresamplesofLa1-xCaxMnO3(x等于0.2,0.3,0.4,0.5)werepreparedbyhydrothermal-precipitationmethod.ThestructuralcharacterizationofthepowdersamplesweredonebyX-raydiffraction(XRD).XRDpatternsshowedthatallthesamplesatesingleperovskite-typephasewithoutotherimpurityorsecondaryphase.TheshapeandsizeofsampleswereperformedonScanningElectronMicroscopy(SEM).SEMphotographsinvestigatedthattemperatureofhydrothermaleffectsthephaseofsamplesandalkalinityofthereactionmixturebyΔTad-Tcurvemeasurementdeviceatlowmagicfielded(1.4T).
Atlowmagicfielded(1.4T)thewidthofpeakofmagocaloriceffectcurveofLa1-xCaxMnO3isverylargeandthecurietemperature(Tc)canchangeinlargerangeoftemperatureaccordingtocalciumcontent.Furthermore,theperovskitemanganeseoxidesheadvantagessuchasthetunableTc,chemicalstability,highmagicsoftness,properporosity,andlowproductioncosts.
Keywords:hydrothermal-precipitationmethodperovskitenanostructure
magocaloriceffect
论文题目:FeCuNbSiB纳米晶软磁合金磁性能研究
InvestigationontheMagicPropertiesofNanocrystalline
FeCuNbSiBSoftMagicAlloy
研究生姓名:张继超
导师姓名:麻永林教授
专业:材料加工工程
摘 要:
本文主要研究了FeCuNbSiB系纳米晶软磁合金在不同出炉温度下的温度特性,频率特性以及磁冲击稳定性问题.在实验过程中,采用在非真空状态下喷制的Fe73.5Cu1Nb3Si13.5B9非晶态合金及不同出炉温度的热处理工艺制备试样.利用示差扫描热分析(DSC)实验确定该合金的晶化温度以及晶化激活能Ec,利用V-A法确定试样的磁导率,利用恒温干燥箱数字交流电压表和精密交流恒流源对合金的温度特性进行了研究电感测量仪不同温度出炉合金的频率特性,进行了磁冲击稳定性测试560℃×1h炉冷至376℃直接出炉快冷高的铁芯容易得高的性能,容易提前达到饱和,并具有一定的不稳定性.frequencydependenceandstabilityundermagicfieldimpactoftheFeCuNbSiBnanocrystallinesoftmagicalloysatdifferentendingtemperaturewerestudiedinthepresentthesis.Intheexperimentalprocess,thesamplesweremeltedinvacuumfurnaceandsolidifieddirectionallyinantivacuumandheat-treatedinvacuum.ThecrystallinetemperatureandactivationenergyEcweredeterminedbythedifferentialscanningcalorimeter.Thepermeabilityofsamplesweremeasuredbyvoltammetry.ThecharacteristicoftemperaturewasstudiedbytheconstanttemperaturedryingboxandtheACnumericvoltmeterandtheACpreciseammeter.Thefrequencydependenceofsamplesatthedifferenttemperaturewasgainedbytheinductancemeter.Thestabilityundermagicfieldimpactwastestedbytheself-madeequipment.ThecrystalstructuresofthealloyswhichhelongoddsinmagicpropertiesandthestabilityunderthemagicfieldimpactatroomtemperaturewereidentifiedbyX-raydiffractionmeasurements.
Theresultsshowthatthepropertiesofthesamplewhichgainedin560℃for1hourandcoolingto370℃,thencooledquicklyareexcellent.Thecoresofhighinitialpermeabilityeasilygetgoodpropertiesinallmagicintensity,butthesecorescanachievethestateofbeingsaturatedaheadofschedulewiththeincreasinggraduallyofintensityandoccursomeinstability.Theareasbeforethesaturationwereextendedbycontrollingtheendingtemperatureduringheat-treated.Sothedeclingtrendbeesslowerthanbefore.Thecoreswilladapttouseinmorewideworkscope.Thelowerendingtemperaturemadethechangeofstructureslowandeasilygainthefinecrystalgrainsandexcellentmagicproperties.Thelowerendingtemperatureandlongertimeofheatpreservationbenefitthestability.Alsothestabilityunderthemagicfieldimpactwasrelativetoremanenceandothermagicpropertiesafterimpact.
