Electrochemical behavior of copper and copper nickel alloys in synthetic sea water

199 Pages·1997·4.3 MB·English

by  Wojcik, Paul Thomas

THEELECTROCHEMICALBEHAVIOROFCOPPER
ANDCOPPERNICKELALLOYSINSYNTHETICSEA
WATER
By
PAULTHOMASWOJCIK
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOLOF
THEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENTOFTHE
REQUIREMENTSFORTHEDEGREEOFDOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
1997
ACKNOWLEDGMENTS
Theauthorwishestoexpresshisgratitudetokeyindividualsfortheircontribution
tothisdissertationandtotheenhancementofthislearningexperience.Hewouldliketo
thankDr.MarkE.Orazemforhisguidance,supportandinsightfulsuggestions.The
authorwouldalsoliketothankmembers,bothpastandpresent,oftheElectrochemical
EngineeringGroupattheUniversityofFloridafortheirstimulatingargumentsand
informativediscussions.OliverMoghissiandSteveCarsonhavebeenagreathelpon
topics ofelectrochemistry, and Pankaj Agarwal and Doug Reimer have been
indispensableintheareasofmeasurementmodelsandcomputersrespectively.His
motherandfatherreceiveaspecialthankyouforsupplyingtheadvice,supportofhis
decisions, andencouragementwhich hasmadethis educational experiencetruly
enjoyable.
TABLEOFCONTENTS
page
ACKNOWLEDGMENTS
ii
LISTOFTABLES vi
LISTOFFIGURES vii
LISTOFSYMBOLS xiv
ABSTRACT xvi
CHAPTER1INTRODUCTION 1
CHAPTER2 BACKGROUND 6
2.1CopperUtilityinSeaWaterEnvironments 6
2.2ModelLimitations 7
2.2.1Limitationsofthermodynamicinformation 7
2.2.2Realsystemchemicalcharacterizationinadequacies 8
2.2.3Under-predictedreactionrates 8
2.2.4Chemicalreactiontimes 8
2.3Thermodynamics 8
2.4CorrosioninAlkalineChlorideSolutions 18
2.5CopperinSeaWaterEnvironments 20
2.6ElectrochemicalBehaviorofCopperinAqueousEnvironmentswith
Flow 24
2.6.1Erosioncorrosion 24
2.6.2Causesandindications 25
CHAPTER3 ELECTROCHEMICALTECHNIQUES 28
1 1
3. LargeSignalAmplitudeMeasurementTechniques 29
3.2SmallSignalAmplitudeMeasurementTechniques 29
3.3ElectrochemicalImpedanceSpectroscopy 30
CHAPTER4EXPERIMENTALMETHOD 36
4.1ImpingingJetSystem 36
4.2SampleandSolutionPreparation 42
4.3ExperimentalProcedure 43
CHAPTER5VMAORDIUALBALETEADMPILMIPTEUDDAENCGEALSVPAENCOTSRTOASTCIOCPAYLLY 48
5.1Variable-AmplitudeGalvanostaticModulationAlgorithm 55
5.2PredictionoftheAmplitudeoftheCurrentPerturbation 56
5.3PredictionoftheValuefortheCurrentMeasuringResistor 58
5.4ApplicationtoCorrosionMeasurements 62
5.5ComparisonWithOtherTechniques 64
5.6ExperimentalStudies 71
CHAPTER6RESULTSANDDISCUSSION 76
6.1TheMeasurementModelApproach 78
6.2LinearSweepVoltammetry 79
6.3CopperinPartially-AeratedElectrolyte:Part1 87
6.4CopperinPartially-AeratedElectrolyte:Part2 105
6.570/30Copper/NickelAlloyinAeratedElectrolyte 11
6.6CopperinAeratedElectrolyte 117
6.7X-rayPhotoelectronSpectroscopyAnalysis 128
6.8CopperRodsinSyntheticSeaWater 136
CHAPTER7COMPARISONWITHPASTRESULTS 147
CHAPTER8CONCLUSIONS 155
CHAPTER9SUGGESTIONSFORFUTUREWORK 158
APPENDICES
A:ELECTROCHEMISTRY 161
B:TIMESUMMARIES 165
REFERENCES 171
BIOGRAPHICALSKETCH 178
LISTOFTABLES
page
Tabler2e.f1:erSeenlceecdtetodastnaonrdmaardlehlyedcrtorgodeenpeolteecnttrioadles(inBaarqdue&ouFsausloklnuteiron1s98a0t)2.5°C 9
Table2.2:Cathodicreactionsforcopperinanalkalineaqueoussolution. 19
Table2.3:ElementalcompositionofASTMD-l141-52formulaAsyntheticsea 21
water.
