ASTM_B_766_-_86_2015.pdf

Designation:B76686(Reapproved 2015)Standard Specification forElectrodeposited Coatings of Cadmium1This standard is issued under the fixed designation B766;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This specification covers the requirements for electrode-posited cadmium coatings on products of iron,steel,and othermetals.NOTE1Cadmium is deposited as a coating principally on iron andsteel products.It can also be electrodeposited on aluminum,brass,beryllium copper,copper,nickel,and powder metallurgy parts.1.2 The coating is provided in various thicknesses up to andincluding 25 m either as electrodeposited or with supplemen-tary finishes.1.3 Cadmium coatings are used for corrosion resistance andfor corrosion prevention of the basis metal part.The as-deposited coating(Type I)is useful for the lowest costprotection in a mild or noncorrosive environment where earlyformation of white corrosion products is not detrimental orharmful to the function of a component.The prime purpose ofthe supplementary chromate finishes(Types II and III)on theelectroplated cadmium is to increase corrosion resistance.Chromating will retard or prevent the formation of whitecorrosion products on surfaces exposed to various environmen-tal conditions as well as delay the appearance of corrosion fromthe basis metal.1.4 Cadmium plating is used to minimize bi-metallic corro-sion between high-strength steel fasteners and aluminum in theaerospace industry.Undercutting of threads on fastener parts isnot necessary as the cadmium coating has a low coefficient offriction that reduces the tightening torque required and allowsrepetitive dismantling.1.5 Cadmium-coated parts can easily be soldered withoutthe use of corrosive fluxes.Cadmium-coated steel parts have alower electrical contact resistance than zinc-coated steel.Thelubricity of cadmium plating is used on springs for doors andlatches and for weaving machinery operating in high humidity.Corrosion products formed on cadmium are tightly adherent.Unlike zinc,cadmium does not build up voluminous corrosionproducts on the surface.This allows for proper functioningduring corrosive exposure of moving parts,threadedassemblies,valves,and delicate mechanisms without jammingwith debris.2.Referenced Documents2.1 The following standards form a part of this document tothe extent referenced herein.2.2 ASTM Standards:2A165 Specification for Electrodeposited Coatings of Cad-mium on Steel(Withdrawn 1987)3B117 Practice for Operating Salt Spray(Fog)ApparatusB183 Practice for Preparation of Low-Carbon Steel forElectroplatingB201 Practice for Testing Chromate Coatings on Zinc andCadmium SurfacesB242 Guide for Preparation of High-Carbon Steel for Elec-troplatingB253 Guide for Preparation of Aluminum Alloys for Elec-troplatingB254 Practice for Preparation of and Electroplating onStainless SteelB281 Practice for Preparation of Copper and Copper-BaseAlloys for Electroplating and Conversion CoatingsB320 Practice for Preparation of Iron Castings for Electro-platingB322 Guide for Cleaning Metals Prior to ElectroplatingB343 Practice for Preparation of Nickel for Electroplatingwith NickelB374 Terminology Relating to ElectroplatingB487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination ofCross SectionB499 Test Method for Measurement of Coating Thicknessesby the Magnetic Method:Nonmagnetic Coatings onMagnetic Basis Metals1This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.06 on Soft Metals.Current edition approved March 1,2015.Published April 2015.Originallyapproved in 1986.Last previous edition approved in 2008 as B766 86(2008).DOI:10.1520/B0766-86R15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 B504 Test Method for Measurement of Thickness of Metal-lic Coatings by the Coulometric MethodB507 Practice for Design of Articles to Be Electroplated onRacksB558 Practice for Preparation of Nickel Alloys for Electro-platingB567 Test Method for Measurement of Coating Thicknessby the Beta Backscatter MethodB568 Test Method for Measurement of Coating Thicknessby X-Ray SpectrometryB571 Practice for Qualitative Adhesion Testing of MetallicCoatingsB602 Test Method for Attribute Sampling