Keywords:nanocrystallinesoftmagicmaterial,thecharacteristicoftemperature,
thecharacteristicoffrequency,thestabilityundermagicfieldimpact,Remanence
论文题目:钕电解阳极气泡和熔体流场的研究
StudyonAnodicBubblesandMeltFlowFieldinNeodymium
Electrolysis
研究生姓名:曹锋
导师姓名:刘中兴教授
协助导师:赵团副教授
专业:材料加工工程
摘 要:
从200多年前稀土的发现到今天,稀土及其合金正得到广泛的应用,使人们对稀土重要性的认识提到了空前的高度.特别是近些年来,开发的新材料几乎都离不开稀土金属.所以迫切的要求提高稀土及其合金的产量和品质.这也就急切要求我们改进稀土及其合金生产的设备和工艺等.而任何重大的改进和革新是离不开理论的指导的.本文即是通过数值模拟的方法,对3KA钕电解槽的气泡分布和熔体流场进行了研究,以期对该型及类似电解槽的结构和工艺改进提出理论性指导,以便探索出更好的槽型和生产工艺.文中具体所做的工作如下:
1.简要评述了稀土熔盐电解的发展现状和趋势.简单分析了气液两相流研究的发展状况.
2.回顾和评价了一些数学模型,较详细地介绍了湍流模式的一些方案.比较各类模型,结合实际情况,选用模型作为本文模型.
3.采用Boussinesq近似和边界层流检测设来改进双方程模型,建立了描述钕电解过程中熔体流动及气泡浓度的二维数学模型,确立了合理的边界条件,成功地解决了熔体流动及气泡在熔体中分布的定量描述问题.
4.利用有限差分法对所建立的数学模型的控制方程实行离散化,完成了由微分方程向代数方程转化的工作,在此基础上,结合半隐式SIMPLE计算方法,设计了计算区域和计算网格,完成了二维程序计算框图.
5.编制了浓度子程,并通过对已有程序的修正,使得浓度子程和速度等子程耦合在一起,得到了计算精度更高,收敛性更好的程序.
6.评估了气泡的平均粒径,计算了气泡的上浮速度,推算了气泡占熔体总的体积份数.
7.利用程序,模拟计算了3kA钕电解槽不同电极插入深度,不同阳极内径以及阳极侧壁开孔时电解槽中气泡浓度分布和熔体流场.
8.根据计算结果,结合已有研究成果,并参照现场操作数据,通过比较和深入分析,总结出了气泡浓度,熔体流动等因素对电解过程的作用规律,为钕电解的设备和工艺流程等设计,提供了必要的依据.
关 键 词:稀土,钕电解,电解槽,阳极气泡,浓度分布,熔体流场,数值模拟
ABSTRACT
Beforeabout200years,rareearthisdiscovered.TodayREandtheiralloyarebeinguseduniversally.ThepeoplemoreandmorerealizeitissoimportantforRE.Especiallyrecentyears,thenewmaterialwhichisexploitedallalmostcontainRE.Theincreasingdemandandstrictlyqualitycontrolofrareearthproducteffectivelydrivethecampaignofdevelopmentofrareearthproductiontechnologiesandfacilities.Butthetheoreticaldirectionisindispensableineverygreatimprovementandreformation.Thedistributionofgasbubblesandthemeltflowfieldalreadyarestudiedbythenumericalsimulationmethodin3KAneodymiumelectrolysiscell.Theseresultswillprovidethetheoreticalfoundation(basis)forthedesignofstructureandtechnologyoftheelectrolysiscellandthesimilarelectrolysiscellsothatanovelelectrolysiscellandthemuchbetterproductiontechnologiesarerevealed.Thearticlehaainly(concretely)acplishedthefollowingworks:
1.Thedevelopmentactualitiesandtendencyofrareearthelectrolysisaresimplymented.Thedevelopmentsituationofgas-liquidtwo-phaseflow'sresearchissimplyremarked.
2.Thevariouathematicalmodelsarereviewedandappraised.Thedifferentprojectsofturbulencemodelareintroducedrelativelydetailedly.Comparingmultifariouodelsandbiningpracticalinstance,wechoosemodelasthepaper'odel.
