High Performance Corrosion-Resistant Materials

2025-04-28

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

1200

Suitable for use in highperformance coatings

1000

Bucket 60

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Bucket 45

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Bucket 40

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Bucket 30

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Bucket 1

020

Peaks indicative of problematic phase believed to be responsible for poor

corrosion resistance (poor salt fog performance)

(Bucket 1) Lot 05-079 (?53/+15 μm)(Bucket 30) Lot 04-193 (+53 μm)

Crystalline

(Bucket 40) Lot 04-200 (?53/+30 μm)(Bucket 45) Lot 04-199 (?30/+15 μm)

L3021B.MDIL3020B.MDIL3019B.MDIL3018B.MDIL3017C.MDI

(Bucket 60) Lot 04-191 (?15 μm)

Amorphous

Figure5.This?gureisacompari-sonoftheXRDdata(intensityvs.diffractionangle2θ)forseverallotsofSAM2X5amorphousmetalpow-der,revealingtherelationshipbetweenparticlesizedistributionandprocess-ingconditionstotheformationofdevit-ri?edmicrostructure.

Figure6.SamplesofamorphousmetalHVOFcoatingsusedforlong-termcorrosiontesting.Source:MetallurgicalandMaterialsTransactionsA—Farmeretal.—Fig.4.AdaptedfromRef.8.

(orbetterthan)AlloyC-22.Theadditionof3at%tungstentotheSAM1651enhancedthepassive?lmstabilityandalsoyieldedmoreductileanddamage-tolerantamorphousmetalribbons.

PotentialcurrentdataobtainedduringtheCPofaSAM40MSRinnaturalseawaterat30?CisshowninFig.12.TheOCPwas?0.296VversusAg/AgCl,andthecurrentdensitymeasuredbetweenOCPand0.9voltswasbelow1μA/cm2,whichisindicativeofpassivity,withadistinctanodicoxidationpeakwasobservedatapproxi-mately0.5V,whichisbelievedtobeduetotheoxidationofMointhepassive?lm.

PotentialcurrentdatafortwowroughtAlloyC-22sam-plesandaSAM2X7MSRinnaturalseawaterat30?CisshowninFig.13.Ingeneral,themeasuredcurrentdensi-tiesfortheSAM2Xseriesofiron-basedamorphousmetalMSRswerelessthanthosemeasuredforwroughtsamplesofAlloyC-22,indicatingbetterpassivityoftheamorphousmetals.TheanodicoxidationpeaksforSAM2X7(Fig.12)andAlloyC-22arebelievedtobeduetotheoxidationofmolybdenum.

PotentialcurrentdatafortwowroughtAlloyC-22sam-ples,andanas-sprayedHVOFcoatingofSAM2X5,whichwasdepositedonaType316Lstainlesssteelsubstrate,innaturalseawaterat90?CisshowninFig.14.Ingeneral,themeasuredcurrentdensityfortheiron-basedamor-phousmetalthermalspraycoatinginheatedseawaterwaslessthanthosemeasuredforwroughtsamplesofAlloyC-22,indicatingbetterpassivityofHVOFSAM2X5coatinginthisparticularenvironment.ThedistinctanodicoxidationpeaksforAlloyC-22,andthefaintpeakforthe

12HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

SAM2X5 Coating (E316L463)

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1,2

720

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540Counts(i) Cr2B(ii) M23C6(iii) bcc ferrite(iv) WC

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12,4

Figure7.XRDdata(intensityvs.diffractionangle2θ)forhighvelocityoxyfuel(HVOF)coatingofFe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4(SAM2X5)onType316LstainlesssteelsubstratepreparedwithJP5000thermalspraygun.Thiscoating,identi?edasE316L463,waspre-paredwithLot#04-265powder,whichhadabroadrangeofparticlesizes(?53/+15μm).Source:JournalofMate-rialsResearch—Farmeretal.—Fig.2.AdaptedfromRefs8,49.

020

2θ

SAM2X5 Coating (E316L329)

1200

1,2

1000

1,3

(i) Cr2B(ii) M23C6

(iii) bcc ferrite(iv) WC

2,4

800CountsFigure8.XRDdata(intensityvsdiffractionangle2θ)forhighvelocityoxyfuel(HVOF)coatingofFe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4(SAM2X5)onaType316LstainlesssteelsubstrateanddepositedwithaJK2000thermalspraygunatPlasmaTechIncorporated(PTI).Thiscoating,iden-ti?edasE316L329,waspreparedwithLot#04-200powder,whichhadarelativelycoarserangeofpar-ticlesizes(?53/+30μm).Source:AdaptedfromFig.3ofRef.49.

600

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2θ

SAM2X5thermalspraycoating,areallbelievedtobeduetotheoxidationofmolybdenum.

PotentiostaticPolarization—PotentialStepData

Potentialsteptestinginnaturalseawaterheatedto90?CwasdonewithwroughtAlloyC-22(referencematerial),fullydenseandcompletelyamorphousMSRsofSAM2X5,optimizedHVOFcoatingspreparedwithcoarse(?53/+30μm)powdersofSAM2X5,andoptimizedHVOFcoatingspreparedwithrelatively?ne(?30/+15μm)powdersofSAM2X.ThesecoatingswerepreparedwithSAM2X5powdersuppliedbyTNCanddepositedbyPTIinTorrance,CA.Coatingspreparedwith?nerpowderswerefoundtohaveasmallervolumefractionofcrystallineprecipitatesthanthosepreparedwithcoarserpowders.Toeliminatetheneedforsurfaceroughnesscorrectionsintheconversionofmeasuredcurrentandelectrodeareatocurrentdensity,theSAM2X5coatingswerepolishedtoa600-grit?nishbeforetesting.

Figures15and16showmeasuredtransientsincur-rentdensityatconstantappliedpotentialsof1000and1200mVversusOCP(open-circuitpotential)forseveraldifferentmaterialsinnaturalseawaterat90?C.Themate-rialscomparedineach?gureincludewroughtAlloyC-22(referencematerial),afullydenseandcompletelyamor-phousMSRofSAM2X5,HVOFcoatingspreparedwithcoarse(?53/+30μm)powdersofSAM2X5,andHVOFcoatingspreparedwithrelatively?ne(?30/+15μm)pow-dersofSAM2X5.Theconstantpotentialwasappliedafter1hattheOCP.Thepassive?lmontheMSRsamplesandHVOFcoatingsofSAM2X5wasmorestablethanthatonwroughtnickel-basedAlloyC-22underthesecondi-tions,whichleadtotheconclusionthatthisiron-basedamorphousmetalhadsuperiorcorrosionresistance.

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS13

SAM2X5 Coating (E316L504)

1000

800

600Counts(i) Cr2B(ii) M23C6

(iii) bcc ferrite(iv) WC

Figure9.XRDdata(intensityvsdiffractionangle2θ)forhighvelocityoxyfuel(HVOF)coatingofSAM2X5onaType316Lstainlesssteelsubstrate,depositedwithaJK2000thermalspraygunatPlasmaTechIncorporated(PTI).Thiscoating,identi?edasE316L504,waspreparedwithLot#04-199powder,whichhadarelatively?nerangeofparticlesizes(?30/+15μm),andisastandardsizedistributionforHVOFapplications.Source:Jour-nalofMaterialsResearch—Farmeretal.—Fig.4.AdaptedfromRef.49.

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Table5.ThermalAnalysisData(DTAorDSC)forFe-BasedGlass-FormingAlloys,IncludingSAM2X5(Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4),SuitableforThermalSprayDepositionAlloySAM40SAM2X1SAM2X3SAM2X5SAM2X7

Tg(?C)568–574575578579573

Tx(?C)623620626628630

Tm(?C)11101124113111331137

TL(?C)13381190–12101190–12101190–12101190–1210

Trg0.530.570.570.570.57

1.21.00.80.60.40.20.0?0.2?0.4?0.6

1.E?091.E?08Corriosion resistance of SAM1651tests in various aggressive brines

Seawaterat 90°C3.5-m NaClat 90°C5M CaCl2at 105°CSource:JournalofNuclearTechnology—Farmeretal.—Table2.AdaptedfromRef.47.

Transientsincurrentdensityataconstantappliedpotentialof1000mVarecomparedinFig.15.Gradu-allyincreasingcurrentdensityobservedduringtestingofAlloyC-22wasindicativeofpassive?lmbreakdown.TheHVOFcoatingofSAM2X5preparedwithrelatively?ne(?30/+15μm)powderhadatemporarylossofpassivityat1×104s,butunderwentrepassivationat6×104s.Incontrast,thecoatingpreparedwithcoarse(?53/+30μm)powderappearedtobecompletelystable,asdidtheMSR.ThedifferencesinthecorrosionresistanceoftheSAM2X5coatingspreparedwithcoarse(?53/+30μm)andrel-atively?ne(?30/+15μm)powdersarenotcompletelyunderstood.SincethecoatingpreparedwiththecoarserpowderhadslightlymoreCr2B,WC,M23C6,andbccfer-ritethanthecoatingsproducedwiththe?nerpowder,thesuperiorpassive?lmstabilityfoundwiththesepowderscannotbeattributedtotheformationofthesepotentiallydeleteriouscrystallinephases.Differencesintheinterfa-cialcomposition,structure,andareaofindividualparticlesthatcomprisethecoatingsmayberesponsible.Thepassive?lmontheMSRandHVOFcoatingsofSAM2X5preparedwithcoarse(?53/+30μm)powderwasmorestablethanthatonwroughtnickel-basedAlloyC-22undersimilarcon-ditions,whichleadtotheconclusionthatthisiron-based

E(V vs Ag/AgCl)Figure10.Cyclicpolarizationdataforthreedrop-castingotsofSAM1651(SAM7)Fe-basedamorphousmetalwithyttriuminthreedifferentenvironments:seawaterat90?C,3.5molalNaClat90?C,and5MCaCl2at105?C.Source:ASMEPressureVessels&Piping—Farmeretal.AdaptedfromRef.5.

amorphousmetalhadsuperiorcorrosionresistance.InallcaseswithSAM2X5,MSRsperformedbetterthanHVOFcoatings.

Astheappliedpotentialwasincreasedto1200mV,asshowninFig.16,theAlloyC-22sampleslostallpassivity,whiletheMSRsandthermalspraycoatingsofSAM2X5

1.E?07Current density (A/cm2)

1.E?061.E?051.E?041.E?031.E?021.E?011.E+0014HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

1.21.00.80.60.40.20.0?0.2?0.4?0.6

1.E?09Comparison of Alloy C-22 & SAM1651

variants in 5M CaCl2 at 105°C

SAM1651 + 3 At. % WSAM1651Alloy C-22ERPEcorrCurrent density (A/cm2)

Figure11.Cyclicpolarizationdataforawroughtprismofnickel-basedAlloyC-22,adrop-castingotofiron-basedSAM7(SAM1651)amorphousmetal,andameltspunribbonofSAM8(SAM1651(SAM7)+3at%tungsten),allobtainedwith5MCaCl2at105?C.Source:ECSTransactions—Farmeretal.—Fig.2.AdaptedfromRefs8,38.

maintainedpassivity.Thepassivityofcoatingspreparedwiththe?nerpowderstabilizedatthishigheranodicpotential.

Currentdensitytransientsat100–1500mVweremea-suredwithaSAM2X5thermalspraycoatingpreparedwithrelatively?ne(?30/+15μm)SAM2X5powderindeaeratednaturalseawaterat90?C.Datafor100,600,700,and1500mVareshowninFig.17.Completepassive?lmstabilityofthisSAM2X5samplewasmaintainedatpotentialsupto600mV,withcurrentdensity?uctuationsobservedat700mVwhichwereindicativeoftheonsetofpassive?lmmetastability.Similarcurrentdensity?uc-tuationswereobservedatpotentialsupto1400mV.Atanappliedpotentialof1500mV,passivitywascompletelylost.

Currentdensitytransientsat100–1500mVweremea-suredwithaSAM2X5thermalspraycoatingpreparedwithrelativelycoarse(?53/+30μm)SAM2X5powderindeaeratednaturalseawaterat90?C,asshowninFig.18.Completepassive?lmstabilityofthisSAM2X5samplewasmaintainedatpotentialsupto1400mV.However,atanappliedpotentialof1500mV,passivitywascompletelylost.Coatingsproducedwithcoarsepowderexhibitedlessmetastabilitythancoatingsproducedwith?nepowder.Figure19showsacomparisonandsummaryofthedatapresentedinFigs15–18,aswellasothersupportingdata.Theasymptoticcurrentdensityreachedafter24hateachappliedpotential(eachdatapointrepresentsa24-htest)isplottedforwroughtAlloyC-22,fullydenseandcom-pletelyamorphousMSRsofSAM2X5,HVOFcoatingsofSAM2X5preparedwithcoarse(?53/+30μm)powder,andHVOFcoatingsofSAM2X5preparedwithrelatively?ne(?30/+15μm)powder.Asapracticalmatter,alldatainthis?gurewereplottedasafunctionofpotentialrelativetotheAg/AgClreferenceelectrodetoenablecomparisononacommonscale,sinceeachindividualsamplehaditsownuniqueOCP.Fromthisplotofcurrentdensityversuspotential,itappearsthatstabilityofthepassive?lmon

Cyclic polarization of

SAM40 MSR in seawater at 30°C

E (V vs Ag/AgCl)Potential (V vs Ag/AgCl)Figure12.This?gureshowspotentialcurrentdataobtainedduringthecyclicpolarization(CP)ofaSAM40meltspunribbon(MSR)innatu-ralseawaterat30?C.TheOCPwas?0.296VversesAg/AgCl,andthecurrentdensitymeasuredbetweenOCPand0.9Vwasbelow1μA/cm2,whichisindicativeofpassivity,withadistinctanodicoxi-dationpeakwasobservedatapproximately0.5V,whichisbelievedtobeduetotheoxidationofmolybdenuminthepassive?lm.

1.E?081.E?071.E?061.E?051.E?041.E?031.E?021.E?011.61.41.21.00.80.60.40.20.0?0.2?0.4?0.6?11.0?10.0?9.01.E+00Oxidation ofmolybdenum inpassive filmOCP = ?0.296 Vlog(Iocp ) = ?9.5?8.0?7.0?6.0?5.0?4.0?3.0?2.0Log Current density (A/cm2)

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS15

Cyclic polarization of

SAM2X7 MSR and nickel-based Alloy C-22 in seawater at 30°C

1.61.41.21.0Potential (V vs Ag/AgCl)0.80.60.40.20.0?0.2?0.4

?0.6

1.0E?111.0E?101.0E?091.0E?081.0E?071.0E?061.0E?051.0E?041.0E?031.0E?02

Current density (A/cm2)

Figure13.This?gureshowspotentialcur-rentdatafortwowroughtAlloyC-22samplesandaSAM2X7MSRinnaturalseawaterat30?C.Source:MetallurgicalandMateri-alsTransactionsA—Farmeretal.—Fig.8.AdaptedfromRefs8,49.

SAM2X7 MSRWrought Alloy C-22Cyclic polarization of as-sprayed

HVOF SAM2X5 & Wrought Alloy 22 in seawater at 90°C

1.61.41.21.0Potential (V vs Ag/AgCl)0.80.60.40.20.0

Alloy C-22?0.2?0.4

?0.6

1.0E?101.0E?091.0E?081.0E?071.0E?061.0E?051.0E?041.0E?031.0E?02

Current density (A/cm2)

Figure14.This?gureshowspotentialcurrentdatafortwowroughtAlloyC-22samplesandanas-sprayedHVOFcoatingofSAM2X5,whichwasdepositedonaType316Lstainlesssteelsub-strate,innaturalseawaterat90?C.Source:Met-allurgicalandMaterialsTransactionsA—Farmeretal.—Fig.9.AdaptedfromRefs8,49.

Wrought Alloy C-22 (SN # CC-22 4006)Wrought Alloy C-22 (SN# CC-22 4002)Wrought Alloy C-22 (SN # JE1594)As-sprayed HVOF SAM2X5 (SN # E316L442)As-SprayedHVOF SAM2X5

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

JOSEPHC.FARMER

LawrenceLivermoreNationalLaboratory,Livermore,CA;UnitedStatesNavalPostgraduateSchool,Monterey,CA

INTRODUCTION

Theoutstandingcorrosionthatmaybepossiblewithamor-phousmetalshasbeenrecognizedforseveralyears[1–11].Compositionsofseveraliron-basedamorphousmetalshavebeenpublished,includingseveralwithverygoodcorrosionresistance.ExamplesincludethermallysprayedcoatingsofFe-10Cr-10-Mo-(C,B),bulkFe-Cr-Mo-C-B,andFe-Cr-Mo-C-B-P[12–14].Thecorrosionresistanceofaniron-basedamorphousalloywithyttrium(Y),Fe48Mo14Cr15Y2C15B6,hasalsobeenestablished[15–17].Yttriumwasaddedtothisalloytolowerthecriticalcoolingrate(CCR).Severalnickel-basedamorphousmetalshavebeendevelopedthatexhibitexceptionalcorrosionperformanceinacidsbuthavenotbeenincludedinthisstudy,whichisrestrictedtoFe-basedmaterials.Verygoodthermalspraycoatingsofnickel-basedcrys-tallinecoatingsweredepositedwiththermalspraybutappeartohavelesscorrosionresistancethannickel-basedamorphousmetals[18].Thetwoiron-basedamorphousmetalcoatingsemphasizedinthispublicationareSAM2X5(Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4)andSAM1651(Fe48Mo14Cr15Y2C15B6).Thesematerialshavebeendevelopedintheformofthincoatings,aswellasthicklayersformingcompositesurfaces,toprovideexcep-tionalcorrosionresistanceinenvironmentsincluding,butnotlimitedto,5MCaCl2at105–120?Candnaturalseawaterat30–90?C.

Corrosionresistantmaterialssuchasthesecan?llimportantneeds.Forexample,accordingtotheUnitedStatesDepartmentofTransportation,therewere583,000bridgesintheUnitedStatesin1998.Ofthistotal,200,000bridgesweresteel,235,000wereconventionalreinforcedconcrete,108,000bridgeswereconstructedusingprestressedconcrete,andthebalancewasmadeusingothermaterialsofconstruction.Approximately15%ofthebridgesaccountedforatthispointintimewerestructurallyde?cient,primarilyduetocorrosionofsteelandsteelreinforcement.Theannualdirectcostofcorrosionforhighwaybridgeswasestimatedat$8.3billiontoreplacestructurallyde?cientbridgesovera10-yearperiodoftime,$2billionformaintenanceandcostofcapitalforconcretebridgedecks,$2billionformainte-nanceandcostofcapitalforconcretesubstructures,and$0.5billionformaintenanceofpaintingofsteelbridges.Lifecycleanalysisestimatesindirectcoststotheuserduetotraf?cdelaysandlostproductivityatmorethan

10timesthedirectcostofcorrosionmaintenance,repair,andrehabilitation.

