1 Introduction Electro depositionofNi Znalloyshaveattractedmuchinterestoverthepastdecadeformanyapplications suchasthecorrosionprotectionofsteelinvehicle s<1,2>,especiallyinmarineatmosphere.Recently,itwasshownthattheinclusionofphosphorus,anonmetall icelement,inthesealloyscouldmodifytheirmicrostruc tureduringelectro depositionandimprovetheircorrosionresistance<3>.Electrolessnickel zinc phosphorus(Ni Zn P)alloyshavebettercorrosionresistanceandthey wereusuallydepositedfromalkalinesolutionscontaininghypophosphiteasreducingagent,NH3 NH4Clasbufferagentandsodiumcitrateascomplexingagent<4～11>. Theyhadbeenstudiedindepositiontechniqueandin somepropertieswhichincludemagneticandcorrosivechar acters<5,6,8～11>. Inourpreviouswork<12>,electrolessNi Zn Palloysweredepositedfromanalkalinebath,containingsodi umhypophosphiteasreducer,boricacidasbufferag entandsodiumcitrateascomplexingagent,whichcanen hancetheplatingrateandavoidstimulatingodorof ammoniainplatingprocess.Therelationshipbetweenthedepositionparametersandthecomposition,thestr ucture,thesurfacemorphologyandthecorrosionresistanceofthealloyhasbeenstudied.Theresultsshowthatt hedepositplatedfromdifferentdepositionconditionswasdifferentcorrosionresistanceandthedepositofh igherpercentageofzincandlesspercentageofphosphorushasbettercorrosionresistancethanthatofthedeposi toflesspercentageofzincandhigherpercentageofphosphor us.Basesonthiswork,theobjectiveofthispaperis toexaminetheeffectofheattreatmentonthestructure,themicrohardness,thesurfacemorphologyandthecorrosionresistanceoftheNi Zn(Fe) Palloy.Thereasons ofthepropertieschangeforthisalloywasinvestigated. 2 Experimentaldetails TheNi Zn(Fe) PalloywaselectrolesslydepositedfromabathcontainingNiSO4·6H2O0.08mol/L,Zn SO4·7H2O0.02mol/L,NaH2PO2·H2O0.2mol/L,C6H5O7Na30.3mol/L,H3BO30.5mol/L.Thetempera turewaskeptat(90±0.5)℃andpHofthesolutionwasadjustedto9.0bysolutionofsodiumhydroxide.Theplatingtimewas2.0h.Theloadingcapacityofelect rolessdepositionwas60cm2/L.Thecompositionofthede positwasdeterminedbyanenergy dispersiveX rayspectrometryforelementalanalysis(EDS,ISIS 300,Ox fordInstruments)attachedtoascanningelectronmicroscope(SEM,LEO 1530).Theacceleratingvoltageof theelectrongunwas20kV.Thecoatingthicknessisa bout20μm.Thesurfacemorphologyofthedepositwasinvestigatedbythisscanningelectronmicroscope (SEM).TopreparetheDSCspecimen,thealloywaspe eledoffbymechanicalmethodfromstainlesssteel foil,whichwasdepositedinaboveelectrolessbath.Theheattreatmentprocesswascarriedoutinavacuum(6.66× 106Pa)atdesiredtemperaturesfor1h.Themicrohard nessmeasurementswereperformedonavickersmicro hardnesstesterunderaloadof100g,whichthethicknessofthesedepositswaskeptabout20μmtoeliminateer rorsinthemeasurementofmicrohandness.ThestructureofthedepositwasmeasuredbyX raydiffraction(XRD)onaRigakuD/max RCdiffractometerwithaCutarget andamonochronmatorat40kVand40mA. Theanodicpolarizationcurvesandtheimpedancesp ectrawereobtainedatroomtemperaturebymeansofaCHI 660BElectrochemicalAnalyzer.Theworkingelectr odeof0.5cm2insurfaceareawhichsubstrateiscarbonsteelwasplatedinaboveelectrolesssolutionandt hecoatingthicknessisalsoabout20μm.Theauxiliaryelec trodewasalargeareaplatinumplate(4cm2)andther eferenceelectrodewasasaturatedcalomelelectrode(SCE).Thescanningratewas3mV/s.Thecorrosionre sistanceofthedepositatroomtemperaturewasdeter minedbymeasuringmasslossimmersedin3.5wt%NaClsolution(pH7.0)asafunctionofimmersiontime.3 Resultsanddiscussion 3.1 Thecompositionoftheas plateddeposit Thedepositwasobtainedoncarbonsteelsheetof6cm 2surfacearea,whichwasmechanicallypolishedandchemicallyetchedindilutesulphateacidbeforeth eexperiments.Becauseironincarbonsteelismoreactivethannickel,thereplacementbetweenironinsubstratea ndNi2+intheelectrolessplatingbathtookplacewhenthecarbonsteelsheetwasimmersedintotheelectroles splatingbathandsothebathcontainsferrousions(Fe2+)whichwasreducedintoironwithnickellater;thust hedepositconsistofNi,Zn,FeandP.Fig1showsatypi calEDXspectrum.Thedepositcontains67.2%nickel,14.1%zinc,2.9%ironand15.9%pho
More abstracts about the 热处理对化学沉积Ni-Zn(Fe)-P合金结构和性质的影响(英文)