Table2.4:Coppercompoundspossibleinacopper/syntheticseawatersystem. 22
Thecolorandsolubilityinwateraregivenforeachcompound(Weast
1984).
Tablea2n.5d:hHyedtreorxoigdeenceaorubsoneaqutielsib(rSiatuimnvmol&viMnogrogxaidnes1,98h1yd).roxides,carbonates, 23
Table5.1:CurrentmeasuringresistorrangesforaPAR273potentiostat. 61
Tableb5e.2:viPsauarlaimzeetderbyvailnuseesrtfioorneolfecRtraicnadlCcirvcauliutess1inatnodF2i.guCirrecu5i.5t.s1and2can 65
Table6.1:Timelinehighlightingmajoreventsfortheexperimentpresentedin 92
Figures6.5-6.16.
TableW7.a1t:erCr(iEtfiicradl,V1e9l7o7c)i.tyandShearStressforCopper-BasedAlloysinSea 150
TableBl:SummaryofexperimentaleventsfordatapresentedinSection6.3. 166
TableBlcont. 167
TableB2:SummaryofexperimentaleventsfordatapresentedinSection6.4. 168
TableB3:SummaryofexperimentaleventsfordatapresentedinSection6.5. 169
TableB4:SummaryofexperimentaleventsfordatapresentedinSection6.6. 170
5
LISTOFFIGURES
Page
Figure252.°C1:.PSootleindtisaulb-sptHanecqeusiluinbdreirumcodnisaigdrearamtfioornaarceopCpue,rC/uw2a0t,eransdysCtueOm.atThe 12
nEluemcbterroschienmtihciaslfEiqguuirleicborirareisnpAoqnduetoourseaScotliuotnisongsi.veAnminortheedAettlaaisleodf
descriptionofthisfigureisgiveninthereference(Pourbaix1974).
Figure2.2:Potential-pHequilibriumdiagramforacopper/watersystemat 13
25°C.SolidsubstancesunderconsiderationareCu,Cu20,andCu(OH)2
(Pourbaix1974).Thenumbersinthisfigurecorrespondtoreactionsgiven
intheAtlasofElectrochemicalEquilibriainAqueousSolutions.Amore
detaileddescriptionofthisfigureisgiveninthereference(Pourbaix
1974).
Figure2.3:Potential-pHequilibriumdiagramforacopper/seawatersystemat 14
25°C.SolidsubstancesunderconsiderationareCu,Cu20,CuCl,CuO,and
tChue2r(eOfHe)r3enCcle.wThhiechnugmivbeesrsadinettahiilsedfidgeusrcercipotriroenspoofntdhitsofriegaucrteio(nBsiagnicvhein&in
Longhi1973).
