2023年全國碩士研究生考試考研英語一試題真題（含答案詳解+作文范文）_第1頁
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1、SECRETARIATUSEHeadershouldbeblank.SECRETARIATUSEFootershouldbeblankELECTROCHEMICALBEHAVIOFHOTROLLED304STAINLESSSTEELDURINGCHEMICALPICKLINGINHClBASEDELECTROLYTESLILianFu1CAENENPeter1VANTRAPPENJoost1CELISJeanPierre21.UGINE

2、ALZBelgiumNV(Arcelgroup)Swinnenwijerweg5B3600GenkBelgium2DepartmentMTMKatholiekeUniversiteitLeuvenKasteelparkArenberg44B3001LeuvenBelgiumAbstract:Themechanismkiicsofchemicalpicklingofhotrolled304stainlesssteeloxidizedath

3、ightemperatureswasinvestigatedinHClbasedelectrolyteswithweightlosscrosionpotentialEISmeasurements.CrosionproductswereacterizedwithSEMEDXXPS.ThemechanismofchemicalpicklinginHClbasedelectrolytesisassociatedwithanodicbright

4、ening.Ahighlyionicallyconductivecrosionproductlayercoveringthebrightenedsurfaceensuresahighcrosionrateoftheunderlyingstainlesssteel.TheadditionofferricionstoHClbasedelectrolytessignificantlyenhancesthecrosionrate.Ontheco

5、ntrarytheinfluenceofHClbecomeslessimptantbecausehighlyconcentratedresultinginabrighteningofthestainlesssteelsurface.Theeffectofferrousionsonthecrosionrateisnegligible.Thegetransferresistanceofhotrolledstainlesssteeldecre

6、aseswithpicklingtimeduetotheprogressiveremovalofoxidelayers.Keywds:304stainlesssteelpicklingHClbasedelectrolytesoxidelayercrosionpotentialelectrochemicalimpedancespectroscopy(EIS)anodicbrightening0.IntroductionThepicklin

7、gofstainlesssteelscommonlyincludesthermalmechanicalelectrochemicalchemicaltreatments[12].Thethermaltreatmentsoftensthemetalreleasesthewkhardeninginducesaunifmgrainstructureeliminatessurfacedefects[3].Duringthatprocessing

8、anoxidelayerachromiumdepletedsublayeraregenerallyfmedonstainlesssteels.SubsequentmechanicalelectrochemicalchemicaltreatmentsareappliedfremovingtheoxidelayerthechromiumdepletedmonchemicalpicklinginmixedHFHNO3acidsiseffect

9、ivebutnowadaystheuseofsuchHNO3containingmixedacidsisrestrictedfenvironmentalconcerns[146].Alternativeprocessesaresinglemultistepproceduresinoxidizingacidse.g.HFHClH2SO4.AmongtheseacidsH2SO4[79]HCl[910]aresolelyusedfthepi

10、cklingofmildsteels.Ironoxideseffectivelydissolveinsuchacidsthebasematerialremainsalmostunaffected.Howevertheseacidsalonecanhardlyremoveoxidelayersonstainlesssteelsbecausetheseoxidelayersarecompactquiteinsoluble.Meoverbes

11、idestheoxidelayersthechromiumdepletedsublayerhasalsotoberemoved.Indeedthatsublayerhasalowercrosionresistanceincomparisontothebulkstainlesssteel.Oxidizingagentssuchasferricionsdissolvethechromiumdepletedlayerinsequencethe

12、oxidelayersareundercut[1112].InoxidizingHFmixedHFH2SO4electrolytesintergranularcrosiontakesplace[13]thepicklingisusuallyinsufficientduetoanactivetopassivetransitionofthestainlesssteel[12].Byusingatwosuccessivesteppicklin

13、ginHClHFelectrolytesasurfacefinishfreeofoxidescaleswithalimitedintergranularcrosionwaspreviouslyachieved[1113].SECRETARIATUSEHeadershouldbeblank.SECRETARIATUSEFootershouldbeblankthreeelectrodeswereimmersedindeionizedwate

14、rf30min.Thentheelectrodeswereimmersedinthetestelectrolyteelectrochemicalmeasurementswerestarted.Sincethesurfaceofoxidizedstainlesssteelsamplesevolvesduringpicklingduetotheprogressiveremovaloftheoxidelayersthechromiumdepl

15、etedlayerEISmeasurementscannotbeperfmedoverabroadrangeoffrequencies.TherefedynamicEISmeasurementswereperfmedataconstantfrequencyedbetween20Hz2kHz.Theperturbationpotentialamplitudewas10mV.2.Results2.1.PicklingkiicsinHClba

16、sedelectrolytesTheevolutionwithimmersiontimeofweightlosscrosionpotentialofoxidized304stainlesssteelisdependentonHClferricionconcentrations(Figures12).Theweightlossineachelectrolyteincreaseslinearlywithimmersiontime(Figur

17、es1a2a)exceptduringtheinitialstagewhereaparabolicregimewasnoticed(seeinsetinFig.1a).Theparabolicregimeisribedtothesimultaneousremovaloftheoxidelayersthedissolutionofunderlyingmetalwhereasthesubsequentlinearregimeisrelate

18、dtometaldissolution[11].Thatlinearrelationindicatesaunifmcrosionthatisconfirmedbytheconstantcrosionpotentialafteracertainimmersiontime(Figures1b2b).Meoverthelinearincreaseinweightlosstheconstantcrosionpotentialindicateth

19、atthe304stainlesssteelishighlyreactiveintheHClbasedelectrolytesusedthattheactivetopassivetransitionnoticedinHFH2SO4electrolytes[12]doesnottakeplace.050100150200250300350400012345670102030400.00.20.40.60.80.54MFe30.27MFe2

20、(a)Weightloss(mgcm2)Immersiontime(s)HClcontent0.69M2.74M5.49M6.86M0501001502002503003504000.320.280.240.200.160.12(b)0.54MFe30.27MFe2Crosionpotential(V.vs.AgAgCl)Immersiontime(s)0.69MHCl2.74MHCl5.49MHCl6.86MHClFig.1Effec

21、tofHClconcentrationon(a)weightloss(b)crosionpotentialofoxidized304stainlesssteelinelectrolytescontaining0.54Mferricions0.27Mferrousions.Insetof(a)showstheweightlossattheinitialstage.Theweightlossappearstobealmostindepend

22、entoftheHClconcentrationwithintheacidcontentused(Fig.1a)whereasasignificantdependenceontheferricioncontentisnoticed(Fig.2a).Chlidesbehaveasdepassivatstohinderthepassivationofstainlesssteel[21]thustolowerthecrosionpotenti

23、al(Fig.1b).HoweversincetheweightlossisalmostindependentofHClcontent(Fig.1a)itseemsthatthechlidesusedinthisstudyarepresentatsufficientleveltodepassivatethewholesurface.Incontrastferricionsactaselectronacceptsincreasethecr

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