1、Designation: B 700 08Standard Specification forElectrodeposited Coatings of Silver for Engineering Use1This standard is issued under the fixed designation B 700; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi
2、sion. 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 This specification covers requirements for electrodepos-ited coatings of silver used for engineering purposes that maybe mat, b
3、right, or semibright and are not less than 98 % silverpurity.1.2 Coatings of silver covered by this specification areusually employed for solderable surfaces, electrical contactcharacteristics, high electrical and thermal conductivity, ther-mocompression bonding, wear resistance of load-bearing sur-
4、faces, and spectral reflectivity.1.3 In the Appendixes important characteristics of elec-trodeposited silver coatings are briefly described which mustbe considered when used in engineering applications, namelyelectrical conductivity (see Appendix X1), silver migration(seeAppendix X2), thickness (see
5、Appendix X3), hardness (seeAppendix X4), and atmospheric tarnish (see Appendix X5).1.4 The following hazards caveat pertains only to the testmethods section of this specification: This standard does notpurport to address the safety concerns, if any, associated withits use. It is the responsibility o
6、f the user of this standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 183 Practice for Preparation of Low-Carbon Steel forElectroplatingB 242 Guide for Preparation of High-C
7、arbon Steel forElectroplatingB 252 Guide for Preparation of Zinc Alloy Die Castings forElectroplating and Conversion CoatingsB 253 Guide for Preparation of Aluminum Alloys for Elec-troplatingB 254 Practice for Preparation of and Electroplating onStainless SteelB 281 Practice for Preparation of Coppe
8、r and Copper-BaseAlloys for Electroplating and Conversion CoatingsB 322 Guide for Cleaning Metals Prior to ElectroplatingB 343 Practice for Preparation of Nickel for Electroplatingwith NickelB 374 Terminology Relating to ElectroplatingB 481 Practice for Preparation of Titanium and TitaniumAlloys for
9、 ElectroplatingB 482 Practice for Preparation of Tungsten and TungstenAlloys for ElectroplatingB 487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination of CrossSectionB 499 Test Method for Measurement of Coating Thick-nesses by the Magnetic Method: Nonmagnet
10、ic Coatings onMagnetic Basis MetalsB 504 Test Method for Measurement of Thickness of Me-tallic Coatings by the Coulometric MethodB 507 Practice for Design ofArticles to Be Electroplated onRacksB 542 Terminology Relating to Electrical Contacts andTheir UseB 567 Test Method for Measurement of Coating
11、Thicknessby the Beta Backscatter MethodB 568 Test Method for Measurement of Coating Thicknessby X-Ray SpectrometryB 571 Practice for Qualitative Adhesion Testing of MetallicCoatingsB 578 Test Method for Microhardness of ElectroplatedCoatingsB 579 Specification for Electrodeposited Coatings of Tin-Le
12、ad Alloy (Solder Plate)B 602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB 678 Test Method for Solderability of Metallic-CoatedProductsB 697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic CoatingsB 762 Test Method of Variables S
13、ampling of Metallic andInorganic CoatingsB 849 Specification for Pre-Treatments of Iron or Steel forReducing Risk of Hydrogen EmbrittlementB 850 Guide for Post-Coating Treatments of Steel for Re-ducing the Risk of Hydrogen Embrittlement1This specification is under the jurisdiction of ASTM Committee
14、B08 onMetallic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.08.02 on Precious Metal Coatings.Current edition approved Aug. 1, 2008. Published September 2008. Originallyapproved in 1981. Last previous edition approved in 2002 as B 700 97(2002).2B08For referenced ASTM sta
15、ndards, visit the ASTM website, www.astm.org,or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
16、PA 19428-2959, United States.D 3951 Practice for Commercial PackagingE 1004 Practice for Determining Electrical ConductivityUsing the Electromagnetic (Eddy-Current) MethodF 519 Test Method for Mechanical Hydrogen Embrittle-ment Evaluation of Plating/Coating Processes and ServiceEnvironments3. Termin
17、ology3.1 DefinitionsMany of the terms used in this specifica-tion are defined in Terminologies B 374 or B 542.3.2 Definitions of Terms Specific to This Standard:3.2.1 rack-platingan electrodeposition process in whicharticles to be coated are mounted on racks or other fixturesduring the process.3.2.2
18、 significant surfacessurfaces that are normally vis-ible, directly or by reflection, or that are essential to theserviceability or function of the article or which can be thesource of corrosion products or tarnish films that interfere withthe function or desirable appearances of the article. Whennec
