Table Of ContentDonghai Xu · Shuwei Guo
Corrosion
Characteristics,
Mechanisms and
Control Methods of
Candidate Alloys in
Sub- and Supercritical
Water
Corrosion Characteristics, Mechanisms and Control
Methods of Candidate Alloys in Sub-
and Supercritical Water
·
Donghai Xu Shuwei Guo
Corrosion Characteristics,
Mechanisms and Control
Methods of Candidate Alloys
in Sub- and Supercritical
Water
DonghaiXu ShuweiGuo
DepartmentofEnergyandPower DepartmentofEnergyandPower
Engineering Engineering
Xi’anJiaotongUniversity Xi’anJiaotongUniversity
Xi’an,Shaanxi,China Xi’an,Shaanxi,China
ISBN978-981-16-5524-1 ISBN978-981-16-5525-8 (eBook)
https://doi.org/10.1007/978-981-16-5525-8
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Preface
Supercriticalwater(SCW)referstowaterattemperatureandpressurethatisabove
itscriticalpoint(T=374°C,p=22.1MPa),whereliquidandgasphasescannot
bedistinguished.SCWisahomogeneousandnonpolarsolventwithhighdiffusivity
and advantageous transport properties, and can be used as an excellent reaction
medium.However,hightemperature,highpressure,highconcentrationofdissolved
oxygenand/orhighconcentrationofionscancauseseverereactorcorrosioninsub-or
supercriticalwaterenvironment,suchassupercriticalwateroxidation,supercritical
watergasificationandnuclearreactor.Chemicalcorrosion,stresscorrosioncracking
and/orhydrogenembrittlementeasilyappear,soseverelyshorteningreactorlifetime.
Inthisbook,weaimtoprovidereaderswithcomprehensiveandsystematicintro-
ductionandsummaryofcorrosioncharacteristics,mechanismsandcontrolmethods
ofcandidatealloysinsub-andsupercriticalwaterenvironment.Firstofall,corrosion
typesofcandidatealloysandtheeffectsofmajoralloyingelementsoncorrosionresis-
tanceofpotentialalloysinsub-andsupercriticalwaterarecomparedandanalyzed.
Atthesametime,researchstatusofcandidatematerials,anddevelopmentandappli-
cationtrendsofseveralcorrosion-resistantalloysaresummarized.Then,corrosion
characteristics of Ni–Cr, Ni–Cr–Mo, Ni–Fe–Cr and Ni–Fe–Cr–Mo–Cu corrosion-
resistantalloys,FeCrAlalloyandZircaloyarediscussedindetail,includingthecorro-
sionrate,thestructureandcompositionofoxidefilm,theeffectsofvarioussurface
treatment processes, etc. More specifically, we investigated corrosion behavior of
Ni-basedalloy,Fe–Ni-basedandstainlesssteelsinSCW.Theeffectsofaggressive
species on the corrosion behavior of Ni-based alloys are also explored in SCW.
Wefurtherproposethetotalcorrosionprocessesandmechanismsoftypicalcandi-
datealloysinsub-andsupercriticalwaterenvironment.Finally,weattempttostudy
corrosion control methods such as ceramic coatings and passivation processes in
supercritical water oxidation and in subcritical water, respectively. The challenges
and development trends of corrosion research of candidate materials in sub- and
supercritical water environments are identified at the end of this book. The infor-
mationinvolvedinthisbookisvaluablefortheoreticallyguidingmaterialselection
anddesignandoperatingparameteroptimizationofkeyequipmentinthesub-and
supercriticalwatertechnologies.
v
vi Preface
Generallyspeaking,thecontentofthisbookissuitableforstudentsandresearchers
whoareinterestedinalloycorrosioninsub-andsupercriticalwater.Peoplefromall
walksoflifearealsoverywelcometoread.Atlast,therearemanypeoplewhohave
helpedalotintheprocessofwritingthisbookwewishtothank.Herein,wesincerely
appreciatethehelpandcontributionfromProf.ShuzhongWang,YangGuo,Zefeng
Jing,YanhuiLiandJianqiaoYanginXi’anJiaotongUniversityinChina,andProf.
DigbyD.MacdonaldinUniversityofCaliforniaatBerkeleyinUSA.Manygraduate
students (including Zhijiang Ma, Guanyu Jiang, Wangpeng Yang, Yu Wang, etc.)
fromXi’anJiaotongUniversityhavemadegreatcontributionstothepreparationof
thisbook,includingdatatreating,figureplotting,textwriting,proofreadingandso
on.
ThisbookwassupportedbytheProjectsfromNationalNaturalScienceFounda-
tionofChina(22078258,21576219),theNationalKeyResearchandDevelopment
ProgramofChina(2021YFE0104900)andtheFundamentalResearchFundsforthe
CentralUniversities(xtr042019015,xjh012019005,xzd012020031).
