METHOD FOR PRODUCING CrTiV HYDROGEN STORAGE ALLOYS.docx

METHOD FOR PRODUCING CrTiV HYDROGEN STORAGE ALLOYS.docx

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METHODFORPRODUCINGCrTiVHYDROGENSTORAGEALLOYS

（1of24）

UnitedStatesPatentApplication

20040134308

KindCode

A1

Takata,Hiroaki; etal.

July15,2004

METHODFORPRODUCINGCr-Ti-VHYDROGENSTORAGEALLOYS

Abstract

Theinventionrelatestoamethodforproducinghigh-performanceCr--Ti--Vhydrogenstoragealloysutilizingthermitprocess,wherebyresidenceofadverselyaffectingimpuritiesisinhibited,additionofnotlessthan10at%ofTiasanalloycomponentisrealized,andthermalburdenonthecrucibleusedinthemethodisreduced.Themethodincludesthestepsof:

（A）providinganalloymaterial

（1）comprisingaCroxide,aVoxide,andareducingagentAl,andanalloymaterial

（2）comprisingTi;（B）placingsaidalloymaterialsinacrucibleforthermitreductionsothatthealloymaterial

（1）isplacedabovethealloymaterial

（2）;（C）ignitingthealloymaterial

（1）placedinstep（B）andmeltingallmetalelementscontainedinthealloymaterialswithheatofthermitreactionofthealloymaterial

（1）;and（D）makinganalloymeltobtainedinstep（C）intoanalloy.

Inventors:

Takata,Hiroaki;（Himeji-shi,JP）;Oka,Yutaka;（Kobe-shi,JP）;Nakagawa,Junichi;（Takaraduka-shi,JP）;Neoda,Akira;（Uji-shi,JP）

CorrespondenceNameandAddress:

DARBY&DARBYP.C.

P.O.BOX5257

NEWYORK

NY

10150-5257

US

SerialNo.:

476070

SeriesCode:

10

Filed:

October24,2003

PCTFiled:

April25,2002

PCTNO:

PCT/JP02/04129

U.S.CurrentClass:

75/10.27

U.S.ClassatPublication:

075/010.27

Intern'lClass:

C22B004/06

ForeignApplicationData

Date

Code

ApplicationNumber

Apr27,2001

JP

2001-132799

Aug21,2001

JP

2001-250225

Claims

Whatisclaimedis:

1.AmethodforproducingaCr--Ti--Vhydrogenstoragealloyutilizingthermitprocesscomprising:

materialpreparationstep（A）ofprovidinganalloymaterial

（1）comprisingaCroxide,aVoxide,andareducingagentAl,andanalloymaterial

（2）comprisingTi;materialintroductionstep（B）ofplacingsaidalloymaterialsinacrucibleforthermitreductionsothatthealloymaterial

（1）isplacedabovethealloymaterial

（2）;metalmeltingstep（C）ofignitingthealloymaterial

（1）placedinthecrucibleinstep（B）forthermitreactionandmeltingallmetalelementscontainedinthealloymaterialswithheatofthethermitreactionofthealloymaterial

（1）toobtainanalloymelt;andstep（D）ofmakingsaidalloymeltobtainedinstep（C）intoanalloy.

2.Themethodofclaim1,whereinsaidalloymaterial

（1）furthercomprisesanoxidizingagentforprovidingadditionalheatbythermitreaction,andwhereinacontentofsaidAlisasumof70to90%ofatheoreticalAlamountrequiredforreducingtheCroxideandtheVoxide,andanamountrequiredforreducingsaidoxidizingagent.

3.Themethodofclaim2,whereinsaidoxidizingagentisselectedfromthegroupconsistingofbariumperoxide,potassiumchlorate,sodiumchlorate,andmixturesthereof.

4.Themethodofclaim1,whereininsaidstep（B）,aseparationlayerhavingameltingpointhigherthanthatofAlisprovidedbetweenthealloymaterials

（1）and

（2）.

5.Themethodofclaim4,whereinsaidseparationlayerisselectedfromthegroupconsistingofanironplate,asteelplate,andanalloysteelplate,eachof0.05to3.0mmthick.

6.Themethodofclaim5,whereinsaidseparationlayercontainsanauxiliarycomponentselectedfromthegroupconsistingofFe,Mn,Mo,Ni,Co,andmixturesthereof.

7.Themethodofclaim1,whereinsaidcrucibleforthermitreductioncomprisesaseparatorplatehavingaslidingnozzle,saidseparatorplatebeingcapableofseparatinganinteriorofsaidcrucibleintoatleastupperandlowercompartments,andwhereininplacingthealloymaterials

（1）and

（2）inthecrucibleinsaidstep（B）,thealloymaterials

（1）and

（2）arearrangedseparatedbysaidseparatorplate.

8.Themethodofclaim,whereinatleastoneofthealloymaterials

（1）and

（2）furthercomprisesanauxiliarycomponentselectedfromthegroupconsistingofFe,Mn,Mo,Ni,Co,andmixturesthereof.

9.Themethodofclaim1,whereinsaidalloymaterials

（1）and

（2）areprovidedsothataresultingCr--Ti--Vhydrogenstoragealloycontains25to70at%Cr,15to45at%Ti,5to45at%V,and0.01to2at%Al,andhasameltingpointnothigherthan1600.degree.C.

10.Themethodofclaim1,furthercomprisingstep（E）ofmeltingsaidalloyobtainedinstep（D）witharareearthmetalselectedfromthegroupconsistingofLa,Ce,andmischmetalinanamountofnotlessthan0.2at%ofsaidalloytoobtainanalloymelt,deoxidizingsaidalloymelttoloweritsoxygencontenttonothigherthan0.1wt%,andcoolingandsolidifyingsaiddeoxidizedalloymelt.