3.Thetwodimensionalmathematicalmodelwhichdescribeeltflowandgasbubblethicknessincourseofneodymiumelectrolysishasbeenestablishedbyapplyingtwi-equationodelwhichientbyadoptingBoussinesqapproximationandboundarylaminarflowhypothesis.Thenwedefinetheboundaryconditionsandsuccesullyresolvethequantitativedepictingproblemofmeltflowandgasbubblesdistributioninmeltingbath.
4.Thecontrollingequationsaredispersedbyfinitedifferentialmethod.Wehetranerreddifferentialequationstoalgebraicequations.Onthebasisofthefront,wedesigncalculationalareaandgriddingandpletetwodimensionalprogramflowchartwithSIMPLEmethod.
5.Wepilethesubroutineofthicknessandmakeit,thesubroutineofvelocityandsooncouplebymodifyinginbeingprogram.Weultimatelygaintheprogramwithhighercalculationalprecisionandbetterastringency.
6.Weevaluatetheeragediameterofgasbubbles,calculatetheascendinelocityofgasbubblesandreckonthevolumepercentageofgasbubblesinmeltingbath(meltingpartment,meltingcharge).
7.Throughtheprogram,thethicknessdistributionofgasbubblesandmeltflowfieldwithdifferentthedepthofthepolesinserted,thedistancebetweenthepolesandopeningholesonpositivepolehebeensimulatedandcalculatedin3KAneodymiumelectrolysiscell.
8.Intermsofcalculatingresults,withexistingresearchfulfruitsandonspotoperationaldatabasis,weconcludethelawwhichtheelectrolysiscourseisaffectedbythethicknessofgasbubblesandmeltflowthroughparingandthoroughlyanalyzing.Theseworkswillofferthenecessarybase(basis)forthedesignofneodymiumelectrolysiacilityandtechnologyflow.
Keywords:rareearth,neodymiumelectrolysis,electrolysiscell,anodicbubbles,thicknessdistribution,meltflowfield,numericalsimulation
论文题目:稀土对BNbRE钢组织及性能的影响
TheEffectofREonMicrostructureofBNbRESteel
研究生姓名:杨丽颖
导师姓名:李春龙总工
专业:材料加工工程
摘 要:
本文就稀土残留在钢轨钢中对其组织的影响展开了系统的研究.测定稀土对相变点的影响.研究了稀土对珠光体组织,奥氏体晶粒尺寸的影响,对热轧态及淬火态析出物碳化铌的大小,形状,分布的影响,对硫化物的形态的影响,在热轧态中对位错塞积以及位错与碳化铌交互作用的影响,对珠光体片间距,渗碳体形态的影响,以及稀土对热轧态带状组织的影响.
研究结果表明:对相变点测定发现随着稀土残留量增加,奥氏体向珠光体转变点Ar1Ar3降低,马氏体转变Ms点升高.对微观组织的研究主要比较了稀土残留量为0%和稀土残留量为0.0271%两种化学成分的试验钢的微观组织,由光学显微照片发现稀土细化奥氏体晶粒,用截线法测量其晶粒平均直径由34.48(m减小到26.32(m.扫描电镜背散射像发现稀土使热轧态析出物碳化铌尺寸减小,长由2.8~6.7(m减小到1.0(m~4.5(m,宽由1.1~1.7(m减小到0.3(m~0.8(m.形状由矩形或长条形转变为圆形.由分布在晶界或晶界附近变为分布在晶内或晶界上,带状分布形式减弱,部分碳化铌弥散分布在基体上.透射电镜观察发现稀土残留量为0%及稀土残留量为0.0021%碳化铌析出在铁素体与渗碳体交界处,稀土残留量为0.0271%碳化铌析出在两片渗碳体间的铁素体中部.稀土也使淬火态碳化铌尺寸减小,长由4.8~6.0(m减小到1.6~2.0(m,宽由0.4~0.9(m减小到0.5~0.6(m.稀土残留量为0.0271%时,碳化铌和稀土硫化物都沿轧制方向分布.在稀土硫化物附近析出的碳化铌为不规则形状,而在其它部位析出的碳化铌为规则的圆形,矩形或长条形.稀土改变了硫化物形状,由长条形变为圆形或椭圆形.稀土残留量为0%的试验钢中,透射电镜像发现在碳化铌的周围存在位错圈.珠光体片间距由0.25(m减小到0.20(m,渗碳体的形态发生了改变.
