4 Effect of the heat treatment on the structure and the properties of the electroless Co Fe B aWord文件下载.docx

4 Effect of the heat treatment on the structure and the properties of the electroless Co Fe B aWord文件下载.docx

《4 Effect of the heat treatment on the structure and the properties of the electroless Co Fe B aWord文件下载.docx》由会员分享，可在线阅读，更多相关《4 Effect of the heat treatment on the structure and the properties of the electroless Co Fe B aWord文件下载.docx（9页珍藏版）》请在冰点文库上搜索。

Balloy

Sen-LinWang

a,

andLiang-LiangHonga

aDepartmentofAppliedChemistry,CollegeofMaterialsScienceandEngineering,HuaqiaoUniversity,Quanzhou362021,PRChina

Received19February2006;

revised14April2006;

accepted18April2006. 

Availableonline5June2006.

Abstract

TheCo

Balloywaselectrolesslydepositedfromthesolutionusingpotassiumborohydride（KBH4）asareducingagentandethylenediamineasthestabilizer.ThecrystallizationbehaviorofthealloycoatingwasstudiedbyusingthedifferentialscanningcalorimetryandX-raydiffraction.Thestructureoftheas-plateddepositisamorphous.ThedepositwasconvertedintoCo3BandCoFephasesat464.9 

°

C.Theeffectoftheheattreatmentonthesurfacemorphology,themagneticpropertiesandthemicrohardnessoftheCo

Bdepositwereinvestigated.Asaresult,themicrohardnessandthemagneticperformancesofthedepositrisewiththeincreaseoftheheattreatmenttemperatureupto500 

C,thentheydecrease.Thedeposittreatedat500 

Cconsistsofnano-grains（thesizeofthegrainsisabout20 

nm）,andhasoptimalmagneticproperties.

Keywords:

Co

Balloy;

Heattreatment;

X-raydiffraction;

Magneticproperty

ArticleOutline

1.

Introduction

2.

Experimentaldetails

3.

Resultsanddiscussion

3.1.Thecompositionandthecrystallizationbehaviorofthedeposit

3.2.Theeffectofheattreatmentonthesurfacemorphologyofthedeposit

3.3.Theeffectofheattreatmentonthemagneticpropertiesofthecoating

3.4.Theeffectofheattreatmentonthemicrohardnessofthedeposit

4.

Summary

Acknowledgements

References

1.Introduction

Thesoftmagneticfilmsareusuallypreparedbyelectro-deposition.Forexample,theelectrodepositedCoFehashighsaturationmagnetism（MS）andlowcoercivity（HC）,whichhasbeenreported[1]and[2].However,suchsoftmagneticfilmspreparedbytheelectroplatingmethodarenotuniforminthethicknessandcompositionbecauseoftheununiformityofthecurrentdensitydistribution.Theelectrolessplatingdoesnotsufferfromtheseproblems,andthusitshouldbemoresuitableforplatinguniformfilmsonsubstrateswithcomplexmorphologies.Uptodate,severalgroupshavereportedthepreparationofsoftmagneticthinfilmsbytheelectrolessdeposition[3],[4]and[5].Forexamples,T.Osaka'

sresearchgroupreportedtheelectrolessCo

Bthinfilmsusingdimethylamineborane（DMAB）asareducingagent,whichhaveasaturationmagnetismvalueashighas1.6 

T[6],[7]and[8];

T.P.XuansimplyusedpotassiumborohydrideasreducingagenttoplatetheCo

Bthinfilms.BasedonT.P.Xuan'

swork[9],wesubsequentlydevelopedaCo

Balloybathbytheadditionofpotassiumborohydrideasreducingagentandethylenediamineasstabilizer.Inthisstudy,theeffectofheattreatmentonthestructure,themicrohardness,thesurfacemorphologyandthemagneticpropertiesoftheCo

Balloywereinvestigated.

2.Experimentaldetails

Balloywaselectrolesslydepositedfromthesolutioncontaining:

CoSO4·

7H2O0.08 

mol 

L−1,FeSO4·

7H2O0.02 

L−1,C4H4O6KNa·

4H2O0.30 

L−1,KBH40.059 

L−1,NaOH0.50 

L−1,C2H8N210.0 

mL 

L−1.Thetemperaturewaskeptat50 

C.Theplatingtimewas2.5 

h.Theloadcapacityoftheelectrolessplatingwas40 

cm2 

L−1.Thesubstratesweremechanicallypolishedandchemicallyetchedbeforetheexperiments.

Theheattreatmentexperimentsofthesampleinavacuum（0.67 

Pa）werecarriedoutatvarioustemperaturesfor1.0 

h.Thecompositionofthedepositwasdeterminedbyanenergy-dispersiveX-rayspectroscopy（EDX,ISIS-300,OxfordInstruments）attachedonascanningelectronmicroscope（SEM,LEO-1530）.ThesurfacemorphologiesofthedepositwereobservedbytheSEM.ThestructureofthedepositwasstudiedbytheX-raydiffraction（XRD）onaRigakuD/max-RCdiffractometerwithamonochromatizedCuKαradiation,andwasalsomeasuredbytransmissionelectronmicroscope（TEM,JEM-100CXII）.ThemicrohardnessmeasurementsweremeasuredbyusingaVickersmicrohardnesstesterunderaloadof100 

g.Thethicknessofthesedepositswaskeptatthesamevalue,whicheliminatederrorsinthemeasuringofhardness.Thesamplesforabovemeasurementswereplatedonthecarbonsteelsubstrates,whichhas6.00 

cm2surfacearea.Thecrystallizationtemperatureofthecoatingwasmeasuredbyadifferentialscanningcalorimeter（DSC-2960,TAInstruments）inanatmosphereofpureargongas.TopreparetheDSCspecimens,thealloywasdepositedonstainlesssteelsheet,andthenpeeledoffbyusingthemechanicalmethod.Themagneticmeasurementsweremadeusingavibratingsamplemagnetometer（VSM）.Thesamplewasplatedonthecoppersubstratewhosesurfaceareaisabout0.25 

cm2.

