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简介:采用元胞自动机模型建立了05Cr17Ni4Cu4Nb不锈钢固溶过程的二维模型,模拟了固溶过程中的晶粒形核生长以及化合物相的扩散溶解,模拟结果动态地再现了固溶过程的微观组织特征。通过该模型分析了固溶温度和固溶时间对固溶处理后微观组织的影响。
简介:通过电化学分析与测试,研究B4C体积分数分别为20%、30%、40%的B4C/Al基复合材料及其基体合金(6061铝合金)在不同浓度及不同温度的硫酸溶液中的腐蚀行为。由动态极化曲线和阻抗谱得到相应的电化学参数,并利用阻抗分析软件对该复合材料和基体合金腐蚀过程的等效电路进行模拟,分析腐蚀机理,通过Arrhenius方程计算腐蚀过程中B4C/Al基复合材料与6061铝合金的反应活化能,并分析两者的焓变与熵变,对腐蚀前后2种材料界面的微观结构进行观察。结果表明:B4C/Al基复合材料在硫酸溶液中的腐蚀速率随B4C颗粒含量增加而增大,基体铝合金在硫酸中的耐腐蚀性能高于B4C/Al基复合材料。B4C/Al基复合材料和基体铝合金在硫酸中的腐蚀速率都随硫酸溶液浓度增加而增大;当溶液温度升高时,二者的腐蚀速率都快速增加。B4C/Al基复合材料和Al基体合金在硫酸溶液中的腐蚀都表现为明显的点蚀。铝基体材料在硫酸溶液中的反应活化能大于B4C/Al基复合材料,计算所得活化焓与活化熵的值均表明复合材料的腐蚀反应比基体合金更容易进行,因而遭受腐蚀更严重。
简介:TheNaYF4:Yb,Ernanocrystalsweresynthesizedviathethermaldecompositionofmetaloleateprecursors.Thenanocrystalsinhexagonalstructurewerehighlyuniformandinsizeof25nm.Thebrightupconversionluminescencewasobservedundertheexcitationof980nmlaserandtheupconversionemissionspectrawereinvestigatedatdifferentpumppowers.Theemissionintensityratioofredlighttogreenlightlinearlyincreasedwithpumppowerincreasing.ThisresultindicatedthatthereexistedalargethresholdpowerofsaturationpumpforthefirstexcitationstateinNaYF4:Yb,Ernanocrystalscomparingtothatinbulkmaterial.
简介:Resinsofcomplexesmadefromagarose-Ce4+(RCA-Ce)andchitosan-Ce4+(RCC-Ce)wereprepared.Hydrolysisratesofmethamidophos,omethoateandchlorpyrifostreatedbyRCA-Cewere32.39%,27.12%and46.62%,respectively,thoseofchlorpyrifosandmethamidophosinmungbeansproutjuice38.28%and35.45%,andthatofchlorpyrifosinteaextract59.76%.HydrolysisratesofproteininteaextracttreatedbyRCA-Ceincreasedby86.46%.RCC-Cecouldbeemployedintheapplejuiceproduction.Thecontentsofmethamidophosandparathion-methylinthejuicetreatedbyRCC-Cedecreased58.76%and71.92%.Furthermore,RCC-Cewasusedtoclarificationforbeerbythewaysofacolumn.RCC-Cecouldhydrolyzesensitiveproteinandincreasecontentsoffreeaminoacidinthebeer.Therefore,thebeertreatedbyRCC-CecouldstayoxidationandagingprocedureduetosomemetalionsbeingabsorbedbyRCC-Ce.
简介:YbAl3(BO3)4crystalofgoodopticalqualitywasgrownbythefluxmethod.ThestructureofYbAl3(BO3)4crystalwasdeterminedbysingle-crystalX-raydiffraction.TheexperimentshowsthatYbAl3(BO3)4belongstothedoubleborateswithatrigonalstructure.ThespacegroupisR32anditsunitcellconstantsweremeasuredtobea=0.92965nm,c=0.72129nm,V=0.53673nm3,Z=3.Thetransmittancespectraweremeasured.Thecut-offofYbAl3(BO3)4crystalis216nm,andtherearetwoabsorptionpeakslocatedat940and975nmfrom190nmto2600nm.ThethermalpropertiesofYbAl3(BO3)4crystalwerestudiedforthefirsttime.Theaveragethermalexpansioncoefficientsweredeterminedtobe2×10-6/℃,9.5×10-6/℃alonga-andc-direction.ThespecificheatofYbAl3(BO3)4crystalwasmeasuredtobe0.6695J·(g·℃)-1atroomtemperature.AllresultsindicatethattheYbAl3(BO3)4crystalisanexcellentstoichioimetriclasermaterial.
简介:Thesynthesisofprecursorofgreenphosphors,LaPO4:Ce,Tb,bymeansofco-precipitationwithcocurrentflowfeedwasstudied.Theeffectsofthereactiontemperature,thekindandconcentrationoftheacidinthebottomwater,andthechargingrateonthephysicalproperties,suchasparticlesize,wereinvestigated.Itisfoundthattheparticlesizeofthepowderiscontrollablebyadjustingacidityinbottomwaterandchargingrate.Thepowderwithdiametersizeof3to5μmwasobtained.ItsXRDandSEMwereanalyzed.XRDpatternsoftheas-preparedgreenphosphorpowdersdisplaythetypicalpeaksofCePO4.SEMshowsthatthemorphologyofpowdersisball-shaped.
简介:YLiF4:Er3+wassynthesizedbyhydrothermalmethod.ConcentrationofEr3+ischangedfrom0to5%.TheabsorptionofEr3+inallsamplesfrom200to1200nmwasmeasuredatroomtemperature.TheJ-OparameterscalculatedfromabsorptionspectrumareΩ2=1.05×10-20cm2,Ω4=1.25×10-20cm2andΩ6=1.35×10-20cm2.Infrared-to-visibleupconversionemissionofYLiF4:Er3+wasobservedwhenexcitedby980nm.TheresultsshowthattheEr3+contentislessthan1.5%,excite-stateabsorptionisthemainmechanismofupconversionemission.WhenEr3+contentislargerthan1.5%,bothoftheexcite-stateabsorptionandenergytransferleadtotheupconversionluminescence.TheupconversionintensitywasenhancedwiththeincreasingofEr3+concentration.Atroomtemperature,thelifetimeof2H11/2and4S3/2is205μswhilethatof4F9/2is188μsforsampleEr-2.Thetransitionratesandquantumefficiencywerealsocalculated.Thequantumefficienciesof4S3/2and4F9/2are27.9%and10.7%,respectively.
简介:二进制铕建筑群EuL3(L=4-tert-butylbenzoate)和第三的铕建筑群EuL3TTA0.1(TTA=2-thenoyltrifluoroacetone),EuL3DBM0.5(DBM=dibenzoylmethane)和EuL3phen0.5(phen=1,10-phenanthroline)被综合。poly(甲基methacrylate)(PMMA)或有composites与铕建筑群做了的丙烯酸的酸(AA)的甲基methacrylate(MMA)的共聚物被基在原处准备聚合。铕建筑群,ligands,N,N-dimethylformamide(DMF)和做的聚合物的光性质上的单体的影响被调查。结果证明二进制、第三的建筑群的荧光刺激乐队根据他们的紫外吸收乐队。所有建筑群和做的聚合物composites展出了Eu3+离子的敏化ligand的红典型排放。聚合物composites的荧光紧张在EuL3/PMMA的顺序增加了