简介:AresearchonkineticsofAlevaporationfromliquidU—Alalloyswasmadeinavacuuminductionmelting(VIM)furnaceat1673—1843K.TheevaporationrateofAlwasfoundtobefirstorderwithrespecttoAlcontentinthemelt.TheoverallmasstransfercoefficientofAlwasdeterminedanditwasfoundthattheevaporationrateofAlincreasedwithincreasingtemperatures.TheapparentactivationenergyofAlevaporationat1673-1843Kwas171.5kJmol-1.ThevalueofmasstransfercoefficientofAlintheliquidphasewasestimatedtobe3.77×10-6,7.41×10-6,and9.40×10-6ms-1at1673,1753,and1843K,respectively.Meanwhile,ratedeterminingstepswerediscussedanditwasconcludedthattheevaporationrateofAlismainlycontrolledbyliquidphasemasstransfer.
简介:SiCwhiskerswith'rosarybead'morphologyweresynthesizedusingsuitablesiliconsourceandcarbonsourcethroughsolidreactionatthetemperatureabove1537K.ThediameterandlengthoftheSiCwhiskerswereabout0.1-1.0μmand20-100μm,respectively.Thelargestdiameteroftheirenlargedendsofthewhiskerswasabout0.2-1.0μm,anditgraduallyandsmoothlydecreasedtothesizeoftheplainpartofthewhiskers.TheresultsofX-raydiffractionanalysisshowthatthecrystallinestructureoftheobtainedSiCwhiskersisβ-SiC.ItisconsideredthattheSiCwhiskersgrowviaavapor-solidmechanism.
简介:TheCW-CO2laserdrivengasreactionwasappliedtopreparenano-sizedSiCpowder,SiH4andC2H4ofhighpurties,asstartingmaterials,weremixedtacertainrationandintroducedintotheresactioncell.Thegasesflewacrossthelaserbeamorthogonallyandthuswereheatedbylaserbeam.Thenano-sizedSiCultrafinepowderwswereformedthroughthermicgasreation.Thefinalproductivityofthisprocesswas97%,Theobtainedpowderswerecharacterizedandanalyzed.ChemicalanalysisrevealedthattheSiCcontentwas95.38wt%,Oxygen,theprimaryimpurity,weighted1.32%whiletraceimpurities,suchascalcium,magnesiumandothermetals,wereonly0.03%,XRD,XPSandTEMindicatedthatthpowderparticleswerenearlysphericalandnotagglomerated.Theparticlesizerangedfrom10nmto25nmwithanaverageof15nm,Theparticlestredtobenoncrystalline.
简介:交流UPS的主要功能,是为电力系统中的各种变配电设备、监控用计算机等提供高质量的不间断电源。本文重点介绍了常时逆变器供电方式的UPS电路结构,并将电路中功率模块内的半导体元件全部置换成SiC半导体元件。全SiC功率模块用于SiC-UPS时,电力变换损耗约减小30%,轻载时的运转效率达到90%以上,而且可靠性高。
简介:我们集中于与Ni-Al金属间化合的混合物扔合金由的ligth重量的表面加强在原处改进非铁的扔的表面性质的燃烧反应部件。在我们的以前的工作,元素的Ni和艾尔粉末紧缩的绿色被SHS(自我繁殖的高温度合成)反应到形式Ni3Al金属间化合的化合物有熔融的艾尔合金并且同时的热的反应与艾尔扔结合了合金。但是象微小的裂缝和孔那样的一些缺点在反应协议被仍然是。我们因此使用了压力阻止热裂缝并且与液体艾尔合金充满毛孔由压榨扔过程。压缩艾尔合金与Ni3Al金属间化合的混合物结合了是sectioned并且由光显微镜学和扫描电子显微镜学(SEM)观察了。在结合的接口附近并且在反应协议形成的intermetallics的stoichiometric作文被散光谱学(版本)和电子探查的精力识别微分析(EPMA).Si富人层被艾尔的顺序的团结在结合的接口附近在艾尔合金方面上形成合金。在反应Ni3Al协议观察的孔与液体艾尔合金被充满。从熔融的艾尔合金的Si粒子在反应Ni3Al金属间化合的协议的毛孔被检测。扔合金和Ni3Al金属间化合的化合物的艾尔被把压力用于液体艾尔合金很很熟加入。
简介:ItwasshownbyTEMandX-rayanalysisthatNi3AlisthemainphaseoftheintermetallicsynthesizedundercompressionfromthepowdermixtureofNiwithAlalloyedbyB.TheNi3Bisasecondaryphase.ThevalueofthelatticeparameteroftheintermetallicNi3AlwithandwithoutBincreaseswhentheconcentrationofAlincreases.TheincreaseinAlconcentrationfrom23.5to25.0intheinitialpowdermixtureleadstodecreasingthesolubilityofBintheNi3Alphase.