ThesealloyswererecentlydiscussedatameetingoftheMaterialsResearchSociety(MRS)inregardtotheirben-e?cialapplicationtothesafestorageofspentnuclearfuel(SNF).Theexceptionalcorrosionresistancemakesthemattractiveforcoatingspentnuclearfuelcontainers.Thehighboroncontentof(SAM2X5)Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4makesitaneffectiveneutronabsorber,andsuitableforcriticalitycontrolapplications,appliedasathicklayertothebasketstructureinsidesuchcontainers.

DESIGNINGFORCORROSIONRESISTANCE

Aspointedoutintheliterature,anestimateoftherel-ativepittingresistanceofalloyscanbemadeusingthepittingresistanceequivalencenumber(PREN),whichiscalculatedusingtheelementalcompositionofthealloy[19–24].PRENvaluesfortheFe-basedamorphousmetalsofinteresthere,andthecrystallinereferencematerials,whichincludeType316LstainlesssteelandNi-basedAlloyC-22,havebeencalculatedusingthefollowingequations.Equation(1)hasbeenusedforestimatingthePRENfornickel-basedalloysandaccountsforthebene?cialeffectsofCr,Mo,W,andNoncorrosionresistance[20].PREN=[%Cr]+3.3×[%Mo+%W]+30×[%N].

(1)

ThoughthisequationpredictscomparablecorrosionresistanceforAlloyC-276andAlloyC-22,AlloyC-22isknowntobemorecorrosionresistant.Anequationthathasbeenusedtomakereasonablepredictionsoftherelativecorrosionresistanceofausteniticstainlesssteelsandnickel-basedalloyssuchasAlloyC-22is[20].PREN=[%Cr]+3.3×([%Mo]+0.5×[%W])+k×[%N].

(2)Thefactorkisanadjustableparameterusedtoaccountforthebene?cialeffectsofnitrogen.Reasonablevaluesofthefactorkrangefrom12.8to30,with16beingacceptedasareasonablevalue[22].Estimatesusedtoguidethisalloydevelopmentwerebasedontheassumptionthatthevalueofkis16.PRENvaluescalculatedwithEquation(2)indicatedthattheresistanceoftheSAM2X5andSAM1651amorphousmetalformulationsshouldbemoreresistanttolocalizedcorrosionthanType316Lstainlesssteelornickel-basedAlloyC-22.AsinthecaseofcrystallineFe-basedandNi-basedalloys,itwasfoundexperimen-tallythattheadditionofCr,Mo,andWsubstantiallyincreasedthecorrosionresistanceoftheseamorphousalloys.Additionalpassive?lmstabilitymayhavebeenobserved,whichcannotbeattributedtocompositionalone,andmaybeattributabletotheglassystructure.Additionalworkisrequiredtofurtherunderstandtherelativerolesofcompositionandcrystallinestructureinhighperformanceamorphousmetalcoatings,suchastheonesdiscussed

WileyEncyclopediaofComposites,SecondEdition.EditedbyLuigiNicolaisandAssuntaBorzacchiello.?2012JohnWiley&Sons,Inc.Published2012byJohnWiley&Sons,Inc.

2HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

here.Anobviousde?ciencyassociatedwiththeuseofaparameterbasedonchemicalcompositionalonetoassesstherelativecorrosionresistanceofbothcrystallineandamorphousalloysisthatmicrostructureeffectsonpas-sive?lmbreakdownareignored.Thelackofcrystallinestructureisbelievedtobeakeyattributeofcorrosion-resistantamorphousmetals.

TheHighPerformanceCorrosion-ResistantMaterials(HPCRM)ProgramwasledbyLawrenceLivermoreNationalLaboratory(LLNL)anddevelopedafamilyofiron-basedamorphousmetalswithverygoodcorrosionresistancethatcanbeappliedasaprotectivethermalspraycoating.Severalpromisingformulationswithinthisalloyfamilywereformedbyadditionchromium(Cr),molybdenum(Mo),andtungsten(W)forenhancedcorro-sionresistanceandboron(B)toenableglassformationandneutronabsorption.CompositionsexploredduringthisstudyincludeSAM35(Fe54.5Mn2Cr15Mo2W1.5B16C4Si5),SAM40(Fe52.3Mn2Cr19Mo2.5W1.7B16C4Si2.5),SAM2X5(Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4),SAM6(Fe43Cr16Mo16B5C10P10),SAM7orSAM1651(Fe48Mo14Cr15Y2C15B6),andSAM10(Fe57.3Cr21.4Mo2.6W1.8B16.9).TheparentalloyforpreparingthisseriesofamorphousalloysisknownasSAM40(Fe52.3Cr19Mn2Mo2.5W1.7B16C4Si2.5)andwasoriginallydevelopedbyBranagan[25–36].

Compositionswithhighconcentrationofboronandgoodcorrosionresistance,suchasSAM2X5andSAM1651,maybebene?cialforapplicationssuchasthelong-termstorageofSNFwithenhancedcriticalitysafety[37–43].Inregardtosuchhightemperatureapplications,ithasbeenshownthatthecorrosionresistanceofsuchiron-basedamorphousmetalsismaintainedatoperatingtemperaturesuptotheglasstransitiontemperature[19,20].OnthebasisoftheworkofPerepezkoetal.,theupperoperatingtemperatureforsuchmaterialsisbelievedtobeabout570?C(Tg≈579?C)[44].Abovethecrystallizationtemperature(Tx≈628?C),deleteriouscrystallinephasesformed,andthecorrosionresistancewaslost.

Otheramorphousalloysmaybemorecorrosionresis-tantthantheSAM1651andSAM2X5discussedhere.Inadditiontosynthesizingthesealloys,meltspunribbon(MSR)samplesofFe43Cr16Mo16B5C10P10(SAM6)werealsoprepared[13].AsshowninFig.1,whileMSRsam-plesofAlloy22werecompleteddissolvedinhydrochloric

acidafterseveral-daysexposure(left),MSRsampleswithSAM6compositiondidnotdissolve(right).SYNTHESISAMORPHOUSALLOYS

SAM2X5andSAM1651canbeappliedascoatingswiththesamecorrosionresistanceasafullydensecompletelyamorphousMSR,providedthatitsamorphousnatureispreservedduringthermalspraying,whereasbothAlloyC-22andType316Lstainlesslosemuchoftheircorrosionresistanceduringthermalspraying,owingtotheforma-tionofdeleteriousintermetallicphasesthatdepletethematrixofkeyalloyelements.Thus,thesematerialsmayprovidetherepositoryengineerwithsomeuniquemateri-alsfordesignenhancement.TheHPCRMteamdevelopedawiderangeofalloycompositionsandevolvedtheseuniquealloysfromMSRtodrop-castingots,togas-atomizedparticles,andeventuallytothermallystrayedcoatingsranginginthicknessfromafewmils(thousandthsofaninch)toathicknessapproaching0.5in.,andcontrolledthemicrostructurebyaddingdispersednanophaseoxidestoprecipitatedintermetallicphases[45–75].Melt-SpinningProcess

Thedevelopmentofanappropriatepowdercompositionfortheproductionofacorrosion-resistantthermalspraycoatingrequiresthatthealloy?rstbetestedinaformwithnoporosityandwithlittleornocrystallinephasespresent.Testingofsuchmaterialsenablesdeterminationofthebestpossiblecorrosionperformanceforagivencomposition.Meltspinningandarcmeltingwithdropcastinghavebeenusedasmethodstosynthesizecompletelyamorphous,Fe-based,corrosion-resistantalloyswithneartheoreticaldensity,therebyenablingtheeffectsofcoatingmorphologyoncorrosionresistancetobeseparatedfromtheeffectsofelementalcomposition.

CoolingratesapproachingonebillionKelvinpersecond(109K/s)maybeachievedwithphysicalvapordeposition(PVD)andcanbeusedtoproduceamorphousmetalthin?lms.However,otherprocessesarerequiredtoproducefree-standingmaterialsandcoatingsofpracticalthicknessforcorrosionandwearresistance.ThethicknessofPVD?lmsistypically1–5μm.MaximumcoolingratesofonemillionKelvinpersecond(106K/s)havebeen

(a)(b)

Figure1.AlloyC-22dissolvedinconcen-tratedHCl(a),whileameltspunribbonofSAM6remainedintactforanexposurelastingseveralmonths(b).Extremecorro-sionresistanceispossiblewithiron-basedamorphousmetals.Source:MetallurgicalandMaterialsTransactionsA—Farmeretal.—Fig.17.AdaptedfromRefs8,49.

achievedwithmeltspinningandarethereforeidealforproducingamorphousmetalsoveraverybroadrangeofcompositions.TheMSRsamplesproducedwiththisequipmentareseveralmeterslong,severalmillimeterswideandapproximately150μmthick[24].Incontrast,thecoolingrateinatypicalthermalsprayprocesssuchasHVOFisontheorderoftenthousandKelvinpersecond(104K/s).Thecompositionalrangeofmaterialsthatcanberenderedasamorphousmetalswiththermalsprayisthereforemorerestricted.

Themeltspinninginvolvestheejectionofaliq-uidmeltontoarapidlymovingcopperwheelwithapressure-controlledgas.Theliquidmeltsolidi?esontothewheel,withsubsequentseparationfromthewheelbythermalcontractionandcentrifugalforce,andcollectioninachamber.Bychangingthetangentialvelocityofthewheel,aswellasotherprocessingparameters,thecoolingratecanbecontrolledoveraverybroadrange.Thespeci?cprocessingparametersforthemelt-spinningprocesscanbeselectedtoestablishcoolingratesthatarerepresentativeofagiventhermalsprayprocess.Ifaspeci?ccoolingrateproducesanamorphous,glassymetalduringmeltspinning,itshouldalsoproduceaglassystructureduringthermalspray.Itisthereforepossibletousemeltspinningtosimulatethetypeofmicrostructurethatcanbeachievablewiththermalspraying,suchasthehighvelocityoxyfuel(HVOF)process.Furthermore,anentireseriesofdevelopmentalmaterials,withdifferentcompositions,heatcapacities,andthermalconductivity,canbemadewiththesamecoolingrates,sothattheeaseofprocessingeachcanbecompared.

Byexploitingthemelt-spinningprocess,severalalloycompositionsofFe-basedamorphousmetalshavebeenproduced,characterized,andtested.Severalofthesewerecompositionalmodi?cationsoftheSAM40masteralloyandwerepreparedbyfollowingthegeneralformula:[(SAM40)100?x+Zx]whereZistheaddedelementandxistheamountoftheadditioninatomicpercent[24].Additivesinvestigatedincludednickel,chromium,molybdenum,tungsten,yttrium,titanium,andzirco-nium.Thenickelandmolybdenumadditionsareknowntogreatlyin?uencetheelectrochemicalpropertiesofconventionalstainlesssteelalloys.Theyttrium,titanium,andzirconiumadditions,whilenotnormallyaddedtosteels,areknowntoformverystableoxidesandareexpectedtoincreasethestabilityandpassivityoftheoxide?lminavarietyofenvironments.TheSAM1651formulationhasthesamenominalelementalcompo-sitionastheY-containingFe-basedamorphousmetalformulationdiscussedintheliterature[13–15].Theserare-earth-containingmaterialshavebeenselectedwithparticularemphasisonglass-formingability,thermalstability,hardness,andcorrosionresistance,allunderconditionsofinterest.

Themelt-spinningprocesswasusedtoperformasys-tematicstudyofvariouselementalcompositions,eachbasedontheFe-basedSAM40masteralloy,with1,3,5,and7atomicpercentadditionsofspeci?celementsbelievedtobebene?cialtoglassformationorcorro-sionresistance.Elementaladditionsinvestigatedincludednickel,molybdenum,yttrium,titanium,zirconium,and

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS3

chromium.Thedensitiesoftheamorphousmetalspre-paredwithmeltspinningweredetermined,andallwerelessdensethannickel-basedN06022(AlloyC-22),andthereforeofferaweightadvantageoversuchclassicalcorrosion-resistantalloys.The?rstrecrystallizationpeakforeachoftheMSRswasdeterminedwithdifferentialthermalanalysis(DTA)andwassimilartothatofthemas-teralloy(SAM40).Theformulawiththeyttriumadditionsshowedrecrystallizationpeaksathighertemperaturesthanachievedwithotherformulae,corroboratingthefactthatyttriumadditionsdoindeedpromotethermalstabilityandglassformability.Someformulaeexhibitedasecondrecrystallizationprocessatahighertemperaturethanthe?rst,withtitanium-andzirconium-basedformulationsshowingtheseprocessesatthehighesttemperatures.Allthe‘‘as-cast’’amorphousmetalformulaeproducedbytheHPCRMTeamexhibitedhardnessfarsuperiortomanyoftheconventionalmaterialsofinterest,suchasType316Lstainlesssteelandnickel-basedN06022(AlloyC-22).Thus,coatingsofthesematerialswouldalsobeexpectedtobelesspronetoerosion,wear,andgougingthancon-ventionalengineeringalloys.Partiallydevitri?edsamplesoftheHPCRMmaterialsexhibiteddramaticincreasesinhardness.Thus,carefullycontrolledheattreatmentofthesematerialscanbeusedtoachievedramaticimprove-mentsinresistancetoerosion,wear,andpenetration.ThermalSprayProcess

Severalthermalsprayprocesseshavebeendevelopedbyindustryandinclude?amespray,wire-arc,plasmaspray,water-stabilizedplasmaspray,HVOF,anddetonationgun.AnyofthesecanbeusedforthedepositionofFe-basedamorphousmetals,withvaryingdegreesofresidualporos-ityandcrystallinestructure.ThecoatingsdiscussedhereweremadewiththeHVOFprocess,whichinvolvesacom-bustion?ameandischaracterizedbygasandparticlevelocitiesthatarethreetofourtimesthespeedofsound(mach3–4).Thisprocessisidealfordepositingmetalandcermetcoatings,whichhavetypicalbondstrengthsof5000–10,000poundspersquareinch(5–10ksi),porositiesoflessthanonepercent(<1%),andextremehardness.Optimizationofthethermalsprayprocessthroughcarefulselectionofpowdersizeandprocesstempera-turehasnowyieldedcoatingsofSAM40(nonoptimizedelementalcoating)thatarevirtuallypore-free,andforallpracticalpurposes,fullydense.Thesenewcoatingarchitectureshavealsobeenshown,throughdetailedexaminationwithX-raydiffraction(XRD)andscanningelectronmicroscopy(SEM),tobeamorphous.Anopti-mizedthermalsprayprocessisnowbeingusedtorenderSAM2X5andSAM1651amorphousmetalformulationsashighperformancecorrosion-resistantcoatings,withnearlyfulldensity,nosigni?cantporosity,andgoodbondstrength.

Itisnoteworthythatceramiccoatings,appliedwiththermalsprayprocessessuchasHVOFdeposition,havebeenpreviouslyinvestigatedasameansofprotectingcon-tainersforthetransportation,aginganddisposalofhighlevelradioactivewastes,andSNF[45–75].Otherapplica-tionsmayincludetunnelboringmachinesandwindmills.

4HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

Energy-DispersiveAnalysiswithX-Rays—CompositionElectronmicroanalysisofMSRswasperformedonaseriesofFe-basedformulationsandonAlloyC-22andType316Lstainlessreferencematerials.SEMwasusedtoimagesuper?cialmicrostructureusingbothsecondaryandbackscatteredelectrondetectors.SemiquantitativeelementalcompositionoftheMSRswasdeterminedwithenergy-dispersiveX-rayspectroscopy(EDS,EDAX).

SegmentsofeachribbonwereimagedusingaQuantaSeries200environmentalscanningelectronmicroscope(ESEM).Imageswereobtainedfrombothsidesoftheribbon,usingbothsecondaryelectronandbackscatteredelectrondetectors.Thesideofeachribbonthathadbeenincontactwiththemelt-spinningcopperwheelwasdistin-guishableasbeingnoticeablyrougherthanthenoncontactside.

Semiquantitativeelementalcompositionwasdeter-minedwithEDS.Compositionalanalysiswasperformedonthesmoothersideofeachribbon,astheroughersideswerefoundinsomecasestobecontaminatedwithsmallamountsofcopper,presumablyfromcontactwiththecopperwheelduringthemelt-spinningprocess.Quanti?cationofthelightelements,suchasboron(B)andcarbon(C),wasfoundtobeunreliableforthesecomplexsampleformulations.Thegiven(formulation)valuesfortheseelementswerethereforeassumedandusedincalculatingthecompositionalvaluesfortheremainingheavierelements.Microanalysisofeachsamplewasper-formedatthreerandomlyselectedlocationsat×10,000magni?cation,withtheaveragebeingreportedhere.X-RayDiffraction—CrystalStructure

ThebasictheoryofXRDofamorphousmaterialsiswelldevelopedandhasbeenpublishedintheliterature[60,76,77].Inthecaseofamorphousmaterials,broadpeaksareobserved.Duringthisstudy,XRDwasdonewithCuKαX-rays,acrystallinegraphiteanalyzer,andaPhilipsverticalgoniometer,usingtheBragg-Brentanomethod.TheX-rayopticswereself-focusing,andthedistancebetweentheX-rayfocalpointstothesamplepositionwasequaltothedistancebetweenthesamplepositionandthereceivingslitforthere?ectionmode.Thus,theintensityandresolutionwereoptimized.Par-allelverticalslitswereaddedtoimprovethescatteringsignal.Stepscanningwasperformedfrom20to90?(2θ)withastepsizeof0.02?at4–10s/point,dependingontheamountofsample.Thesampleswereloadedintolowquartzholdersincetheexpectedintensitywasverylow;thus,requiringthatthebackgroundscatteringbeminimized.ThermalProperties

ThethermalpropertiesoftheseFe-basedamorphousmet-alshavebeendeterminedbyPerepezkoetal.[43].ThermalanalysisoftheseFe-basedamorphousmetals,withdif-ferentialscanningcalorimetry(DSC)orDTA,alloweddeterminationofimportantthermalpropertiessuchasglasstransitiontemperature(Tg),crystallizationtem-perature(Tx),andmeltingpoint(Tm).Resultsfromthe

thermalanalysisofamorphoussamplesprovidedinitialassessmentoftheglass-formingabilityofthesematerialsthroughconventionalmetrics,suchasthereducedglasstransitiontemperature(Trg=Tg/TL).MechanicalProperties

Aspreviouslydiscussed,hardnessdetermineswearresis-tance,aswellasresistancetoerosion–corrosion.Vickersmicrohardness(HV)wasthestandardapproachusedbyBranaganandotherstoassessthehardnessofthesethermalspraycoatings[72].A300-gloadwasusedsinceitwasbelievedthatthisloadandtheaffectedareawerelargeenoughtosampleacrossanyexistingmacroporosity,therebyproducingaspatiallyaveragedmeasurement.Microhardnessmeasurementswerealsomadewitha100-gloadsinceitwasbelievedthatthisloadandtheaffectedareaweresmallenoughtoaccuratelysamplebulkmaterialproperties.Microhardnessmeasurementsmadewiththe100-gloadwere1050–1200kg/mm2(HVN)foras-sprayedHVOFcoatingsand1300–1500kg/mm(HVN)formaterialsthatwereannealed700?Cfor10mintoinducedevitri?cation.Microhardnessmeasurementsmadewiththe100-gloadwere1050–1200kg/mm(HVN)foras-sprayedHVOFcoatings;and1300–1500kg/mm(HVN)formaterialsthatwereannealed700?Cfor10mintoinducedevitri?cation.Theincreaseinhardnesswithdevitri?cationisattributedtotheformationofcrystallineprecipitates.