19、essary, the significant surfaces shall be indicated on thedrawings of the parts, or by the provisions of suitably markedsamples.3.2.2.1 DiscussionVariation in the coating thickness frompoint-to-point on a coated article is an inherent characteristic ofelectroplating processes. Therefore, the coating
20、 thickness willhave to exceed the specified value at some points on thesignificant surfaces to ensure that the thickness equals orexceeds the specified value at all points. The average coatingthickness on the article usually will be greater than thatspecified; how much greater is largely determined
21、by the shapeof the article (see Practice B 507) and the characteristics of theelectroplating process. Additionally, the average coating thick-ness on an article will vary from article to article within aproduction lot. If all the articles in a production lot are to meetthe thickness requirement, the
22、 average coating thickness of aproduction lot as a whole will be greater than the averagenecessary to ensure that a single article meets requirements.3.2.3 strike or flasha thin, typically less than 0.25-m (10-in.) metallic coating layer between metallic coatings toimprove adhesion.3.2.4 underplatin
23、gan application of a metallic coatinglayer between the basis metal or substrate and the topmostmetallic coating or coatings (see 6.3.4).4. Classification4.1 Electrodeposited coatings of silver shall be classified forType based on minimum purity, Grade whether bright,semibright, or mat, Class if supp
24、lementary surface treatment isapplied, and thickness in micrometers.4.2 PuritySpecify by Type as follows:Type 199.9 % minType 299.0 % minType 398.0 % minNOTE 1Metallic or organic brighteners used for grain refinement maybe present in the electrodeposit so long as they do not interfere with thestated
25、 function of the coating and are acceptable to the purchaser (seeAppendix X1).4.3 Surface AppearanceSpecify by Grade in letter codeas follows:Grade A, MatElectrodeposits without luster, obtainedfrom electroplating solutions operated without the use ofbrighteners.Grade B, BrightElectrodeposits obtain
26、ed by the use ofbrighteners in the electroplating bath.Grade C, BrightElectrodeposits obtained by mechanicalor chemical polishing of Grade A silver coatings.Grade D, Semibright Semi-lustrous electrodeposits ob-tained by the use of addition agents in the electroplating bath.4.4 Supplementary Surface
27、Treatment Specify by Class inletter code as follows:Class NA finish that has had no supplementary tarnishresistant (that is, chromate) treatment (see Appendix X5).Class SA finish that has had a supplementary tarnishresistant (that is, chromate) treatment.NOTE 2Class S is not suitable for food servic
28、e applications.5. Ordering Information5.1 To make application of this standard complete, thepurchaser needs to supply the following information to theseller in the purchase order or other governing document:5.1.1 Name, designation, and year of issue of this standard.5.1.2 Type (see 4.2), Grade (see
29、4.3), Class (see 4.4) andThickness (see 6.6 and Appendix X3).5.1.3 Nature of SubstrateIf, for example, it is highstrength steel, the need for stress relief (see 6.3.2.1) andembrittlement relief (see 6.3.5.1). If it is copper, an undercoatis needed (see S1.3) for some applications.5.1.4 Significant S
30、urfaces (see section 3.2.2).5.1.5 Appearance (see 6.7).5.1.6 Underplates (see 6.3.4 and S1.3).5.1.7 Requirements and methods of testing for one or moreof the following: need for and type of test specimens (see 8.1),thickness (see 6.6, 8.2, and Appendix X3), adhesion (see 6.8and 8.3), hardness (see 6
31、.10.1 and 8.7), absence of embrittle-ment (see 8.4), solderability (see 6.9 and 8.5), spectral reflec-tance (see 6.10.2 and 8.8), or electrical conductivity (see 6.10.3and 8.9).5.1.8 Sampling Plans and Quality Assurance (see Section 7and S1.2).6. Coating Requirements6.1 Nature of CoatingThe coating
32、essentially shall besilver, considering the type specified, produced by electrodepo-sition from aqueous electrolytes.6.2 Purity of CoatingThe coating shall meet the chemicalcomposition requirements of the specified type as defined in4.2 and measured as described in 8.6.6.3 Process:6.3.1 The basis me
33、tal shall be subjected to such cleaningprocedures as are necessary to ensure a surface satisfactory forsubsequent electroplating. Materials used for cleaning shallhave no damaging effects on the basis metal resulting in pits,intergranular attack, stress corrosion cracking, or hydrogenembrittlement.N
34、OTE 3For basis metal preparations, the following appropriateASTM standards are recommended: Practices B 183, , B 252, B 254,B 281, B 322, B 343, B 481, and B 482, and Guides B 252, B 253.B7000826.3.2 Preplating OperationsElectroplating shall be ap-plied after all basis metal heat treatments and mech