关 键 词:BNbRE钢微观组织交互作用相变点
ABSTRACT
ThepapersystemicallystudytheeffectofREonmicrostructureofrailsteel.ThecontentincludetheeffectofREonAgrainsize,theeffectofREonNbCofsize,shape,distribution.REonsufferpoundshape.TheeffectofREondislocationsblock.TheeffectofREondistanceofPbetweentwoPslicetheeffectofREonFe3CthicknessandtheeffectofREonheatrollbeltshapemicrostructure.
DeterminephrasetranormspotfindthatwithREremainquantityincreasingAr1Ar3spotthatAchangeintoPdecrease,MsspotthatMchangeincrease.
ThepapermainlyparetwoREremainquantityexperimentsteelofmicrostructure.TheyareREremainingquantity0%andREremainquantity0.0271%.Accordingtoopticmicroscopepicture,withREremainsquantityincreasingREmakeAgrainsizetiny.Agrainequallydiameterdecreaserom34.48(mto26.32(m.AccordingtoscanelectronicmicroscopepictureofBack-scatteredelectronicmicrostructuredifferentREremainquantityinheatrollstateandquenchstatemakeNbCshape,size,distributionchange.TheexperimentresultindicatethatheatrollstateNbCsizedecreaselengthfrom2.8~6.7(mto1.0~4.5(m,widefrom1.1~1.7(mto0.3~0.8(m.itsshapefromrectangletostriporcircular.Itsdistributionalsochangeromonthegrainedgetograininnerandfromstripdistributiontodispersedistribution.ThelengthNbCafterquenchingdecreasefrom4.8~6.0(mto1.6~2.0(m.widedecreasefrom0.4~0.9(mto0.5~0.6(m.NbCandSpoundalternatewithalongrolldirectiondistribution.NearSpoundNbCshapebeeirregularbutatotherpositionNbCiscircularrectangleorstrip.REchangeSpoundshape,itsshapefromstriptocircularorellipse.Pdistancebetweentwoslicedecreaserom0.25(mto0.20(m.Atthesametime,Fe3Cthicknessincreasefrom0.05(mto0.11(m.
Keywords:BNbREsteelmicrostructureinteractioneffectphrasechangespot
论文题目:金属锰在含碳耐火材料中的作用机理研究
StudyontheInfluencesofManganeseontheStructureand
PropertiesofCarbonRefratories
研究生姓名:杜艳华
导师姓名:赵文广副教授
协助导师:侯谨防高工
专业:材料加工工程
摘 要:
本文研究了金属Mn对碳材料中碳网络化结构形成的影响及其对含碳耐火材料性能的影响.
以天然鳞片状石墨和Mn粉为原料,以酚醛树脂为结合剂制成Mn-C试样.对干燥后试样进行差热分析后于930~1600℃烧成,然后采用XRD和SEM等分析手段对烧成后试样进行物相组成和显微结构分析.XRD分析表明,Mn-C试样在烧成过程中会形成一系列锰碳化合物,这些化合物是不稳定的过渡相化合物,随温度的升高逐渐发生分解析出单质锰和碳.SEM分析表明,当试样中Mn和C的质量比为1:4,烧结温度为1400℃时,Mn对碳形成网络化结构影响显着.
以烧结板状刚玉,锆莫来石,天然鳞片状石墨为原料,以酚醛树脂为结合剂,Mn,Al,Si,B4C粉为添加剂,经1450℃烧成后制成铝碳和铝锆碳试样.对其抗渣侵蚀性能和抗氧化性能进行了研究,结果表明:在铝锆碳试样中,当Mn与Al,Si复合加入且Mn与C的质量比为1:4时,试样抗渣侵蚀性能和抗氧化性能较好,当Mn与Si复合加入且Mn与C的质量比为3:7时,试样抗氧化性能较好.在铝碳试样中,当Mn与Al,Si,B4C复合加入且Mn与C的质量比为1:4时,试样抗渣渗透性能较好.
