1、Designation: B 605 95a (Reapproved 2004)Standard Specification forElectrodeposited Coatings of Tin-Nickel Alloy1This standard is issued under the fixed designation B 605; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、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 the requirements for electrode-posited tin-nickel alloy coatings from aqueous solutions in-
3、tended for the corrosion protection of fabricated articles ofiron, steel, zinc-base alloys, copper, and copper alloys. Thecomposition of the alloy remains constant at 65/35 tin-nickel inspite of wide fluctuations in both composition and operatingconditions. The composition corresponds quite closely
4、to anequiatomic ratio, and the process favors the co-deposition oftin and nickel atoms at identical rates.1.2 This specification does not apply to sheet, strip, or wirein the fabricated form. It also may not be applicable to threadedarticles having basic major diameters up to and including 19mm beca
5、use of the nonuniformity of thickness that can beexpected on fine threads. However, a decision to use thecoating on such components may be made by the purchaser.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the us
6、er of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2B 183 Practice for Preparation of Low-Carbon Steel forElectroplatingB 242 Practice for Preparation of High-Carb
7、on Steel forElectroplatingB 246 Specification for Tinned Hard-Drawn and Medium-Hard-Drawn Copper Wire for Electrical PurposesB 252 Guide for Preparation of Zinc Alloy Die Castings forElectroplating and Conversion CoatingsB 281 Practice for Preparation of Copper and Copper-BaseAlloys for Electroplati
8、ng and Conversion CoatingsB 322 Practice for Cleaning Metals Prior to ElectroplatingB 374 Terminology Relating to ElectroplatingB 487 Test Method for Measurement of Metal and OxideCoating Thicknesses by Microscopical Examination of aCross SectionB 499 Test Method for Measurement of Coating Thick-nes
9、ses by the Magnetic Method: Nonmagnetic 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 567 Test Method for Measurement of Coating Thicknessby the Beta Back
10、scatter MethodB 568 Test Method for Measurement of Coating Thicknessby X-Ray SpectrometryB 571 Practice for Qualitative Adhesion Testing of MetallicCoatingsB 602 Test Method for Attribute Sampling of Metallic andInorganic CoatingsB 634 Specification for Electrodeposited Coatings ofRhodium for Engine
11、ering UseB 697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic Coatings2B 762 Test Method of Variables Sampling of Metallic andInorganic CoatingsB 765 Guide for Selection of Porosity and Gross DefectTests for Electrodeposits and Related Metallic Coating
12、sB 809 Test Method for Porosity in Metallic Coatings byHumid Sulfur Vapor (Flowers-of-Sulfur)B 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 EmbrittlementD 3951 Pract
13、ice for Commercial Packaging3. Terminology3.1 Definitions:3.1.1 Many terms used in this standard are defined inTerminology B 374.3.1.2 significant surfacethat portion of a coated articlessurface where the coating is required to meet all the require-ments of the coating specification for that article
14、. Significantsurfaces are those that are essential to the serviceability or1This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of SubcommitteeB08.08.04 on Soft Metals.Current edition approved April 1, 2004. Published
15、April 2004. Originallyapproved in 1975. Last previous edition approved in 1999 as B 605 95a (1999).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 Doc
16、ument Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.function of the article, or which can be a source of corrosionproducts or tarnish films that interfere with the function ordesirable appearance of
17、the article. Significant surfaces arethose surfaces that are identified by the purchaser by, forexample, indicating them on an engineering drawing of theproduct or marking a sample item of the product.3.1.3 undercoatinga metallic coating layer between thebasis metal or substrate and the topmost meta
18、llic coating. Thethickness of an undercoating is usually greater than 0.8 m.This is in contrast to strikes or flashes, whose thicknesses aregenerally lower.4. Classifications4.1 Coating GradesSix grades of coatings, designated byservice condition numbers, are covered by this specification.For each c
19、oating grade a coating thickness grade is specified(see Tables 1-3).4.2 Service Condition NumberThe service conditionnumber indicates the severity of exposure for which the gradeof coating is intended.SC5extended severe serviceSC4very severe serviceSC3severe serviceSC2moderate serviceSC1mild service
20、SC0mild service (copper and copper alloys only)NOTE 1Typical service conditions for which the service conditionnumbers are appropriate are given in Appendix X1.4.3 Coating Thickness NotationThe coating thickness isspecified for each service condition in the following manner:Basis metal/Undercoating
21、(thickness)/Sn-Ni (thickness). Forexample, Fe/Cu4/Sn-Ni25 would indicate a 25 m tin-nickelcoating over an iron or steel article with a 4-m thick copperundercoating. All thickness notations are minimum thick-nesses.5. Ordering Information5.1 To make the application of this standard complete, thepurch
22、aser needs to supply the following information to theseller in the purchase order or other government documents.5.1.1 The name, designation, and date of issue of thisstandard,5.1.2 Location of significant surface(s) (see section 3.1.2),5.1.3 The service number or coating thickness notation (see4.2 a
23、nd 4.3),5.1.4 Undercoating, if required (see 6.2 and Tables 1-3),5.1.5 Any requirement for submission of sample coatedarticles (see 7.2.1),5.1.6 Whether or not location of rack marks is to be defined(see 7.2.1),5.1.7 Any requirement for porosity testing and the criteriafor acceptance (see 7.5.2),5.1
