1、Designation: B 700 97 (Reapproved 2002)Standard 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
2、 year 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.1. Scope1.1 This specification covers requirements for electrodepos-ited coatings of silver used for engineering purpose
3、s that maybe mat, bright, 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 o
4、f load-bearing sur-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(see Appendix
5、 X2), thickness (see 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
6、 the responsibility of 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:B 183 Practice for Preparation of Low-Carbon Steel forElectroplating2B 242 Practice f
7、or Preparation of High-Carbon Steel forElectroplating2B 252 Guide for Preparation of Zinc Alloy Die Castings forElectroplating Conversion Coatings2B 253 Guide for Preparation of Aluminum Alloys for Elec-troplating2B 254 Practice for Preparation of and Electroplating onStainless Steel2B 281 Practice
8、for Preparation of Copper and Copper-BaseAlloys for Electroplating and Conversion Coatings2B 322 Practice for Cleaning Metals Prior to Electroplating2B 343 Practice for Preparation of Nickel for Electroplatingwith Nickel2B 374 Terminology Relating to Electroplating2B 481 Practice for Preparation of
9、Titanium and TitaniumAlloys for Electroplating2B 482 Practice for Preparation of Tungsten and TungstenAlloys for Electroplating2B 487 Test Method for Measurement of Metal and OxideCoating Thicknesses by Microscopical Examination of aCross Section2B 499 Test Method for Measurement of Coating Thick-ne
10、sses by the Magnetic Method: Nonmagnetic Coatings onMagnetic Basis Metals2B 504 Test Method for Measurement of Thickness of Me-tallic Coatings by the Coulometric Method2B 507 Practice for Design of Articles to be Electroplated onRacks2B 542 Terminology Relating to Electrical Contacts andTheir Use3B
11、567 Test Method for Measurement of Coating Thicknessby the Beta Backscatter Method2B 568 Test Method for Measurement of Coating Thicknessby X-Ray Spectrometry2B 571 Test Methods for Adhesion of Metallic Coatings2B 578 Test Method for Microhardness of ElectroplatedCoatings2B 579 Specification for Ele
12、ctrodeposited Coatings of Tin-Lead Alloy (Solder Plate)2B 602 Test Method for Attribute Sampling of Metallic andInorganic Coatings2B 678 Test Method for Solderability of Metallic-CoatedProducts2B 697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic Coati
13、ngs2B 762 Method of Variables Sampling of Metallic and Inor-ganic Coatings2B 849 Specification for Pre-treatments of Iron or Steel forReducing the Risk of Hydrogen Embrittlement2B 850 Guide for Post-Coating Treatments of Steel for Re-ducing the Risk of Hydrogen Embrittlement2D 3951 Practice for Comm
14、ercial Packaging41This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.08.02 on Precious Metal Coatings.Current edition approved May 10, 1997. Published February 1998. Originallypublished as B 700 81.
15、 Last previous edition B 700 90.2Annual Book of ASTM Standards, Vol 02.05.3Annual Book of ASTM Standards, Vol 02.04.4Annual Book of ASTM Standards, Vol 15.09.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.E 1004 Practice for Determi
16、ning Electrical ConductivityUsing the Electromagnetic (Eddy-Current) Method5F 519 Test Method for Mechanical Hydrogen Embrittle-ment Evaluation of Plating Processes and Service Environ-ments63. Terminology3.1 DefinitionsMany of the terms used in this specifica-tion are defined in Terminologies B 374
17、 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 significant surfacessurfaces that are normally vis-ible, directly or by reflection, or that are ess
18、ential 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. Whennecessary, the significant surfaces shall be indicated on thedrawings of the parts, or by the provision
19、s 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 thickness willhave to exceed the specified value at some points on thesignificant surfaces to ensur
20、e 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 by the shapeof the article (see Practice B 507) and the characteristics of theelectroplating process
21、. 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 average coating thickness of aproduction lot as a whole will be greater than the averagenecessary t
22、o 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 underplatingan application of a metallic coatinglayer between the basis metal or substrate and the topmostmetal
23、lic 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 supplementary surface treatment isapplied, and thickness in micrometers.4.2 PuritySpecify by Type as fol
24、lows: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 function of the coating and are acceptable to the purchaser (seeAppendix X1).4.3 Surface Appearance
25、Specify by Grade in letter codeas follows:Grade A, MatElectrodeposits without luster, obtainedfrom electroplating solutions operated without the use ofbrighteners.Grade B, BrightElectrodeposits obtained by the use ofbrighteners in the electroplating bath.Grade C, BrightElectrodeposits obtained by me
26、chanicalor chemical polishing of Grade A silver coatings.Grade D, SemibrightElectrodeposits obtained by the useof addition agents in the electroplating bath.4.4 Supplementary Surface Treatment Specify by Class inletter code as follows:Class NA finish that has had no supplementary tarnishresistant (t
27、hat 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 service applications.5. Ordering Information5.1 To make application of this standard complete, thepurchaser needs to supply
28、 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 4.3), Class (see 4.4) andThickness (see 6.6 and Appendix X3).5.1.3 Nature of SubstrateIf, for example, it is highstre
29、ngth 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 Surfaces (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
30、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 6.10.1 and 8.7), absence of embrittle-ment (see 8.4), solderability (see 6.9 and 8.5), spectral reflec-tance (see 6.10
31、.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 essentially shall besilver, considering the type specified, produced by electrodepo-sition from aqueous electrolytes.
32、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 metal shall be subjected to such cleaningprocedures as are necessary to ensure a surface satisfactory forsubsequent ele
33、ctroplating. Materials used for cleaning shall5Annual Book of ASTM Standards, Vol 03.03.6Annual Book of ASTM Standards, Vol 15.03.B 700 97 (2002)2have no damaging effects on the basis metal resulting in pits,intergranular attack, stress corrosion cracking, or hydrogenembrittlement.NOTE 3For basis me
34、tal preparations, the following appropriateASTM standards are recommended: Practices B 183, B 242, B 252,B 254, B 281, B 322, B 343, B 481, and B 482, and Guide B 253.6.3.2 Preplating OperationsElectroplating shall be ap-plied after all basis metal heat treatments and mechanicaloperations such as fo
35、rming, 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 are made ofsteels with ultim
36、ate 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 supplied by thepurchaser. Specif
37、ication 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 thick, shall be applied before the silverele
38、ctroplate 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 over (hardness of31 HRC or greater),
39、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 widely.6.4 Surface AppearanceThe coat
40、ings 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 shall be at least that specified (see App
41、endix 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 nature of the basismetal and good comme
42、rcial 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 anddie marks may adversely affect the ap
43、pearance 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 they are applied is smooth and free f
44、rom 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, abrasive blasting, chemical treatment
45、s, 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 of blistersand peeled areas indicatin
46、g 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 bright, smooth, and uniform. Atleast
47、 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 8.7.6.10.2 Spectral ReflectanceThe s
48、pectral 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 described in 8.9.7. Sampling7.1 A ran
49、dom 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 they require of the product. Test Meth
