1、Designation: B816 00 (Reapproved 2015)Standard Specification forCoatings of Cadmium-Zinc Mechanically Deposited1This standard is issued under the fixed designation B816; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 GeneralThis specification covers the requirements fora coating that is a mixture of cadmium and zinc deposited onmetall
3、ic 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 contact food orbeverages, or for dental and other equipme
4、nt 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 during fabrication,adequate ventilation should be provided to
5、 exhaust toxicfumes.1.3 Similar DocumentsOther kinds of mechanically de-posited coatings are covered by Specifications B635, B695,and B696.1.4 The following precautionary caveat pertains only to thetest method portion, Section 9, of this specification. Thisstandard does not purport to address all of
6、 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. Referenced Documents2.1 ASTM Standards:2B117 Practice for Operatin
7、g Salt Spray (Fog) ApparatusB183 Practice for Preparation of Low-Carbon Steel forElectroplatingB242 Guide for Preparation of High-Carbon Steel for Elec-troplatingB320 Practice for Preparation of Iron Castings for Electro-platingB322 Guide for Cleaning Metals Prior to ElectroplatingB374 Terminology R
8、elating 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 MetalsB571 Practice for Qualitative Adhesion
9、Testing of MetallicCoatingsB602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB635 Specification for Coatings of Cadmium-Tin Mechani-cally DepositedB695 Specification for Coatings of Zinc Mechanically De-posited on Iron and SteelB696 Specification for Coatings of Cadmium Mechan
10、icallyDepositedB697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic CoatingsB762 Test Method of Variables Sampling of Metallic andInorganic CoatingsE27 Method for Spectrographic Analysis of Zinc and ZincAlloys by the Solution-Residue Technique3E396 Test
11、 Methods for Chemical Analysis of CadmiumE536 Test Methods for Chemical Analysis of Zinc and ZincAlloysF1470 Practice for Fastener Sampling for Specified Me-chanical Properties and Performance Inspection3. Terminology3.1 DefinitionsSome of the terms used in this are definedin Terminology B374.4. Cla
12、ssification4.1 Thickness ClassesThe coating is classified in fourthickness classes, as defined in Table 1.4.2 Coating TypesThe coating is classified by type, asdefined in Table 2.1This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct r
13、esponsibility of SubcommitteeB08.06 on Soft Metals.Current edition approved March 1, 2015. Published April 2015. Originallyapproved in 1991. Last previous edition approved in 2009 as B816 00(2009). DOI:10.1520/B0816-00R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontac
14、t ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Ordering In
15、formation5.1 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 issue of thisspecification,5.1.2 Thickness class (see 4.1), i
16、ncluding 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-carbonsteel, mild steel, copper, brass:5.1.4.1 State if precoating stre
17、ss 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),5.1.4.3 If special cleaning precautions are to be followed(see A1.1
18、), 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 composition (see 9.2),5.1.6.4 Thickness (see 9.5),5.1.6.5 Adh
19、esion (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 (see section 13.1).6. Significance and Use6.1 Corrosion Resis
20、tance, GeneralThis functional coatingis used to provide corrosion resistance.The performance of thiscoating depends largely on its thickness and the kind ofenvironment to which it is exposed. Published results ofenvironmental corrosion studies have demonstrated that thecoating provides corrosion res
21、istance 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 couplethat results in the corrosion of steel and aluminum parts
22、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 permanent hydrogenembrittlement in products made from high-strength ste
23、els, 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 Process:7.2.1 CoatingThe cadmium-zinc coating shall be pro-duced by
24、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 that act ascatalysts or film-forming compounds.7.3 Appearance:7.3.
25、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 Surface DefectsDefects and variations in appear-ance in the coating th
26、at 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 generally perform better in service when thesubstrate over which th
27、ey 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 special treatments, such asgrinding, polishing, abrasive blasting, chemic
28、al etches, and electropolish-ing. However, these are not normal in the treatment steps preceding theapplication of the coating. When they are desired, they are the subject of4Holford, Raymond N., Jr., “Five Year Outdoor Exposure CorrosionComparison,” Mechanical Finishing, July 1988.TABLE 1 Thickness
29、 ClassesClassCoatingThicknessMinimum, mTypical Applications7 7 Automotive fasteners12 12 Increased corrosion 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, witho
30、ut supplemen-ary treatments.Lowest cost where white corro-ion products are acceptable.For elevated temperature 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 corrosi
31、on protection.IIb With brown to olive drab colorsupplementary chromatecoating.Greater corrosion resistancesthan 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.)LubricityMaxi
32、mum corrosion resistanceB816 00 (2015)2special 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 specified class as defined in 4.1.7.4.2 Significa
33、nt 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 that deface visible surfaces on theassembled
34、 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 RequirementThe coating re-quirement of this specific
35、ation 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 lot is inherent inmechanically deposited
36、coatings. Therefore, if all of thearticles in a production lot are to meet the thicknessrequirement, the average coating thickness for the productionlot as a whole will be greater than the specified minimum.NOTE 2The thickness of mechanically deposited coatings varies frompoint to point on the surfa
37、ce 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 fromthickness requirements.NOTE 3Processes u
38、sed to produceType II finishes remove some of thecoating. 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 adherent, as defined ortested in accordance
39、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 25 192 hClass 50 300 h7.6.2 Type II Coatings, Whit
40、e 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 withdrawn from processingbefore the organic coating
41、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 organic coating or lubricant shall be removed
42、 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 test and the resistance to corrosion inother
43、 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 direct guide to the corrosionresistance of th
44、e 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 purchaser and producer are urged to employ statis
45、-tical process control in the coating process. Properlyperformed, statistical process control will assure coated prod-ucts of satisfactory quality and will reduce the amount ofacceptance inspection. The sampling plan used for the inspec-tion of the quality coated article shall be agreed upon between
46、the purchaser 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. The inspectionlot is then classified as com
47、plying 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 B602, Guide B697, and Test MethodB762 contain sampling pla
48、ns that are designed for samplinginspection of coatings.8.1.2 Test Method B602 contains four sampling plans, threefor use with tests that are nondestructive and one when they aredestructive. Test Method B602 provides a default plan if one isnot specified.8.1.3 Guide B697 provides a large number of p
49、lans and alsogives guidance in the selection of a plan. Guide B697 providesa default plan if one is not specified.8.1.4 Test Method B762 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 B762contains several plans and also gives instructions for calculat-ing plans to meet special needs. Test Method B762 provides adefault plan if one is not specified.8.1.5 Guide F1470 can be used for fasteners such asinternally thread