EnvironmentsUsedforCorrosionTesting

Inadditionofnaturalseawaterand3.5-molalsodiumchlo-ridesolutions,severalstandardizedtestsolutionshavebeendevelopedbasedonastandardwell-watercompo-sitiondeterminedbyHarraretal.andbelievedtoberepresentativeofgroundwatersclosetoaproposednuclearwasterepository[78].Relevanttestenvironmentsareassumedtoincludesimulateddilutewater(SDW),sim-ulatedconcentratedwater(SCW),andsimulatedacidicwater(SAW)at30,60,and90?C,respectively.Thecom-positionsofalltheenvironmentsaregiveninTable1.ThecompositionsofthesetestmediaarebasedontheworkofGdowskietal.[79–81].

SaltfogtestswereconductedaccordingtothestandardGeneralMotors(GM)saltfogtest,identi?edasGM9540P,oranabbreviationofthattest[82].TheprotocolforthistestissummarizedinTable2.Referencesamplesincluded1018carbonsteel,Type316Lstainlesssteel,nickel-basedAlloyC-22,TiGrade7,andthe50:50nickel–chromiumbinary.

CYCLICPOLARIZATION—PASSIVEFILMSTABILITYSpontaneousbreakdownofthepassive?lmandlocalizedcorrosionrequirethattheopen-circuitcorrosionpotential(OCP)exceedthecriticalpotential[83–86]

Ecorr≥Ecritical.

(3)

Theresistancetolocalizedcorrosionisquanti?edthroughmeasurementoftheOCP(Ecorr),thebreakdown

Table1.CompositionofConcentratedBrineTestMediaBasedonStandardWellWaterIonSDW(mg/L)

SCW(mg/L)SAW(mg/L)K+13434003400Na+140940,90040,900Mg+2111000Ca+2111000F?1141,4000Cl?16767006700NO3?16464006,400SO4?216716,70016,700HCO3?1Si(60?94770,0000C)272727Si(90?C)494949pH

8.1

2.7

Source:JournalofNuclearTechnology—Farmeretal.—Table5.AdaptedfromRef.47.

Table2.TheStandard24-hTestCyclefortheGM9540PSaltFogTestShift

ElapsedTime(h)

Event

Ambientsoak

Saltsolutionmistfor30s,followedbyambientexposure?at13–28?C(55–82F)

1.5

Saltsolutionmistfor30s,followedbyambientexposureat13–28?C(55–82?F)

4.5

Saltsolutionmistfor30s,followedbyambientexposureat13–28?C(55–82?F)Wetsoak8–16

Highhumidityexposurefor8hat49±0.5?C(120±1?F)and100%RH,includinga55-minramptowetconditionsDrysoak16–24

Elevateddryexposurefor8hat60±0.5?C(140±1?F)andlessthan30%RH,includinga175-minramptodryconditions

Notethatthesaltsolutionmistsconsistedof1.25%solutioncontaining0.9%sodiumchloride,0.1êlciumchloride,and0.25%sodiumbicarbonate.Source:JournalofNuclearTechnology—Farmeretal.—Table4.AdaptedfromRef.47.

potential(Ecritical),andtherepassivationpotential(Erp).ThegreaterthedifferencebetweentheOCPandtherepassivationpotential(??E),themoreresistantamaterialistomodesoflocalizedcorrosionsuchaspittingandcrevicecorrosion.Inintegratedcorrosionmodels,generalcorrosionisinvokedwhenEcorrislessthanEcritical(Ecorr

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

whenEcorrexceedsEcritical[83].Thedataprovidedinthispublicationaresuf?cienttoestablishwhengeneralandlocalizedcorrosionoccur,andtheratesofgeneralcorrosionarewhengeneralcorrosionisinvoked.Notethatthesedataonlyapplyfortheenvironmentsexploredduringtesting.

Cyclicpolarization(CP)isusedasameansofmea-suringthecriticalpotential(Ecritical)ofcorrosion-resistantmaterials,relativetotheirOCP(Ecorr).Inthepublishedscienti?cliterature,differentbasesexistfordeterminingthecriticalpotentialfromelectrochemicalmeasurements.Thecriticalpotentialisfrequentlyde?nedasthepointwherethepassivecurrentdensityincreasesduringtheforward?6(anodic)scantoalevelbetween1and10μA/cm2(10–10?5A/cm2).Alternativede?nitionsoftherepassi-vationpotentialareused.Onede?nitionisthepointduringthereverse(cathodic)scanwherethecurrentdensitydropstoalevelindicativeofpassivity,which7isassumedtobebetween0.1and1μA/cm2(10?6–10?A/cm2).Analterna-tivede?nitionisthepointwheretheforwardandreversescansintersect,apointwherethecurrentdensitybeingmeasuredduringthereversescandropstoalevelknowntobeindicativeofpassivity.Theseauthorspreferthelatterde?nition.

De?nitionsofthethresholdandrepassivationpoten-tialsvaryfrominvestigatortoinvestigator.Grussetal.de?netherepassivationpotentialasthepointwherethecurrentdensitydropsto10?6–10?7A/cm?2[84].Scullyetal.de?nethethresholdpotentialforcrevicecorrosionofAlloy22asthepointduringthescanofelectrochemi-calpotentialintheforwarddirectionwherethecurrentdensityincreasestoalevelof10?6–10?5A/cm?2.Scullyetal.generatedCPdatawithverytightcrevicesandcon-centratedelectrolytesconsistingof5MLiCl,0.024–0.24MNaNO3,and0.026–0.26MNa2SO4andHCl[85].Testingwasconductedattwotemperaturelevels,80and95?C.Thecreviceswereformedwithamultiplecreviceformer,PTFEtape,andanappliedtorqueof70in.pounds.Underthesecircumstances,someelectrochemicalactivityindicativeofcrevicecorrosionwasobservedatpotentialsrangingfrom71to397mVversusAg/AgCl,dependingonthecomposi-tionoftheelectrolyte.Usingacurrentdensitycriterionforrepassivationof10?5A/cm2,repassivationpotentialsweredeterminedtobeslightlyabove,butrelativelyclosetotheOCP.

CPmeasurementshavebeenbasedonaproceduresim-ilartoASTM(AmericanSocietyforTestingandMaterials)G5standardwithslightmodi?cation[87–90].TheASTMG5standardcallsfora1NH2SO4electrolyte,whereassyntheticbicarbonate,sulfate–chloride,chloride–nitrate,andchloride–nitratesolutions,withsodium,potassium,andcalciumcations,aswellasnaturalseawaterhavebeenusedforthisinvestigation.Thechlorideanionpro-motespassive?lmbreakdown,whilethenitrateservesasaninhibitor.Furthermore,theASTMG5standardcallsfortheuseofdeaeratedsolutions,whereasaeratedanddeaeratedsolutionswereusedhere.Aftera24-hholdperiod,duringwhichtheOCPisdetermined,thepoten-tialisscannedinthepositive(anodic)directionfromalevelslightlymorenegativethanthecorrosionpotential(cathodiclimit)toareversalpotential(Erev)nearthat

6HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

requiredforoxygenevolution(anodiclevel).Duringthepositivescan,anodicoxidationpeaksmaybeobserved(centeredatEpeak)thathavebeencorrelatedwiththeoxi-dationofmolybdenumatthealloysurface(passive?lm),aswellascurrentexcursionsthatareusuallyassociatedwithbreakdownofthepassive?lm.Duringthenegative(cathodic)scan,ahysteresisloopwillbeobservedincaseswherepassivityhasbeenlost.Asthescancontinues,thecurrentdensitymayeventuallydecreasetoalevelequiv-alenttothatexperiencedduringthepositivescanandindicativeofreformationofthepassive?lm.Thepoten-tialatwhichthisoccursisknownastherepassivationpotential(Erp).

Temperature-controlledborosilicateglass(Pyrex)elec-trochemicalcellswereusedforCPandothersimilarelectrochemicalmeasurements.Thiscellhasthreeelec-trodes,aworkingelectrode(testspecimen),therefer-enceelectrode,andthecounterelectrode.Astandardsilver-silver-chlorideelectrode,?lledwithnear-saturationpotassiumchloridesolution,isusedasthereferenceandcommunicateswiththetestsolutionviaaLugginprobeplacedincloseproximitytotheworkingelectrode,therebyminimizingOhmiclosses.Numericalcorrectionsforthereferenceelectrodejunctionpotentialhavebeenestimatedandhavebeenfoundtobeinsigni?cant[82].Theelectro-chemicalcellisequippedwithawater-cooledjunctiontomaintainreferenceelectrodeatambienttemperature,therebymaintainingintegrityofthepotentialmeasure-ment,andawater-cooledcondensertopreventthelossofvolatilespeciesfromtheelectrolyte.AllpowdersusedtoproducethesecoatingswereproducedbyTheNanoS-teelCompany(TNC),andtheHVOFcoatingsusedtogeneratethedatainthispublicationwereproducedbyPlasmaTechnologyIncorporated(PTI).Syntheticbrinesolutions(5MCaCl2andothers)werepreparedatLLNLwithreagent-gradechemicalsanddeionizedwater.ThenaturalseawaterusedinthesetestswasobtaineddirectlyfromHalfMoonBayalongthenortherncoastofCaliforniaandwastransportedtothelaboratoryinacleanpolyethy-lenecontainer.ThisHalfMoonBayseawaterisreferredtoasnaturalseawaterinthispublication.

CPofMSRswasfurtherusedtocomparetherelativecorrosionresistanceofalargenumbercandidatealloycompositionsinnear-boilingnaturalseawaterat90?C.ThedifferencebetweentheOCP(Ecorr)andtherepassivationpotential(Erp)wasusedasabasisofcomparisonfortherelativecorrosionperformanceofcandidatealloys.Severalofthecandidatealloycompositionshadalargermetricvalue(Erp?Ecorr)thanthereferencematerial,whichhasbeenestablishedasnickel-basedAlloyC-22,owingtoitsownoutstandingcorrosionperformance.Duringthisearlyphaseofthestudy,itwasconcludedthatseveraltypesofiron-basedamorphousmetalsexistwhichallhavepassive?lmstabilitiesinseawaterat30and90?CthatarecomparabletothatofType316stainlesssteelandnickel-basedAlloyC-22.

PotentiostaticStep—ThresholdforPassiveFilmBreakdownPotentiostaticsteptestshavebeenusedtodeterminethepotentialatwhichthepassive?lmbreaksdownonthe

referencematerial,AlloyC-22,andonthetwoamorphousmetalsofprimaryinterest,SAM2X5andSAM1651.Dur-ingprolongedperiodsofataconstantappliedpotential(potentiostaticpolarization),whicharetypically24hinduration,thecurrentismonitoredasafunctionoftime.Incaseswherepassivityislost,thecurrentincreases,andthetestsampleisaggressivelyattacked.Incaseswherepassivityismaintained,thecurrentdecaystoarelativelyconstantasymptoticlevel,consistentwiththeknownpas-sivecurrentdensity.Inthesetests,periodsofpolarizationareprecededby1hattheOCP.

Allweretestedinnaturalseawaterheatedto90?C.Toeliminatetheneedforsurfaceroughnesscorrectionsintheconversionofmeasuredcurrentandelectrodeareatocurrentdensity,theSAM2X5coatingswerepolishedtoa600-grit?nishbeforetesting.Aconstantpotentialwasappliedafter1hattheOCP.

RelationshipbetweenThermalPhaseStabilityandCorrosionResistance

Toassessthesensitivityoftheseiron-basedamorphousmetalstodevitri?cation,whichcanoccuratelevatedtemperature,MSRsofFe-basedamorphousmetalswereintentionallydevitri?edbyheattreatingthematvarioustemperaturesfor1h.Afterheattreatment,thesampleswereevaluatedinlowtemperatureseawater(30?C)todeterminetheimpactoftheheattreatmentonpassive?lmstabilityandcorrosionresistance.Thetemperaturesusedfortheheattreatmentwere150,300,800,and1000?C.Untreated(asreceived)ribbonswerealsotestedandpro-videinsightintothebaselineperformance.DeterminingCorrosionRatewithLinearPolarizationThelinearpolarizationmethodwasusedasamethodfordeterminingtheapparentcorrosionratesofthevariousamorphousmetalcoatings.Theprocedureusedforlin-earpolarizationtestingconsistedofthefollowingsteps:(i)holdingthesamplefor10sattheOCP;(ii)beginningatapotential20mVbelowtheOCP,increasingthepotentiallinearlyataconstantrateof0.1667mV/stoapotential20mVabovetheOCP;(iii)recordingthecurrentbeingpassedfromthecounterelectrodetotheworkingelectrodeasafunctionofpotentialrelativetoastandardAg/AgClreferenceelectrode;and(iv)determiningtheparametersinthecathodicTafellinebyperforminglinearregres-siononthevoltage–currentdata,from10mVbelowtheOCPto10mVabovetheOCP.Theslopeofthislinewasthepolarizationresistance,Rp(ohms),andwasde?nedinthepublishedliterature[91].WhilenovaluesfortheTafelparameter(B)ofFe-basedamorphousmetalshaveyetbeendeveloped,itwasbelievedthataconservativevalueofapproximately25mVwasreasonable,basedontherangeofpublishedvaluesforseveralFe-andNi-basedalloys.Thecorrosioncurrentdensitywasthende?nedintermsofB,Rp,andA,theactualexposedareaofthesamplebeingtested.

??RE??

??I.

(4)

Ecorr

Theparameter(B)wasde?nedintermsoftheslopesoftheanodicandcathodicbranchesoftheTafelline:

βaβc

2.303(β.

a+βc)

(5)

ValuesofBwerepublishedforavarietyofiron-basedalloysandvariedslightlyfromonealloy–environmentcombinationtoanother.Forexample,valuesforcarbonsteel,aswellasType304,304L,and430stainlesssteels,inavarietyofelectrolytesthatincludeseawater,sodiumchloride,andsulfuricacid,rangedfrom19to25mV.Avaluefornickel-basedAlloy600inlithiatedwaterat288?Cwasgivenasapproximately24mV.WhilenovalueshaveyetbeendevelopedfortheFe-basedamorphousmetalsthatarethesubjectofthisinvestigation,itwasbelievedthataconservativerepresentativevalueofapproximately25mVwasappropriatefortheconversionofpolarizationresistancetocorrosioncurrent.GiventhevalueforAlloy600,avalueof25mVwasalsobelievedtobeacceptableforconvertingthepolarizationresistancefornickel-basedAlloyC-22tocorrosioncurrent.

ThegeneralcorrosionratewascalculatedfromthecorrosioncurrentdensitythroughapplicationofFaraday’sLaw.Thecorrosioncurrent,Icorr(A),wasthende?nedas:

Icorr=

BR,(6)

wheretheparameterBwasconservativelyassumedtobe

approximately25mV.Thecorrosioncurrentdensity,Icorr(A/cm),wasde?nedasthecorrosioncurrent,normalizedbyelectrodearea,A(cm2).Thecorrosion(orpenetration)ratesoftheamorphousalloyandreferencematerialswerecalculatedfromthecorrosioncurrentdensitieswiththefollowingformula,whichissimilartothatgivenbyJones[92]:

dpicorrdt=ρ,(7)

alloynalloyF

wherepwasthepenetrationdepth,twastime,icorrwasthecorrosioncurrentdensity,ρalloywasthedensityofthealloy(g/cm3),nalloywasthenumberofgramequivalentspergramofalloy,andFwasFaraday’sconstant.Thevalueofnalloywascalculatedwiththefollowingformula:

n????falloy=

jnj??

a,(8)

wherefjwasthemassfractionofthejthalloyingelementinthematerial,njwasthenumberofelectronsinvolvedintheanodicdissolutionprocess,whichwasassumedtobecongruent,andajwastheatomicweightofthejthalloyingelement.Congruentoxidationordissolutionwasassumed,whichmeantthatthedissolutionrateofagivenalloyelementwasassumedtobeproportionaltoitsconcentrationinthebulkalloy.Theseequationswereusedtocalculatefactorsfortheconversionofcorrosioncurrentdensitytothecorrosionrate.Theconversionfactorsforconvertingcorrosioncurrentdensitytocorrosionrateareapproximately6.38–10.7μmcm2/μA/yearforType316L

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS7

stainlesssteel,5.57–9.89μmcm2/μA/yearforAlloyC-22,and5.39–7.89μmcm2/μA/yearforSAM2X5,dependingontheexactcompositionofeachalloywithinthespeci?edranges.

EffectsofJunctionPotentialonElectrochemicalMeasurements

Itisimportanttounderstandthemagnitudeoftheerrorinthepotentialmeasurementsduetothejunctionpotential.AcorrectionhasbeenperformedbasedontheHendersonEquation,aspresentedbyBardandFaulkner[93].

??|zi|ui??

C(β)?C(α)????|zi|uiCi(α)Ej=??izi

ii|z????RTln??i

i|uiCi(β)?Ci(α)F

|z,(9)

i|uiCi(β)i

whereEjisthepotentialacrossthejunctionconnecting

theαandβphases,ziisthevalenceoftheithion,uiisthemobilityoftheithion,Ci(α)istheconcentrationoftheithionintheαphase,Ci(β)istheconcentrationoftheithionintheβphase,Ristheuniversalgasconstant,Tistheabsolutetemperature,andFisFaraday’sconstant.Thecalculatedjunctionforseveraltestsolutionshasbeenesti-matedwithionicpropertiesusedinthecalculationwerealsotakenfromBardandFaulkner.Thesecorrectionsarenotverylarge,withthelargestbeing<～10mV.ThisvaluecorrespondstothejunctionpotentialforSSWat90?C.Itisconcludedthatinsigni?canterrorresultsfromneglectingtocorrectforthejunctionpotential.

EXPERIMENTALRESULTSCompositionofAmorphousMetals

Themelt-spinningprocesswasusedtoperformasys-tematicstudyofvariouselementalcompositions,eachbasedontheFe-basedDAR40composition,with1,3,5,and7atomicpercentadditionsofspeci?celementsbelievedtobebene?cialtoglassformationorcorrosionresistance.Elementaladditionsinvestigatedincludednickel(Ni),molybdenum(Mo),yttrium(Y),titanium(Ti),zirconium(Zr),andchromium(Cr).Thetwoformula-tionsofgreatestinterestatthepresenttime,basedoncorrosionresistanceandeaseofprocessing,areSAM2X5(Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4),whichhasarelativelyhighCCR,andyttrium-containingSAM1651(Fe48.0Cr15.0Mo14.0B6.0C15.0Y2.0),whichhasarelativelylowCCR.ThenominalcompositionsofthesealloysaresummarizedinTable3.Theactualcompositionsofseveralsamplesusedinthisstudyweredeterminedwithenergy-dispersiveX-rayspectroscopy(EDS)andaresummarizedinTable4.ThemeasurementsweredoneforwroughtsamplesofType316Lstainlesssteelandnickel-basedAlloyC-22;MSRsofSAM40,SAM2X1,SAM2X3,SAM2X5,andSAM2X7;andadrop-castingotofSAM1651.

8HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

Table3.TheMelt-SpinningProcessWasUsedtoPerformaSystematicStudyofVariousElementalCompositions,EachBasedontheFe-BasedSAM40Composition,with1,3,5,and7AtomicPercentAdditionsofSpeci?cElementsBelievedtoBeBene?cialtoGlassFormationorCorrosionResistanceNominalCompositioninAtomicPercent—UsedtoPrepareSamplesAlloy316LC-22SAM40SAM2X1SAM2X3SAM2X5SAM2X7SAM3X1SAM3X3SAM3X5SAM3X7SAM1651

Speci?cation/FormulaUNSS31603UNSN06022

Fe52.3Mn2Cr19Mo2.5W1.7B16C4Si2.5(SAM40)99+Mo1(SAM40)97+Mo3(SAM40)95+Mo5(SAM40)93+Mo7(DAR40)99+Y1(DAR40)97+Y3(DAR40)95+Y5(DAR40)93+Y7

Fe48Mo14Cr15Y2C15B6

Fe68.04.052.351.850.749.748.651.850.749.748.648.0

Cr18.025.019.018.818.418.117.718.818.418.117.715.0

Mn1.50.12.02.01.91.91.92.01.91.91.90.0

Mo1.58.02.53.55.47.49.32.52.42.42.314.0

W0.01.41.71.71.61.61.61.71.61.61.60.0

B*0.00.016.015.815.515.214.915.815.515.214.96.0

C*0.00.04.04.03.93.83.74.03.93.83.715.0

Si1.01.02.52.52.42.42.32.52.42.42.30.0

Y0.00.00.00.00.00.00.01.03.05.07.02.0

Ni10.060.00.00.00.00.00.00.00.00.00.00.0

P*0.00.00.00.00.00.00.00.00.00.00.00.0

Co0.00.50.00.00.00.00.00.00.00.00.00.0

Total100100100100100100100100100100100100

Elementaladditionsinvestigatedincludednickel(Ni),molybdenum(Mo),yttrium(Y),titanium(Ti),zirconium(Zr),andchromium(Cr).Thetwo

formulationsofgreatestinterestatthepresenttime,basedoncorrosionresistanceandeaseofprocessing,areSAM2X5(Fe????.?Cr???.?Mn??.??Mo?.??

W??.??B????.??C??.??Si??.??),whichhasarelativelyhighcriticalcoolingrate(CCR),andyttrium-containingSAM1651(Fe48.0Cr15.0Mo14.0B6.0C15.0Y2.0),whichhasarelativelylowCCR.Source:JournalofMaterialsResearch—Farmeretal.—Table1.AdaptedfromRef.47,49.

Table4.TheActualCompositionsofSeveralSamplesUsedinThisStudyWereDeterminedwithEnergy-DispersiveX-RaySpectroscopy(EDS)

ActualCompositionsinAtomicPercent—DeterminedbyEnergy-DispersiveX-RaySpectroscopyAlloy316LC-22SAM40SAM2X1SAM2X3SAM2X5SAM2X7SAM3X1SAM3X3SAM3X5SAM3X7SAM1651

Speci?cation/FormulaUNSS31603UNSN06022

Fe52.3Mn2Cr19Mo2.5W1.7B16C4Si2.5(SAM40)99+Mo1(SAM40)97+Mo3(SAM40)95+Mo5(SAM40)93+Mo7(DAR40)99+Y1(DAR40)97+Y3(DAR40)95+Y5(DAR40)93+Y7

Fe48Mo14Cr15Y2C15B6

Fe67.63.951.952.049.348.846.949.149.448.847.349.1

Cr18.725.219.219.117.917.616.919.218.918.417.814.6

Mn1.30.12.62.72.62.42.31.81.71.52.10.0

Mo1.27.82.52.95.37.210.03.13.02.62.513.9

W0.01.41.51.62.52.52.53.02.82.62.60.0

B*0.00.016.015.815.515.014.915.815.515.214.95.9

C*0.00.04.04.03.83.73.74.03.93.83.714.0

Si1.21.12.21.93.12.72.92.91.92.22.20.3

Y0.00.00.00.00.00.00.01.02.94.86.81.9

Ni10.060.00.00.00.00.00.00.00.00.00.00.2

P*0.00.00.00.00.00.00.00.00.00.00.00.0

Co0.00.50.00.00.00.00.00.00.00.00.00.0

Total100100100100100100100100100100100100

ThemeasurementsweredoneforwroughtsamplesofType316Lstainlesssteelandnickel-basedAlloyC-22;meltspunribbonsofSAM40,SAM2X1,SAM2X3,SAM2X5,andSAM2X7;andadrop-castingotofSAM1651.

STRUCTURALCHARACTERIZATIONOFMELTSPUNRIBBONS

MSRspreparedbyTNCwerecharacterizedwithXRDbyLLNLandotherinstitutions.DiffractionpatternsofMSRsofAlloyC-22andType316Lstainlesssteelshowedthatthesesampleswereindeedcrystallineandthatthemelt-spinningprocesscouldnotcapturethemetastableglassystateforthesecompositions.Figure2showsXRDdataforMSRsamplesofiron-basedamorphousmetalsidenti?edas:SAM40,SAM2X1,SAM2X3,SAM2X5,SAM2X7,SAM6,SAM7orSAM1651,andSAM8.Allribbonswerecompletelyamorphous.Thesedatawereindicativeofamorphousstructure,andacompletelackofcrystallinestructure,whichwasattributedtothe

relativelyhighconcentrationsofboron,andacoolingrateabovetheCCR.

HARDNESS

Suchmaterialsareextremelyhard,andprovideenhancedresistancetoabrasionandgouges(stressrisers)fromback?lloperations,andpossiblyeventunnelboring.ThehardnessofType316LStainlessSteelisapproximately150VHN,thatofAlloyC-22isapproximately250VHN,andthatofHVOFSAM2X5rangesfrom1100–1300VHN[25].SAM2X5andSAM1651coatingscanbeappliedwiththermalsprayprocesseswithoutanysigni?cantlossofcorrosionresistance.

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS9

2500200015001000500020

502θ

SAM8 ~ SAM1651 + WSAM7 ~ SAM1651SAM6SAM2X7SAM2X5SAM2X3SAM2X1SAM40

Figure2.This?gureshowsX-raydiffrac-tiondatafortheSAM2Xseriesofmeltspunribbon(MSR)samples.Source:Metallurgi-calandMaterialsTransactionsA—Farmeretal.—Fig.3.AdaptedfromRef.8.

Counts(a)

(b)

25 μm

Figure3.Thesescanningelectronmicrographsofgas-atomizedSAM1651(SAM7)powdershowtheasymmetricnonsphericalmorphology,whichresultsfromtheincreasedmeltviscositywiththerareearth(yttriumaddition).

GASATOMIZEDPOWDERS

Scanningelectronmicrographsofgas-atomizedSAM1651(SAM7)powderinFig.3showtheasymmetricnonspher-icalmorphology,whichresultsfromtheincreasedmelt

viscositywiththerareearth(yttriumaddition).Thisirregularpowdermorphologycomplicatesthepneumaticconveyanceofthepowderinthermalsprayprocessesandmakesthermalspraydepositionrelativelydif?cult.Aresearcheffortisunderwaytorenderthisformulationasasphericalpowderthatcan?owmoreeasily.Insharpcontrast,electronmicrographsfortwolotsofSAM2X5powderproducedoveraspanoftwoyearsareshowninFig.4:(i)Lot#04-265and(ii)Lot#06-123.Thesepow-dershavepredominantlysphericalmorphology,whichisessentialforgood?owcharacteristicsinthermalsprayprocesses.

Theabsenceofcrystallinestructureisgenerallybelievedtobeonefactorthatcontributestothecorrosionresistanceofamorphousalloys.Acorrelationhasbeenobservedbetweentheformationofsubstantialamountsofdeleteriouscrystallinephases,suchasferrite,inFe-basedamorphousmetals,andthesusceptibilitytocor-rosioninchloride-containingenvironments.Acompletelyamorphouscoatingrequiresthatthestartingfeedpowderbecompletelyamorphous,notingthatthepowdersaresoftenedandnotmeltedduringspraying.Thecrystallinestructureofpowderscanvarywithparticlesize,sincedifferentcoolingratesareexperiencedbyparticleswithdifferentsizes.

AcomparisonoftheXRDdata(intensityversesdiffrac-tionangle2θ)forseverallotsofSAM2X5amorphousmetalpowderisshowninFig.5andrevealstherelationshipbetweenparticlesizedistributionandprocessingcondi-tionstotheformationofdevitri?edmicrostructure.Duringgasatomization,thepowderlotswithsmallparticlesizes(Lots#04-191and04-199)cooledatarateabovetheCCRandthereforemaintainedanamorphousmicrostruc-ture.Theparticlesizescoveredbythesetwolotsofpowderwerebelow30μm.However,largerparticlescooledslower,andwithsomepointswithintheparticlescoolingbelowtheCCR,therebycausinglocalizeddevitri?cation(Lots#04-200and#04-193).Theparticlesizescoveredbytheselotsofpowderwereabove30μm.Attemptstoremeltandgasatomizethisformulationcausedevitri?cationinpowdersofallparticlesizeandarethereforeundesirable(Lot#05-079).

10HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

(a)

(b)

Figure4.ElectronmicrographsareshownfortwolotsofSAM2X5powderproducedoveraspanoftwoyears:(a)Lot#04-265and(b)Lot#06-123.Thesepowdershavepredominantlysphericalmorphology,whichisessentialforgood?owcharacter-isticsinthermalsprayprocesses.

CharacterizationofThermalSprayCoatingsUsedinTesting—SAM2X5

Severalgenerictypesofthermalspraycoatingshavebeenproduced,characterization,andtested,asshowninFig.6.Withoutadequatecontrol,thermalspraycoatingsproducedwithamorphouspowdersmaydevelopsubstantialresidualcrystallinestructure(RCS).XRDdata(intensityvs.diffractionangle2θ)foraSAM2X5(Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4)HVOF(HVOFcoating)ona316LstainlesssteelsubstrateandpreparedwithaJP5000thermalspraygunisshowninFig.7.Thiscoatingisidenti?edasE316L463,showssubstantialRCS,andwaspreparedwithLot#04-265powder,whichalsohadsubstantialRCSandarelativelybroadrangeofparticlesizes(?53/+15μm).Similarly,XRDdataforaSAM2X5HVOFcoatingdepositedon316LwithaJK2000thermalspraygunatPTIisshowninFig.8.Thiscoatingisidenti?edasE316L329,showsevenmoreRCS,andwaspreparedwithLot#04-200powder,whichalsohad

substantialRCSandarelativelycoarserangeofparticlesizes(?53/+30μm).Thediffractionpeaksareduetofourprimarycrystallinephasesthatformintheamorphousmetalpowderduringdevitri?cation:(i)Cr2B,(ii)M23C6,(iii)bccferrite,and(iv)WC.AthirdSAM2X5HVOFcoating-deposited316LwithaJK2000gunatPTIisshowninFig.9andhadlittleornoRCS.Thiscoatingisidenti?edasE316L504,showslittleornoRCS,andwaspreparedwithLot#04-199powder,whichhadalmostnotRCSandarelatively?nerangeofparticlesizes(?30/+15μm).ThermalProperties

ThethermalpropertiesoftheseFe-basedamorphousmetalshavebeendeterminedbyPerepezkoetal.[43].SAM3X1hasaglasstransitiontemperatureof～560?C,acrystallizationtemperatureof～614?C,ameltingpointof～1108??C,andareducedglasstransitiontemperatureof～0.52C.SAM3X5,whichhassigni?cantlymoreyttriumthan?SAM3X1,hasaglasstransitiontemperatureof～590C,acrystallizationtemperatureof～677?C,ameltingpointof～1143??C,andareducedglasstransitiontemperatureof0.52C.Incontrast,theyttrium-containingSAM1651(SAM7)formulationhasaglasstransitiontemperatureof～584?C,acrystallizationtemperatureof～653?C,ameltingpointof～1121?C,andareducedglasstransitiontemperatureof～0.55?C.TheCCRofSAM1651hasbeendeterminedtobe≤80K/s,whichissigni?cantlylessthanothercorrosion-resistantiron-basedamorphousmetalssuchasSAM2X5.

SAM2X5hasaglasstransitiontemperatureof～579?C,acrystallizationtemperatureof～628?C,ameltingpointof～1133?C,andareducedglasstransitiontemperatureof～0.57?C(withavalueof0.6beingideal).SAM2X7,analloyinthesamefamilyasSAM2X5,hasaglasstransitiontemperature?of～573?C,acrystallizationtem-peratureof～630C,ameltingpointof～1137?C,andareducedglasstransitiontemperatureof0.57?C.Incon-trast,theyttrium-containingSAM1651formulationhasaglasstransitiontemperature?of～584?C,acrystallizationtemperatureof～653C,ameltingpointof～1121?C,andareducedglasstransitiontemperatureof～0.55.TheCCRsforSAM2X7andSAM1651havebeendeterminedtobe～610and≤80K/s,respectively.Clearly,theyttriumaddi-tionsinSAM1651enhanceglass-formingabilityofthesematerials.ThedatafortheSAM2XalloysisgiveninTable5andanexample.CYCLICPOLARIZATION

CPdataforthreedrop-castingotsofSAM1651Fe-basedamorphousmetalwithyttriuminthreedifferentenviron-mentsisshowninFig.10:seawaterat90?C,3.5-molalNaClat90?C,and5MCaCl2at105?C.AllthreeCPcurvesshowoutstandingpassivity.CPdataforawroughtprismofnickel-basedAlloyC-22,adrop-castingotofFe-basedSAM1651amorphousmetal,andanMSRofSAM8(SAM1651?+3at%tungsten),allobtainedwith5MCaCl2at105CisshowninFig.11.BoththeSAM1651andtheSAM8showedpassive?lmstabilitycomparableto

16HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

Potentiostatic polarization for

24 h at OCP + 1000 mV in seawater at 90°C

1.0E?03

Wrought Ni-based Alloy C-22 (CC-22 4010)SAM2X5 melt spun ribbonSAM2X5 HVOF coating ?53/+30 μm (E316L497)SAM2X5 HVOF coating ?30/+15 μm (E316L503)Alloy C-221.0E?05

SAM2X5 HVOF fine powder1.0E?04Current density (A/cm2)Figure15.Transientsincurrentdensityataconstantappliedpotentialof1000mVver-susOCPforwroughtAlloyC-22(referencematerial),afullydenseandcompletelyamor-phousmeltspunribbon(MSR)ofSAM2X5,HVOFcoatingspreparedwith?53/+30μmpowdersofSAM2X5,andHVOFcoatingspreparedwith?30/+15μmpowdersofSAM2X5,allinnaturalseawaterheatedto90?C,arecompared.Source:JournalofMaterialsResearch—Farmeretal.—Fig.8.AdaptedfromRef.49.

1.0E?06

1.0E?07

SAM2X5 MSR1.0E?08

0.E+002.E+04SAM2X5 HVOF coarse powder4.E+046.E+048.E+041.E+05

Time (s)

Potentiostatic polarization for

24 h at OCP + 1200 mV in seawater at 90°C

1.0E?03

Alloy C-221.0E?04Current density (A/cm2)SAM2X5 HVOF coarse powder1.0E?05

SAM2X5 HVOF fine powder1.0E?06

Figure16.Transientsincurrentden-sityataconstantappliedpotentialof1200mVversusOCPforwroughtAlloyC-22(referencematerial),afullydenseandcompletelyamorphousmeltspunribbon(MSR)ofSAM2X5,HVOFcoat-ingspreparedwith?53/+30μmpow-dersofSAM2X5,andHVOFcoatingspreparedwith?30/+15μmpowdersofSAM2X5,allinnaturalseawaterheatedto90?C,arecompared.Source:JournalofMaterialsResearch—Farmeretal.—Fig.9.AdaptedfromRef.49.

1.0E–07

SAM2X5 MSR1.0E?08

0.E+00

Wrought Ni-based Alloy C-22 (CC-22 4010)SAM2X5 melt spun ribbonSAM2X5 HVOF coating ?53/+30 μm (E316L497)SAM2X5 HVOF coating ?30/+15 μm (E316L503)4.E+04

Time (s)

6.E+04

8.E+04

1.E+05

2.E+04

wroughtAlloyC-22wasmaintainedatappliedpotentialsbelowapproximately250mVversusAg/AgCl,thepointatwhichadramaticchangeinslopewasobserved.Sim-ilarly,itwasconcludedthatstabilitiesofpassive?lmsonSAM2X5thermalspraycoatingsweremaintainedatappliedpotentialsbelowapproximately900mVversusAg/AgCl.Thestabilityofthepassive?lmontheSAM2X5MSRwasmaintainedatappliedpotentialsbelowapprox-imately1200mVversusAg/AgCl.Passive?lmsontheSAM2X5samplesexhibitedbetterstabilitythanthoseonAlloyC-22.Thesedataenabledaclearandunambiguousdeterminationofthethresholdpotentialsforpassive?lmbreakdowninanoncrevicedcondition.

TheeffectofpowdersizeonthecorrosionperformanceofFe-basedamorphousmetalcoatingswasstudied.Coat-ingspreparedwithcoarse(?53/+30μm)powdersmayhavesurfacefeaturesmorelikefullydense,MSRsthandidcoatingspreparedwithrelatively?ne(+30/+15μm)pow-ders.Inpotentialstepexperimentswiththeapplicationof900,1000,1100,1200,1300,and1400mVversusOCP,thepassive?lmoncoatingspreparedwith?ne(+30/+15μm)powdersexhibitedcurrentdensitytransients,whichindi-catedperiodiclossesofpassivity,withinterveningperiodsofrepassivation.Suchtransientwasnotobservedwithcoatingspreparedwithcoarser(?53/+30μm)powders.Thepassive?lmonnickel-basedAlloyC-22startedtodestabilizeat900mVversusOCP,whereaspassive?lmstabilityofMSRsofSAM2X5wasmaintainedatanappliedpotentialof1500mVandlostat1600mV.InthecaseofthethermalspraycoatingsofSAM2X5preparedwithrela-tivelycoarsepowder,thepassive?lmmaintainedstabilityat1400mVversusOCPbutloststabilityat1500mV.In

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS17

1.E?021.E?03

15001.E?04Current density (A/cm2)Potentiostatic polarization of SAM2X5 (?30/+15) for

24 h (each step) in seawater at 90°C

7001.E?051.E?061.E?07

100 mV versus OCP1.E?081.E?091.E?10

010,00020,00030,00040,00050,000Time (s)

60,00070,00060080,00090,000Figure17.Transientsincurrentdensityatvariouslevelsofconstantappliedpotentialrangingfrom100to1500mVversusOCPforarecentlyoptimizedSAM2X5HVOFcoating(?30/+15μmpowder)indeaeratednaturalseawaterat90?Careindicativeofgoodpassive?lmstability.Source:JournalofMaterialsResearch—Farmeretal.—Fig.10.AdaptedfromRefs5,49.

