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1、Designation:B244?09(Reapproved2014)EndsedbyAmericanElectroplaters’SocietyEndsedbyNationalAssociationofMetalFinishersStardTestMethodfMeasurementofThicknessofAnodicCoatingsonAluminumofOtherNonconductiveCoatingsonNonmagicBa

2、sisMetalswithEddyCurrentInstruments1ThisstardisissuedunderthefixeddesignationB244thenumberimmediatelyfollowingthedesignationindicatestheyearofiginaladoptioninthecaseofrevisiontheyearoflastrevision.Anumberinparenthesesind

3、icatestheyearoflastreapproval.Asuperepsilon()indicatesaneditialchangesincethelastrevisionreapproval.ThisstardhasbeenapprovedfusebyagenciesoftheU.S.DepartmentofDefense.1.Scope1.1Thistestmethodcoverstheuseofeddycurrentinst

4、rumentsfthenondestructivemeasurementofthethicknessofanonconductivecoatingonanonmagicbasismetal.Itisintendedtosupplementmanufacturers’instructionsftheoperationoftheinstrumentsisnotintendedtoreplacethem.1.2Thistestmethodis

5、particularlyusefulfmeasuringthethicknessofananodiccoatingonaluminumalloys.Chemicalconversioncoatingsaretoothintobemeasuredbythistestmethod.1.3ThevaluesstatedinSIunitsaretoberegardedasthestard.Thevaluesgiveninparenthesesa

6、refinfmationonly.1.4Thisstarddoesnotpurpttoaddressallofthesafetyconcernsifanyassociatedwithitsuse.Itistheresponsibilityoftheuserofthisstardtoestablishappropriatesafetyhealthpracticesdeterminetheapplicabilityofregulatylim

7、itationspritouse.2.ReferencedDocuments2.1ASTMStards:2B499TestMethodfMeasurementofCoatingThicknessesbytheMagicMethod:NonmagicCoatingsonMagicBasisMetals3.Terminology3.1DefinitionsofTermsSpecifictoThisStard:3.1.1accuracyn—t

8、hemeasureofthemagnitudeoferrbetweentheresultofameasurementthetruethicknessoftheitembeingmeasured.3.1.2adjustmentn—thephysicalactofaligningainstrument’sthicknessreadingstomatchthoseofaknownthicknesssample(removalofbias)in

9、dertoimprovetheaccuracyoftheinstrumentonaspecificsurfacewithinaspecificptionofitsmeasurementrange.Anadjustmentwillaffecttheoutcomeofsubsequentreadings.3.1.3calibrationn—thehighlevelcontrolleddocumentedprocessofobtainingm

10、easurementsontraceablecalibrationstardsoverthefulloperatingrangeoftheinstrumentthenmakingthenecessaryinstrumentadjustments(asrequired)tocrectanyoutoftoleranceconditions.3.1.3.1Discussion—Calibrationofcoatingthicknessinst

11、rumentsisperfmedbytheequipmentmanufactureranauthorizedagentbyanauthizedtrainedcalibrationlabatyinacontrolledenvironmentusingadocumentedprocess.Theoutcomeofthecalibrationprocessistoresterealigntheinstrumenttomeetexceedthe

12、manufacturer’sstatedaccuracy.3.1.4referencestardn—aspecimenofknownthicknessusedtoverifytheaccuracyofacoatingthicknessmeasuringinstrument.3.1.5verificationofaccuracyn—obtainingmeasurementsonareferencestardpritoinstrumentu

13、sefthepurposeofdeterminingtheabilityofthecoatingthicknessinstrumenttoproducereliablevaluescomparedtothecombinedinstrumentmanufacturer’sstatedaccuracythestatedaccuracyofthereferencestard.4.SummaryofTestMethod4.1Instrument

14、scomplyingwiththistestmethodmeasurecoatingthicknessbytheuseofeddycurrents.Aprobeisplaceddirectlyonthecoatedsurfaceinaperpendicularpositionelectroniccircuitryisusedtoconvertareferencesignalintoacoatingthicknessmeasurement

15、.1ThistestmethodisunderthejurisdictionofASTMCommitteeB08onMetallicInganicCoatingsisthedirectresponsibilityofSubcommitteeB08.10onTestMethods.CurrenteditionapprovedMay12014.PublishedMay2014.iginallyapprovedin1949.Lastprevi

16、ouseditionapprovedin2009asB244–09.DOI:10.1520B024409R14.2FreferencedASTMstardsvisittheASTMwebsitewww.astm.gcontactASTMCustomerServiceat.FAnnualBookofASTMStardsvolumeinfmationrefertothestard’sDocumentSummarypageontheASTMw

17、ebsite.Copyright?ASTMInternational100BarrHarbDrivePOBoxC700WestConshohockenPA194282959.UnitedStates18.5Curvature—Measurementsareaffectedbythecurvatureofthetestspecimen.Theinfluenceofcurvaturevariesconsiderablywiththemake

