ASTM B733 标准

Designation:B733–97StandardSpecificationforAutocatalytic(Electroless)Nickel-PhosphorusCoatingsonMetal1ThisstandardisissuedunderthefixeddesignationB733;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheDepartmentofDefense.1.Scope1.1Thisspecificationcoversrequirementsforautocatalytic(electroless)nickel-phosphoruscoatingsappliedfromaqueoussolutionstometallicproductsforengineering(functional)uses.1.2Thecoatingsarealloysofnickelandphosphoruspro-ducedbyautocatalyticchemicalreductionwithhypophosphite.Becausethedepositednickelalloyisacatalystforthereaction,theprocessisself-sustaining.Thechemicalandphysicalpropertiesofthedepositvaryprimarilywithitsphosphoruscontentandsubsequentheattreatment.Thechemicalmakeupoftheplatingsolutionandtheuseofthesolutioncanaffecttheporosityandcorrosionresistanceofthedeposit.Formoredetails,seeASTMSTP265(1)2andRefs(2)(3)(4)and(5)alsorefertoFigs.X1.1,Figs.X1.2,andFigs.X1.3intheAppendixofGuideB656.1.3Thecoatingsaregenerallydepositedfromacidicsolu-tionsoperatingatelevatedtemperatures.1.4Theprocessproducescoatingsofuniformthicknessonirregularlyshapedparts,providedtheplatingsolutioncircu-latesfreelyovertheirsurfaces.1.5Thecoatingshavemultifunctionalproperties,suchashardness,heathardenability,abrasion,wearandcorrosionresistance,magnetics,electricalconductivityprovidediffusionbarrier,andsolderability.Theyarealsousedforthesalvageofwornormismachinedparts.1.6Thelowphosphorus(2to4%P)coatingsaremicroc-rystallineandpossesshighas-platedhardness(620to750HK100).Thesecoatingsareusedinapplicationsrequiringabra-sionandwearresistance.1.7Lowerphosphorusdepositsintherangebetween1and3%phosphorusarealsomicrocrystalline.Thesecoatingsareusedinelectronicapplicationsprovidingsolderability,bond-ability,increasedelectricalconductivity,andresistancetostrongalkalisolutions.1.8Themediumphosphorouscoatings(5to9%P)aremostwidelyusedtomeetthegeneralpurposerequirementsofwearandcorrosionresistance.1.9Thehighphosphorous(morethan10%P)coatingshavesuperiorsalt-sprayandacidresistanceinawiderangeofapplications.Theyareusedonberylliumandtitaniumpartsforlowstressproperties.Coatingswithphosphoruscontentsgreaterthan11.2%Parenotconsideredtobeferromagnetic.1.10ThevaluesstatedinSIunitsaretoberegardedasstandard.1.11Thefollowingprecautionarystatementpertainsonlytothetestmethodportion,Section9,ofthisspecification.Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimita-tionspriortouse.2.ReferencedDocuments2.1ASTMStandards:B368TestMethodforCopper-AcceleratedAceticAcid-SaltSpray(Fog)Testing(CASSTesting)3B374TerminologyRelatingtoElectroplating3B380TestMethodofCorrosionbytheCorrodkoteProce-dure3B487TestMethodforMeasurementofMetalandOxideCoatingThicknessesbyMicroscopicalExaminationofaCrossSection3B499TestMethodforMeasurementofCoatingThick-nessesbytheMagneticMethod:NonmagneticCoatingsonMagneticBasisMetals3B504TestMethodforMeasurementofThicknessofMe-tallicCoatingsbytheCoulometricMethod3B537PracticeforRatingofElectroplatedPanelsSubjectedtoAtmosphericExposure3B567MethodforMeasurementofCoatingThicknessbytheBetaBackscatterMethod3B568MethodforMeasurementofCoatingThicknessbyX-RaySpectrometry31ThisspecificationisunderthejurisdictionofASTMCommitteeB-08onMetalPowdersandMetalPowderProductsandisthedirectresponsibilityofSubcom-mitteeB08.08.01onEngineeringCoatings.CurrenteditionapprovedJuly10,1997.PublishedOctober1997.OriginallypublishedasB733–84.LastpreviouseditionB733–90(1994).2Theboldfacenumbersgiveninparenthesesrefertoalistofreferencesattheendofthetext.3AnnualBookofASTMStandards,Vol02.05.1Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959,UnitedStates.B571TestMethodsforAdhesionofMetallicCoatings3B578TestMethodforMicrohardnessofElectroplatedCoatings3B602TestMethodforAttributeSamplingofMetallicandInorganicCoating3B656GuideforAutocatalyticNickel-PhosphorusDeposi-tiononMetalsforEngineeringUse3B667PracticeforConstructionandUseofaProbeforMeasuringElectricalContactResistance4B678TestMethodforSolderabilityofMetallic-CoatedProducts3B697GuideforSelectionofSamplingPlansforInspectionofElectrodepositedMetallicandInorganicCoatings3B762MethodforVariableSamplingofMetallicandInor-ganicCoatings3B849SpecificationforPre-TreatmentofIronorSteelforReducingtheRiskofHydrogenEmbrittlement3B850SpecificationforPost-CoatingTreatmentsofIronorSteelforReducingtheRiskofHydrogenEmbrittlement3B851SpecificationforAutomatedControlledShotPeeningofMetallicArticlesPriortoNickel,AutocatalyticNickel,Chromium,orAsAFinalFinish3D1193SpecificationforReagentWater5D2670MethodforMeasuringWearPropertiesofFluidLubricants(FalexMethod)6D2714MethodforCalibrationandOperationofanAlphaLFW-1FrictionandWearTestingMachine6D3951PracticeforCommercialPackaging7D4060TestMethodforAbrasionResistanceofOrganicCoatingsbytheTaberAbraser8E60PracticeforPhotometricMethodsforChemicalAnaly-sisofMetals9E156TestMethodforDeterminationofPhosphorusinHigh-PhosphorusBrazingAlloys(PhotometricMethod)10E352TestMethodsforChemicalAnalysisofToolSteelsandOtherSimilarMedium-andHigh-AlloySteel9F519TestMethodforMechanicalHydrogenEmbrittle-ment11G5PracticeforStandardReferenceMethodforMakingPotentiostaticandPotentiodynamicAnodicPolarizationMeasurements12G31PracticeforLaboratoryImmersionCorrosionTestingofMetals12G59PracticeforConductingPotentiodynamicPolarizationResistanceMeasurements12G85PracticeforModifiedSaltSpray(Fog)Testing122.2MilitaryStandards:MIL-R-81841RotaryFlapPeeningofMetalParts13MIL-S-13165ShotPeeningofMetalParts13MIL-STD-105SamplingProceduresandTablesforInspec-tionbyAttribute132.3ISOStandards:ISO4527AutocatalyticNickel-PhosphorusCoatings—SpecificationandTestMethods143.Terminology3.1Definition:3.1.1significantsurfaces—thosesubstratesurfaceswhichthecoatingmustprotectfromcorrosionorwear,orboth,andthatareessentialtotheperformance.3.2OtherDefinitions—TerminologyB374definesmostofthetechnicaltermsusedinthisspecification.4.CoatingClassification4.1Thecoatingclassificationsystemprovidesforaschemetoselectanelectrolessnickelcoatingtomeetspecificperfor-mancerequirementsbasedonalloycomposition,thicknessandhardness.4.1.1TYPEdescribesthegeneralcompositionofthede-positwithrespecttothephosphoruscontentandisdividedintofivecategorieswhichestablishdepositproperties(seeTable1).NOTE1—Duetotheprecisionofsomephosphorusanalysismethodsadeviationof0.5%hasbeendesignedintothisclassificationscheme.Roundingofthetestresultsduetotheprecisionofthelimitsprovidesforaneffectivelimitof4.5and9.5%respectively.Forexample