简介:Inthepresentwork,anovelhybridcompositecomposedofTi-aluminidemulti-layeredpartandcontin-uous-SiCf-reinforcedTi-matrixpartusingavacuumhotpressing/hotisostaticpressure(VHP/HIP)sinteringprocesswassynthesized.Then,thedamagetolerancebehaviorofthishybridcompositewasstudiedbytensiletestsandinsituscanningelectronmicroscopy(SEM)three-pointbendingtests.Theresultsindicatethatthemechanicalpropertiesandcrackpropagationofthehybridcompositearestronglyinfluencedbytheextrinsictoughnessmecha-nism.Indetail,thecrackdeflectionofmulti-layeredcompositeandstrengtheningeffectofSiCf-reinforcedmatrixcompositeareobservedinthehybridcomposite.Owingtothestrengtheningeffectofcontinuous-SiCrre-inforcedTi-matrixpart,thetensilestrengthofhybridcompositeismuchhigherthanthatofneatTi-aluminidemulti-layeredcomposite.Furthermore,itisfoundthattheoptimaldamagetoleranceabilityisoptimizedwhenthenotchpositionislocatedattheTi-aluminidemulti-layeredpartduetothecrackdeflectionofmulti-layeredstructure.
简介:TheeffectofAl-3Ti-0.2C-5Sr(wt%)grainrefinerontherefiningperformanceandmodificationofA356alloywasinvestigatedusingopticalmicroscope(OM).ThemorphologyandcrystalstructureofternaryAl-Ti-SrphasesinAl-3Ti-0.2C-5Srrefinerwereanalyzedbyscanningelectronmicroscopy(SEM)andtransmissionelectronmicroscopy(TEM).TheresultsshowthattheternaryAl-TiSrphasesinAl-3Ti-0.2C-5SrrefinercanpromotethegrainrefiningefficiencyofA356alloy.TheternaryAl-Ti-Srphasesco-existintwomorphologies,i.e.,blocky-likephaseandsurround-likephase,besides,whichbothhavethesamechemicalcompositionofAl_(34)Ti_3Sr.ThecrystalstructureofAl_(34)Ti_3Srisface-centeredcubic,andthelatticeparameterisdeterminedtobeabout1.52nm.
简介:Extractionoftitanium(Ⅳ)fromrealchlorideleachliquorofilmenitewascarriedoutwith0.1molL~(-1)di-(2-ethylhexyl)phosphoricacid(HDEHP)inkerosene.EquilibriumandkineticsstudiesforTi(Ⅳ)werecarriedoutinthepresenceofimpuritiesthatwereleachedwithTi(Ⅳ).ParametersaffectingextractionrateofTi(Ⅳ)fromchloridemediainthepresenceofFe(Ⅲ),Mg(Ⅱ),andAl(Ⅲ)werestudiedtoevaluatethestoichiometryofextractedTi(Ⅳ)species.ItisfoundthattheextractionrateofTi(Ⅳ)isdependentontheextractantconcentrationandpHofsolution.Undertheoptimumconditions,morethan95%Ti(Ⅳ)canbeextracted.Onthebasisofslopeanalysismethod,theextractedspeciesofTi(Ⅳ)appearstobe[TiO(H_2A_2)_2]_(org),whereH_2A_2referstoHDEHP.Further,thekineticstudiesoftheextractionprocessofTi(Ⅳ)andothermetalionimpuritieswerecarriedoutbyaLewiscellwithaconstantinterfacialareaof16.7cm~2.AnalysisoftheexperimentalresultssuggeststhatTiO~(2+)extractionratebyHDEHPisthefirstwithrespecttohydrogenionconcentrationandHDEHPconcentration.Theresultsareinterpretedbyareactionmechanismwheretheextractionprocessiscontrolledbyadiffusionprocessattheinterfaceratherthaninthebulkphase.
