GM 4372M~4374M-1992(英文)装怖用铬镀层-铜、镍、铬类型

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1、GMGfl4372M92a9OOb3790008348737-GENERALMOTORSENGINEERINGSTANDARDSMaterialsandProcesses-MetalsIIIDECORATIVECHROMIUMPLATING-COPPER,NICKEL,CHROMIUMTYPEGM4372MGM4373MGM4374M1SCOPE.Thesespecificationscoverbasicrequirementsisusedbetweenthesemibrightandbrightnickellayers,thenforelectropl

2、atedpartsofthecopper-nickel-chromiumtypeasthesemibrightthicknessshallbeaminimumof40%.usedonsteel,zincdiecast,copperbasedalloys,andplasticcomponents,andwrought,die-castorforgedaluminumand3.1.3Minimumthicknessandcorrosionresistanceperfor-aluminumalloys,excludingwheels.mancerequirem

3、entsfortexturedfinishes(matte,vaporblast,brush,etc.)applyaftertexturing.1.1GM4372MandGM4374Mareintendedforexteriorparts3.1.4Exceptionstotheminimumplatingthicknessaregener-andprovide2levelsofcorrosionprotection.GM4374Mpro-allyshownasadetailonthepartdrawingbyeithervidescorrosionpro

4、tectionforsevereserviceconditionsthatdesignatingplatingcheckpoint(s)orbyindicatinginanappro-includelikelydamagefromdenting,scratchingandabrasivepriateviewthearea(s)withdeviatedthickness(es)allowed.wearinadditiontocorrosiveenvironmentssuchasencoun-Theseexceptionsmuststillmeetthesp

5、ecifiednumberofcor-teredbyautomotivebumpersandrelatedcomponents.Thisrosiontesthours.specificationdiffersfromGM4372Minthatitrequiresalongercorrosion(CASS)exposure.GM4372Mprovidescorro-3.2NICKELELECTROCHEMICALPOTENTIALsionprotectionforcorrosiveenvironmentswhichreceivelittle(GM4372M

6、ANDGM4374MONLY).Determinepotentialadditionalmechanicalabuse.BothspecificationsrequirethedifferencefollowingASTMB764.useofdiscontinuouschromiumplateinadditiontoamultiplelayernickelsystem.3.2.1Thebrightnickellayershallexhibitananodicelectro-chemicalpotentialdifferenceof100mVminimum

7、tosemi-1.2GM4373Misintendedforinteriorapplications.Itdoesbrightnickelonallsignificantsurfaces.Conformancetothisnotrequiretheuseofdiscontinuouschromiumormultiplerequirementshallbedeterminedwith99%confidence(3layernickelsystems.sigma)usingappropriatestatisticalchartingtechniquesona

8、routinequalitycontrolbasis.1.3Whenspecif