Xi’an,China DonghaiXu
Contents
1 Introduction ................................................... 1
1.1 SupercriticalWaterTechnology ............................... 1
1.1.1 CharacteristicsofSupercriticalWater ................... 1
1.1.2 SupercriticalWaterOxidation .......................... 2
1.1.3 SupercriticalWaterGasification ........................ 3
1.1.4 SupercriticalWater-CooledReactor ..................... 4
1.2 ProblemsinSupercriticalWaterTechnology .................... 5
1.2.1 ProblemsinSupercriticalWaterOxidation ............... 5
1.2.2 ProblemsinSupercriticalWaterGasification ............. 6
1.2.3 ProblemsinSupercriticalWater-CooledReactor .......... 7
1.3 Studies on Candidate Materials for Supercritical Water
Technology ................................................ 9
1.3.1 MajorCandidateMaterials ............................ 9
1.3.2 ResearchOverviewonCandidateMaterials .............. 10
1.4 Development and Application of Ni-Based
Corrosion-ResistantAlloy ................................... 11
1.4.1 DevelopmentofNi-BasedAlloys ....................... 13
1.4.2 ApplicationsofNi-BasedAlloys ....................... 13
1.5 AlloysUsedinSubcriticalWaterinNuclearReactors ............ 16
References ..................................................... 17
2 CorrosionTypesandElementalEffectsofNi-BasedandFeCrAl
Alloys ......................................................... 23
2.1 CorrosionTypesofNi-BasedAlloys .......................... 23
2.1.1 GeneralCorrosion ................................... 24
2.1.2 PittingCorrosion ..................................... 25
2.1.3 CreviceCorrosion .................................... 27
2.1.4 IntergranularCorrosion ............................... 29
2.1.5 Environment-AssistedFracture ......................... 30
2.2 ElementEffectsofNi-BasedAlloys ........................... 35
2.3 ElementEffectsofFeCrAlAlloys ............................ 38
vii
viii Contents
2.3.1 Chromium(Cr) ...................................... 39
2.3.2 Aluminum(Al) ...................................... 40
2.3.3 Silicon(Si) .......................................... 41
2.3.4 ReactiveElements ................................... 42
2.3.5 OtherElements ...................................... 43
References ..................................................... 44
3 CorrosionCharacteristicsofCandidateAlloys .................... 51
3.1 CorrosionCharacteristicsofNi–CrAlloys ..................... 51
3.1.1 CorrosionWeightChange ............................. 51
3.1.2 OxidesFormedonAlloySurface ....................... 53
3.1.3 ComparisonofCorrosionCharacteristics ................ 57
3.2 CorrosionCharacteristicsofNi–Cr–MoAlloys ................. 58
3.2.1 CorrosionWeightChange ............................. 62
3.2.2 OxidesFormedonAlloySurface ....................... 65
3.2.3 ComparisonofCorrosionCharacteristics ................ 66
3.3 CorrosionCharacteristicsofNi–Fe–CrAlloys .................. 73
3.3.1 CorrosionWeightChange ............................. 73
3.3.2 OxidesFormedonAlloySurface ....................... 79
3.3.3 SurfaceTreatmentProcesses ........................... 86
3.3.4 ComparisonofCorrosionCharacteristics ................ 88
3.4 Corrosion Characteristics of Ni–Fe–Cr–Mo–Cu Alloys
andOtherNi-BasedAlloys .................................. 89
3.4.1 OxidesFormedonAlloySurface ....................... 89
3.4.2 ComparisonofCorrosionCharacteristics ................ 91
3.5 CorrosionCharacteristicsofFeCrAlAlloys .................... 97
3.5.1 OxidationKinetics ................................... 97
3.5.2 CorrosionProcessandMechanism ..................... 99
3.5.3 InfluenceofWaterChemistry .......................... 106
3.5.4 InfluenceofIrradiation ............................... 108
3.5.5 InfluenceofTemperature .............................. 109
3.6 CorrosionCharacteristicsofTypicalZircaloy ................... 109
3.6.1 CorrosionProcess .................................... 109
3.6.2 InfluenceofAlloyingElements ........................ 111
3.6.3 InfluenceofpH ...................................... 112
3.6.4 InfluenceofSecondaryPhasePrecipitates ............... 115
3.6.5 SteamOxidationinLossofCoolantAccident ............ 116
References ..................................................... 117
4 CorrosionMechanismsofAlloysinSupercriticalWater ............ 127
4.1 OxidationProcessesandInvolvedChemicalReactions ........... 127
4.1.1 ReactionsofTypicalElements ......................... 128
4.1.2 ReactionsofNi/Cr/FeOxidesandNi/FeHydroxides ...... 139
4.1.3 ReactionsinComplicatedSCWEnvironment ............ 140
4.1.4 OverallOxidationProcessEvaluation ................... 141
Contents ix
4.2 TotalCorrosionProcessesandMechanisms .................... 144
References ..................................................... 149
5 CorrosionBehaviorofAlloysinSupercriticalWaterOxidation
Processes ...................................................... 155
5.1 High-TemperatureCorrosionofFe–Ni-BasedandNi-Based
AlloysinSCW ............................................. 155
5.1.1 Introduction ......................................... 155
5.1.2 Experiment ......................................... 156
5.1.3 ResultsandDiscussion ............................... 158
5.1.4 Conclusions ......................................... 170
5.2 Corrosion Properties of Alloys in SCW Containing
Phosphate,Sulfate,ChlorideandOxygen ...................... 171
5.2.1 Introduction ......................................... 171
5.2.2 ExperimentSection .................................. 172
5.2.3 ResultsandDiscussion ............................... 174
5.2.4 Conclusion .......................................... 186
References ..................................................... 186
6 CorrosionControlMethodsinSupercriticalWaterOxidation
Processes ...................................................... 191
6.1 CorrosionofCeramicCoatingson316SSinOxygenated
Sub-andSupercriticalWater ................................. 191
6.1.1 Introduction ......................................... 191
6.1.2 ExperimentalSection ................................. 192
6.1.3 ResultsandDiscussions ............................... 194
6.1.4 Conclusions ......................................... 206
6.2 Corrosion of Passivated 316 SS in Subcritical Water
ContainingOxygenandNaCl ................................ 208
6.2.1 Introduction ......................................... 208
6.2.2 ExperimentalSection ................................. 209
6.2.3 ResultsandDiscussions ............................... 210
6.2.4 Conclusions ......................................... 221
6.3 CorrosionofCoatedandUncoated316SSinSupercritical
WaterOxidationofMunicipalSludge ......................... 222
6.3.1 Introduction ......................................... 222
6.3.2 ExperimentalSection ................................. 223
6.3.3 ResultsandDiscussions ............................... 224
6.3.4 Conclusions ......................................... 234
SupplementaryMaterials ......................................... 235
References ..................................................... 236
7 ProspectsandChallengesofCandidateAlloysUsedinSub-
andSupercriticalWaterEnvironment ............................ 241
Chapter 1
Introduction
1.1 SupercriticalWaterTechnology
1.1.1 CharacteristicsofSupercriticalWater
Supercriticalwater(SCW)referstowateratatemperaturethatisaboveitscritical
point (T = 374 °C,p = 22.1 MPa), where liquid and gas phases cannot be distin-
guished. SCW is completely different from the water at normal temperature with
respecttophysicalparameterssuchasdensity,solubility,dielectricconstant,ionic
product,viscosityanddiffusioncoefficient.SCWpossessestransportpropertiesthat
aresimilartothoseofagasandthesolubilitypropertiesofthefluid[1,2],andits
densitylieswithintheintervalbetweenagasandaliquid,withthesepropertiesbeing
sensitive to the pressure [3]. When water approaches the critical point, its dissoci-
ation constant (ionic product) are approximately higher three orders of magnitude
higher(K ≈10–11)thanthatofwaterat25°C(K ≈10–14).However,thedissoci-
w w
ationconstantdropssharply[4],whenthecriticalpointisexceeded.Comparedwith
normaltemperaturewater,SCWpossessesamuchlowerviscosityandahigherself-
diffusioncoefficient;bothchangebyaboutanorderofmagnitudecomparedwiththe
valuesatambienttemperature.Thelowerviscosityandhigherdiffusioncoefficient
makeSCWagoodtransportmedium[5].Whenwaterchangesfromtheliquidstate
tothesupercriticalstate,thenumberofhydrogenbondsisgreatlyreduced,thereby
resultinginagreatlyreduceddielectricconstant.SCWvariesfromapolarstateto
a non-polar state and its solvent power is reversed [3, 6]. Water-insoluble organic
matteratnormaltemperaturecanbedissolvedinSCW,andsomegases(e.g.,O and
2
CO )arealsocompletelymisciblewithSCW.Thus,SCWprovidesanopportunity
2
tocarryoutchemicalreactionsinasinglefluidphaseratherthanamultiphasesystem
underconventionalconditions.Thepotentialadvantagesarethathigherconcentra-
tionofreactantscanbeobtainedandthereisnointer-phasemasstransferthatlimits
thereactionrate[4].Inotherwords,asinglehomogeneousphaseallowsreactionsto
©Xi’anJiaotongUniversityPress2022 1
D.XuandS.Guo,CorrosionCharacteristics,MechanismsandControlMethods
ofCandidateAlloysinSub-andSupercriticalWater,
https://doi.org/10.1007/978-981-16-5525-8_1