Potentiostatic polarization of SAM2X5 (?53/+30) for

24 h (each step) in seawater at 90°C

1.E?021.E?03

1500Current density (A/cm2)1.E?041.E?051.E?061.E?07

5001.E?081.E?091.E?10

010,00020,00030,00040,00050,00060,00070,00080,00090,000Time (s)

100 mV versus OCP800Figure18.Transientsincurrentdensityatvariouslevelsofconstantappliedpoten-tialrangingfrom100to1500mVversusOCPforarecentlyoptimizedSAM2X5HVOFcoating(?53/+30μmpowder)innaturalseawaterat90?Careindicativeofexceptionalpassive?lmstability.Source:JournalofMaterialsResearch—Farmeretal.—Fig.11.AdaptedfromRefs38,49.

1400thecaseofthethermalspraycoatingsofSAM2X5pre-paredwiththerelatively?nepowder,theonsetofpassive?lmdestabilizationwasobservedat900mVversusOCP.Potentialsteptestingindeaeratedseawaterheatedto90?ChasbeenperformedwithSAM1651(SAM7)andAlloyC-22thermalspraycoatings,aswellaswroughtAlloyC-22.ThenaturalseawaterusedinthesetestswasobtaineddirectlyfromHalfMoonBayalongthenorth-erncoastofCalifornia.Testswerealsoperformedonthereferencematerial,AlloyC-22,inbothwroughtandthermallysprayedcondition.Toeliminatetheneedforsurfaceroughnesscorrectionsintheconversionofmea-suredcurrentandelectrodeareatocurrentdensity,theSAM1651(SAM7)coatingwaspolishedtoa600-grit?n-ishbeforetesting.TheAlloyC-22thermalspraycoatingwastestedintheas-sprayedcondition,soaroughnessfactormustbeappliedtoconverttheapparentcurrentdensityintoactualcurrentdensity.Thecurvesrepresenttheasymptoticcurrentdensityreachedafter24hatthecorrespondingpotential.Inthisseriesofexperiments,thepassive?lmonwroughtAlloyC-22alsocommencesbreakdownatapotentialofapproximately600mVabove

18HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

Comparison of corrosion resistance of

SAM2X5 HVOF coatings and melt spun ribbon to

Alloy C-22 in seawater at 90°C

1.E?02

1.E?03

Alloy C-221.E?04

SAM2X5 HVOF)2mc1.E?05

/A( ytisne1.E?06

d tnerru1.E?07

CSAM2X5 MSR1.E?08

SAM2X5 HVOF coating ?53/+30 μm (E316L497)1.E?09

SAM2X5 HVOF coating ?30/+15 μm (E316L503)SAM2X5 melt spun ribbonWrought Ni-based Alloy C-22 (CC-22 4010)1.E?10

?0.50.00.51.01.5Potential (V vs Ag/AgCl)

Figure19.PotentialsteptestinghasbeenperformedonwroughtAlloyC-22(referencematerial),fullydenseandcompletelyamor-phousmeltspunribbonsofSAM2X5,optimizedHVOFcoatingspreparedwith?53/+30μmpowdersofSAM2X5,andoptimizedHVOFcoatingspreparedwith?30/+15μmpowdersofSAM2X5.Allweretestedinnaturalseawaterheatedto90?C.Source:Jour-nalofMaterialsResearch—Farmeretal.—Fig.12.AdaptedfromRef.49.

theOCP.Passive?lmbreakdownontheHVOFcoatingofSM1651occurredatanappliedpotentialbetween500and600mV,wherebreakdownoccurredatapproximately400mVfortheAlloyC-22HVOFcoating.Innear-boilingseawater,thepassive?lmstabilityofSAM1651(SAM7)iscomparabletothatofAlloyC-22butinferiortothatofSAM2X5.

EffectsofThermallyDrivenDevitri?cation—AlloyStability—SAM2X5

Theimpactofannealingonthephasestabilityandcor-rosionresistanceoftheamorphousalloysisofgeneralinterest[94].Toassessthesensitivityoftheseiron-basedamorphousmetalstodevitri?cation,whichcanoccuratelevatedtemperature,MSRsamplesoftheparentalloy,SAM2X5(Fe52.3Mn2Cr19Mo2.5W1.7B16C4Si2.5),wereintentionallydevitri?edbyannealingthemat150,300,800,and1000?Cfor1h.Thefullpolarizationcurvesforthesamplesannealedat150and800?CareshowninFig.20,whiletheforwardscansforallsamplesareshowninFig.21.Thesesampleswerethenevaluatedinnaturalseawaterat90?CwithCPtodeterminetheimpactofannealingonpassive?lmstabilityandcor-rosionresistance.Untreated(asreceived)ribbonswere

alsotestedandprovidedinsightintothebaselineper-formance.TheCPcurvesfortheas-receivedsampleandthesamplesannealedat150–300?Cexhibitedonlyslighthysteresis,withnoobviouschangeintheformalrepas-sivationpotentialwithannealingtemperature.However,samplesannealedat800–1000?C,wellabovethecrystal-lizationtemperatureof～623?C(Table5),showedlargehysteresisloops,andadramaticloweringoftheformalrepassivationpotential.SimilarresultswereobtainedwithMSRsofFe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4(SAM2X5).Theoperationallimitforthesematerialsmaybeboundedbyeithertheglasstransitionorthecrystal-lizationtemperature.

TheanodicbranchesofCPcurves(forwardscans)forawroughtsampleofAlloyC-22,anMSRsampleofSAM2X5,andanHVOFcoatingofSAM2X5,alltestedinnaturalseawaterat90?C,areshowninFig.22.Ingeneral,themeasuredcurrentdensitiesforiron-basedamorphousmetalcoatingsinheatedseawaterwerelessthanthosemeasuredforwroughtsamplesofAlloyC-22,indicatingbetterpassivityofHVOFSAM2X5coatingsinthisparticularenvironment.Thedistinctanodicoxida-tionpeaksforAlloyC-22andtheSAM2X5MSR,andthefaintpeakfortheSAM2X5thermalspraycoating,areallbelievedtobeduetotheoxidationofmolybdenum(Mo).CORROSIONRATES

LinearPolarizationData—CorrosionRates

Linearpolarizationwasusedtodeterminetheapprox-imatecorrosionratesofthethermalspraycoatingsofamorphousmetalsofinterest(HVOFSAM1651orSAM7andothercoatings)andthereferencematerial(wroughtnickel-basedAlloyC-22)inthreerelevantenvironments,Seawaterattwotemperaturelevels,andinhotconcen-tratedcalciumchloride(5MCaCl2at105?C).Asthetemperatureoftheseawaterwasincreasedto90?C,thecorrosionratesofHVOFSAM1651(SAM7)coatingsexhib-itedcomparabletoslightlylowercorrosionratesthaneitherwroughtsampleofAlloyC-22.Ingeneral,corrosionratestrendedtohighervalueswithincreasingtemper-ature,asexpected.Incalciumchlorideat105?C,thecorrosionratesofHVOFSAM1651(SAM7)coatingswereslightlylowerthanthatofHVOFAlloyC-22andcompa-rabletoslightlygreaterthanthoseofwroughtAlloyC-22.Ingeneral,thecorrosionratesobservedinthehotcalciumchloride(105?C)werehigherthanthoseobservedintheheatedseawater(90?C),whichwasalsoexpected.

Linearpolarizationwasalsousedtodeterminetheapproximatecorrosionratesofthethermalspraycoat-ingsofamorphousmetalsofinterest(HVOFSAM2X5andothercoatings)sevenrelevantenvironmentsinclud-ing:?seawaterat90?C;3.5-molalNaClsolutionat30and90C;3.5-molalNaClsolutionwith0.525-molalKNO3at90?C;andSDW,SCW,andSAWat90?C.Figure23showsvaluesofthelinearpolarizationcorrosionrate(LPCR)valuesforSAM2X5coatingsamplesduringimmersioninsevendifferentbrinesoverperiodofapproximately135days(thelastlinearpolarizationmeasurementmadeafter133days).Thesesampleswereproducedbydepositing

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS19

Fe52.3Mn2Cr19Mo2.5W1.7B16C4Si2.5 (SAM40) MSR in seawater at 90°C:

After 1 h at 300°C; After 1 h at 800°C

1.41.21.0Potential (V vs Ag/AgCl)0.80.60.40.20.0?0.2?0.4?0.6

1.E?121.E?111.E?101.E?091.E?081.E?071.E?061.E?051.E?041.E?031.E?021.E?011.E?01Figure20.CyclicpolarizationofSAM40(Fe52.3Mn2Cr19Mo2.5W1.7B16C4Si2.5)meltspunribbonsinnaturalseawaterat90?C,aftertheribbonswereannealedatvarioustemper-aturesfor1h.Annealingtemperatureswere150,300,800,and1000?C,withthecurvesfor300and800?Cshown.Source:JournalofMaterialsResearch—Farmeretal.—Fig.5.

1 h at 300°C1 h at 800°C?0.8

Current density (A/cm2)

Fe52.3Mn2Cr19Mo2.5W1.7B16C4Si2.5 (SAM40) MSR in seawater at 90°C:

As-received; 1 h at 150°C, 300°C, 800°C and 1000°C1.41.21.0Potential (V vs Ag/AgCl)0.80.60.40.20.0?0.2?0.4?0.6

1.E?121.E?111.E?101.E?091.E?081.E?071.E?061.E?051.E?04?0.8

800°C1.E?031.E?02150°CAs-received1000°C300°CCurrent density (A/cm2)

Figure21.Anodicbranches(forwardscans)ofcyclicpolarizationcurvesforSAM40(Fe52.3Mn2Cr19Mo2.5W1.7B16C4Si2.5)meltspunribbonsinnaturalseawaterat90?C,aftertheribbonswereannealedatvarioustemperaturesfor1h.Anneal-ingtemperatureswere150,300,800,and1000?C.Source:JournalofMaterialsResearch—Farmeretal.—Fig.6.AdaptedfromRef.8.

Lot#06-015powderonNi-basedAlloyC-22substrateswithahydrogen-fueledHVOFprocess.InthecaseoftheLPCRandOCPmeasurements,theAlloyC-22substrateswerecylindricalrods,eachhavingonehemisphericaltip,withSAM2X5depositedontheouterdiametersoftherods,aswellasovertheentiresurfaceofthehemispher-icaltip.Thenominallengthanddiameterofeachrodwere8and5/8in.,respectively.Thecoatingthicknesswasapproximately17±2mils.

Figure24showsvaluesoftheOCPforSAM2X5coatingsamplesduringimmersioninsevendifferentbrinesoverperiodofapproximately135days.Thesesampleswerepro-ducedbydepositingLot#06-015powderonNi-basedAlloyC-22substrateswithahydrogen-fueledHVOFprocess.InthecaseoftheOCPandLPCRmeasurements,theAlloyC-22substrateswerecylindricalrods,eachhavingonehemisphericaltip,withSAM2X5depositedontheouterdiametersoftherods,aswellasovertheentiresurfaceofthehemisphericaltip.Thenominallengthanddiameterofeachrodwere8and5/8in.,respectively.Thecoatingthicknesswasapproximately17±2mils.

Testenvironmentswere(i)naturalseawaterat90?C;(ii)3.5-molalNaClsolutionat30?C;(iii)3.5-molalNaClsolutionat90?C;(iv)3.5-molalNaCland0.525-molalKNO3solutionat90?C;(v)SDWat90?C;(vi)SCWat90?C;and(vii)SAWat90?C.Aftermorethanfourmonthsexposure,theLPCRvaluesforthesecoatingsintheseventestsolutionswere(i)12.3μm/year,(ii)2.91μm/year,(iii)176μm/year,(iv)2.83μm/year,(v)2.61μm/year,(vi)12.4μm/year,and(vii)81.1μm/year,respectively.Clearly,thegreatestelectrochemicalactivities,whichwerequanti?edintermsofthemeasuredLPCRvalues,wereobservedin3.5-molalNaClsolutionandSAW,bothat90?C,withtheSAWhavinganacidicpH.The

20HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

1.41.21.0Potential (V vs Ag/AgCl)0.80.60.40.20.0?0.2?0.4?0.6

1.E?121.E?11?0.8

As-sprayed HVOF coating and melt spun robbon SAM2X5compared to Wrought Alloy C-22 in seawater at 90°C

SAM2X5 HVOF coatingAlloy C-22SAM2X5 MSRFigure22.This?gureshowstheanodicbranchesofcyclicpolarizationcurves(forwardscans)forawroughtsampleofAlloyC-22,anMSRsampleofSAM2X5,andanHVOFcoatingofSAM2X5onType316Lstainlesssteel,alltestedinnatu-ralseawaterat90?C.Source:JournalofMateri-alsResearch—Farmeretal.—Fig.7.AdaptedfromRef.49.

1.E?101.E?091.E?081.E?071.E?061.E?051.E?041.E?031.E?021.E?01120Current density (A/cm2)

Corrosion rates for HVOF SAM2X5

1000.0Corrosion rates (μm/year)100.0

10.0

Figure23.ApparentcorrosionratesofSAM2X5coatings(powderLot#06-015powder)onAlloyC-22rodsdur-ingimmersioninsevendifferentbrinesoverperiodofapproximately135days,asdeterminedwithlinearpolar-ization.Source:JournalofNuclearTechnology—Farmeretal.—Fig.8.AdaptedfromRefs47,49.

1.0

C22-1 Seawater 90°CC22-3 3.5m NaCl 90°CC22-5 SDW 90°CC22-7 SAW 90°CC22-2 3.5m NaCl 30°CC22-4 3.5m NaCl + 0.525m KNO3 90°CC22-6 SCW 90°C0.1

020406080Time (days)

100140nexthighestLPCRvalueswereobservedinnaturalseawaterandSCW,bothat90?Cwithnear-neutralpH.Notsurprisingly,thelowestLPCRvalueswereobservedin3.5-molalNaClsolutionandSDW,bothat30?Cwithnear-neutralpH,aswellasin3.5-molalNaCland0.525-molalKNO3solutionat90?C.ThenitrateinhibitorreducedtheLPCRvalueobservedin3.5-molalNaClsolutionfrom176to2.83μm/year,nearlytwoordersofmagnitude.Thebarchartshowninthefollowing?guresummarizesthesetrendsincorrosionrategraphically.CorrosionRates—Weight-LossandDimensionalMeasurements

Pertinentstandardsforweight-lossanddimensionalmeasurementshavebeenpublishedbyASTM[95–99].Weight-lossanddimensionalmeasurementswereusedtodeterminethecorrosionratesofSAM2X5coatings(Lot#06-015powder)onAlloyC-22weight-losssamplesandareshowninFig.25.Dependingontheassumedcoatingdensity,theseratesweredeterminedtobe

(i)14.3–15.9μm/yearinnaturalseawaterat90?C,(ii)8.4–9.3μm/yearin3.5-molalNaClsolutionat30?C,(iii)26.1–29.7μm/yearin3.5-molalNaClsolutionat90?C,(iv)4.6–5.1μm/yearin3.5-molalNaCland0.525-molalKNO3solutionat90?C,(v)8.3–9.4μm/yearinSDWat90?C,(vi)2.8–3.0μm/yearinSCWat90?C,and(vii)16.5–18.1μm/yearinSAWat90?C.Inthecaseof3.5-molalNaClsolutionat90?C,theelectrochemicalmeasurementoverpredictedtheactualcorrosionratedeterminedwithweight-lossanddimensionalmeasure-mentsbyafactorofaboutsix(×6).InthecaseofSAWat90?C,theelectrochemicalmeasurementalsooverpredictedtheactualcorrosionratedeterminedwithweight-lossanddimensionalmeasurements,thistimebyafactorofabout?ve(×5).

Weight-lossanddimensionalmeasurementswerealsousedtodeterminethecorrosionratesofSAM2X5coatings(Lot#06-015powder)onAlloyC-22crevice-corrosionsamplesafter135daysimmersion,asshowninFig.26.Dependingontheassumedcoatingdensity,theseratesweredeterminedtobe(i)14.7–17.3μm/yearinnatural

1.E+00

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS21

Corrosion potential of HVOF SAM2X5

0?50OCP (V vs Ag/AgCl)?100?150?200?250?300?350?400?450

C22-1 Seawater 90°CC22-3 3.5m NaCl 90°CC22-5 SDW 90°CC22-7 SAW 90°CC22-2 3.5m NaCl 30°CC22-4 3.5m NaCl + 0.525m KNO3 90°CC22-6 SCW 90°C20406080100120140

Time (days)

Figure24.OCPvaluesofSAM2X5coatings(powderLot#06-015powder)onAlloyC-22rodsduringimmersioninsevendifferentbrinesoverperiodofapproximately133days.Source:JournalofNuclearTechnology—Farmeretal.—Fig.9.AdaptedfromRefs47,49.

HVOF SAM2X5 on Alloy C-22 weight loss sample

measured corrosion rates after 135 days

1000

175.7Corrosion rate (μm/year)Based on weight loss - coating densityBased on weight loss - completely dense alloyLinear polarization81.129.726.115.914.312.35.14.69.48.39.38.412.418.116.5100

1Seawater3.5-m NaCl3.5-m NaCl3.5-m NaClSDW 90°CSCW 90°CSAW 90°C90°C30°C90°C+ 0.525 m

KNO3 90°C

Figure25.After135daysimmer-sion,weight-lossanddimensionalmeasurementswereusedtodeter-minethecorrosionratesofSAM2X5coatingsonAlloyC-22weight-losssamples.Source:Farmeretal.—JournalofNuclearTechnology—Fig.12.AdaptedfromRef.47.

seawaterat90?C,(ii)8.8–9.9μm/yearin3.5-molalNaClsolutionat30?C,(iii)28.8–32.5μm/yearin3.5-molalNaClsolutionat90?C,(iv)4.2–4.3μm/yearin3.5-molalNaCland0.525-molalKNO3solutionat90?C,(v)8.2–9.5μm/yearinSDWat90?C,(vi)2.7–3.2μm/yearinSCWat90?C,and(vii)19.7–22.5μm/yearinSAWat90?C.Inthecaseof3.5-molalNaClsolutionat90?C,theelectrochemicalmeasurementoverpredictedtheactualcorrosionratedeterminedwithweight-lossanddimen-sionalmeasurementsbyafactorofaboutsix(×6).InthecaseofSAWat90?C,theelectrochemicalmeasurementalsooverpredictedtheactualcorrosionratedeterminedwithweight-lossanddimensionalmeasurements,thistimebyafactorofabout?ve(×5).

Whileelectrochemicalmeasurementssuchaslinearpolarizationcouldbeusedtodeterminequalitativetrendsincorrosionratesduringtheselong-termimmersiontests,absolutevaluesinthemostaggressiveelectrolyteswereoverpredictedbyafactorof?ve-to-six(×5to×6).In

2.6contrast,thecorrosionratesdeterminedwithlinearpolar-izationprovedtobenonconservativeinthemorebenignelectrolytes,andunderpredictedtheactualcorrosionratesbyafactorofabouttwo-to-three(×2to×3).Linearpolar-izationisabene?cialmethodfordeterminingqualitativetrendsincorrosionrateinrealtimebutcannotmeasurecorrosionratesaccuratelyenoughforreliablelong-termprediction.

