1、Designation: B 816 00 (Reapproved 2004)e1Standard Specification forCoatings of Cadmium-Zinc Mechanically Deposited1This standard is issued under the fixed designation B 816; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEKeywords were added editorially in August 2004.1. Scope1.1 GeneralThis specification covers the requirements fora coatin
3、g that is a mixture of cadmium and zinc deposited onmetallic products by mechanical deposition. The coating isprovided in four thickness classes (see Table 1) and severalfinish types (see Table 2).1.2 ToxicityWarning: Cadmium is toxic; therefore thesecoatings should not be used on articles that will
4、 contact food orbeverages, or for dental and other equipment that may beinserted into the mouth. Also, the coatings should not be usedon articles that will be heated to high temperatures, becausecadmium will form toxic fumes. Similarly, if coated articles arewelded, soldered, or otherwise heated dur
5、ing fabrication,adequate ventilation should be provided to exhaust toxicfumes.1.3 Similar DocumentsOther kinds of mechanically de-posited coatings are covered by Specifications B 635, B 695,and B 696.1.4 The following precautionary caveat pertains only to thetest method portion, Section 9, of this s
6、pecification. Thisstandard does not purport to address all of the safety concerns,if any, associated with its use. It is the responsibility of the userof this standard to establish appropriate safety and healthpractices and determine the applicability of regulatory limita-tions prior to use.2. Refer
7、enced Documents2.1 ASTM Standards:2B 117 Practice for Operating Salt Spray (Fog) ApparatusB 183 Practice for Preparation of Low-Carbon Steel forElectroplatingB 242 Guide for Preparation of High-Carbon Steel forElectroplatingB 320 Practice for Preparation of Iron Castings for Electro-platingB 322 Gui
8、de for Cleaning Metals Prior to ElectroplatingB 374 Terminology Relating to ElectroplatingB 487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination of aCross SectionB 499 Test Method for Measurement of Coating Thick-nesses by the Magnetic Method: Nonmagnetic
9、Coatings onMagnetic Basis MetalsB 571 Practice for Adhesion of Metallic CoatingsB 602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB 635 Specification for Coatings of Cadmium-Tin Me-chanically Deposited1This specification is under the jurisdiction of ASTM Committee B08 onMetal
10、lic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.08.04 on Soft Metals.Current edition approved Aug. 1, 2004. Published August 2004. Originallyapproved in 1991. Last previous edition approved in 2000 as B 816 00.2For referenced ASTM standards, visit the ASTM website, www
11、.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.TABLE 1 Thickness ClassesClassCoatingThicknessMinimum, mTypical Applications7 7 Automotive fasteners12 12 Increased corr
12、osion resistance (for ex-ample, bellville washers)25 25 Exterior hardware50 50 Pole line hardware in severe envi-ronmentsTABLE 2 Coating TypesType Description Typical ApplicationsI As-coated, without supplemen-ary treatments.Lowest cost where white corro-ion products are acceptable.For elevated temp
13、erature ap-lication that will degradeType II coatings (see 1.2).IIa With yellow to bronze color sup-lementary chromate coating.Delay the appearance of whitecorrosion products. Increasetotal corrosion protection.IIb With brown to olive drab colorsupplementary chromatecoating.Greater corrosion resista
14、ncesthan IIa. To provide a matchto military equipment.IIc Type IIa, dyed. Color codingDecorative purposesIId Type IIa with an added lubricantor organic finish (oil, wax, lac-uer, etc.)LubricityMaximum corrosion resistance1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshoh
15、ocken, PA 19428-2959, United States.B 695 Specification for Coatings of Zinc MechanicallyDeposited on Iron and SteelB 696 Specification for Coatings of Cadmium MechanicallyDepositedB 697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic CoatingsB 762 Test
16、 Method of Variables Sampling of Metallic andInorganic CoatingsE 27 Method for Spectrographic Analysis of Zinc and ZincAlloys by the Solution-Residue Technique3E 396 Test Methods for Chemical Analysis of CadmiumE 536 Test Method for Chemical Analysis of Zinc and ZincAlloysF 1470 Guide for Fastener S
17、ampling for Specified Mechani-cal Properties and Performance Inspection3. Terminology3.1 DefinitionsSome of the terms used in this are definedin Terminology B 374.4. Classification4.1 Thickness ClassesThe coating is classified in fourthickness classes, as defined in Table 1.4.2 Coating TypesThe coat
18、ing is classified by type, asdefined in Table 2.5. Ordering Information5.1 In order to make the application of this specificationcomplete, the purchaser needs to supply the following infor-mation to the seller on the purchase order or other governingdocuments:5.1.1 The name, designation, and year of