关 键 词:含碳耐火材料,锰,抗氧化性,抗渣侵蚀性
ABSTRACT
TheeffectofMnontheformationofthecarbonworkstructureincarbonmaterialsandonthepropertiesofcarbonrefractorieshebeeninvestigated.
TheMn-Cspecimenswerefabricatedusingnaturalflakygraphiteandmanganesepowderasstartingmaterials,phenolicresinascement.Thespecimensweresinteredat930℃through1600℃.ThethermaldynamicbehiorwasanalyzedbyusingaDTA/TGthermalanalyzer.ThephaseandmicrostructureofthespecimenswerestudiedbyusingXRDandSEMrespectively.XRDanalysisshowsthataseriesofMncarbidehebeenformedduringsintering.SomeMncarbidedeposewhenthetemperatureincreases.TheSEMobservationshowsthattheobviousinfluencesofMnontheformationofcarbonworkstructureoccurredatthemassratioofmanganesetocarbonof1:4,andatthesinteringtemperatureof1400℃.
Al2O3-CandAl2O3-ZrO2-Cspecimenswerepreparedusingsinteredtabularcorundum,zirconia-mulliteandnaturalflakygraphiteasrawmaterials,Mn,Al,Si,B4Cadditivesandphenolicresinascement.Thespecimensweresinteredat1450℃.SlayresistanceandoxidationresistanceoftheAl2O3-CandAl2O3-ZrO2-Cspecimenswerestudied.TheexperimentresultsindicatethatslayresistanceandoxidationresistanceofAl2O3-ZrO2-CspecimenisexcellentwhenMn,Al,Siareadded,andthemassratioofmanganesetocarbonis1:4.AsatiactoryoxidationresistanceofAl2O3-ZrO2-CspecimenisobtainedwhenMnisaddedwithSiandthemassratioofmanganesetocarbonis3:7.PerabilityresistanceofAl2O3-CisimprovedwhenMnisaddedwithAl,Si,B4C,andthemassratioofmanganesetocarbonis1:4.
Keywords:CarbonrefratoryManganeseOxidationresistanceSlayresistance
论文题目:含铜高纯净钢的固溶与时效
SolutionandAgingProcessinCu-containingHighPuritySteels
研究生姓名:王海燕
导师姓名:刘宗昌教授
专业:材料加工工程
摘 要:
随着现代工业的发展,世界发达国家逐渐着眼于开发高性能的新一代钢铁材料.冶金技术的发展为以高纯净和高均匀性为特征的新一代钢铁材料的开发提供了可能,铜是一个能够不依赖碳,氮强化钢材的合金元素,因此在高纯净钢的发展中得到广泛重视.含铜高强低合金钢具有高强度,高韧性,良好的可焊性,耐蚀性等多种优良性能,它是目前建设桥梁,船舶,汽车,化工石油设备及高压容器等用的主要钢材.
铜在钢中的析出是引起钢材强化的原因,因此,认识铜在钢中的析出规律是分析铜时效强化的重要依据.通过对含铜钢析出过程诸多因素的深入研究,可以进一步认识含铜高纯净钢的基本强化行为,为新一代铜合金化钢材的开发与应用提供理论支持.
本文采用实验室箱炉完成固溶与时效工艺,利用透射电镜观察了固溶与时效各阶段基体和析出相形貌,尺寸,结构,体积分数等信息,并通过硬度测试把析出颗粒特征与其材料机械特性定量联系起来.在此基础上,就固溶态基体特性对析出强化行为的影响作了有益的探索.
研究结果表明,含铜高纯净钢固溶处理后,铜以一种不均匀的短程有序畴形式存在于基体中,它对随后的时效过程起重要作用,析出贯序可能为:过饱和α-Fe→Cu原子富集的有序畴→bcc结构Cu偏聚区→过渡相→ε-Cu稳定相,本实验析出强化过程中未曾观察到有ε-Cu纯铜析出相出现,所以,ε-Cu纯铜并非主要强化相,强化效应是有序畴+bcc结构Cu偏聚区共同作用的结果.