CorrosiveattackoftheSAM2X5coatingafterimmer-sionfor135daysinSDW,SCW,andSAWat90?Cischaracterizedasnonexistenttolight,withthepossi-bilityofhydrogenabsorptionandcrackingatverylowpH.SAM2X5-coatedweight-lossandcrevicesamplesimmersedinSDWshowednoevidenceofcorrosion,andonlyslightdiscoloration.IdenticalsamplesimmersedinSCWandSAWshowednosigni?cantcorrosionandonlyslightdiscoloration.However,inthelowpHSAWenvironment,anarrayof?necrackswasobservedinthecenterofallweight-losssamples,withcorrosionproductsinsidethecrack.Sincethistypeofcrackingwas

3.02.82.92.822HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

HVOF SAM2X5 on Alloy C-22 crevice samplesmeasured corrosion rates after 135 days

1000

175.7Corrosion rate (μm/year)Based on weight loss - coating densityBased on weight loss - completely dense alloyLinear polarization81.132.528.817.314.712.39.98.84.34.32.89.58.2Seawater3.5-m NaCl3.5-m NaCl3.5-m NaClSDW 90°CSCW 90°CSAW 90°C90°C30°C90°C+ 0.525m

KNO3 90°C

100

22.519.7Figure26.After135daysimmer-sion,weight-lossanddimensionalmeasurementswereusedtodeter-minethecorrosionratesofSAM2X5coatingsonAlloyC-22crevice-corrosionsamples.Source:Farmeretal.—JournalofNuclearTechnology—Fig.11.AdaptedfromRefs38,47.

onlyobservedwithacidicsolutions,itisbelievedthatthecrackingmaybeduetothecoating’sabsorptionofhydrogennearthecracks.Thegalvaniccouplingoftheanodicoxidationofmetalwithinthecrackcoulddrivecathodichydrogenreductionnearthecracks.ThecrackingobservedinlowpHweight-losssamplescouldthereforebeduetohydrogen-inducedcracking.SAM2X5-coatedcylindersusedforLPCRandOCPdeterminationinSDWandSAW90?Cshowednodiscolorationorrustspotsontheouterdiameter(barrel),andnocorrosionproductsattheinterfacebetweenthecoatingandtheinsulatingsheath.AnidenticalcylinderusedforLPCRandOCPdeterminationinSCW90?Cshowednodiscolorationorrustspotsontheouterdiameter(barrel),buttheformationofpatchesofrustattheinterfacebetweenthecoatingandtheinsulatingsheath,andawhite?lmofsaltprecipitatesfromtherapiddryingoftheelectrolyteduringremovalofthesamplefromthetestsolution.

CorrosiveattackoftheSAM2X5coatingafterimmer-sionfor135daysinnaturalseawaterat90?Cischaracter-izedaslighttomoderate.Weight-lossandcrevicesampleshadonlyslightstain,withsomesparsepitsaroundtheperimeterofthesample,andwiththeinhibitoryeffectsofnitrateinnear-boilingconcentratedchloridesolutionsclearlyevident.Inthiscase,theSAM2X5-coatedcylin-derusedforLPCRandOCPdeterminationshowedslightdiscolorationandsomesmallrustspotsontheouterdiam-eter,butnocorrosionproductsattheinterfacebetweenthecoatingandtheinsulatingsheath.

CorrosiveattackoftheSAM2X5coatingafterimmer-sionfor135daysinpure3.5-molalNaClsolutionwithoutnitrateinhibitororotherionsischaracterizedaslighttomoderateat30?Candmoderatetoheavyat90?C.Afterimmersionin3.5-molalNaClsolutionat30?Cfor135days,SAM2X5-coatedweight-lossandcrevicesampleshadstainonthesurface,withsomesparserustspots.In3.5-molalNaClsolutionat90?C,identicalsamplesdevelopedheav-ierstainandrustspots,aswouldbeexpectedathighertemperature.TheSAM2X5-coatedcylinderusedforLPCRandOCPdeterminationin3.5-molalNaClsolutionat30?Cshowedafewsparserustspotsontheouterdiameter,butnocorrosionproductsattheinterfacebetweenthecoatingandtheinsulatingsheath.AnidenticalcylinderusedforLPCRandOCPdeterminationin3.5-molalNaClsolutionat90?Cshowedadenserustspotsontheouterdiame-ter,butpreferentialformationofcorrosionproductsattheinterfacebetweenthecoatingandtheinsulatingsheath.CorrosiveattackoftheSAM2X5coatingafterimmer-sionfor135daysin3.5-molalNaCland0.525-molalKNO3solutionat90?Cischaracterizedasverylight,owingtothebene?cialinhibitoreffectofnitrate.Weight-lossandcrevicesampleshadonlyslightstain,withsomesparsepitsaroundtheperimeterofthesample,andwiththeinhibitoryeffectsofnitrateinnear-boilingconcen-tratedchloridesolutionsclearlyevident.Inthiscase,theSAM2X5-coatedcylinderusedforLPCRandOCPdetermi-nationshowedslightdiscoloration(someverysmallrustspots)ontheouterdiameter,butnocorrosionproductsattheinterfacebetweenthecoatingandtheinsulatingsheath.ThesetrendsareillustratedwithFig.27.

Similarlong-termcorrosiontestingwasconductedwithoptimizedyttrium-containingSAM1651coatings,asshowninFigs28–32.ThecorrosionratesweredeterminedinsituwithlinearpolarizationandareshowninFig.28.After70days,allcorrosionrateswerebetween1and10μm/year.CorrespondingmeasurementsoftheOCPareshowninFig.29.ThetrendintheOCPmayindicatesometendencytowardennoblement,whichisprobablyduetoslightchangesinthesurfacecompositionduringthetestperiod.Afterexposure,coatedcylindricalsamplesusedfortheinsituelectrochemicaltesting,andcoatedplateswereremoved,photographed,withtheinterfacialcross-sectionsexaminedwithSEMandEDS.Clearly,thesesamplesallexhibitedexceptionalcorrosionresistance,evenafterfourmonthsinconcentratednear-boilingbrines(90?C).

2.63.22.72.912.4HIGHPERFORMANCECORROSION-RESISTANTMATERIALS23

(a)(b)

Figure27.CorrosiveattackofbarrelsectionofSAM2X5-coatedrodsafter135daysat90?Cinrangeofrepresentativeenvironments:(a)3.5-molalNaCl+0.525-molalKNO3and(b)acidicSAW.

1000

070719-C-5-RC9 SW 90°C070719-C-5-RC10 3.5-m NaCl 30°C070719-C-6-RC11 3.5-m NaCl 90°CCorrosion rate (μm/year)100

070719-C-6-RC12 3.5-m NaCl + 0.525m KNO3 90°C070720-C-1-RC13 SDW 90°C070720-C-1-RC14 SCW 90°C070720-C-2-RC15 SAW 90°C10

005101520253035404550556065707580859095100Time (days)

Figure28.CorrosionratesofSAM1651coatingduringprolongedexposureinavarietyofconcentratedbrinesat90?C.

0.00?0.05?0.10Potential (V vs Ag/AgCl)?0.15?0.20?0.25?0.30?0.35?0.40?0.45

070719-C-5-RC9 SW 90°C070719-C-5-RC10 3.5-m NaCl 30°C070719-C-6-RC11 3.5-m NaCl 90°C070719-C-6-RC12 3.5-m NaCl + 0.525m KNO3 90°C070720-C-1-RC13 SDW 90°C070720-C-1-RC14 SCW 90°C070720-C-2-RC15 SAW 90°C05101520253035404550556065707580859095100

Time (days)

Figure29.Open-circuitcorrosionpotential(OCP)ofSAM1651coatingduringprolongedexposureinavarietyofconcentratedbrinesat90?C.Theslightchangeobservedduringthisperiodoftimemaybeindicativeofsomeslightchangeinsurfacecompositionduetocorrosionandoxidation.

24HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

Natural seawaterat 90°C3.5-m NaCl at 90°C3.5-m NaCl + 0.525-m KNO 390°C

Figure30.Corrosiveattackof4-×4-in.steelplatescoatedwithSAM1651afterlong-termexposure(>4months)invariousconcentratedbrinesat90?C.

SDW at 90°CSCW at 90°CSAW at 90°C

Natural seawater at 90°C3.5-m NaCl at 90°C3.5-m NaCl + 0.525-m KNO 390°C

Figure31.CorrosiveattackofbarrelsectionsrodscoatedwithSAM1651afterlong-term(>4months)exposureinvari-ousconcentratedbrinesat90?C.

SDW at 90°CSCW at 90°CSAW at 90°C

FeNiBack-scatteredelectron image (BEI)

YMgOFigure32.ESEMandEDScharac-terizationofcorrosionspotsonearlierunoptimizedSAM1651afterlong-term(>4months)immersion.

CrSecondary

electron image (SEI)

MoSiMapping of Fe, Ni, Y, Mg, O, Cr, Mo and Si at corrosion site

with energy-dispersive spectroscopy (EDS)

InearliertestswithunoptimizedSAM1651,afewverysparserustspotswereobserved?withsamplesexposedtonaturalseawaterat90C.Examinationofthecoatingcross-sectionwithanESEMequippedwithenergy-dispersivespectroscopy(EDS)showedthatthespotswereonlysuper?cial,withnothrough-coatingcorrosion.ThesedataareshowninFig.32.ThesespotsmayhavebeenduetothecorrosionofembeddedparticlesofferritefedtotheHVOFspraygun,whichwerevirtuallyeliminatedthroughprocessimprovementandoptimization.

SaltFogTesting—Veri?cationofCorrosionResistance—SAM1651andSAM2X5

Thecorrosionresistanceoftheamorphousmetalcoat-ingswasveri?edduringsaltfogtesting.Aspreviouslydiscussed,thesaltfogtestwasusedtocomparevari-ouswroughtantthermalsprayalloys,MSRs,arc-melteddrop-castingots,andthermalspraycoatingsfortheirsusceptibilitytocorrosionbysaltsprays,likethosethatmightbeencounteredaboardnavalships.Thistestisalsoknownasthesaltspraytest.Themostrecenttestshavefocusedonreferencematerials,includingtheSAM40mas-teralloyandtheSAM2X5andSAM1651amorphousmetalformulations,intheformofarc-melteddrop-castingots,MSRs,andHVOFcoatingswithnosigni?cantporosityandnear-theoreticaldensity.Incontrast,the?rsttestsfocusedonearlythermalspraycoatings,whichhadresid-ualporosityandcrystallinestructure,andlowerresistancetocorrosion.

Bothsaltfogtestswereconductedaccordingtothestan-dardGMssaltfogtest,identi?edasGM9540P,whichissimilartothestandardASTMsaltfogtest,whichisiden-ti?edasASTMB117andtitled‘‘StandardTestMethodofSaltSpray(Fog)Testing.’’ThetestprotocolforGM9540PissummarizedinTable2.Samplesofiron-basedamorphousmetalthermalspraycoatingsandseveralreferencesam-pleswereevaluatedwiththeGM9540Ptestprotocol.ThefourreferencesamplesincludedType316Lstainlesssteel,nickel-basedAlloyC-22(N06022),TiGrade7,andthe50:50nickel–chromiumbinary.

Earlysaltfogtestingcon?rmedthecorrosionresis-tanceofthecorrosionresistanceofthermalspraycoatingsofSAM2X5relativetootheralloyswithlessmolybdenum.Aspreviouslydiscussed,thesecoatingsweredepositedwiththeHVOFprocess,usingamorphousmetalpowders.HVOFcoatingsofType316Lstainlesssteelandthepar-entalloy,SAM40,showedsigni?cantrustingafteronly13cyclesintheGMsaltfogtest.Incontrast,HVOFcoat-ingsonnickel-basedAlloyC-22andamorphousSAM2X5showednoobviouscorrosionorrustingaftermorethan60cycles.

Figure33showsasamplecoatedwithSAM2X5,pre-paredwithLot#06-015powderandthermallysprayedwiththeJK2000gunusinghydrogenfuel,anda1018car-bonsteelcontrol(reference)samples,aftereightfullcyclesintheGMsaltfogtest.Norustwasseenonthesether-mallysprayedamorphousmetalcoatings,thoughslightdiscolorationofwasobservedonsome.Insharpcontrast,severeattackof1018carbonsteelreferencesampleswasobserved.

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS25

After GM salt fog test

1018 steel #1

1018 steel #2

SAM2X5 lot 06-015 #1

SAM2X5 lot 06-015 #2

316L substrate316L substrate

SAM2X5 lot 06-015 #1

SAM2X5 lot 06-015 #2

C-22 substrateC-22 substrate

Figure33.ResultsofsaltfogtestingofSAM2X5thermalspraycoatingsand1018carbonsteelcontrolsamples.NocorrosionoftheSAM2X5coatingswasobservedaftereightcycles,whilethe1018carbonsteelsamplesexperiencedsevereattack.Source:JournalofMaterialsResearch—Farmeretal.—Fig.15.AdaptedfromRef.49.

Figure34.HighvelocityoxyfuelprocessatCaterpillarusedtocoathalf-scalecontainerswithSAM1651amorphousmetal.Qual-ityassurancechecksofthecoatingthicknessandroughnessweremadeduringthecoatingprocess.Source:MetallurgicalandMaterialsTransactionsA—Farmeretal.—Fig.1.AdaptedfromRef.8.

Figure34showshalf-scaleprototypicalSNFcontain-ers,fabricatedfromType316Lstainlesssteel,beingcoatedwithSAM1651andSAM2X5.TheseprototypeswerethensubjectedtothestandardGMssaltfogtestidenti?edasGM9540P.Aftereightcyclesinthissaltfogtest,SAM1651andSAM2X5coatingsontheprototypicalcon-tainersprovedtobecorrosionresistant,whereasthesteelreferencesamplesunderwentaggressiveattack,asshowninFigs35and36.InthecaseoftheSAM1651-coatedcontainer,somerunningrustwasobservedononebottom

26HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

Figure35.EffectofGM9540PsaltfogtestonHVOFcoatingofSAM1651amorphousmetalonhalf-scaleSNFprototypicalcontainer(bottomcenter).Source:MetallurgicalandMaterialsTransactionsA—Farmeretal.—Fig.19.AdaptedfromRefs8,49.

(a)(b)

Figure36.Samplesandprototypesaftereight(8)fullcyclesintheGMsaltfogtest:(a)referencesam-plesof1018carbonsteel,(b)Type316LstainlesssteelplatecoatedwithLot#06-015SAM2X5powder,(c–f)half-scalemodelofspentnuclearfuel(SNF)con-tainerfabricatedfromType316Lstainlesssteelpipe(Schedule10s)coatedwithLot#06-015SAM2X5pow-der.Source:JournalofNuclearTechnology—Farmeretal.—Fig.5.AdaptedfromRef.47.

(c)(d)(e)(f)

ofthecontainer,whichmayonaccountofsurfaceprepa-rationbeforecoating.Onthebasisofthesetests,ithasbeenconcludedthatthesenewamorphousmetalcoatings,preparedwithpowdershaveaparticlesizedistributionsuitableforHVOF,canprotectalesscorrosion-resistantsubstrate,suchassteelreinforcementbars,fromcorrosion.APPLICATIONS

StorageofSpentNuclearFuel

ThisalloywasrecentlydiscussedatameetingoftheMRSinregardtoitsbene?cialapplicationtothesafestor-ageofSNF[37–43].TheexceptionalcorrosionresistancemakesthemattractiveforcoatingSNFcontainers.Thehighboroncontentof(SAM2X5)Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4makesitaneffectiveneutronabsorberandsuitableforcriticalitycontrolapplications(Fig.37).Averagemeasuredvaluesoftheneutronabsorptioncrosssectionintransmission(??t)forType316Lstainlesssteel,AlloyC-22,boratedstainlesssteel,aNi–Cr–Mo–Gdalloy,andSAM2X5havebeendeterminedtobeapproximately1.1,1.3,2.3,3.8,and7.1,respectivelyandarediscussedindetailintheliterature.Thehighboroncontentofthisparticularamorphousmetalmakesitaneffectiveneutronabsorberandsuitableforcriticalitycontrolapplications.Thismaterialanditsparentalloyhavebeenshowntomaintaincorrosionresistanceuptotheglasstransitiontemperatureandtoremainintheamorphousstateafterreceivingrelativelyhighneutrondose.

Figure37.Prototypicalbasketassemblyforspentnuclearfuelstoragecontainercoatedwithneutron-absorbinglayerofhighbornSAM2X5alloy.Source:MetallurgicalandMaterialsTrans-actionsA—Farmeretal.—Fig.2.AdaptedfromRef.8.

MitigatingDeteriorationofInfrastructure

TheinfrastructurefortransportationintheUnitedStatesallowsforahighlevelofmobilityandfreightactivityforthecurrentpopulationof300millionresidentsandseveralmillionbusinessestablishments.AccordingtoaDepartmentofTransportationstudy,morethan230mil-lionmotorvehicles,ships,airplanes,andrailroadscars

wereusedon6.4millionkilometers(4millionmiles)ofhighways,railroads,airports,andwaterwaysin1998.Pipelinesandstoragetankswereconsideredtobepartofthisdeterioratinginfrastructure.Theannualdirectcostofcorrosionintheinfrastructurecategorywasestimatedtobeapproximately$22.6billionin1998[99,100].

Therewere583,000bridgesintheUnitedStatesin1998.Ofthistotal,200,000bridgesweresteel,235,000wereconventionalreinforcedconcrete,108,000bridgeswereconstructedusingprestressedconcrete,andthebal-ancewasmadeusingothermaterialsofconstruction.Approximately15%ofthebridgesaccountedforatthispointintimewerestructurallyde?cient,primarilyowingtocorrosionofsteelandsteelreinforcement.Theannualdirectcostofcorrosionforhighwaybridgeswasestimatedat$8.3billiontoreplacestructurallyde?cientbridgesovera10-yearperiodoftime,$2billionformaintenanceandcostofcapitalforconcretebridgedecks,$2billionformain-tenanceandcostofcapitalforconcretesubstructures,and$0.5billionformaintenanceofpaintingofsteelbridges.Lifecycleanalysisestimatesindirectcoststotheuserduetotraf?cdelaysandlostproductivityatmorethan10timesthedirectcostofcorrosionmaintenance,repair,andrehabilitation[99,100].

Intheearly1970sonepoxy-coatedreinforcingsteel(ECR)wasquali?edasanalternativetoblackbartohelpaddresstheproblemsassociatedwithcorrosion.Forthepast30years,ECRhasbeenspeci?edbyseveralStateDepartmentsofTransportationformajordecksandsubstructuresexposedtochlorides.Atthesametime,ECRwasaugmentedbyuseoflowwater-to-cementratio(w/c)concrete,possiblywithcorrosioninhibitors.However,inFloridacoastalwaters,ECRhasprovenineffectivebecauseofthecombinedeffectsofhigheraveragetemperatureandmoreprolongedmoistexposure[99,100].