,coatingwithatestresultforphosphorusof9.7%wouldhaveaclassificationofTYPEV,seeAppendixX4,AlloyTYPEs.4.2ServiceConditionBasedonThickness:4.2.1Serviceconditionnumbersarebasedontheseverityoftheexposureinwhichthecoatingisintendedtoperformandminimumcoatingthicknesstoprovidesatisfactoryperfor-mance(seeTable2).4.2.2SC0MinimumService,0.1µm—Thisisdefinedbyaminimumcoatingthicknesstoprovidespecificmaterialprop-ertiesandextendthelifeofapartoritsfunction.Applications4AnnualBookofASTMStandards,Vol03.04.5AnnualBookofASTMStandards,Vol11.01.6AnnualBookofASTMStandards,Vol05.02.7AnnualBookofASTMStandards,Vol09.02.8AnnualBookofASTMStandards,Vol06.01.9AnnualBookofASTMStandards,Vol03.05.10Discontinued;see1992AnnualBookofASTMStandards,Vol03.05.11AnnualBookofASTMStandards,Vol15.03.12AnnualBookofASTMStandards,Vol03.02.13AvailablefromStandardizationDocumentsOrderDesk,Bldg.4SectionD,700RobbinsAve.,Philadelphia,PA19111-5094,Attn:NPODS.14AvailablefromAmericanNationalStandardsInstitute,11W.42ndSt.,13thFloor,NewYork,NY10036.TABLE1DepositAlloyTypesTypePhosphorus%wtINoRequirementforPhosphorusII1to3III2to4IV5to9V10andaboveTABLE2ServiceConditionsCoatingThicknessRequirementsServiceConditionMinimumCoatingThicknessSpecificationµmin.(mm)SC0MinimunThickness0.10.000004()SC1LightService50.0002()SC2MildService130.0005()SC3ModerateService250.001()SC4SevereService750.003()B733–972includerequirementsfordiffusionbarrier,undercoat,electricalconductivityandwearandcorrosionprotectioninspecializedenvironments.4.2.3SC1LightService,5µm—Thisisdefinedbyaminimumcoatingthicknessof5µmforextendingthelifeofthepart.Typicalenvironmentsincludelight-loadlubricatedwear,indoorcorrosionprotectiontopreventrusting,andforsolderingandmildabrasivewear.4.2.4SC2MildService,13µm—Thisisdefinedbymildcorrosionandwearenvironments.Itischaracterizedbyindus-trialatmosphereexposureonsteelsubstratesindryoroiledenvironments.4.2.5SC3ModerateService,25µm—Thisisdefinedbymoderateenvironmentssuchasnonmarineoutdoorexposure,alkalisaltsatelevatedtemperature,andmoderatewear.4.2.6SC4SevereService,75µm—Thisisdefinedbyaveryaggressiveenvironment.Typicalenvironmentswouldincludeacidsolutions,elevatedtemperatureandpressure,hydrogensulfideandcarbondioxideoilservice,high-temperaturechlo-ridesystems,veryseverewear,andmarineimmersion.NOTE2—Theperformanceoftheautocatalyticnickelcoatingdependstoalargeextentonthesurfacefinishofthearticletobeplatedandhowitwaspretreated.Rough,nonuniformsurfacesrequirethickercoatingsthansmoothsurfacestoachievemaximumcorrosionresistanceandminimumporosity.4.3PostHeatTreatmentClass—Thenickel-phosphoruscoatingsshallbeclassifiedbyheattreatmentafterplatingtoincreasecoatingadhesionandorhardness(seeTable3).4.3.1Class1—As-deposited,noheattreatment.4.3.2Class2—Heattreatmentat260to400°Ctoproduceaminimumhardnessof850HK100.4.3.3Class3—Heattreatmentat180to200°Cfor2to4htoimprovecoatingadhesiononsteelandtoprovideforhydrogenembrittlementrelief(seesection6.6).4.3.4Class4—Heattreatmentat120to130°Cforatleast1htoincreaseadhesionofheat-treatable(age-hardened)alumi-numalloysandcarburizedsteel(seeNote3).4.3.5Class5—Heattreatmentat140to150°Cforatleast1htoimprovecoatingadhesionforaluminum,nonage-hardenedaluminumalloys,copper,copperalloysandberyl-lium.4.3.6Class6—Heattreatmentat300to320°Cforatleast1htoimprovecoatingadhesionfortitaniumalloys.NOTE3—Heat-treatablealuminumalloyssuchasType7075canundergomicrostructuralchangesandlosestrengthwhenheatedtoover130°C.5.OrderingInformation5.1Thefollowinginformationshallbesuppliedbythepurchaserineitherthepurchaseorderorontheengineeringdrawingoftheparttobeplated:5.1.1Title,ASTMdesignationnumber,andyearofissueofthisspecification.5.1.2Classificationofthedepositbytype,servicecondi-tion,class,(see4.1,4.2and4.3).5.1.3Specifymaximumdimensionandtolerancerequire-ments,ifany.5.1.4Peening,ifrequired(see6.5).5.1.5Stressreliefheattreatmentbeforeplating,(see6.3).5.1.6HydrogenEmbrittlementReliefafterplating,(see6.6).5.1.7Significantsurfacesandsurfacesnottobeplatedmustbeindicatedondrawingsorsample.5.1.8SupplementalorSpecialGovernmentRequirementssuchas,specificphosphoruscontent,abrasionwearorcorro-sionresistanceofthecoating,solderability,contactresistanceandpackagingselectedfromSupplementalRequirements.5.1.9Requirementforavacuum,inertorreducingatmo-sphereforheattreatmentabove260°Ctopreventsurfaceoxidationofthecoating(seeS3).5.1.10Testmethodsforcoatingadhesion,composition,thickness,porosity,wearandcorrosionresistance,ifrequired,selectedfromthosefoundinSection9andSupplementalRequirements.5.1.11Requirementsforsampling(seeSection8).NOTE4—Thepurchasershouldfurnishseparatetestspecimensorcouponsofthebasismetalfortestpurposestobeplatedconcurrentlywiththearticlestobeplated(see8.4).6.MaterialsandManufacture6.1Substrate—Defectsinthesurfaceofthebasismetalsuchasscratches,porosity,pits,inclusions,rollanddiemarks,laps,cracks,burrs,coldshuts,androughnessmayadverselyaffecttheappearanceandperformanceofthedeposit,despitetheobservanceofthebestplatingpractice.Anysuchdefectsonsignificantsurfacesshallbebroughttotheattentionofthepurchaserbeforeplating.Theproducershallnotberesponsibleforcoatingsdefectsresultingfromsurfaceconditionsofthemetal,iftheseconditionshavebeenbroughttotheattentionofthepurchaser.6.2Pretreatment—PartstobeautocatalyticnickelplatedmaybepretreatedinaccordancewithGuideB656.Asuitablemethodshallactivatethesurfaceandremoveoxideandforeignmaterials,whichmaycausepooradhesionandcoatingporos-ity.NOTE5—Heattreatmentofthebasematerialmayeffectitsmetallur-gicalproperties.Anexampleisleadedsteelwhichmayexhibitliquidorsolidembrittlementafterheattreatment.Carefulselectionofthepreandpostheattreatmentsarerecommended.TABLE3ClassificationofPostHeatTreatmentCLASSDescriptionTemperature(°C)Time(h)1NoHeatTreatment,AsPlated2HeatTreatmentforMaximumHardnessTYPEI260202851632084001TYPEII350to3801TYPEIII360to3901TYPEIV365to4001TYPEV375to40013HydrogenEmbrittlementandAdhesiononSteel180to2002to44Adhesion,CarburizedSteelandAgeHardenedAluminum120to1301to65AdhesiononBerylliumandAluminum140to1501to26AdhesiononTitanium300–3201–4B733–9736.3StressRelief:6.3.1PretreatmentofIronandSteelforReducingtheRiskofHydrogenEmbrittlement—Partsthataremadeofsteelwithultimatetensilestrengthofgreaterthan1000Mpa(hardnessof31HRCorgreater),thathavebeenmachined,ground,coldformed,orcoldstraightenedsubsequenttoheattreatment,shallrequirestressreliefheattreatmentwhenspecifiedbythepurchaser,thetensilestrengthtobesuppliedbythepurchaser,SpecificationB849maybeconsultedforalistofpre-treatmentsthatarewidelyused.6.3.2Peening—Peeningpriortoplatingmayberequiredonhigh-strengthsteelpartstoinduceresidualcompressivestressesinthesurface,whichcanreducelossoffatiguestrengthandimprovestresscorrosionresistanceafterplating.