3.Resultsanddiscussion

3.1.Thecompositionandthecrystallizationbehaviorofthedeposit

Fig.1showstheEDXspectrumofthedeposit.Itisfoundthatthechemicalcompositionisalmostthesameinthedifferentzones,andthecoatingonlycontainstheCoandFeelements（EDXspectrumcannotdetectelementboron）.Theatomicpercentageofthedepositiscalculatedas83.08%forcobalt,16.92%foriron,wherethecontentofboronisneglected.Theboroncontentinthedepositsisusuallybelow6.0 

at.%,whichhasbeenmeasuredbyplasmaemissivespectrum[10].Fig.1alsodemonstratesthehighpurityofthecoating.

Full-sizeimage（4K）

Fig.1. 

TheEDXspectrumofthedeposit.

ViewWithinArticle

Thedifferentialscanningcalorimetry（DSC）curvesofthecrystallizationprocessfortheCo

BcoatingatvariousheatingrateisillustratedinFig.2.TwoexothermicpeaksappearineachDSCcurve,andthepeakat450.0–480.0 

Cisstrong,whilethepeakat200.0–210 

Cisweak.Thestrongpeakmovestoahighertemperatureregionwiththeincreaseoftheheatingrate.Fig.3indicatesthattheXRDpatternsofthedepositafterheattreatmentfor1.0 

hatvarioustemperatures.AccordingtotheXRDpatterns,thestrongDSCpeakobservedat450.0–480.0 

CcorrespondstotheformationofCo3B（Pnma）andCoFe（Pm3m）phases,andthefirstweakpeakat200.0–210.0 

CisascribedtotheevolutionofH2orthestructuralrelaxation.FromtheXRDpattern,itcanbefoundthattheas-plateddepositconsistsofanamorphousphase.Thecrystallizationpeaksat2θ 

= 

45.0°

and65.0°

areduetotheX-raydiffractionfromiron（Im3mphase）ofthesubstrate.Theelectrondiffractionpattern（Fig.4）ofthedepositedfilmalsosuggeststhatthestructureoftheas-plateddepositisamorphous.WhentheCo

Balloydepositwastreatedatabout500 

C,thecrystallizationpeakswereobserved,whichisduetothecrystallizationoftheamorphousCo

BalloyintoCo3Bphase[11].

Full-sizeimage（44K）

Fig.2. 

TheDSCcurvesofthecoating.

Full-sizeimage（10K）

Fig.3. 

TheXRDpatternsofthedepositatvarioustemperaturesheattreatmentfor1 

h.

Full-sizeimage（39K）

Fig.4. 

Theelectrondiffractionpatternoftheas-plateddeposit.

3.2.Theeffectofheattreatmentonthesurfacemorphologyofthedeposit

Fig.5showsthesurfacemorphologiesofthedepositsofas-platedandheatedatdifferenttemperature.Theas-plateddepositconsistsofcompactparticleswiththediameterofabout20 

nm,asshowninFig.5（a）.Theboundaryamongtheparticlesissomeunclear.Afterheattreatmentat250 

C,thecompactparticlesofthedepositincreaseto40 

nm（Fig.5（b））.Furthermore,theparticlesofthedepositaftertreatedat250 

Carerelativelyeven.Astheheattreatmenttemperatureincreasedto400 

C,thesizeofcompactparticlesofthedepositinFig.5（c）becamenotasevenasthattreatedat250 

C.Thediameterofcompactparticlesvariesfrom20to80 

nm.Whenincreasingthetreatmenttemperature,theshapeofthecompactparticlesofthedepositdidnotchangeuntiltheheattreatmenttemperaturewascontrolledbelow400 

C,whichindicatedthattheheattreatmentatthistemperatureregiondidnotproducenewphase.TheseSEMresultsagreewellwiththatoftheXRDmeasurements.Whentheheattreatmenttemperaturewasincreasedto500 

C,manyfinegrains（about20 

nm）wereformed,whichmaybeduetothetransformationoftheamorphousalloyphaseintothecrystallizedCo3BandCoFephases,asshowninFig.5（d）.Inaword,theheattreatmenttemperatureaffectsthestructureofthedepositandthesizeofthegrains.

Full-sizeimage（282K）

Fig.5. 

TheSEMphotosofthedepositafterheattreatmentatvarioustemperatures（°

C）for1 

h:

（a）as-plated;

（b）250;

（c）400and（d）500.

3.3.Theeffectofheattreatmentonthemagneticpropertiesofthecoating

Themagnetichysteresiscurvesfortheas-platedandheat-treateddepositsatdifferenttemperatureareshowninFig.6.Thesaturationmagnetization（MS）（Ycoordinateaxisintercept）andthecoercivity（HC）（Xcoordinateaxisintercept）was,respectivelydeterminedfromFig.6,andtheresultswasillustratedinFig.7.ThesaturationmagnetizationofthedepositismorethanthatoftheCo

Bdeposit[6].Thesaturationmagnetizationandthecoercivityrosewiththeincreaseofheattreatmenttemperaturefrom50to450 

C.Themaximumofthesaturationmagnetizationandthecoercivityr