关 键 词:铜,高纯净钢,固溶,时效
ABSTRACT
Withthedevelopmentofmodernindustry,theinvestigationofthenewtypestructuralsteelsispaidmoreandmoreattention.Metallurgicaltechnologyprovidespossibilityforthenewtypesteels,whichcharacterwithhighpurityandhighuniformity.CuisakindofalloyelementwhichcanincreasethestrengthofsteelindependoftheCandN,soitreceivemoreattentioninthedevelopmentofhighpuritysteels.HighstrenghthlowalloysteelcontainingCuhemanyexcellentperformance,i.ehighstrength,hightoughness,wellweldablity,corroderesistance,ithasbeenappliedtoconstructionofbridge,shipping,automobileandhighpressurevesselwidly.
InordertomasterprecipitatingstrengtheningbehiorofCuinsteel,wemustinvestigatetheprecipitationbehior.Bymeansofstudyofnumerousplicationinprecipitatingcourse,wecanacquaintessentialstrengtheningrulesandprovidetheorybasiorexplorationandapplicationofnewtypestructuralsteels.
ThemicrostructureofhighpurityFe-1.15%Custeelindifferentsolutiontemperaturehasbeeninvestigatedbymeansoftranissionelectronmicroscopy(TEM),ItshardnesshebeencharacterizedbyVikericrohardneseasurementsInaddition,theeffectofmatrixperform-
anceonprecipitaionbehiorwasanalyzedbasedonexperiments.
Theresultsshowedthatcopperisnotdistributedequallyinmatrixaftersolutiontreat-
ment,butexistsasakindofunevenshortdistanceorderingdomain,whichmicrostructureeffectsonthefollowingagingbehiorgreatly.Thetranormationsequencewithagingmaybeα-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.TheevolutionbehioroftheCe(OH)4driedpowdersintheheatingprocesswascharacterizedbyDTA/TGandXRD.TheresultsindicatethatCe(OH)4deposetoCeO2atatemperaturearound200℃andformscubicfluoritestructureceriabelow650℃.Thephase,particleshapes,particlesizeandspecificsurfaceareaofthedopedceriapowderswerecharacterizedbyXRD,TEMandBET.Theresultsshowthatdopedceriapowderscalcinedat650℃heacubicfluoritestructure,aneragesizeof14to30nm,andahighdispersionbehiours.
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,theactionmechanisinsteelofthemandtheadditionmethodsofaddingintosteelofthemhebeensummarizedindetail.
TheeffectofpoundtreatmentwithRE-CaoninclusionsinsteelwasstudiedbyuseofmetallographicalexaminationandSEM.Ithasbeenshownthatthepoundtreatmentcannotonlyresultinaconsiderabledegreeofdesulfurationandcleanlinessofsteel,butalsobringuniqueinclusionmordifyingeffectofREintofullplay:HarmfuleffectsofinclusionstotheperformanceofsteelcanbeeliminatedbyRareEarthadditionsthroughformationofdispersivelydistributed,undeformableandstableRareEarthsulphideandoxysulfideinplaceofelongatedMnS.
Ithasbeenshownthateffectsoninclusionmorphologyaremostsatiactorywhenadding0.04percentREintosteel,andwhentheratioofRE/Sinsteelis1.4.ButwhentheREamountaddedintosteelreached0.06percent,itbecamenotveryeffectiveonthecontrollingofinclusionmorphology.
Ithasbeenmadeclearerinthispaperthat,althoughCaandREheverysimilareffectsondeoxidation,desulfurization,butREioreeffectivethanCainsulfideshapecontrol.IthasbeenshownthatthebinationofdesulfurizationbyCatreatmentandfollowedbyaddingallamountofREisoneofeffectivewaystocontrolinclusionsinsteelpletelyandtoimprovecleanlinessofsteel.SotherewillbeagoodfuturetouseRE-Capoundtreatmenttodevelopcleansteel.
Keywords:RareEarth,Calsium,CleanSteel,InclusionModifacation
控制理论与控制工程
论文题目:倒立摆系统的非线性控制研究
TheNon-linearControlandResearchaboutPendulumSystem
研究生姓名:洪晓英
导师姓名:崔桂梅副教授
专业:控制理论与控制工程
摘 要:
倒立摆系统的控制研究长期以来被认为是控制理论及其应用领域里引起人们极大兴趣的问题.它是检验各种新的控制理论和方法的有效实验装置,作为一个高阶,非线性,不稳定系统,倒立摆的稳定,随动控制相当困难,在控制领域中是一个极具挑战性的难题.