18、typeofinstrumentbutalwaysbecomesmepronouncedastheradiusofcurvaturedecreases.8.6SurfaceRoughness:8.6.11Measurementsareinfluencedbythesurfacetopographyofthesubstratethecoatingaroughsurfacewillgiveindividualinstrumentreadin

19、gsthatwillvaryfrompointtopoint.Inthiscaseitisnecessarytomakemanyreadingsatdifferentpositionstoobtainanaveragevaluethatisrepresentativeofthemeancoatingthickness.Ifthebasismetalisroughitmayalsobenecessarytocheckadjustifnec

20、essarythezerooftheinstrumentatseveralpositionsonasampleoftheuncoatedroughsubstrate.Iftheroughnessofthesubstratesurfaceissmallrelativetothecoatingthicknessitseffectwillprobablybenegligible.8.6.2Ifthebasismetalisroughitmay

21、alsobenecessarytocheckadjustifnecessarythezerooftheinstrumentatseveralpositionsonasampleoftheuncoatedroughsubstrate.Iftheroughnessofthesubstratesurfaceissmallrelativetothecoatingthicknessitseffectwillprobablybenegligible

22、.8.7FeignParticles—Theprobesofeddycurrentinstrumentsmustmakephysicalcontactwiththetestsurfacearetherefesensitivetofeignmaterialthatpreventsintimatecontactbetweentheprobethecoatingsurface.Boththetestsurfaceinstrumentprobe

23、shouldbekeptfreeoffeignmaterial.8.8Pressure—Thepressurewithwhichtheprobeisappliedtothetestspecimenaffectstheinstrumentreadingsshouldtherefebekeptconstant.8.9NumberofReadings—Theprecisionofthemeasurementscanbeimprovedbyin

24、creasingthenumberofreadingsinaccdancewithstatisticalprinciples.9.Procedure9.1Operateeachinstrumentinaccdancewiththeinstructionsofthemanufacturer.GiveappropriateattentiontothefactslistedinSection8.9.2Verifytheaccuracyofth

25、einstrumentatthetestsiteeachtimetheinstrumentisputintoserviceatfrequentintervalsduringusetoassureproperperfmance.9.3Manyinstrumentscanbeadjustedindertoimprovetheiraccuracyonaspecificsurfacewithinaspecificptionofitsmeasur

26、ementrange.Theeffectsofpropertiesofthesubstrate(compositionshaperoughnessedgeeffectselectricalproperties)coating(compositionmasssurfaceroughness)aswellasambientsurfacetemperaturesmayrequireadjustmentstobemadetotheinstrum

27、ent.Followthemanufacturer’sinstructions.9.4Observethefollowingprecautions:9.4.1BasisMetalThickness—Checkwhetherthebasismetalthicknessexceedsthecriticalthickness.Ifnoteitherusethebackupmethodin7.5makesurethatthecalibratio

28、nadjustmenthasbeenmadeonareferencestardhavingthesamethicknesselectricalpropertiesasthetestspecimen.9.4.2EdgeEffects—Donotmakereadingsclosetoanedgeholeinsidecneretc.ofaspecimenunlessthevalidityofthecalibrationadjustmentfs

29、uchameasurementhasbeendemonstrated.9.4.3Curvature—Donotmakereadingsonacurvedsurfaceofaspecimenunlessthevalidityofthecalibrationadjustmentfsuchameasurementhasbeendemonstrated.9.4.4NumberofReadings—Becauseofnmalinstrumentv

30、ariabilityitisnecessarytomakeseveralreadingsateachposition.Localvariationsincoatingthicknessmayalsorequirethatanumberofmeasurementsbemadeinanygivenareathisappliesparticularlytoaroughsurface(see8.9).9.4.5SurfaceCleanlines

31、s—Befemakingmeasurementscleananyfeignmattersuchasdirtgreasecrosionproductsfromthesurfacewithoutremovinganycoatingmaterial.10.Accuracy10.1Theinstrumentitscalibrationitsoperationshallbesuchthatthecoatingthicknesscanbedeter

32、minedwithin10%1mwhicheverisgreaterofthetruethickness.11.Rept11.1Thereptshallincludethefollowinginfmation:11.1.1Typeofinstrumentusedincludingmanufacturermodelnumberprincipleofoperationdateofcalibration11.1.2Sizedeionoftes

33、tspecimen11.1.3Whetherspecialjigswereused11.1.4Typeofcoatingthicknessstardreferencestardthemethodusedfaccuracyverificationanycalibrationadjustment11.1.5Thenumberofmeasurementstakenthevalueofeachmeasurement11.1.6Operatide

34、ntification11.1.7Date.NOTE1—Althoughtheeticallythistestmethodcanbeusedfmeasuringnonconductivecoatingsonamagicbasismetalitsusefcoatingsbelow25m(1mil)isnotrecommendedthemagicmethodoutlinedinTestMethodB499shallbeused.12.Pre

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