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外文翻译--在硫酸盐溶液中对AZ91D镁合金进行化学镀镍磷合金 英文版.pdf

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外文翻译--在硫酸盐溶液中对AZ91D镁合金进行化学镀镍磷合金 英文版.pdf

AbstractThedepositsalloWmoreNi–P©K1.1.74thetheirofpropertiesThelurandfectiallomagnesiummagnesiumordinarycanmagnesiumshould09258388/doi10.1016/j.jallcom.2004.07.083JournalofAlloysandCompounds3912005104–109ElectrolessNi–PplatingonAZ91DmagnesiumalloyfromasulfatesolutionChangdongGu,JiansheLian,GuangyuLi,LiyuanNiu,ZhonghaoJiang∗TheKeyLabofAutomobileMaterials,MinistryofEducation,CollegeofMaterialsScienceandEngineering,JilinUniversity,NanlingCampus,Changchun130025,ChinaReceived14May2004accepted9July2004Availableonline8December2004DirectelectrolessNi–PplatingontheAZ91Dmagnesiumalloyfromaplatingbathcontainingsulfatenickelwasinvestigatedinthepaper.nucleationmechanismofNi–PdepositsontheAZ91DmagnesiumalloywasstudiedbyusingXRDandSEM.TheelectrolessNi–PwerepreferentiallynucleatedontheH9252Mg17Al12phaseandextendedtotheprimaryandeutecticH9251phasesoftheAZ91Dmagnesiumy.TheeffectoftheacidpickletreatmenttimeoftheAZ91DmagnesiumalloysubstrateontheelectrolessNi–Pplatingwasalsoinvestigated.ithprolongingtheacidpickletreatmenttime,theclusterofelectrolessNi–Pdepositionbecamesmallerandthedepositswerefoundtobecompact.ThedepositionrateofelectrolessNi–Pplatingwasproportionaltotheacidpickletreatmenttime.Thehardnessvaluesofthecoatingswereabout660VHNandwerenotinfluencedbythepretreatments.2004ElsevierB.V.Allrightsreserved.eywordsSurfacesandinterfacesElectrochemicalreactionMetalsXraydiffractionIntroductionMagnesiumisoneofthelightestmetalswithadensityofg/cm3andmagnesiumalloyshavebeenusedwildlyinaerospace,electronicsandautomobilefieldsbecauseofhighstrengthtoweightratio.However,theapplicationmagnesiumalloyshasbeenlimitedduetotheirundesirableincludingpoorcorrosionandlowwearresistance.corrosionofmagnesiumalloysdependsontheirmetalgyandenvironmentalfactors.Metallurgicalmanipulationsomeothercreativesynthesistechniquesprovideanefvewaytoimprovethecorrosionresistanceofmagnesiumys1,2.Theothereffectivewaytopreventcorrosionofalloyistocoatthesubstratematerial3.Sinceisoneofthemostelectrochemicallyactivemetal,coatings,suchasnickel,copperandzinccoatings,onlyprovideaphysicalbarriertocorrosionattackofsubstrate.So,anycoatingsonmagnesiumalloysbeasuniform,adheredandporefreeaspossible.∗Correspondingauthor.Fax864315095876.Emailaddressjiangzhjlu.edu.cnZ.Jiang.hasnumerouspropertieswearductilitytionwithouteasofplatingthatmagnesiumnearlypapersiumsulfandalloin–seefrontmatter©2004ElsevierB.V.Allrightsreserved.ElectrolessdepositiontechniqueofNi–Palloycoatingsbeenawellknowncommercialprocessthathasfoundapplicationsinmanyfieldsduetoexcellentofcoatings,suchashighcorrosionresistant,highresistant,goodlubricity,highhardnessandacceptable4–7.Anotheradvantageoftheelectrolessdepositechniqueisthatveryuniformedcoatingscanbeobtainedspecialrequirementsforsubstrategeometries.Howver,electrolessnickelplatingondifficultsubstrates,suchmagnesiumalloys,hasmanychallengesintheprocessingplatingandthereisverylimitedreportsonelectrolessonmagnesiumalloys.Furthermore,itcanbenotedinmanypreviousreportsontheelectrolessplatingonalloys8–11,thenickelionswereprovidedbybasicnickelcarbonateintheplatingbath.Inthis,directelectrolessNi–PplatingontheAZ91Dmagnealloywasundertakenbyusingaplatingbathcontainingatenickel.ThenucleationmechanismofNi–PdepositstheeffectoftheacidpickletreatmenttimeofmagnesiumysubstratesontheelectrolessNi–Pplatingwerealsovestigated.C.Guetal./JournalofAlloysandCompounds2.ExperimentalThesubstratematerialusedwasAZ91Ddiecastmagnesiumalloywithasizeof30mm40mm5mm.ThechemicalcompositionofthealloyisgiveninTable1.ThesampleswereabradedwithNo.1500SiCpaperbeforethepretreatmentprocesses.ThetechnicalflowchartoftheelectrolessdepositionontheAZ91DmagnesiumalloyisshowninFig.1.