简介:摘要目的将超声引导下甲状腺TI-RADS分类与病理结果对比,以此确定超声引导下甲状腺TI-RADS分类、诊断的准确性。方法将96例甲状腺结节患者284个结节进行分类结果同病理结果做对比对照,评价TI-RADS鉴别甲状腺良恶性准确率。结果284个甲状腺结节TI.RADS,2类36个,3类79个,4a类78个,4b类67个,5类24个。2类与病理诊断符合率为100.0%,3类病理诊断符合率94.2%,4a类病理诊断符合率92.6%,4b类病理诊断符合率67.2%,5类病理诊断符合率70.8%。结论超声甲状腺TI-RADS分类与病理虽然具有一定的误差现象,但仍然可以为该病诊治提供有立的依据,具有较高的临床价值。
简介:PhotocatalyticH2productionhasemergedasoneofthemostcleanandpromisingrenewableenergysources.InspiteoftheeffortstoobtainefficientphotocatalystsabletoproduceH2fromSunlightandwater,thereisstilltheneedtopreparecheaperandenvironmentalfriendlierphotocatalysts.Phosphatebasedmaterialscouldbegoodcandidatestofulfilltheserequirements.InthismanuscriptwehavepreparedasetofmixedTi3+/Ti4+valence,open-frameworktitaniumphosphates(of-TiPO4)andmixedtitaniumoxide/phosphatederivatives(cr-TiP),correlatingtheirstructureandcompositionwiththephotocatalyticactivityforH2production.Wedeterminedthatmixedtitaniumoxide/phosphatecrystallinephasesproducedenhancedH2evolutionunderSunsimulatedlightirradiationthanmixedTi3+/Ti4+valence,open-frameworktitaniumphosphatesandtitaniumoxidephases.
简介:Nb-24Ti-18Si-2Al-2Hf-4CrandNb-24Ti-18Si-2Al-2Hf-8Cralloyswerepreparedbyarcmeltinginawater-cooledcrucibleunderargonatmosphere.Microstructuralcharacteristicsandoxidationresistanceofthealloysat1250℃wereinvestigated.Theresultsshowthat,whentheCrcontentis4at%,themicrostructuresconsistof(Nb,Ti)_(ss)andNb_5Si_3;asCrcontentincreasesto8at%,C14LavesphaseCr_2Nbisformed.Theisothermaloxidationtestsshowthattheoxidationkineticsofthetwoalloysfollowsimilarfeatures.Theweightgainsofthetwoalloysafteroxidationat1250℃for100hare235.61and198.50mg·cm~(-2),respectively.Duringoxidation,SiO_2,TiO_2,Nb_2O_5andCrNbO_4areformedatfirst.Then,Ti_2Nb_(10)O_(29)isformedafteroxidationfor20minandbeginstochangeintoTiNb_2O_7astheoxidationproceeds.SiO_2isformedassolidstateatfirstbutlaterevolvesintoglassystatetoimprovethecohesionofthescale.Afteroxidationfor100h,oxidationproductsconsistofSiO_2,TiNb_2O_7,Nb_2O_5andCrNbO_4.
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简介:纵的张力的性质原文如此有不同纤维体积部分的f/Ti-6Al-4Vcomposites被蒙特卡罗2-D模仿有限元素模型。纤维力量的随机的分发被二参数的Weibull功能表示。同时,接触元素和出生死亡元素被用来在debonding和纤维破裂以后描述界面的滑动过程(或矩阵裂开)分别地,它被子程序认识到在ANSYS-APDL(ANSYS参量的设计语言)应允了。试验性的结果证明收益应力和最终的张力的强度原文如此有增加的f/Ti-6Al-4Vcomposites增加纤维体积部分,当他们的相应紧张只是时相反。另外,几乎,一样的失败模式被获得在原文如此有各种各样的纤维体积部分的f/Ti-6Al-4Vcomposites什么时候界面砍力量被修理。最后,张力的力量由有限元素预言了分析与由全球分享负担的模型,预言了那相比本地人分享负担的模型和混合物的常规统治,因此画结论那个本地分享负担的模型为最终的张力的力量的预言是很完美的。