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Technology of Iron Carbide Synthesis

By Samuel Adams,2014-08-05 21:06
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Technology of Iron Carbide Synthesisof,Iron,iron

    Technology of Iron Carbide Synthesis TechnologyofIron

    M.Bahgat

    CentralMetallurgicalResearch

    ManuscriptreceivedJuly5,

    J.Mater.Sci.Techno1.,Vo1.22No.3,2006

    CarbideSynthesis

    andDevelopmentInstitute(CMRDI),P.O.Box87Helwan,Cairo11421,Egypt

    2005,inrevisedformSeptember24,2005]

    423

    Ironcarbidesareverypromisingmetallurgicalproductsandcanbeusedforsteelmakingprocess,wheremtplays

    asanaIternativerawmateria1withsignificanteconomicadvantages.AIsoIthasmanyotherapplications,

    e.

    .catalysts.magnets.sensors.Thepresentreviewinvestigatesthedifferentpropertiesandusesofthe

    ironcarbides.Thecommercialproductionandthedifferentvarietiesfortheironcarbidessynthesis(gaseous

    carburization.mechanochemicaIsynthesis,Iaserpyrolysis,plasmapyrolysis,chemlcaIvapordeposmtmonand

    ionimplantation1werereviewed.AIsotheeffectofdifferentfactorsonthecarburizationprocessIikegas

    composition.rawmaterial,temperature,reactiontime,catalystpresenceandsulturadditionwasIndicated.

    KEYW0RDS:Ironcarbides;Cementite;Carburization;Reduction

    1.Introduction

    Duringthelastyearsmanyscientistsintensively handledthepreparationorthemannfacturingof ironcarbideusingdifferenttechniques,e..carbur

    ization,reductioncarbonization,mechanicalprepara- tion,laserpyrolysis,plasmapyrolysis,chemicalvapor deposition,sono-chemicaldecomposition.Theyused themetalliciron.difrerentironoxides,anddifierent ironcompoundsasastartingmaterial,indicatingthe effectofdifferentparametersonthecarbidizationpro- cess.Ironcarbidesareinterestingmaterialsthatcan beusedassensors,magnets,catalystsandasalterna- tiverawmaterialsforthesteelproduction.Ironcar

    bidehasvaluablefeasibilityforitsapplicationinsteel

    makingprocesseswhereitactsasalternativepureiron sourceswithoutmanyenvironmentalandeconomical drawbacks.Ironcarbidehasmanycharacters.Itis nonpyrophoric,anditsproductioncostsarelower thanthatfordirectreducedironfDRI).Ironcarbide canactasahighqualityscrapandgivesalowerN2 contentinproducedsteel,whichmakestheproduc

    tionofhighaualityflatrolledproductfeasible[11.Be-

    sidesthat[2,itiseasilyiniectedintheelectricarc furnacefEAF)withoutenvironmentalpollutionand electricalenergysavingwhereitcontainscarbonas achemicalenergysource.AfullEAFchargeofiron carbideissaidtosaveabout25%energy.Rapidmelt

    ingbyinjectioncanbeexpectedduetofinenessof thecarbideparticles.Poortrampelementsincar

    bideallowsforrevivingalargeamountoflowgrade scraps.Also,itiseasilytransportedandstoreddueto

oxidationresistivityupto280.Candsonobriquet

    tingrequiredwhichatthesametimemeansusing thefineoresinitspreparationwitheconomicben

    efits.So,ironcarbidefeedstocksoffersthePoten

    tialforthedevelopmentofnewsteelmakingtech

    nologiesforthenextmillennium.Itisperhaps,a metallurgicalproductwhosetimehasfinallyarrived. AccordinglY,allovertheworldhaspaidmuchatten

    tiontothissubject.Theapplicationinthedevelop

    ingcountrieswhichhaveironoresresourcesstarted inresearchworkandsometrailsinironcarbideman

    ufacturingfe.g.Egypt).Bahgatetal-I4Jwerepartic

    ipantsinanEgyptianprojectthatwasdesignedto Ph.D..Email:mbahgat70@yahoo.com

    produceironcarbidefromthewasteironoxide finesthatareUSUallyformedduringhandlingand transportationofironorepelletsfortheMidrex shaftfurnaceatAlexandriaIronandSteelCompany fANSDK).