简介:使用不同成分的Zn-Al钎料对铜铝异种金属进行火焰钎焊,研究其力学性能。利用光学显微镜、扫描电镜和能谱研究不同Zn-Al钎料对Cu/Al钎焊接头钎焊性、力学性能及显微组织的影响。结果表明:随着Al含量的增加,Zn-Al钎料在Cu和Al上的铺展面积逐渐增大。当钎料中Al含量为15%时,Cu/Al接头的抗剪强度达到最大值88MPa;随着组织的变化,钎缝硬度值呈现HV122到HV515不等的分布。另外,钎缝组织的成分主要为富Zn相和富Al相,但是当钎料中Al含量为2%和15%以上时,靠近Cu侧的界面处会分别形成CuZn3和Al2Cu两种完全不同的金属间化合物。研究Zn-Al钎料中铝含量对Cu/Al接头界面化合物类型的影响。
简介:在situcomposites在艾尔矩阵上研究严重塑料变丑的影响规则,10?wt%艾尔3在situ的Zr/2024Al增强粒子合成被准备由直接融化反应(DMR),然后,合成是由有90的一个方向的热伪造?%塑料变丑。然后,前进状态的微观结构合成被观察,并且机械性质的变化法律和磨擦表演在以后并且在塑料使变形前被比较。结果显示艾尔3增强Zr的粒子旋转并且闯入10-20的更小的尺寸?ng可溶的biopolymer有三个转变金属离子的牛的浆液白朊(BSA)(M,M=Cu,公司,Mn)。白朊一定的金属离子的有约束力的模式和比率被调查。BSA-M建筑群被紫外力的、圆形的二色性(CD)描绘系列和polyacrylamide胶化电气泳动(页)。当聚合物支架和金属建筑群作为催化活跃中心工作了,BSA服务了。当到BSA的转变金属离子建筑群的有约束力的比率是5:1时,结果证明BSA的结构仍然保持未改变。而且,清除superoxide阴离子自由的基(O\(_{2}^{\bullet-}\??
简介:HotcompressionbehaviorofTiC–Al2O3/AlcompositeswasstudiedusingtheGleeble-1500systematatemperaturerangeof300–550°Candatstrainraterangeof0.01–10.00s-1.TheassociatedstructuralchangeswerestudiedbyTEMobservations.Theresultsshowthatstressleveldecreaseswithdeformationtemperatureincreasingandstrainratedecreasing,whichcanberepresentedbyaZener–Hollomonparameterinanexponent-typeequationwithhotdeformationactivationenergyQof172.56kJ·mol-1.Dynamicrecoveryoccurseasilywhenstrainratesarelessthan10.00s-1.Dynamicrecrystallizationcanoccuratstrainrateof10.00s-1.
简介:CurrentlytheservicelifeofCDQshaftsinChinaismainlyrestrictedbythepropertiesoftheinclinedfluebricks.Inthiswork,basedonthesystematicanalysisofthedamagemechanismofinclinedfluerefractories,highperformancemullite-SiCbricksweredeveloped.Thebrickswereproducedbycorundum,andalusite,SiCandotherhighpurityrawmaterials.Metalsiliconandaluminaultramicropowderwereaddedtoformdispersionmulti-phasestructure,fortifyingthematrixandimprovingthemicrostructure.Theproductshaveexcellentpropertiessuchaslowporosity,highdensity,goodwearresistance,highrefractorinessunderload,andgoodthermalshockresistance.Theproductscanreplacetheordinarymullite-SiCbricksandobtainagoodservicelife.
简介:Moleculardynamics(MD)simulationswereperformedtoinvestigateF+continuouslybombardingSiCsurfaceswithenergiesof100eVatdifferentincidentanglesat300K.Thesimulatedresultsshowthatthesteady-stateuptakeofFatomsincreaseswithincreasingincidentangle.Withthesteady-stateetchingestablished,aSi-C-Freactivelayerisformed.ItisfoundthattheetchingyieldofSiisgreaterthanthatofC.IntheF-containingreactionlayer,theSiFspeciesisdominantwithincidentangleslessthan30o.Forallincidentangles,theCFspeciesisdominantoverCF2andCF3.
简介:ASiC/2024compositewasmadebysemisolidcasting.ThewettingbetweenSiCandAlmatrixisimprovedbytreatingSiCparticlesatahightemperature,coatingK2ZrF6,andaddingMgtotheAlmelt,AneffectivewaytoremovethegasaroundSiCparticleswasalsofound.Microstructureswereobservedunderopticalmicroscope(OM)andscanningelectronmicroscopy(SEM).TheresultsshowthatSiCparticlesandAlmatrixarewellbondedandnogapsorcavitiesaroundtheparticlesareobserved.SiCparticlesdistributehomogeneouslyintheAlmatrix.TheexistenceofSiCparticlesresultsintheincreaseofwearresistanceandstrength.