19、 issue of thisspecification,5.1.2 Thickness class (see 4.1), including a maximum thick-ness if appropriate,5.1.3 Coating type (see 4.2), including required color ifType IIc is used, and required lubricant or organic finish ifType IId is used,5.1.4 Nature of the substrate, for example: high-carbonste
20、el, mild steel, copper, brass:5.1.4.1 State if precoating stress relief heat treatment isrequired and the time and temperature to be used if differentfrom the standard values (see section 12.1),5.1.4.2 State if special pretreatments are required to modifythe surface of the article (see Note 1),5.1.4
21、.3 If special cleaning precautions are to be followed(see A1.1), and5.1.5 Identification of significant surfaces (see 7.4.2).5.1.6 Requirements and methods of testing one or more ofthe following:5.1.6.1 Need for and type of special test specimens (see9.1),5.1.6.2 Appearance (see 7.3),5.1.6.3 Deposit
22、 composition (see 9.2),5.1.6.4 Thickness (see 9.5),5.1.6.5 Adhesion (see 9.6),5.1.6.6 Corrosion resistance (see 9.7),5.1.6.7 Absence of hydrogen embrittlement, waiting timeprior to testing and testing loads (see 9.8), and5.1.7 The sampling plan to be used (see 8.1) and responsi-bility for inspection
23、 (see section 13.1).6. Significance and Use6.1 Corrosion Resistance, GeneralThis functional coat-ing is used to provide corrosion resistance. The performance ofthis coating depends largely on its thickness and the kind ofenvironment to which it is exposed. Published results ofenvironmental corrosion
24、 studies have demonstrated that thecoating provides corrosion resistance greater than equivalentthicknesses of zinc coatings in industrial environments andgreater corrosion resistance than equivalent thicknesses ofcadmium coatings in marine environments.46.2 Galvanic Corrosion ResistanceThe galvanic
25、 couplethat results in the corrosion of steel and aluminum parts incontact with each other in corrosive environments can also beminimized by plating the steel parts with this mechanicallydeposited coating.6.3 Hydrogen Embrittlement, Absence ofThe mechanicalcoating process does not produce any perman
26、ent hydrogenembrittlement in products made from high-strength steels, forexample, fasteners or lock washers.7. Coating Requirements7.1 Nature of CoatingThe coating shall be a mechanicallydeposited mixture of cadmium and zinc with the composition45 to 75 mass % zinc, remainder cadmium.7.2 Coating Pro
27、cess:7.2.1 CoatingThe cadmium-zinc coating shall be pro-duced by mechanical deposition in accordance with the processdescription given in Annex A1.7.2.2 Supplementary TreatmentsType II coatings shall beproduced by treatment with acidic solutions that containhexavalent chromium compounds and anions t
28、hat act ascatalysts or film-forming compounds.7.3 Appearance:7.3.1 GeneralThe coating on all readily visible surfacesshall be uniform in appearance, well compacted, and completein coverage. Superficial staining from rinsing and drying andmild variations in color and luster are acceptable.7.3.2 Surfa
29、ce DefectsDefects and variations in appear-ance in the coating that arise from surface conditions of thesubstrate (scratches, pores, roll marks, inclusions, etc.) and thatpersist in the coating despite the observance of good metalfinishing practices shall not be cause for rejection.NOTE 1Coatings ge
30、nerally perform better in service when the sub-strate over which they are applied is smooth and free of torn metal,inclusions, pores, and other defects. The specifications covering theunfinished products should provide limits for these defects. A metalfinisher can often remove defects through specia
31、l treatments, such asgrinding, polishing, abrasive blasting, chemical etches, and electropolish-ing. However, these are not normal in the treatment steps preceding the3Withdrawn.4Holford, Raymond N., Jr., “Five Year Outdoor Exposure Corrosion Compari-son,” Mechanical Finishing, July 1988.B 816 00 (2
32、004)e12application of the coating. When they are desired, they are the subject ofspecial agreement between the purchaser and the seller.7.4 Thickness:7.4.1 Conformance to Specified ClassThe thickness of thecoating everywhere on the significant surfaces shall conform tothe requirements of the specifi
33、ed class as defined in 4.1.7.4.2 Significant SurfacesSignificant surfaces are usuallydefined as those normally visible (directly or by reflection) thatare essential to the appearance and serviceability of the articlewhen assembled in normal position; or that can be the sourceof corrosion products th
34、at deface visible surfaces on theassembled article. Significant surfaces are further defined atthose surfaces that are identified as such by the purchaser, forexample, by indicating them on an engineering drawing of theproduct or by marking a sample item of product.7.4.3 Minimum Thickness Requiremen
