Designation:B781−93a(Reapproved2012)StandardGuideforSilver-CadmiumOxideContactMaterial1ThisstandardisissuedunderthefixeddesignationB781;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thisguideprovidesguidelinesforusersandmanufac-turersofsilver-cadmiumoxidematerialproducedinstrip,rod,wire,andpartformforelectricalcontactapplications.1.2Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.ItistheresponsibilityoftheuserofthisstandardtobecomefamiliarwithallhazardsincludingthoseidentifiedintheappropriateMaterialSafetyDataSheet(MSDS)forthisproduct/materialasprovidedbythemanufacturer,toestablishappropriatesafetyandhealthpractices,anddeterminetheapplicabilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2B311TestMethodforDensityofPowderMetallurgy(PM)MaterialsContainingLessThanTwoPercentPorosityB476SpecificationforGeneralRequirementsforWroughtPreciousMetalElectricalContactMaterialsC914TestMethodforBulkDensityandVolumeofSolidRefractoriesbyWaxImmersionNOTE1—TestMethodB311isapplicabletofullydenseforms.SpecificationB476isapplicabletostrip,rod,orwireonly.TestMethodC914isapplicabletoformslessthan99%dense.3.Terminology3.1lot,n—(usageinvolvingdiscretemanufacturedparts)—allpartsofthesameform,anddimensions,fromthesamealloymeltorbatchofparticulate(ifmanufacturedbyconsolidation),processedunderthesameconditions,andsubmittedforinspec-tionatthesametime.4.SignificanceandUse4.1Silver-cadmiumoxideisapopularcontactmaterialthathasbeenusedinawiderangeofapplicationsinswitches,relaysandcontactorsforswitchinglamps,motorsandresistiveloads.Silver-cadmiumoxideisacompositematerialconsistingofametalmatrix,silver,withametaloxide,cadmiumoxide,dispersedthroughoutthematrix.Compositionsofupto30%cadmiumaremade,butmostapplicationsu...
