Designation:B766−86(Reapproved2015)StandardSpecificationforElectrodepositedCoatingsofCadmium1ThisstandardisissuedunderthefixeddesignationB766;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope1.1Thisspecificationcoverstherequirementsforelectrode-positedcadmiumcoatingsonproductsofiron,steel,andothermetals.NOTE1—Cadmiumisdepositedasacoatingprincipallyonironandsteelproducts.Itcanalsobeelectrodepositedonaluminum,brass,berylliumcopper,copper,nickel,andpowdermetallurgyparts.1.2Thecoatingisprovidedinvariousthicknessesuptoandincluding25µmeitheraselectrodepositedorwithsupplemen-taryfinishes.1.3Cadmiumcoatingsareusedforcorrosionresistanceandforcorrosionpreventionofthebasismetalpart.Theas-depositedcoating(TypeI)isusefulforthelowestcostprotectioninamildornoncorrosiveenvironmentwhereearlyformationofwhitecorrosionproductsisnotdetrimentalorharmfultothefunctionofacomponent.Theprimepurposeofthesupplementarychromatefinishes(TypesIIandIII)ontheelectroplatedcadmiumistoincreasecorrosionresistance.Chromatingwillretardorpreventtheformationofwhitecorrosionproductsonsurfacesexposedtovariousenvironmen-talconditionsaswellasdelaytheappearanceofcorrosionfromthebasismetal.1.4Cadmiumplatingisusedtominimizebi-metalliccorro-sionbetweenhigh-strengthsteelfastenersandaluminumintheaerospaceindustry.Undercuttingofthreadsonfastenerpartsisnotnecessaryasthecadmiumcoatinghasalowcoefficientoffrictionthatreducesthetighteningtorquerequiredandallowsrepetitivedismantling.1.5Cadmium-coatedpartscaneasilybesolderedwithouttheuseofcorrosivefluxes.Cadmium-coatedsteelpartshavealowerelectricalcontactresistancethanzinc-coatedsteel.Thelubricityofcadmiumplatingisusedonspringsfordoorsandlatchesandforweavingmachineryoperatinginhighhumidit...