    Actuallytheironcarbidehasmanyotherimpor- tantrolesinthemicroprocesses.Itwasshownthat ironcarbideinsteadofmetallicironisusedoratleast partiallyinvolvedinthecarbonnanotubesfCNTs) growthfromdifferentironprecursorswhereascarbon ischemicallyboundwithinthecat~ystinarathersta- bilizedform,namelyFe3C51.Theroleofthecarbide

    phaseasanintermediateinthecatalystmediated

    graphitetormationbypromotingthesuccessivesegre- gationofwellorderednewgraphitelayersonitssur

    face.Ironcarbide[6,7Jinanano-sizedstructureoreven

    thecommercialcementitepowderwhichareprepared bythemechano-synthesisprocessescanbeusedas catalystforcarbondioxidehydrogenation.Alsothe ironcarbideascatalystisactiveforthedehydration oftertiaryalcoholsiSJandforproductionofelemental carbonfiberbylaserpyrolysis.Inadditionironcar

    bidecanbeusedinthemagneticrecordingmedium duetoitselectricalconductivityandlow1ighttrans

    missionproperty.Ironcarbide(FesC2)hashighlight

    barrierpropertiesandispurelyblack,soitcanbe usedascolorantforapencillead.Alsoitsapplication intheheatsourceyeslowerignitiontemperature.

    Fromalltheabovethisreviewwaswrittentohigh

    lightonthevariousmethodsappliedfortheprepara- tionormanufacturingoftheironcarbideaimingto clarifythewayformanydevelopments.

    2.Properties

    Cementiteisthenameforironcarbide.Itisthe secondphaseformedwhencarbonexceedsthesolubil

    itylimitanditdefinesthepointwherethesolubilityof carboninironisatitsmaximumasshownintheiron

    ironcarbidephasediagraminFig.1.Thisshowsthe equilibriumdiagramforcombinationsofcarbonina solidsolutionofiron.Thediagramindicatesthatiron andcarboncombinedtoformFe-FCatthe6.67r%C. Thepurposeofcarbonadditiontoironistochange thepropertiesoftheironencarbonisaddedto

    iron,itbecomesamuchstrongermaterial,depending ontheamountofcarbonadded.

424

Temperature

    ,oF 3000 2802 2800 2720 2600 2552 24O0 2200 2066 2000 1800 1670 16OO 1400 1333 1200 1O0O 400 A

    ?6+L E-

    I

    I

    I

    ?

    J.Mater.Sci.Techno1.,Vo1.22No.3,2006

    ,

:'::

    !;?:

    ?Austenitesolidsolution

    :ofcarboningammairon?. -?

    ~

    lo

    

    gn.

    et

    .

    ic

    IJulllt/'~ (1414oF)i2|""CM

    B

    I

    I

    ?

    ?

    I

    T=Austenite a=Ferrite 6=Deitoiron CM=Cementite Austenitein liquid

    L

    Pma

    austenite 2066oF

to

    remperature /oC

    CMbegins tosolidify,, \,/

    L+Fe3C

    1539

    1492

    Austenite Iedeburite and

    cementite ?

    :Fe.

    ?

    7+~e3C

    ,,

    Austenite A123Jtopeadite;,,:burite

    400

    13O

    910

    760

    723

    Fe3C

    6.6

    Hypo-eutectoid

    O.83%1%,o————

Fig?1=Ironironcarbidephasediagram

    10

    4%5%6%65%

    Castiron

    Fig.2Ironcarbideproductionflowsheet

    roduct

    bin

    ??'r,???,,??

    ........

    r.

    e-.......}.?一n.一一

    .

    ..

    H......,.