Figure252.°4C:.PSootleindtisaulb-sptHanecqeusiluinbdreirumcodnisaigdrearamtfioornaarceopCpue,rC/us2e0a,waCtueCrl,systemat 1
Cu(OH)2,andCu2(OH)3Cl.Thenumbersinthisfigurecorrespondto
rfeiagucrteio(nBsigaincvhein&intLhoengrhefier1e9n7c3e).whichgivesadetaileddescriptionofthis
Figure2.5:Potential-pHequilibriumdiagramforacopper/seawatersystemat 16
25°C.SolidsubstancesunderconsiderationareCu,Cu20,CuO,CuCl,and
CuC03-Cu(OH)2.Thenumbersinthisfigurecorrespondtoreactions
g(Biivaenncihnit&heLroenfgehreinc1e97w3h)i.chgivesadetaileddescriptionofthisfigure
7
Figure2.6:Potential-pHequilibriumdiagramforacopper/seawatersystemat 1
25°C.SolidsubstancesunderconsiderationareCu,Cu20,CuCl,
Cu(OH)2,andCuC03Cu(OH)2.Thenumbersinthisfigurecorrespondto
rFeiagcutrieon(sBigainvcehnii&ntLhoenrgehfier1e9n7c3e)w.hichgivesadetaileddescriptionofthis
Figure3.1:Current/Potentialcurvestodemonstratelinearresponsefromsmall 35
signalperturbation(Gabrielli,1980).
Figurec4o.n1d:ucStheedarhesrtree.ssThaesadifmuenncstiioonnloefssjetquvaenltoictiytyr/frorretphreeesxenptesritmheenrtaatliowoofrkthe 38
radialposition/electroderadius.
Figure4.2:Experimentalconfigurationusedforinvestigatingtheinfluenceofjet 46
velocityonthecorrosionofcopperandcopperalloysinsyntheticsea
water.
Figure4.3:Schematicillustrationoftheimpingingjetcellandimportantcell 47
components.
Figureex5.p1er:iSmcehnetmaotnicthiellcuosrtrroatsiioonnopfottehnetiianlfloufenacseyosfteampowtietnhtiaoscthaatincgiinmgpedance 53
baseline.
Figure5.2:Sequentialcurrentpotentialcurvesforasystemwithatransient 54
corrosionpotential.
Figure5.3:Potentialperturbationfortestcircuit,Circuit1,resultingfrom 55
traditionalgalvanostaticimpedancemeasurementsusingfixedamplitude
currentperturbations.
Figureme5.t4h:oCdosmfpoarrtihseovnarbieatbwleeeanmptlheitoundeepaolignotriatnhdmtwhirtehepaoi1n0tmprVedtiacrtgieotn 58
potentialperturbation.
Figure5.5:Testcircuitandconnections. 64
Figurega5l.v7:anIosmtpaetdiac,ncVeApGl,anaenpdloptotfeonrtitoessttactiirccutietcChenlilque1sc.omparingconventional 67
Figure5.8:Therealcomponentoftheimpedanceasafunctionoffrequencyfor 68
testcircuitCell1comparingconventionalgalvanostatic,VAG,and
potentiostatictechniques.
.
Figure5.9:Theimaginarycomponentoftheimpedanceasafunctionof 68
VfrAeGq,uenacnydfpoortetnetsitocsitractuiicttCeeclhlni1qcueosm.paringconventionalgalvanostatic,
Figure5.10:ImpedanceplaneplotfortestcircuitCell2comparingconventional 69
galvanostatic,VAG,andpotentiostatictechniques.Notetheorderof
magnitudechangeintheimpedancevaluescomparedtoCell1
Figure5.11:Therealandimaginarycomponentsoftheimpedanceasafunction 70
offrequencyfortestcircuitCell2comparingconventionalgalvanostatic,
VAG,andpotentiostatictechniques.
FigureA5S.1T2:MI1m1p4e1dasnyncteheptliacnesepalowtatfeorr.9C9o.m9p%arpuirseoncobpeptewreeelnecVtAroGdeainmdmersedin 73
potentiostatictechniquessuggestthatsmallchangesinthesystem
amdevaesrusreelmyeenftfsectcomnedauscutreedmienntthsemVaAdeGimnotdheepaorteenrteiporsotdautciicbmleo.dewhile
Figure5.13:Impedanceplaneplotfor99.9%purecopperelectrodeimmersedin 74
ASTM1141syntheticseawater.Comparisonbetweenconventionalfixed
amplitudegalvanostatic,VAG,andpotentiostatictechniques.