(SeeSupplementaryRequirements).6.3.3Steelpartswhicharedesignedforunlimitedlifeunderdynamicloadsshallbeshotpeenedorrotaryflappeened.NOTE6—Controlledshotpeeningisthepreferredmethodbecausetherearegeometry’swhererotaryflappeeningisnoteffective.SeeS11.2.6.3.3.1Unlessotherwisespecified,theshotpeeningshallbeaccomplishedonallsurfacesforwhichthecoatingisrequiredandallimmediateadjacentsurfaceswhentheycontainnotches,fillets,orotherabruptchangesofsectionsizewherestresseswillbeconcentrated.6.4Racking—Partsshouldbepositionedsoastominimizetrappingofhydrogengasincavitiesandholes,allowingfreecirculationofsolutionoverallsurfacestoobtainuniformcoatingthickness.Thelocationofrackorwiremarksinthecoatingshallbeagreeduponbetweentheproducerandpurchaser.6.5PlatingProcess:6.5.1Toobtainconsistentcoatingproperties,thebathmustbemonitoredperiodicallyforpH,temperature,nickelandhypophosphite.Replenishmentstotheplatingsolutionshouldbeasfrequentasrequiredtomaintaintheconcentrationofthenickelandhypophosphitebetween90and100%ofsetpoint.Theuseofastatisticalregimentoestablishthecontrollimitsandfrequencyofanalysismaybeemployedtoensurequalitydepositsareproduced.6.5.2Mechanicalmovementofpartsandagitationofthebathisrecommendedtoincreasecoatingsmoothnessanduniformityandpreventpittingorstreakingduetohydrogenbubbles.6.6PostCoatingTreatmentforIronandSteelforReducingtheRiskofHydrogenEmbrittlement—Partsthataremadeofsteelwithultimatetensilestrengthsof1000Mpa(hardnessof31HRCorgreater),aswellassurfacehardenedparts,shallrequirepostcoatinghydrogenembrittlementreliefbakingwhenspecifiedbythepurchaser,thetensilestrengthtobesuppliedbythepurchaser.SpecificationB850maybecon-sultedforalistofposttreatmentsthatarewidelyused.6.6.1Heattreatmentshallbeperformedpreferablywithin1hbutnotmorethan3hofplatingonplatedafterplatingofsteelpartstoreducetheriskofhydrogenembrittlement.Inallcases,thedurationoftheheattreatmentshallcommencefromthetimeatwhichthewholeofeachpartattainsthespecifiedtemperature.6.6.2High-strengthsteelpartswithactualtensilestrengthsgreaterthan1000MPa(correspondinghardnessvalues300HV10,303HBor31HRC)andsurfacehardenedpartsshallbeprocessedaftercoatinginaccordancewithSpecificationB850.6.7HeatTreatmentAfterPlatingtoImproveAdhesion—Toimprovetheadhesionofthecoatingtovarioussubstrates,theheattreatmentsinTable3shouldbeperformedassoonaspracticalafterplating(see4.3).6.8HeatTreatmentAfterPlatingtoIncreaseHardness:6.8.1Toincreasethehardnessofthecoatingaheattreat-mentofover260°Cisrequired.Table3describestheheattreatmentformaximumhardness.6.8.2SeeAppendixes3and4andGuideB656;Figs.X1.2andFigs.X1.3.6.8.3Aheattreatmentat260°Cforgreaterthan20hshouldbeusedtoreducethelossofsurfacehardnessandstrengthofsomeferrousbasismetals.Avoidrapidheatingandcoolingofplatedparts.Sufficienttimemustbeallowedforlargepartstoreachoventemperature.NOTE7—Thelengthoftimetoreachmaximumhardnessvarieswiththephosphoruscontentofthedeposit.Highphosphorusdepositsmayrequirelongertimeorahighertemperature,orboth.Individualalloysshouldbetestedformaximumhardnessattainable,especiallyforcondi-tionsoflowertemperaturesandlongertimes.NOTE8—Inertorreducingatmosphereorvacuumsufficienttopreventoxidationisrecommendedforheattreatmentabove260°C.Donotusegascontaininghydrogenwithhigh-strengthsteelparts.7.Requirements7.1Process—Thecoatingshallbeproducedfromanaque-oussolutionthroughchemicalreductionreaction.7.2AcceptanceRequirements—Theserequirementsareplacedoneachlotorbatchandcanbeevaluatedbytestingtheplatedpart.7.2.1Appearance:7.2.1.1Thecoatingsurfaceshallhaveauniform,metallicappearancewithoutvisibledefectssuchasblisters,pits,pimples,andcracks(see9.2).7.2.1.2Imperfectionsthatarisefromsurfaceconditionsofthesubstratewhichtheproducerisunabletoremoveusingconventionalpretreatmenttechniquesandthatpersistinthecoatingshallnotbecauseforrejection(see6.1).Also,discolorationduetoheattreatmentshallnotbecauseforrejectionunlessspecialheattreatmentatmosphereisspecified(seesection5.1.9).7.2.2Thickness—ThethicknessofthecoatingshallexceedtheminimumrequirementsinTable2asspecifiedbytheserviceconditionagreedtopriortoplating(see9.3).Aftercoatingandifspecified,thepartshallnotexceedmaximumdimensiononsignificantsurface(seesection5.1.3).NOTE9—Thethicknessofthecoatingcannotbecontrolledinblindorsmalldiameterdeepholesorwheresolutioncirculationisrestricted.7.2.3Adhesion—Thecoatingshallhavesufficientadhesiontothebasismetaltopassthespecifiedadhesiontest(see9.4andTestMethodsB571).7.2.4Porosity—Thecoatingsshallbeessentiallyporefreewhentestedaccordingtooneofthemethodsof9.6.Thetestmethod,thedurationofthetest,andnumberofallowablespotsperunitareashallbespecified(seesection5.1.10and9.6).B733–9747.3QualificationRequirements—Theserequirementsareplacedonthedepositandprocessandareperformedonspecimenstoqualifythedepositandplatingprocess.Thetestsforthesequalificationrequirementsshallbeperformedmonthlyormorefrequently.7.3.1Composition—TypeII,III,IV,Vdepositsshallbeanalyzedforalloycompositionbytestingforphosphorus(see9.1).Theweightpercentofphosphorusshallbeintherangedesignatedbytypeclassification(see4.1).7.3.2Microhardness—ThemicrohardnessofClass2depos-itsshallbedeterminedbyTestMethodB578(Knoop).ForClass2coatings,themicrohardnessshallequalorexceedaminimumof850(HK100(orequivalentVickers)(see4.3and9.5).TheconversionofVickerstoKnoopusingTablesE140isnotrecommended.7.3.3HydrogenEmbrittlement—Theprocessusedtode-positacoatingontohighstrengthsteelsshallbeevaluatedforhydrogenembrittlementbyTestMethodF519.8.Sampling8.1Thepurchaserandproducerareurgedtoemploystatis-ticalprocesscontrolinthecoatingprocess.Properlyperformedthiswillensurecoatedproductsofsatisfactoryqualityandwillreducetheamountofacceptanceinspection.8.1.1Samplingplanscanonlyscreenoutunsatisfactoryproductswithoutassurancethatnoneofthemwillbeaccepted.(7)8.2Thesamplingplanusedfortheinspectionofaquantityofcoatedparts(lot)shallbeTestMethodB602unlessotherwisespecifiedbypurchaserinthepurchaseorderorcontract(seesection5.1.11andS.11.1).NOTE10—Usually,whenacollectionofcoatedparts(theinspectionlot8.2)isexaminedforcompliancewiththerequirementsplacedonthepartsarelativelysmallnumberofparts,thesample,isselectedatrandomandinspected.