    一刑,,一.;:

    J.Mater.Sci.Techno1.,Vo1.22No.3,2006 Ironcarbidehaseffectivecatalyticproperties.The hydrogenationofC02catalyzedbymechanosynthe- sizedironcarbideswasstudied.Itwasfoundthat thenanophase[6,7Jcarbidesobtainedbyballmilling elementalironandcarbonpowdersatroomtemper

    aturearemoreactiveandselectiveinthehydrogena- tionofcarbondioxidethanFe/Cmixtures.Alsoa positiveeffectisalsoobservedforabal1..milledcom-- mercialcementitepowder.So,itscatalyticbehav

    iorisattractiveandcompetitivecomparedwiththose ofothercatalyticmaterials.Inconfirmationtothe above,itwasdiscussedthatIsJbothironcarbideand

oxidecatalystsareveryselectivedehydrogenationcat

    alysts.Theironcarbidecatalysthasaselectivitythat resemblesthatofironoxide,butitismoreactive.For example,ironcarbideisabouttwiceasactiveforthe conversionofthesecondaryalcohols.Also,theiron carbideisabout4timesasactivefortheconversion of1-octanolastheironoxide.Thehigheractivityof theironcarbidecatalystimpliesthateitherthesur- faceisnotoxidizedtotheoxideduringtheconversion ofthealcoholortheoxycarbidethatisformedonthe ironcarbidesurfaceismoreactivethantheironoxide surface.

    Themagneticpropert|esoftheironcarbidewere studied.OnthecarburizationofironoxideswithCO gas,ironcarbidewasobserved

    dertheeffectoftemperature,

    thesaturationmagnetization

    117emu/gwithincreasingthe

    at450~600~C[9].

    Un

    itwasdetectedthat

    increasedfrom80to

    reactiontemperature.

    Atthesalnetime,thecoerciveforcedecreasedfrom 170to80Oewithanincreaseinreactiontemperature. Themagneticpropertiesofthinironcarbidefilms formedunderplasma-enhancedche

    micalvapordepo-

    sitionfthinfilms)wereinvestigated[10J.Themagnetic momentsoftheFe7C3andFe3Cfilmsthatprepared

    at300400.Cwerefoundtobealignedperpendicular tothefilmsurface.AfterannealingtheFe7C3film, anincreaseincoercivityandsaturationmagnetiza- tionwasobserved.Incontrast,thecoercivityofthe Fe3Cfilmdecreasedafterannealing.Theeffectofan

    nealingoncoercivityisrelatedtotheparticlesizesin theFe7C3andFe3Cfilms.Further,anapproximate zerocoercivitymeasuredfortheFIe7C3filmat300K isanalogoustothatofsuperparamagneticbehavior offleeparticles.Also,forthemagneticproperties oftheironcarbide.Zhaoeta1.uJpreparedultrafine

    Fe3CandFebylaserinducedpyrolysisofFe(CO)5

    andC2H4.Itwasfoundthatafterpassivation,the Fe3Cparticlesexhibitahighsaturationmagnetiza- tionof132emu/gcomparedtothatoftheFeparticle, 95emu/g.Athinamorphouscarbonlayers,formed onthesurfacesoftheFe3Cparticles,inhibitoxida- tionoftheFe3CandthereforeresuItinhighersatu

    rationmagnetizationachievedbyFe3Cpatticles,rel

    ativetotheFe3Cparticlesonwhichnocarbonlayer Waspresent.AlsothemagneticpropertiesofFedC compoundwerestudied[12j.Itwasobservedthatthe behaviorofthemagneticmoments,hyperfinefieldand isomershiftwithvolumeshowssomesimilaritiesto therelatedcompoundFe4N.

    Thesuperplasticityofironcarbidewasstudied[13.

    Itwasfoundthatfinegrainedironcarbideprepared fromrapidlysolidifiedpowdersexhibitedsuperplastic propertiesoverawiderangeofstrainratesandtem

    peratures.Also,tensileelongationashighas610%

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