本文首先阐述了倒立摆系统控制研究的发展过程和控制现状,介绍了倒立摆系统的结构和数学模型,并详细推导验证了四级倒立摆的数学模型,为更高层次的控制规律的研究打下了良好的基础.其次,本文主要研究了倒立摆系统的各种控制方法,包括现写作技巧论控制方法(极点配置法,线性二次型最优控制),滑模变结构控制方法,两种智能控制方法.以MATLAB语言及其SIMULINK工具为基础,做了大量的仿真研究工作,比较了各种控制方法的控制效果,并提出了状态变量合成和模糊聚类两种新的控制方案,以降低多变量系统的维数,达到有效控制.同时给出了一种模糊动态模型和一种复杂对象模糊动态模型的辨识方法.该辨识方法提出了一种模糊聚类算法,解决了模型辨识中确定隶属函数的问题,采用一种新的模糊系统解决了模糊规则数随输入维数成指数增长的问题.并以倒立摆系统的运行结果为例表明了该方法的正确性.最后,针对网络控制系统中出现的时滞问题,利用模糊聚类的方法来设计了模糊神经网络控制器,并以一级倒立摆的线性化模型为例进行了仿真研究,取得了良好的控制效果.
整个论文的完成,以一定的理论为基础,既具有数学模型的推导,方法理论的探讨,又有各种方法的设计仿真过程,而且研究对象相当典型,因此具有重大的理论和实际意义.
关 键 词:倒立摆,现代控制,变结构控制,智能控制,时滞系统
ABSTRACT
Thecontrolofinvertedpendulumsystemhaslongconsideredanintriguingproblemforcontroltheoryanditsapplications.Itiswellknownastestbedfornewcontroltheoryandtechniques.Asahighlynonlinearandunstablesystem,thestabilizationcontrolofinvertedpendulumsystemisaprimarychallengeforresearchersinthiieldbecauseofthedifficultyoftheproblem.
Afterconciselyintroducingthedevelopmentandcurrentsituationofinvertedpendulumsystemresearch,themechaniandmathematicalmodelofinvertedpendulumarepresented.Mathematicalmodelofthehigherfourlevelinvertedpendulumisparticularlyeducedinthispaper.
Secondly,thethesisdiscusseainlythecontrolmethodsofinvertedpendulumsystembasedonmoderncontroltheoriesandintelligentcontroltheories.ManysimulationresearchesonthecontrolofinvertedpendulumhebeendoneusingMATLABandSIMULINK.Throughparingallkindsofcontrolmethods,bringingforwardtwonewcontrolprojectswhatarestatevarietiessynthesisandfuzzyclusteringtoreducethedimensionofmulti-variablesystem.Anditreachestheeffectiveeffect.
Atthesametime,bringingforwardafuzzydynamicmodelandadistinguishmethodabouttheplicatedfuzzydynamicmodel.Thiethodusesanewfuzzysystemsolvingtheproblemofthefuzzyrules'increasealongwithinputdimension.
Finally,aimatthedelayproblemappearsincontrolsystem,usingfuzzyclusteringmethodtodesignfuzzyworkcontrollertocontrolthesingleinvertedpendulumandetothetop.
Theresearchofthisthesisbasedondefinitetheory,includingthereasoningofmathematicalmodel,discussionofmethodologyandthesimulation.What'ore,theresearchobjectisrathertypical.Sothisresearchhasanimportantacademicandpracticalsignificance.
Keywords:pendulum,moderncontrol,varystructurecontrol,intelligentcontrol,
Thedelaysystem
论文题目:基于Inter的网络题库与考试系统的开发和研究
TheDesignandStudyofItemBankandTestSystemBasedonInter
研究生姓名:刘树淑
导师姓名:靳荣副教授
专业:控制理论与控制工程
摘 要:
以网络教学为代表的现代远程教育的兴起,为传统教学模式提供了新的选择,网络教学突破了传统教学中时间,空间的限制,对于提高学生的自学能力,创造精神和学习效率都有裨益.作