TheInnovativeBridgeResearchandConstruction(IBRC)ProgramwasauthorizedbyCongressintheTransportationEquityActforthetwenty-?rstcenturylegislationinitiallyasasix-yeareffort(1998–2003)butwassubsequentlyextendedthroughMay2005.Themajorityofthefundingwasforactualrepair,rehabilitation,andreplacementofexistingstructuresandfornewconstructionwithalesseramountforresearch,bothbasedoninnovativematerials.Corrosion-resistantreinforcementsconstitutedonecomponentoftheprogram.Reinforcementmaterialsincludedblackbar,ECR,solidstainlesssteel(Types316LNand2205),cladstainlesssteel,galvanizedsteel,andothers[99,100].

Thenewiron-basedamorphousmetalsdiscussedhere,alongwiththetechnologynecessaryforapplyingthesematerialsascoatingstolarge-areasubstrates,includingsteel-reinforcingbars,havebeendevelopedsincetheIBRCprogramandcouldgoalongwaytowardsolvingsomeoftheseproblems.Itisbelievedthatthesecoatingsmaybeabletosubstantiallyenhancethecorrosionresistancesteelreinforcementsinconcretestructures.Thisproposalaimstoevaluatethesenewadvancedmaterialsasapracticalmeansofenhancingtheperformanceofsteel-reinforcingbars.

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS27

CONCLUSIONS

SeveralFe-basedamorphousmetalformulationshavebeenfoundthatappeartohavecorrosionresistancecomparableto,orbetterthanthatofNi-basedAlloyC-22,basedonbreakdownpotentialandcorrosionrate.Theseformulationsusechromium(Cr),molybdenum(Mo),andtungsten(W)toprovidecorrosionresistance,boron(B)toenableglassformation,andyttriumtolowertheCRR.SAM1651(Fe48.0Cr15.0Mo14.0B6.0C15.0Y2.0)hasyttriumaddedandhasanominalCCRofonly80K/s,whileSAM2X5(Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4)hasnoyttriumandischaracterizedbyrelativelyhighCCRsofapproximately600K/s.NotethatSAM1651isalsoknownasSAM7.Thesenewalloyscanbeappliedwithadvancedthermalspraytechnology,forminganabrasion-andcorrosion-resistantcoating.SpecialattributessuchasneutronabsorptionprovideopportunitiesforthestorageofSNFwithenhancedsafety.

SAM1651hasalowCCR,owingtotheadditionofyttrium,whichenablesittoberenderedasacompletelyamorphousthermalspraycoating.Itisrelativelydif?culttoatomize,withpowdersbeingirregularinshape.Thiscausesthepowdertobedif?culttopneumaticallyconveyduringthermalspraydeposition.Gas-atomizedSAM1651powderhasrequiredcryogenicmillingtoeliminateirreg-ularitiesthatmake?owdif?cult.SAM2X5(noyttrium)hasahighCCR,whichcanleadtodevitri?cationduringprocessing.IncontrasttoSAM1651,SAM2X5canberead-ilygasatomizedtoproducesphericalpowdersthatenablemorefacilethermalspraydeposition.

ThehardnessofType316LStainlessSteelisapproxi-mately150VHNthatofAlloyC-22isapproximately250VHNandthatofHVOFSAM2X5rangesfrom1100to1300VHN[12,13].Suchhardnessmakesthesematerialspartic-ularlyattractiveforapplicationswherecorrosion–erosionandweararealsoissues.SinceSAM2X5hashighboroncontent,itcanabsorbneutronsef?cientlyandmaythere-fore?ndusefulapplicationsasacriticalitycontrolmaterialwithinthenuclearindustry.Acknowledgments

ThiswasperformedundertheauspicesoftheUSDepartmentofEnergybyLawrenceLivermoreNationalLaboratorywhichisoperatedbyLawrenceLivermoreNationalSecurity,LLC,fortheUSDepartmentofEnergyandtheNationalNuclearSecurityAdministrationunderContractDE-AC52-07NA27344.Thematerialsdiscussedinthisreviewweredevelopedbythefollowingteamofresearcherswhosecontributionsaregratefullyacknowl-edged:J.FarmerJ.Haslam,S.Day,T.Lian,C.Saw,P.Hailey,andJ-S.Choi(LawrenceLivermoreNationalLab-oratory);N.Yang(SandiaNationalLaboratory);C.BlueandW.Peter(OakRidgeNationalLaboratory);R.BaylesandR.Brown(NavalResearchLaboratory);J.Payer(CaseWesternReserveUniversity);J.PerepezkoandK.Hildal(UniversityofWisconsinMadison);E.LaverniaandL.Ajdelsztajn(UniversityofCaliforniaDavis);D.J.BranaganandJ.Buffa;(TheNanoSteelCompany);M.Beardsley(CaterpillarIncorporated);L.Aprigliano

28HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

(StrategicAnalysisIncorporated);J.Boudreau(BLEIncorporated);andL.Kaufman(CALPHAD).LISTOFABBREVIATIONSBSWBasicSaturatedWaterCCRCriticalCoolingRateCPCyclicPolarization:CR

CorrosionRate

DARPADefenseAdvancedResearchProjectsAgency

DSODefenseSciencesOf?ce

DSCDifferentialScanningCalorimetryDTADifferentialThermalAnalysisDOE

DepartmentofEnergy

EDS,EDAXEnergyDispersiveX-RaySpectroscopyESEMEnvironmentalScanningElectronMicroscopy

EWEquivalentWeight

J-13StandardWellWaterCompositionKConversionFactorMSRMelt-SpunRibbonHLWHighLevelWasteHRCHardnessRockwellC

HVOFHigh-VelocityOxy-FuelProcess:HV,VHNVickersHardnessNumber

M&TEMeasuringandTestEquipmentOSTIOf?ceofScience&TechnologyInternational

PSTPotential-StepTest

PRENPittingResistanceEquivalenceNumberPTIPlasmaTechnologyIncorporatedPVDPhyscialVaporDepositionQAQualityAssurance

QSLQuali?edSupplierList

SAMStructuralAmorphousMetal

SAM_X_Fe-BasedAmorphousAlloyDesignationSAWSimulatedAcidi?edWaterSEMScanningElectronMicroscopySCWSimulatedConcentratedWaterSDWSimulatedDiluteWaterTNCTheNanoSteelCompany

TEMTransmissionElectronMicroscopyVHNVickersHardnessNumberXRD

X-RayDiffraction

NOMENCLATUREajAtomicWeightofj-thComponentfjWeightFractionofj-thComponentfmScatteringFactorforX-RaysfnScatteringFactorforX-raysfScatteringFactorforX-raysicorrCorrosionCurrentDensityi(k)ScatteredX-RayIntensitykWaveVectorforX-RaysnalloyGramEquivalentsofAlloyrmnInter-atomicdistancesAElectrodeAreaB

TafelParameter

EcriticalCriticalPotential:

EcorrOpenCircuitCorrosionPotential:ErevReversalPotential

EpeakPotentialofAnodicOxidationPeak:ErpRepassivationPotential:

FFaraday’sConstant(96,484.6Cequiv?1)IcorrCorrosionCurrent

IeuScatteredX-RayIntensityRUniversalGasConstantRpPolarizationResistanceTTemperature

βaAnodicTafelSlopeβcCathodicTafelSlope

ρ(r)RadialDistributionFunctionρalloyDensityofAlloyθScatteringAngleλWavelength

REFERENCES

1.TelfordM.Thecaseforbulkmetallicglass.MaterToday2004;3:36–43.

2.SorensenN,DiegleR.In:DavisJR,DestefaniJD,edi-torsVolume13,Corrosionofamorphousmetals,Corrosion,MetalsHandbook.9thed.ASME;1987.pp.864–870.

3.PolkDE,GiessenBC.Overviewofprinciplesandapplica-tions.In:GilmanJJ,LeamyHJ,editors,Metallicglasses.MetalsPark(OH):AmericanSocietyofMetals;1978.pp.2–35,p.348.Chapter1.

4.FarmerJC.High-performancecorrosion-resistantamor-phousmetals.ProceedingsofGlobal2003.ANS/ENSInter-nationalWingerMeetingNewOrleans,Louisiana:Amer-icanNuclearSociety,AtomicEnergyofJapan,CanadianNuclearAssociation,andEuropeanNuclearSocity;2003Nov,pp.16–20.

5.FarmerLC,HaslamJJ,DaySD,etal.CorrosionCharacter-izationofIron-basedHigh-performanceAmorphous-metalThermal-sprayCoatings,PVP2005-71664.ProceedingsofASMEPVP:PressureVessels&PipingDivisionConfer-ence,GrandHyatt;2005July17–21;Denver(CO).ThreeParkAvenue,NewYork:AmericanSocietyofMechanicalEngineers;2005.p.7.

6.FarmerJ,EarlC,DotyC,etal.DARPA-DOEHighPer-formanceCorrosion-ResistantMaterials(HCPRM)Prin-cipalInvestigator’sMeeting,TurtleBayResort;2005Jan10–13;Oahu,Hawaii,UCRL-PRES-214672.Liver-more(CA):LawrenceLivermoreNationalLaboratory;2005.p.407.

7.FarmerJC,HaslamJJ,DaySD,etal.Corrosionresistanceofthermallysprayedhigh-boroniron-basedamorphous-metalcoatings—Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4.JMaterRes2007;22(8):2297–2311.

8.FarmerJ,ChoiJ-S,SawC-K,etal.Iron-basedamorphousmetals:high-performancecorrosion-resistantmaterialdevelopment.MetallMaterTransA2009;40A(6):1289–1305.

9.BranaganDJ,MarshallMC,MeachamBE.TheNanoSteelCompany,Incorporated,FinalReportforthePerformanceofLLNLSubcontractFY05,LLNL-RFP-B550033,HighPer-formanceCorrosionResistantMaterials(HPCRM)forNavalWar?ghtingandSafeLong-TermStorage/DisposalofSpentNulcearFuel,JointDOE-DARPAProgram,Instituteof

NanomaterialsResearchandDevelopment,TheNanoSteelCompany,IdahoFalls,Idaho;2005.p.84.

10.ShinimiyaH,NakazawaA,KatoZ,etal.Corrosionresistant

bulkamrophousNi-Cr-Ta-Mo-Nb-5Palloysinconcentratedhydrochloricacids,Paper319,sessiononcorrosionandelectrochemistryofadvancedmaterialsinhonorofKojiHashimoto.In:208thMeetingoftheElectrochemicalSoci-ety,WestingBonaventureHotel;2005Oct16–21;LosAngeles(CA).Pennington(NJ):ElectrochemicalSociety;2005.11.ScullyJR,GerbertA,PayerJH.Corrosionandrelated

mechanicalpropertiesofbulkmetallicglasses.JMaterRes2007;22(2).12.KishitakeK,EraH,OtsuboF.Characterizationof

plasmasprayedFe-10Cr-10Mo-(C,B).AmorphousCoat1996;5(2):145–153.13.PangS,ZhangT,AsamiK,etal.Effectsofchromiumon

theglassformationandcorrosionbehaviorofbulkglassyFe-Cr-Mo-C-BAlloys.MaterTrans2001;43(8):2137–2142.14.PangSJ,ZhangT,AsamiK,etal.Synthesisof

Fe-Cr-Mo-C-B-Pbulkmetallicglasseswithhighcorrosionresistance.ActaMater.2002;50:489–497.15.GuoF,PoonS,Shi?etG.Metallicglassingotsbasedon

yttrium.MetallApplPhysLett2003;83(13):2575–2577.16.LuZ,LiuC,PorterW.Roleofyttriuminglassformation

ofFe-basedbulkmetallicglasses.MetallApplPhysLett2003;83(13):2581–2583.17.PonnambalamV,PoonS,Shi?etG.JMaterRes

2004;19(5):1320.18.ChidambaramD,ClaytonCR,DorfmanMR.Evaluationof

theelectrochemicalbehaviorofHVOF-sprayedalloycoat-ings.SurfCoatTechnol2004;176:307–317.19.Szklarska-SmialowskaZ.Pittingresistanceequivalence

number,effectofalloyingelementsonstainlesssteelsandNi-basealloys.Pittingandcrevicecorrosion.NACE;2005.pp.318–321.Chapter13.20.RebakR,CrookP.Improvedpittingandcrevicecorrosion

resistanceofnickelandcobaltbasedalloys.SymposiumonCriticalFactorsinLocalizedCorrosionIII,194thECSMeeting,Volumes98–17,1999.pp.289–302.21.AgarwalD,KohlerM.Alloy33,anewmaterialresisting

marineenvironment,Paper424,Corrosion97.NACE;1997.22.SedriksA.Introduction,pitting.Corrosionofstainless

steels.NewYork(NY):JohnWiley&Sons;1996.pp.111–113.Chapter4.23.HackHP.Crevicecorrosionbehaviorofmolybdenum-containingstainlesssteelinseawater.MaterPerform1983;22(6):24–30.24.AsphahaniA.Corrosionresistanceofhighperformance

alloys.MaterPerform1980;19(12):33–43.25.BranaganDJ,MarshallMC,MechamBE,etal.Wearand

CorrosionResistantAmorphous/NanostructuredSteelCoat-ingsforReplacementofElectrolyticHardChromium,UCRLReport,LawrenceLivermoreNationalLaboratory;Liver-more(CA);2005.In:ProceedingsoftheInternationalTher-malSprayConferenceandExposition;2006May15–18.Seattle(WA):AmericanSocietyofMaterialsInternational;2006.p.7.26.BranaganD.Methodofmodifyingiron-basedglassesto

increasecrystallizationtemperaturewithoutchangingmelt-ingtemperature.USpatentApplicationNo.20040250929.Filed2004Dec16.

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

27.BranaganD.Propertiesofamorphous/partiallycrystalline

coatings.USpatentApplicationNo.20040253381.Filed2004Dec16.28.BranaganDJ.Highlyactiveliquidmeltsusedforform

coatings.USpatentApplicationNo.20040250926.Filed2004Dec16.29.BranaganDJ.Methodsofforminghardenedsurfaces.US

patentApplicationNo.6,767,419.Filed2000Nov9.Granted2004July27.30.BranaganDJ.Hardmetallicmaterials,hardmetallicmate-rials.USpatentApplicationNo.20040140017.Filed2004July27.31.BranaganDJ.Methodforprotectingasurface.USpatent

ApplicationNo.20040140021.Filed2004July22.32.BranaganDJ.Methodforformingahardmetallicwire.US

patentApplicationNo.20040141868.Filed2004July22.33.BranaganDJ.Formationofmetallicthermalbarriercoat-ings.USpatentApplicationNo.20050013723.Filed2004Feb11.34.BranaganDJ.Hardmetallicmaterials,hardmetalliccoat-ings,methodsofprocessingmetallicmaterialsandmethodsofproducingmetalliccoatings.USpatentApplicationNo.20030051781.Filed2003Mar20.35.BranaganDJ,BurchJV.Methodsofformingsteel.USpatent

ApplicationNo.6,258,185.Filed1999May25.Granted2001July10.36.BranaganDJ,SmolikGE.Advancedneutronabsorbermate-rials.USpatent6,125,912.Filed1999Feb2.Granted2000Oct3.37.BlinkJ,FarmerJ,ChoiJ-S,etal.Applicationsinthenuclear

industryforthermalsprayamorphousmetalandceramiccoatings.TransactionsA2009;40A(6):1345–1354.38.FarmerJ,HaslamJ,DayS,etal.Corrosionresistancesof

iron-basedamorphousmetalswithyttriumandtungstenadditionsinhotcalciumchloridebrineandnaturalseawa-ter,Fe48Mo14Cr15Y2C15B6andW-containingvariants.InMissertN,VirtanenS,DavenportAJ,etal.,editors.Volume3(31),Criticalfactorsinlocalizedcorrosion5.ASymposiuminhonorofHughIssacs,210thMeetingoftheECS;2006;Cancun,Mexico.Pennington,NJ:ElectrochemicalSocietyTransations,ElectrochemicalSociety;2006.pp.485–496.DOI:10.1149/1.2789251.39.FarmerJ,HaslamJ,DayS,etal.AHigh-performance

corrosion-resistantiron-basedamorphousmetal—theeffectsofcomposition,structureandenvironmentoncor-rosionresistance.In:Scienti?cBasisforNuclearWasteManagementXXX.SymposiumNN;2006November27ththroughDecember1st;Boston(MA),MaterialsResearchSocietySymposiumSeries,Volume985.Warrendale(PA);2006.40.LianT,DayD,HaileyP,etal.Comparativestudyonthe

corrosionresistanceofFe-basedamorphousmetal,boratedstainlesssteelandNi-Cr-Mo-Gdalloy.In:Scienti?cBasisforNuclearWasteManagementXXX.SymposiumNN;2006November27ththroughDecember1st;Boston(MA),MaterialsResearchSocietySymposiumSeries,Volume985.Warrendale(PA);2006.41.ChoiJ-S,LeeC,FarmerJ,etal.Applicationof

neutron-absorbingstructuralamorphousmetalcoatingsforspentnuclearfuelcontainertoenhancecriticalitysafetycontrols.In:Scienti?cBasisforNuclearWasteManage-mentXXX.SymposiumNN;2006November27ththroughDecember1st;Boston(MA),MaterialsResearchSocietySymposiumSeries,Volume985,Warrendale(PA);2006.

30HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

42.ChoiJ-S,FarmerJ,LeeC.Applicationofneutron-absorbing

structural-amorphousmetal(SAM)coatingsforspentnuclearfuel(SNF)container:useofnovelcoatingmate-rialstoenhancecriticalitysafetycontrols,UCRL-MI-220385;2006April5.2006LawrenceLivermoreNationalLabo-ratory,Livermore(CA),ProceedingsofCALPHADMeeting;2006May11th.Haifa,Israel;2006.p.32.

43.FarmerJC,ChoiJ-S,SawC-K,RebakRH,DaySD,Lian

T,HaileyPD,PayerJH,BranaganDJ,ApriglianoLF.CorrosionresistanceofamorphousFe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4coating–anewcriticalitycontrolmate-rial.JNuclEngAmNuclSoc2008;161(2):169–189.

44.PerepezkoJH,HildalK.HPCRMAnnualReport,Thermal

andKineticAnalysisofAmorphousFe-BasedAlloysforUseinThermalSprayProcessing.SubmissiontoLawrenceLivermoreNationalLaboratory,UniversityofWisconsin,Madison,Wisconsin;2004Sep9;p.74.

45.FarmerJ,TurchiP,PerepezkoJ.Iron-basedamor-phousmetals,animportantfamilyofhigh-performancecorrosion-resistantmaterials,foreward.TransactionsA2009;40A(6):1288.

46.RebakRB,DaySD,LianT,etal.Environmentaltest-ingofiron-basedamorphousalloys.MetallMaterTransA2008;39A(2):225–234.DOI:10.1007/s11661-007-9460-7.47.FarmerJC,ChoiJ-S,SawC-K,etal.Corro-sionresistanceofamorphousFe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4coating—anewcriticalitycontrolmate-rial,UCRL-JRNL-229505Rev.2,LawrenceLivermoreNationalLaboratory,Livermore(CA);2007Aug14th.JNuclTechnol2008;161(2):169–189.