35、tThe coating re-quirement of this specification is a minimum requirement; thatis, the coating thickness is required to equal or exceed thespecified thickness everywhere on the significant surfaces.Variation in the thickness from point to point on an article andfrom article to article in a production
36、 lot is inherent inmechanically deposited coatings. Therefore, if all of thearticles in a production lot are to meet the thickness require-ment, the average coating thickness for the production lot as awhole will be greater than the specified minimum.NOTE 2The thickness of mechanically deposited coa
37、tings varies frompoint to point on the surface of a product, characteristically tending to bethicker on flat surfaces, and thinner at exposed edges, sharp projections,shielded or recessed areas, and interior corners and holes, depending onthe dimensions, with such thinner areas often being exempted
38、fromthickness requirements.NOTE 3Processes used to produce Type II finishes remove some ofthe coating. Because thickness requirements apply to the finished article,additional thicknesses may have to be applied to compensate for the metalremoved in the Type II process.7.5 AdhesionThe coating shall be
39、 adherent, as defined ortested in accordance with 9.6.7.6 Corrosion Resistance:7.6.1 Type I Coatings on Ferrous ArticlesType I coatedferrous articles shall not develop red corrosion products(“rust”) when submitted to the 5 % salt spray test for thefollowing times:Class 7 36 hClass 12 72 hClass 25 19
40、2 hClass 50 300 h7.6.2 Type II Coatings, White CorrosionType II coatingsshall not develop white corrosion products when submitted tothe salt spray test for 72 h. The organic coating or lubricantshall be removed from Type IId coatings before the test or thetest can be run on articles that are withdra
41、wn from processingbefore the organic coating is applied.7.6.3 Type II Coatings on Ferrous ArticlesType II coatedferrous articles shall not develop red corrosion products(“rust”) when submitted to the 5 % salt spray test for thefollowing times:Class 7 72 hClass 12 96 hClass 25 192 hClass 50 300 hThe
42、organic coating or lubricant shall be removed from TypeIId coatings before the salt spray test or the test can be run onarticles that are withdrawn from processing before the organiccoating is applied.NOTE 4In many instances, there is no direct relation between theresults of an accelerated corrosion
43、 test and the resistance to corrosion inother tests or actual environments, because several factors that influencethe progress of corrosion, such as the formation of protective film, varygreatly with the conditions encountered. The results obtained in the testshould not, therefore, be regarded as a
44、direct guide to the corrosionresistance of the tested materials in all environments where these materialsmay be used. Also, performance of different materials in the test cannotalways be taken as a direct guide to the relative corrosion resistance ofthese materials in service.8. Sampling8.1 The purc
45、haser and producer are urged to employ statis-tical process control in the coating process. Properly per-formed, statistical process control will assure coated productsof satisfactory quality and will reduce the amount of accep-tance inspection. The sampling plan used for the inspection ofthe qualit
46、y coated article shall be agreed upon between thepurchaser and producer.8.1.1 When a collection of coated articles (inspection lot,see 8.2) is examined for compliance with the requirementsplaced on the articles, a relatively small number of the articles(sample) is selected at random and is inspected
47、. The inspectionlot is then classified as complying with the requirements basedon the results of the inspection of the sample. The size of thesample and the criteria for compliance are determined by theapplication of statistics. The procedure is known as samplinginspection. Test Method B 602, Guide
48、B 697, and Test MethodB 762 contain sampling plans that are designed for samplinginspection of coatings.8.1.2 Test Method B 602 contains four sampling plans, threefor use with tests that are nondestructive and one when they aredestructive. Test Method B 602 provides a default plan if oneis not speci
49、fied.8.1.3 Guide B 697 provides a large number of plans andalso gives guidance in the selection of a plan. Guide B 697provides a default plan if one is not specified.8.1.4 Test Method B 762 can be used only for coatingrequirements that have a numerical limit, such as coatingthickness. The test must yield a numeric value and certainstatistical requirements must be met. Test Method B 762contains several plans and also gives instructions for calculat-ing plans to meet special needs. Test Method B 762 provides adefault plan if one is not specified.8.1.5 Guide F