Thesampleswerecleanedthoroughlywithdeionizedwtreatments.allocroscopethephologywanalysiscontentstructuretometerTChemicalAlZnMnFeMgFig.magnesiumaratenessesdepositiontestertionallothe24010asdepositednotheasRwheredcm3.3.1.andideaterasquicklyaspossiblebetweenanytwostepsofthepreTheacidpickletreatmenttimeofthemagnesiumywaschangeableinthisstudy.AscanningelectronmiSEM,JEOLJSM5310,JapanwasemployedforobservationsofthesurfaceandthecrosssectionmoroftheNi–PalloycoatingsandanEDXattachmentasusedforqualitativeelementalchemicalanalysis.EDXwasalsousedforthedeterminationofphosphorusoftheelectrolessNi–Pdeposition.CrystallographicofthesamplewasstudiedbytheXraydiffracXRD,RigakuDymax,JapanwithaCutargetandable1compositionoftheAZ91Ddiecastmagnesiumalloywt.9.1wt.0.64ppm0.17ppm0.01Balance1.ThetechnicalflowchartofelectrolessNi–PplatingontheAZ91Dalloy.haThus,gettinglotrolessXiangorersafterledlayercleaning.signedb40coarsermicrostructureprimaryandthethetoallotheBypretreatmenton3912005104–109105monochromatorat50kVand300mAwiththescanningandstepbeing4◦/minand0.02◦,respectively.ThehardofthemagnesiumalloybeforeandafterelectrolesswereevaluatedusingaHXD1000microhardnesswithVickersindenter,ataloadof100gandaduraof15s.ThedepositionrateRoftheelectrolessNi–Pycanbeexpressedintermsoftheweightgainduringdepositionprocess.AnanalyticalbalanceMETTLERAEMETTLERTOLEDO,SwitzerlandwithaprecisiontoH9262gwasemployedtoweightheasdepositedsamples.ThesamplewasdriedandweighedrepeatedlyuntilfurtherchangeinthereadingtoensurecompletedryingofNi–Palloy.Accordingly,thedepositionrateisexpressedthefollows12,13ω104dAt1RisthedepositionrateH9262m/h,ωtheweightgaing,thedensityofthedeposit,Athesurfaceareaofdeposition2andtthedepositiontimeh.ResultsanddiscussionFunctionsofindividualtreatmentsMagnesiumanditsalloyshavehighlychemicalactivitywhentheycontactwithairorwater,oxideandhydroxfilmswouldbeformedonthesurface1,14,whichwouldveadetrimentaleffectoncoatingadhesionanduniformity.thepretreatingprocessesplayaveryimportantroleinagoodprotectivecoatingonmagnesiumanditsalys.Astudyonsurfacestateduringthepretreatmentofelecnickelplatingonmagnesiumalloyswasreportedbyetal.15.Alkalinecleaningwasusedtoremovesoilsgreasesonthesurfaceofmagnesiumalloy.Butsuchcleanarenotsuitableforremovingoxideandthelike16.So,alkalinecleaning,thesamplesshouldbeetchedorpickinachromicacid/nitricacidsolutiontoremoveanyoxideorotherchemicalcoatingsnotfullyremovedbyalkalineInthispaper,theacidpickletreatmenttimewasdeas0,5,10,20,40and60s,respectively.Fig.2aandgivethemorphologyofacidpickletreatmentafter10ands.ItcanbeseenfromFig.2thatthetreatedsurfacebecamewithprolongingtheacidpickletreatmenttime.TheoftheAZ91DmagnesiumalloyconsistedofH9251MggrainssurroundedbyaeutecticmixtureofH9251H9252Mg17Al1217.Mg17Al12iscathodicwithrespecttomatrix,resultinginanonuniformsurfacepotentialacrosssubstrate1.So,thenextfluorideactivationtreatmentiscreateanequipotentializedfilmMgF2onthemagnesiumysurface.Itisanindispensablestepofpretreatmentinprocessingofelectrolessplatingonmagnesiumalloys.XPSanalysis,Xiangetal.11indicatedthataftertheoffluorideactivation,thefluoridefilmMgF2surfaceofmagnesiumalloywasdiscontinuous.According106andCompoundsFig.pickletothansurfogywithoutsurfterFig.difseethanmaytionandmetalreducingcompletiontobath3.2.thetreatmentdepositstreatmenttheaciddepositsC.Guetal./JournalofAlloys2.ThemorphologiesoftheAZ91Dmagnesiumalloyafterpretreatmentsa40sfollowedbyfluorideactivation.Ref.9,thetimeoffluorideactivationshouldnotbeless10minsoastoformthecompletelyMgF2filmsontheaceofthemagnesiumalloy.Fig.2cshowsthemorpholoftheAZ91Dmagnesiumalloyafterfluorideactivationacidpickletreatment.Itcanbeseenthatthesubstrateacewasslightlycorrodedafterthefluorideactivation.Afacidpickle40sfollowingbythefluorideactivationsee2d,thesubstratesurfacedoesnotshowsignificantlyferencefromthatwiththeacidpickletreatmentof40sFig.2b.Iftheacidpickletreatmenttimewaslarger60s,thesubstratewouldbeseverelycorroded,whichinfluencethepracticalusageofthemagnesiumalloy.DuringtheprocessofelectrolessNi–Pplating,thefuncofsulfatenickelNiSO46H2Oistoprovidenickelions,thesodiumhypophosphiteNa2H2PO2H2Oactsasaagent.SodiumacetateNaC2H3O2isthexingagentofthenickelions.ThioureaactsasasolustabilizerandtheammoniasolutionNH3H2OisusedadjustPHoftheplatingbath.Thefluorideintheplatingistoinhibitcorrosionofthesubstrateduringplating.EffectofacidpickletimeThemorphologiesofelectrolessNi–Pdepositsafter1honAZ91DmagnesiumalloyasafunctionoftheacidpickletimeareshowninFig.3.ItcanbeseenthattheNi–PontheAZ91DmagnesiumalloywithoutacidpickleseeFig.3ashowedmorebumpsandloosethansampleswithacidpickletreatment.Withprolongingthepickletreatmenttime,theclusteroftheelectrolessNi–PbecamesmallerandtheNi–Pdepositswerefoundtoposit12takratesEq.depositionItacidtreatmentwfwNi–PmorphologyingbethepicklemechanicalaandtointhewillFig.Ni–P1theFig.3912005104–109acidpickle10s,bacidpickle40s,cfluorideactivation,anddacidbemorecompact.ThephosphoruscontentintheNi–Pdewasabout3.72wt.byEDXanalysis.Accordingto,thecorrespondingdensityoftheNi–Pdepositcanbeenas8.5g/cm3.Bysungthisdensityvalue,thedepositionoftheelectrolessNi–Pplatingweredeterminedfrom1.TheeffectoftheacidpickletreatmenttimeontherateofelectrolessNi–PplatingisshowninFig.4.canbeseenthatthedepositionratewasproportionaltothepickletreatmenttime.Withprolongingoftheacidpickletime,thesubstratewasmuchmorecorroded,whichouldprovidemorechemicallyactiveonthesubstratesuracefortheelectrolessplating.Furthermore,theacidpicklingouldresultinbettermechanicaladhesionoftheelectrolessplatingonthemagnesiumalloy3,9.Fig.5showstheofthecrosssectionofelectrolessNi–PcoatontheAZ91Dmagnesiumalloy.FromFig.5a,itcanseenthattheelectrolessNi–Pcoatingwasembeddedinmagnesiumalloysubstrateattheinterface.So,theacidpretreatmentprovidessurfacepitstoactassitesforinterlockingtoimproveadhesion3.Incontrast,distinctinterfacewithoutinterlockingbetweenthecoatingthesubstratewasobservedforthesampleFig.5bduelackoftheacidpickletreatment.However,someporesthecoatingsinFig.5mayresultfromtheevaluationofhydrogenduringtheelectrolessdeposition.Furtherworkbedonebythepresentauthorstoeliminatethesepores.6givesthequalitativechemicalanalysisofelectrolessplatingontheAZ91DmagnesiumalloyafterplatinghbyEDXanalysis.Fromtheelementsdistributingfromcoatingsurfacetothesubstratealongthelinelabeledin6,itcanbeseenthatthecoatingwasconnectedcloselytoFig.dtheofandAZ91DFig.theC.Guetal./JournalofAlloysandCompounds3.ThemorphologiesofelectrolessNi–PdepositionontheAZ91Dmagnesium20s,e40sandf60s.substrate.ThehardnesstestsindicatedthatthehardnesstheNi–Pcoatingswasnotinfluencedbythepretreatmentswasabout660VHN,whichisfarhigherthanthatofthemagnesiumalloysubstrateabout100VHN.4.TheeffectoftheacidpickletreatmenttimeonthedepositionrateofelectrolessNi–Pplating.3.3.electrolessXRDatvtrolessdifwithobAfterMgcauseFigs.distinguishedAfterfthe3912005104–109107alloyasafunctionoftheacidpickletreatmenttimea0s,b5s,c10s,NucleationandgrowthInordertounderstandthenucleationandgrowthoftheNi–PplatingontheAZ91Dmagnesiumalloy,andSEManalysisandobservationwereconductedeachstepofpretreatmentandinveryshorttimeinteraloftheelectrolessplating.TheXRDpatternsoftheelecNi–PdepositionontheAZ91DmagnesiumalloyatferentintervalswereshowninFig.7.ComparedFig.7ab,itcanbeseenthattheH9252Mg17Al12phasebecameviousonthesurfaceofthesubstrateafterpretreatment.theelectrolessNi–Pplatingforabout2min,theH925217Al12phaseonthesubstratesurfacedisappearedbethephasehasbeencoatedbytheNi–Pdepositssee7cand8a,buttheprimaryH9251MgphasecanbestillanditsXRDpeakintensitybecameweaker.theelectrolessNi–Pplatingforabout7min,thesuraceoftheAZ91DmagnesiumalloywasfullycoveredbyNi–PdepositsseeFigs.7dand8b.Thephospho

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