48.GraeveOA,KanakalaR,KaufmanL,etal.Sparkplasma

sinteringoffe-basedstructuralamorphousmetals(SAM)withY2O3nanoparticleadditions.MaterLett2007.DOI:10.1016/j.matlet.2008.01.092/4.

49.FarmerJC,HaslamJJ,DaySD,etal.Corrosionresistanceof

thermallysprayedhigh-boroniron-basedamorphous-metalcoatings:Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4,UCRL-TR-227111Rev.1,LawrenceLivermoreNationalLab-oratory,Livermore(CA);2007April16th.JMaterRes2007;22(8):2297–2311.

50.FarmerJ,HaslamJ,DayS,etal.Thecorrosionresis-tanceofFe-basedamorphousmetals:Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4andotherCompositions,ExploringStruc-ture,Processing,andApplicationsAcrossMultipleMaterialsSystems,ProceedingsofMaterialsScience&Technology2007,September16ththrough20th2007,Detroit,Michigan,AmericanCeramicSociety(ACerS),AssociationforIron&SteelTechnology(AIST),AmericanSocietyofMetals(ASM)andTheMinerals,Metals&MaterialsSociety(TMS).pp.381–392.

51.ApriglianoLF,DaySD,HaslamJJ,etal.Industrialsaltfog

testingofaSAM2X5coatedstainlesssteelcylinder,explor-ingstructure,processing,andapplicationsacrossmultiplematerialssystems.In:ProceedingsofMaterialsScience&Technology2007,September16ththrough20th2007,Detroit,Michigan,AmericanCeramicSociety(ACerS),Asso-ciationforIron&SteelTechnology(AIST).AmericanSocietyofMetals(ASM)andTheMinerals,Metals&MaterialsSociety(TMS).pp.393–400.

52.ChoiJ-S,FarmerJ,LeeC,etal.Neutron-absorbingcoatings

forsafestorageof?ssilematerialswithenhancedshielding&criticalitysafety,exploringstructure,processing,andapplicationsacrossmultiplematerialssystems.In:Proceed-ingsofMaterialsScience&Technology2007ConferenceandExhibition,September16ththrough20th2007,Detroit,

Michigan,AmericanCeramicSociety(ACerS),AssociationforIron&SteelTechnology(AIST),AmericanSocietyofMetals(ASM)andtheMinerals,Metals&MaterialsSociety(TMS).pp.431–442.

53.

BlinkJ,ChoiJ,FarmerJ.Applicationsinthenuclearindustryforthermalsprayamorphousmetalandceramiccoatings,exploringstructure,processing,andapplicationsacrossmultiplematerialssystems.In:ProceedingsofMate-rialsScience&Technology2007ConferenceandExhibition,September16ththrough20th2007,Detroit,Michigan,AmericanCeramicSociety(ACerS),AssociationforIron&SteelTechnology(AIST),AmericanSocietyofMetals(ASM)andTheMinerals,Metals&MaterialsSociety(TMS).pp.443–456.

54.

DaySD,LianT,FarmerJC,etal.Cyclicandlinearpolar-izationofyttriumcontainingiron-basedamorphousalloys,exploringstructure,processing,andapplicationsacrossmul-tiplematerialssystems.In:ProceedingsofMaterialsScience&Technology2007ConferenceandExhibition,Septem-ber16ththrough20th2007,Detroit,Michigan,AmericanCeramicSociety(ACerS),AssociationforIron&SteelTech-nology(AIST),AmericanSocietyofMetals(ASM)andTheMinerals,Metals&MaterialsSociety(TMS).pp.457–468.55.

FarmerJ,DayS,LianT,etal.Long-termcor-rosiontestingofthermalspraycoatingsofamor-phousmetals:Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4andFe48Mo14Cr15Y2C15B6,exploringstructure,processing,andapplicationsacrossmultiplematerialssystems.In:Proceed-ingsofMaterialsScience&Technology2007ConferenceandExhibition,September16ththrough20th2007,Detroit,Michigan,AmericanCeramicSociety(ACerS),AssociationforIron&SteelTechnology(AIST),AmericanSocietyofMetals(ASM)andTheMinerals,Metals&MaterialsSociety(TMS).pp.469–480.

56.

DayS,HaslamJ,HaileyP,etal.Corrosionresistanceofhigh-boronhigh-molybdenumiron-basedamorphousmetalFe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4forspentnuclearfuelcriticalitycontrolapplication,exploringstructure,pro-cessing,andapplicationsacrossmultiplematerialssystems.In:ProceedingsofMaterialsScience&Technology2007Con-ferenceandExhibition,September16ththrough20th2007,Detroit,Michigan,AmericanCeramicSociety(ACerS),Asso-ciationforIron&SteelTechnology(AIST),AmericanSocietyofMetals(ASM)andTheMinerals,Metals&MaterialsSociety(TMS).pp.481–493.

57.

HaileyPD,FarmerJC,DaySD,etal.AnodicbehaviorofSAM2X5materialappliedasamorphouscoatings,exploringstructure.In:Processing,andApplicationsAcrossMulti-pleMaterialsSystems,ProceedingsofMaterialsScience&Technology2007ConferenceandExhibition,Septem-ber16ththrough20th2007,Detroit,Michigan,AmericanCeramicSociety(ACerS),AssociationforIron&SteelTech-nology(AIST),AmericanSocietyofMetals(ASM)andTheMinerals,Metals&MaterialsSociety(TMS).pp.495–507.58.

DaySD,HaslamJJ,FarmerJ,etal.Dissolutionmodesandeffectofhightemperatureagingonthecorrosionresistanceofironbasedamorphousalloys,exploringstructure,process-ing,andapplicationsacrossmultiplematerialssystems.In:ProceedingsofMaterialsScience&Technology2007Con-ferenceandExhibition,September16ththrough20th2007,Detroit,Michigan,AmericanCeramicSociety(ACerS),Asso-ciationforIron&SteelTechnology(AIST),AmericanSocietyofMetals(ASM)andTheMinerals,Metals&MaterialsSociety(TMS).pp.509–521.

59.

FarmerJ.Iron-basedamorphousmetals:thehighper-formancecorrosionresistantmaterials(hpcrm)program,

exploringstructure,processing,andapplicationsacrossmul-tiplematerialssystems.In:ProceedingsofMaterialsScience&Technology2007ConferenceandExhibition,Septem-ber16ththrough20th2007,Detroit,Michigan,AmericanCeramicSociety(ACerS),AssociationforIron&SteelTech-nology(AIST),AmericanSocietyofMetals(ASM)andTheMinerals,Metals&MaterialsSociety(TMS).pp.535–566.60.SawCK,LianT,DaySD,etal.XRDtechnique:awayto

discriminatestructuralchangesiniron-basedamorphousmaterials,exploringstructure,processing,andapplicationsacrossmultiplematerialssystems.In:ProceedingsofMate-rialsScience&Technology2007ConferenceandExhibition,September16ththrough20th2007,Detroit,Michigan,AmericanCeramicSociety(ACerS),AssociationforIron&SteelTechnology(AIST),AmericanSocietyofMetals(ASM)andTheMinerals,Metals&MaterialsSociety(TMS).pp.579–587.61.HaslamJJ,FarmerJC,DayS,etal.Characterizationof

corrosionresistantamorphousmetalcoatingssubsequenttomechanicaldeformation,exploringstructure,processing,andapplicationsacrossmultiplematerialssystems.In:Pro-ceedingsofMaterialsScience&Technology2007ConferenceandExhibition,September16ththrough20th2007,Detroit,Michigan,AmericanCeramicSociety(ACerS),AssociationforIron&SteelTechnology(AIST),AmericanSocietyofMetals(ASM)andTheMinerals,Metals&MaterialsSociety(TMS).pp.589–603.62.FarmerJC,HaslamJJ,DaySD,etal.Corrosionresistanceof

thermallysprayedhigh-boroniron-basedamorphous-metalcoatings:Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4,UCRL-TR-227111Rev.1,LawrenceLivermoreNationalLab-oratory,Livermore,CA,2007April16th.JMaterRes2007;22(8):2297–2311.63.FarmerJC.Thedevelopmentofnext-generationmaterials

fornuclearenergy,UCRL-PRES-219330,energyandenvi-ronmentdirectoratereviewcommittee,2006March7–9;Livermore(CA):LawrenceLivermoreNationalLaboratory;2006.p.17.64.FarmerJC.TeamFY05HPCRMAnnualreport:

high-performancecorrosion-resistantiron-basedamorphousmetalcoatings,UCRL-SR-219257;2006Jan.In:Contribu-tionsbyFarmerJC,ChoiJ-S,HaslamJJ,etal.Liver-more(CA):LawrenceLivermoreNationalLaboratory;2006.p.138.65.FarmerJ,HaslamJ,DayS,etal.Corrosionresis-tanceofiron-basedamorphousmetalsinhotconcentratedcalciumchlorideandseawater:Fe48Mo714Cr15Y2C15B6.UCRL-TM-224159.Livermore(CA):LawrenceLivermoreNationalLaboratory;2006Aug30th.p.47.66.FarmerJ,HaslamJ,DayS,etal.Corrosionresis-tanceofiron-basedamorphousmetalsinseawa-ter:Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4,UCRL-TM-223298;2006Aug28.Livermore(CA):LawrenceLivermoreNationalLaboratory;2006.p.60.67.FarmerJC,HaslamJJ,DaySD.HPCRMannual

report:high-performancecorrosion-resistantiron-basedamorphous-metalcoatings:evaluationofcorrosionresis-tance,UCRL-SR-218144;2006Jan.Livermore(CA):LawrenceLivermoreNationalLaboratory;2006.p.68.68.FarmerJC.TeamFY05HPCRMannualreport:

HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

69.FarmerJC.TeamFY05HPCRMannualreport:

report:high-performancecorrosion-resistantiron-basedamorphous-metalcoatings:evaluationofcorrosionresis-tance,UCRL-SR-218144,2006Jan.Livermore(CA):LawrenceLivermoreNationalLaboratory;2006.p.68.71.FarmerJ,HaslamJ,DayS,etal.Corrosionresis-tanceofiron-basedamorphousmetalsinhotconcentratedcalciumchlorideandseawater:Fe48Mo714Cr15Y2C15B6.UCRL-TM-224159.Livermore(CA):LawrenceLivermoreNationalLaboratory;2006Aug30th.p.47.72.FarmerJC,HaslamJJ,DaySD,etal.Corrosioncharac-terizationofiron-basedhigh-performanceamorphous-metalthermal-spraycoatings,PVP2005-71664.In:ProceedingsofASMEPVP:PressureVessels&PipingDivisionConfer-ence,GrandHyatt;2005July17–21;Denver(CO).ThreeParkAvenue,NewYork:AmericanSocietyofMechanicalEngineers;2005.p.7.73.BranaganDJ,MarshallMC,MeachamBE.TheNanoSteel

Company,Incorporated.FinalReportforthePerformanceofLLNLSubcontractFY05,LLNL-RFP-B550033,HighPerformanceCorrosionResistantMaterials(HPCRM)forNavalWar?ghtingandSafeLong-TermStorage/DisposalofSpentNulcearFuel,JointDOE-DARPAProgram,InstituteofNanomaterialsResearchandDevelopment,TheNanoS-teelCompany,IdahoFalls,Idaho;2005.p.84.74.FarmerJ,EarlC,DotyC,etal.DARPA-DOEhighper-formancecorrosion-resistantmaterials(HCPRM)PrincipalInvestigator’sMeeting,TurtleBayResort;2005Jan10–13;Oahu,Hawaii,UCRL-PRES-214672.Livermore(CA):LawrenceLivermoreNationalLaboratory;2005.p.407.75.FarmerJC,HaslamJJ,DaySD,etal.High-performancecorrosion-resistantmaterials:iron-basedamorphous-metalthermal-spraycoatings,high-perfor-mancecorrosion-resistantmaterials(HPCRM)annualreport,UCRL-TR-206717.Livermore(CA):LawrenceLiv-ermoreNationalLaboratory;2004Sep28.p.178.76.SawCK.X-rayscatteringtechniquesforcharacterization

toolsinthelifesciences.In:KumarC,editor.Nanotech-nologiesforthelifescience.Weinheim;Wiley-VCHVerlagGmbH&Co.,KGaA;2006.77.SawCK,SchwarzRB.Chemicalshort-rangeorderin

denserandom-packedmodels.JLess-CommonMet1988;140:385–393.78.HarrarJE,CarleyJF,IsherwoodWF,etal.Reportofthe

CommitteetoReviewtheUseofJ-13WellWaterinNevadaNuclearWasteStorageInvestigations,Project,UCID-21867.Livermore(CA):LawrenceLivermoreNationalLabora-tory;1990.p.111.79.GdowskiGE.Formulationandmake-upofsimulateddilute

water(SDW),lowioniccontentaqueoussolution,Livermore(CA):LawrenceLivermoreNationalLaboratory;TIP-CM-06,RevisionCNTIP-CM-06-0-2;1997April4,Table1.p.3.80.GdowskiGE.Formulationandmake-upofsimulatedcon-centratedwater(SCW),highioniccontentaqueoussolution,Livermore(CA):LawrenceLivermoreNationalLaboratory;TIP-CM-07,RevisionCNTIP-CM-07-0-2;1997April4,Table1.pp.3–4.

32HIGHPERFORMANCECORROSION-RESISTANTMATERIALS

81.GdowskiGE.Formulationandmake-upofsimulatedacidic

concentratedwater(SAW),highioniccontentaqueoussolu-tion,Livermore(CA):LawrenceLivermoreNationalLabo-ratory,TIP-CM-08,RevisionCNTIP-CM-08-0-2;1997April4,Table1.p.3.82.ApriglianoLF.HPCRMannualreport,saltfogcorrosion

testingatNSWCCD,SubmissiontoLawrenceLivermoreNationalLaboratory,NavalSurfaceWarfareCenter,Carde-rockDivision;2005Nov17.p.13.

83.FarmerJ,LuS,McCrightD,etal.Generalandlocalized

corrosionofhigh-levelwastecontainer,transportation,stor-age,anddisposalofradioactivematerials.ASME,PVP2000;408:53–70.

84.GrussKA,CragnolinoGA,DunnDS,etal.Repassivation

potentialforlocalizedcorrosionofalloys625andC22insimulatedrepositoryenvironments,Paper149,Corrosion98.Houston(TX):NationalAssociationofCorrosionEngi-neers;1998.p.9.

85.ScullyJR,HudsonJL,LuntT,etal.Localizedcorrosion

initiationandtransitiontostabilizationinalloys625andC-22,?nalreport,TRW/DOEYMPpurchaseordernumberA10762JM8A;1999Sep30.p.27.86.AsphahaniAI.Corrosionresistanceofhighperformance

alloys.MaterPerform1980;19(12):33–43.87.ASTM.StandardReferenceTestMethodforMakingPoten-tiostaticandPotentiodynamicAnodicPolarizationMea-surements,DesignationG5-94,1997AnnualBookofAmericanSocietyforTestingandMaterials(ASTM)Stan-dards,Section3,Volume3.02;1997.pp.54–57.

88.ASTM.StandardReferenceTestMethodforMakingPoten-tiostaticandPotentiodynamicAnodicPolarizationMeasure-ments,DesignationG5-87,1989AnnualBookofAmericanSocietyforTestingandMaterials(ASTM)Standards,Section3,Volume3.02;1989.pp.79–85.

89.ASTM.StandardPracticeforConventionsApplicableto

ElectrochemicalMeasurementsinCorrosionTesting,Des-ignationG3-89,1997AnnualBookofAmericanSocietyforTestingandMaterials(ASTM)Standards,Section3,Volume3.02;1997.pp.36–44.

90.ASTM.StandardTestMethodforConductingCyclicPoten-tiodynamicPolarizationMeasurementsforLocalizedCorro-sionSusceptibilityofIron-,Nickel-,orCobalt-BasedAlloys,DesignationG61-86,1997AnnualBookofAmericanSoci-etyforTestingandMaterialsStandards,Section3,Volume3.02;1997.pp.231–235.91.TresederRS,BaboianR,MungerCG.PolarizationResis-tanceMethodforDeterminingCorrosionRates,NACE

CorrosionEngineer’sReferenceBook.2nded.1440SouthCreekDrive,Houston(TX):NationalAssociationofCorro-sionEngineers;1991.pp.65–66.

92.JonesDA.Faraday’sLaw,Section3.1.1.Electrochemical

KineticsofCorrosion,Chapter3,PrinciplesandPreventionofCorrosion.2nded.UpperSaddleRiver(NJ):PrenticeHall;Equations3and5;1996.pp.75–76.

93.BardAJ,FaulknerLR.LiquidJunctionPotentials,Section

2.3,PotentialsandThermodynamicsofCells,Chapter2,ElectrochemicalMethods,FundamentalsandApplications.NewYork(NY):JohnWiley&Sons;1980.Equation2.3.39,p.71,Table2.3.2,p.67.

94.KimWT,ClayK,SmallC,etal.Heattreatmentofa

meltSpunFe70Cr18Mo2B10Alloy.JNon-CrystSolids1991;127:273–286.

95.ASTM.CalculationofCorrosionRate,subsection8,Den-sitiesforaVarietyofMetalsandAlloys,AppendixX1,StandardPracticeforPreparing,Cleaning,andEvaluat-ingCorrosionTestSpecimens,DesignationG1-81,1987AnnualBookofAmericanSocietyforTestingandMaterialsStandards,Section3,Volume3.02;1987.pp.89–94.96.ASTM.StandardTestMethodsforPittingandCreviceCor-rosionResistanceofStainlessSteelsandRelatedAlloysbyUseofFerricChlorideSolution,DesignationG48-92,1997AnnualBookofAmericanSocietyforTestingandMaterialsStandards,Section3,Volume3.02;1997.pp.181–186.97.ASTM.StandardPracticeforPreparing,Cleaning,andEval-uatingCorrosionTestSpecimens,DesignationG1-90,1997AnnualBookofAmericanSocietyforTestingandMaterialsStandards,Section3,Volume3.02;1997.pp.15–21.

98.ASTM.StandardSpeci?cationforLow-CarbonNickel-Molybdenum-Chromium,Low-CarbonNickel-Chromium-Molybdenum,Low-CarbonNickel-Chromium-Molybdenum-Copper,andLow-CarbonNickel-Chromium-Molybdenum-TungstenAlloyPlate,Sheet,andStrip,DesignationB575-94,1997AnnualBookofAmericanSocietyforTestingandMaterialsStandards,section2,subsection7.1—weight,Volume2.04;1997.pp.409–410.

99.VirmaniP.CorrosionCostsandPreventativeStrategiesin

theUnitedStates,TechnicalBrief:FHWA-RD-01-157(Fed-eralHighwayAdministration,U.S.DepartmentofTrans-portation,March2002).p.17.

100.HarttWH,PowersRG,LysogorskiDK,etal.JobSiteEvalu-ationofCorrosion-ResistantAlloysforUseasReinforcementinConcrete:FHWA-HRT-06-078(FederalHighwayAdmin-istration,U.S.DepartmentofTransportation,March2002).p.78.

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