35、anicaloperations such as forming, machining, and joining of thearticle have been completed.NOTE 4Silver deposits may be used to facilitate mechanical opera-tions such as forming and drawing. In these applications, silver is appliedbefore such process steps.6.3.2.1 Stress Relief TreatmentParts that a
36、re made ofsteels with ultimate tensile strength of 1000 MPa or over(hardness of 31 HRC or greater) that have been machined,ground, cold-formed or cold-straightened subsequent to heattreatment, may require stress relief heat treatment when speci-fied by the purchaser, the tensile strength to be suppl
37、ied by thepurchaser. Specification B 849 may be consulted for a list ofpretreatments that are used widely.6.3.3 StrikeThe final silver coating shall be preceded by asilver or gold strike for optimum adhesion.6.3.4 UnderplatingA nickel or nickel-alloy intermediatelayer, at least 1 m (39 -in.) thick,
38、shall be applied before thesilver electroplate when the product being plated is made fromcopper or copper alloy. Nickel underplatings are also appliedfor other reasons.6.3.5 Post-Plating Procedures:6.3.5.1 Embrittlement ReliefParts that are made of steelswith ultimate tensile strength of 100 MPa or
39、over (hardness of31 HRC or greater), as well as surface-hardened parts, mayrequire post-coating hydrogen embrittlement relief bakingwhen specified by the purchaser, the tensile strength to besupplied by the purchaser. Specification B 850 may be con-sulted for a list of post-treatments that are used
40、widely.6.4 Surface AppearanceThe coatings surface finish shallmeet the requirements of the specified grade defined in 4.3.6.5 Supplementary Post TreatmentThe coating shall meetthe requirements of the specified class defined in 4.4.6.6 ThicknessThe silver coating thickness on significantsurfaces shal
41、l be at least that specified (seeAppendix X3) whenmeasured as described in 8.2.6.7 AppearanceSilver electroplated coated articles shallbe covered completely on all surfaces as specified in themanufacturing document and shall have a uniform appearancewith no visible defects to the extent that the nat
42、ure of the basismetal and good commercial practice permit. The requirementfor uniform color or appearance need not apply for subsequentpassivation or other treatments of the silver.6.7.1 DefectsDefects in the surface of the basis metalsuch as scratches, pits, non-conducting inclusions, and roll andd
43、ie marks may adversely affect the appearance and perfor-mance of applied coatings. Such defects that persists in thefinish despite the observance of good metal finishing practicesshall not be cause for rejection.NOTE 5Coated finishes generally perform better in service when thesubstrate over which t
44、hey are applied is smooth and free from torn metal,inclusions, pores, and other defects. It is recommended that the specifi-cations covering the unfinished product provides limits for those defects.A metal finisher often can remove defects by means of special treatmentssuch as grinding, polishing, a
45、brasive blasting, chemical treatments, andelectropolishing. However, these are not normal for the treatment stepspreceding application of the finish. When they are desired, they are thesubject of special agreement between the purchaser and the supplier.6.8 AdhesionThe silver coatings shall be free o
46、f blistersand peeled areas indicating poor adhesion when tested inaccordance with 8.3.NOTE 6Some applications may require no separation by any me-chanical means such as machining or milling through the interface.6.9 SolderabilityThe silver plated surfaces shall producesolder coatings which shall be
47、bright, smooth, and uniform. Atleast 95 % of the sample surface shall show good wetting whentested as described in 8.5.6.10 Supplementary Requirements:6.10.1 HardnessIf a hardness requirement is specified, thehardness of the silver coatings shall conform to that specifiedas measured as described in
48、8.7.6.10.2 Spectral ReflectanceThe spectral reflectance of thesilver coatings, if required, shall conform to that specifiedwhen measured as described in 8.8.6.10.3 Electrical ConductivityThe electrical conductivityof the silver coatings, if required, shall conform to thatspecified when measured as d
49、escribed in 8.9.7. Sampling7.1 A random sample of the size required by Test MethodB 602 or Method B 762 shall be selected from the inspectionlot (see 7.2). The articles in the lot shall be classified asconforming or nonconforming to each requirement accordingto the criteria of the sampling plans in the chosen method.NOTE 7Test Method B 602 contains four sampling plans, three foruse with nondestructive test methods; the fourth is for use with destructivetest methods. The three methods for nondestructive tests differ in thequality level t