Description

FIELDOFART

[0001]Thepresentinventionrelatestoamethodforproducinghydrogenstoragealloyshavingexcellenthydrogenstorageperformance,inparticular,amethodforproducingCr--Ti--Vhydrogenstoragealloysusedforstorageandtransportationofhydrogen,negativeelectrodesforrechargeablebatteries,orheatpumps.

BACKGROUNDART

[0002]Hydrogenstoragealloyshavebeenmanufacturedinadrasticallyincreasingamountsincethealloyswereusedforanodesofbatteries.ThehydrogenstoragealloyspresentlyusedforbatteriesaremostlyAB,typealloys,whichcontainLaormischmetal,amixtureoflightrareearthelements,ontheA-site,andNiontheB-site,whichispartiallysubstitutedbyCo,Mn,Al,orthelikeelement.TheamountofhydrogenthatsuchAB.sub.5typealloysarecapableofabsorbinganddesorbingunderthehydrogenpressureof0.01to4MPa（definedaseffectivehydrogenstoragecapacity）isatmost1.2wt%.Whenthealloyhavingsuchaneffectivehydrogenstoragecapacityisusedforproducingahydrogenstoragetankmountedonafuelcellelectricvehicle,whichisunderactivedevelopment,therequiredamountofthealloyweighstoomuch.Inordertoovercomethisdrawback,Cr--Ti--Valloysprincipallyofabody-centeredcubiccrystalstructure（BCCstructure）arerecentlyunderdevelopmentasadifferentlineofhydrogenstoragealloys,whichhaveaneffectivehydrogenstoragecapacityofover2wt%.

[0003]Cr--Ti--Valloyshaveexcellentproperties,butrequirehighertemperaturesintheirproductionformeltingtheessentialelementsVandCrforalloying,whichhavemeltingpointsof1910.degree.C.and1863.degree.C.,respectively.Inaddition,Ti,whichalsohasameltingpointofashighas1670.degree.C.,isanactiveelement,andthusrequirescarefulselectionofacrucibleinwhichitismelted.Thatis,ifaCr--Ti--Valloyismeltedinacruciblemadeofametaloxidesuchasalumina,magnesia,orzirconia,Tireactswiththemaincomponentofthecrucibletocorrodethewallsofthecrucible,whicharecrackedandbecomeunusableformelting.Thusinpractice,alloyscontainingactiveTiwithahighmeltingpointaremerelyunderpilotproductionbyarcmeltinginawater-cooledcoppercrucible.However,inmeltinganalloyinawater-cooledcoppercrucible,theportionofthealloymeltthatisincontactwiththecrucibleisnotmelted,whichleadstosegregationandpoorthermalefficiency.Thusthismethodisnotsuitableformass-production.

[0004]ItisknownthatthereactionofTiwithanoxidecruciblebecomessevererasthetemperatureincreases.Thus,theburdentothecruciblemaybealleviatedifthemeltingpointofthemasteralloyislowered.Inthisregard,JP-9-49034-AdisclosesamethodforproducingaBCChydrogenstoragealloycontainingatleastVandNi,inwhichaV--Ni,Ti--V,orFe--Valloyproducedbythermitreductionisusedasastartingmaterial.JP-2000-96160-AdisclosesamethodforproducingamaterialforaV-containinghydrogenstoragealloyhavingtheAlcontentoflessthan1wt%bythermitreductionofanalloymaterialcontainingV-oxideandoptionallyNi,Fe,Cu,Co,Mn,Cr,Nb,Ta,andthelikeelement,usingAloranAlalloyasareducingagent.JP-11-106847-AdisclosesamethodforreducingtheoxygencontentofaV-containinghydrogenstoragealloyproducedbythermitreduction,whereinthealloyismeltedunderheatingwithadeoxidizingagentsuchasCa,Mg,rareearthelements,orthelike,forimprovingthepropertiesofthealloy.

[0005]Ascanbeseenfromthesemethods,productionmethodsarebeingdevelopedwhichemployalloysofVandatransitionmetalasamasteralloyofahydrogenstoragealloy,insteadofmetalV,whichishighinbothmeltingpointandcost.Alsothethermitreductionisrecognizedasafavorablemethodformass-production,comparedtotheabove-mentionedarcmeltinginawater-cooledcoppercrucible.

[0006]InproducingaCr--Ti--Vhydrogenstoragealloy,however,whenaTioxideandaVoxidearereducedwithmetalAlbythermitreactionforobtainingaTi--ValloyinaccordancewiththemethoddisclosedinJP-9-49034-A,theTioxidecannotbereducedsufficientlywithAl,sothatalargeamountofAlremainsintheresultingalloy,inparticularinproducinganalloyhavingtheTicontentofnotlowerthan10at%.SuchanalloycontaininganexcessamountofAlhasaremarkablylowhydrogenstoragecapacity,andcannotachievetheeffectivehydrogenstoragecapacityofnotlowerthan2wt%.

[0007]Inordertoovercomethisproblem,JP-2000-96160-Adisclosestouse,asareducingagent,85to99%ofthetheoreticalamountofAlrequiredforreducingalltheoxidesinthealloymaterial,inordertoreducetheAlcontentintheresultingalloytonothigherthan1wt%.However,whenthismethodisappliedtoproductionofaCr--Ti--Valloy,theCr--Valloyproducedbythermitreducti