Figure5.14:Therealcomponentoftheimpedanceasafunctionoffrequencyfor 75
dwaattaerprceosmepnatredinigncFoingvuernet5i.o1n3a.l9g9a.lv9a%nocsotpapteircainmdmeVrAseGdtiencshynnitqhueetsi.csea
Figure5.15:Theimaginarycomponentoftheimpedanceasafunctionof 75
wfarteeqruecnocmyp(asreienFgigcuorneve5n.t1i3o)naflorg9al9v.a9n%osctaotpipceranidmmVeArsGedteicnhnsiyqnutehse.ticsea
Figure6.1:Linearsweepvoltammogramatthreedifferentsweeprates.Applied 83
potentialversusresultingcurrent(Charriere1997).
Figure6.2:Cyclicvoltammogramwitharateof66mV/s(Charriere1997). 83
Figure6.3:Potentialtimetracesfor99.9%purecopperinaeratedsyntheticsea 84
water.Velocity(=0.1m/s)maintainedatlowvalueprimarilytoensure
uniformmasstransfertothesurfaceandremovalofcorrosionproducesnot
tightlyadheredtothesurface.
Figureco6n.4s:taPnrtog2r0e0s.s0iomnV.ofIamafiglemsgprroowgirnesgsdfurrionmglpefottetnotiriogshtta,titcotcalonetlraoplsaetdtime= 85
1000seconds(Charriere1997).Filmsoriginateattheperipheryandgrow
towardsthecenterofelectrode.
Figure6.5:Progressionofafilmremovalfromelectrodesurfaceduring 86
potentiostaticcontrolatconstant200.0mV.Imagesprogresslefttoright,
totalelapsedtime=1000seconds(Charriere1997).Filmbecameunstable
andwasremovedbyshearbeginningattheouteredgebecauseofahigher
shearstress.
Figure6.6:Corrosionpotentialof99.9%Cumeasuredasafunctionoftimefor 93
aperiodof33days.Electroderemainedinstagnantfluidfromt=190to
550hours.Acathodicpotentialwasappliedatt=556hoursandflowwas
resumedatt=557hours.
Figure6.61..7:PuVriedecoopmpiecrroingrnaopnh-aoebrtaatiendedelfeocrtrtohleyteexpbeefroirmeenqtuideessccernitbepderiinodT,abtlieme= 94
190hours.
Figure6.61..8:PuVriedecoopmpiecrroingrnaopnh-aoebrtaatiendedelfeocrtrtohleyteexpafetreirmqeunitesdceesnctripbeerdioidn,Ttaibmlee= 94
555hours.
Figure6.9:VideomicrographobtainedfortheexperimentdescribedinTable 95
6p.o1t.enPtuiraledciosptpuerrbainncen.onH-yaderraotgeednebluecbtbrloelsytaenadftbearrqeucioespcpeenrtvpiseirbiloed,atnidme=
556hours.
Figure6.10:Purecopperinnon-aeratedelectrolyteafterflowresumption,time= 95
558hours.
Figure6.11AnexpandedtimescalefortheCorrosionpotentialdatapresentedin 96
Figure6.6.Firstsevendaysofimmersion.
Figure6.12:Impedancedatafor99.9%Cutakenduringthefirstfivehoursof 97
submersion.Thegeneraltrendwasthatthepolarizationimpedance
decreasedforapproximatelysevenhoursaftersubmersionandthen
increasedtoasteadystatevalue.
Figure6.13:Polarizationimpedancecorrespondingtoimpedancescansshownin 98
Figure6.12.Valuesandassociatederrorpredictedthroughtheuseofa
measurementmodel.
Figure6.14:Impedancescansfor99.9%Cubeforeandafterthe16day „„
quiescentperiod.
Figurepo6t.e1n5t:iaClopapppelrieedle(c-t1r.o3deV)cobrerfoosrieonstparotteonftieaxlpearsiamefnutn.ctAiocnhoafntgiemei.nCthaethpoHdic 100
showednoeffectincorrosionpotentialwhileavelocitychangeclearly
affectedthecorrosionpotentialforanon-aeratedsolution.