24、.8 Heat treatment for stress relief, whether it has beenperformed by the purchaser, or is required (see 7.6),5.1.9 Heat treatment after electroplating, if required (see7.7),5.1.10 Any packaging requirement (see section 7.8),5.1.11 Inspection procedure to be used (see Section 9),5.1.12 Any requiremen
25、t for certification (see Section 11),and5.1.13 Any requirement for test specimens (see 8.1.1).6. Material and Process6.1 Composition of CoatingElectrolytes that have beeninvestigated for producing Sn-Ni alloy deposits include cya-nide, fluoborate, pyrophosphate, and acetate, but the only onein gener
26、al commercial use is the fluoride-chloride formula-tion.3The deposit contains 35 6 5 % nickel with the remaindertin (see Note 2).NOTE 2The electrodeposited tin-nickel coating is a single-phase,metastable compound, corresponding approximately to the formula SnNi.It is stable at ordinary temperatures
27、but starts to recrystallize at elevatedtemperatures. The safe working temperature of the coating is 300C,although actual melting does not commence below 800C. The coating ishard (700HV100). Like many such compounds, it is inherently somewhatbrittle, but if it is free of internal stresses, the brittl
28、eness is not sufficientto impair its serviceability or to cause the coating to flake under impact.Because of the brittleness of the tin-nickel, however, it is not possible tofabricate parts by bending coated sheet material, because the compressivestresses in the coating on the inside of the bend usu
29、ally cause some of the3Lowenheim, F. A., Electroplating, McGraw-Hill Inc., 1978.TABLE 1 Tin-Nickel Coatings on SteelServiceConditionNumberThicknessNotationMinimumThickness,m5 Fe/CuA/Sn-Ni as specifiedBas specifiedB(above 45) (above 45)4 Fe/CuA/Sn-Ni 45 453 Fe/CuA/Sn-Ni 25 252 Fe/Sn-Ni 15 151 Fe/Sn-N
30、i 8 8ACopper undercoat shall be at least 4.0 m.BThickness of Sn-Ni shall be stated in a Thickness Notation. A statement ofService Condition 5 is not sufficient.TABLE 2 Tin-Nickel Coatings on Copper or Copper AlloysServiceConditionNumberThicknessNotationMinimumThickness,m5 Cu/Sn-NiAas specifiedBas sp
31、ecifiedB(above 45) (above 45)4 Cu/Sn-NiA45 453 Cu/Sn-NiA25 252 Cu/Sn-NiA15 150 Cu/Sn-NiA44AAn undercoating of copper 4.0 m thick shall be applied on copper-zinc alloysto serve as a zinc diffusion barrier.BThickness of Sn-Ni shall be stated in a Thickness Notation. A statement ofService Condition 5 i
32、s not sufficient.TABLE 3 Tin-Nickel Coatings on Zinc AlloysServiceConditionNumberThicknessNotationMinimumThickness,m4 Zn/CuA/Sn-Ni 45 453 Zn/CuA/Sn-Ni 25 252 Zn/CuA/Sn-Ni 15 151 Zn/CuA/Sn-Ni 8 8AAn undercoating of copper 4.0 m thick shall be applied to prevent zinc fromcontaminating the Sn-Ni platin
33、g bath and to serve as a diffusion barrier.B 605 95a (2004)2coating to flake off. To provide serviceability, the coating must bedeposited in a stress-free condition. In addition, it is generally inadvisableto specify tin-nickel finish for parts subject to deformation in service.6.2 Basis MetalTin-ni
34、ckel can be deposited directly onsteel, copper, and copper-base alloys. However, an undercoat-ing of copper can improve performance in some systems andshall be used under the following conditions:6.2.1 On steel, a copper undercoating with a minimumthickness of 4 m, shall be used for Service Conditio
35、ns 3, 4,and 5.6.2.2 On copper-zinc alloys, a copper undercoating with aminimum thickness of 4 m shall be used for all serviceconditions to prevent diffusion of the zinc.6.2.3 Zinc-base alloys shall have an undercoating of aminimum of 4 m of copper to prevent diffusion of the zincinto the deposit and
36、 to prevent contamination of the electrolytewith zinc.NOTE 3Tin-nickel-coated zinc-alloy diecastings shall never be re-turned for remelting to prevent contamination of the zinc alloy with tin.7. Coating Requirements Coating Requirements7.1 Composition of CoatingThe deposit shall contain65 6 5 % tin,
37、 the balance nickel.7.2 Appearance:7.2.1 The coating on all readily visible surfaces shall besmooth, fine grained, continuous, adherent, free of visibleblisters, pits, nodules, indications of burning, excessivebuildup, staining, and other defects. All tin-nickel coatedarticles shall be clean and und
38、amaged. When necessary,preliminary samples showing the finish shall be supplied forapproval. Where a rack contact mark is unavoidable, itslocation shall be indicated on the article or its drawing.7.2.2 Defects and variations in appearance in the coatingthat arise from surface conditions of the subst
39、rate (scratches,pores, roll marks, inclusions, and the like) and that persist inthe coating despite the observance of good metal finishingpractices shall not be cause for rejection.NOTE 4Coatings generally perform better in service when the sub-strate over which they are applied is smooth and free o
40、f torn metal,inclusions, pores, and other defects. The specifications covering theunfinished product should provide limits for these defects.Ametal finishercan often remove defects through special treatments, such as grinding,polishing, abrasive blasting, chemical etches, and electropolishing. How-e
41、ver, these are not normal in the treatment steps preceding the applicationof the coating. When they are desired, they are the subject of specialagreement between the purchaser and the seller.NOTE 5Proper preparatory procedures and thorough cleaning areessential to ensure satisfactory adhesion and co
42、rrosion resistance perfor-mance of the coating. Materials used for cleaning should not damage thebasis metal, for example, by causing defects such as pits, intergranularattack, stress corrosion cracking, and unwarranted hydrogen embrittle-ment. It is recommended that the following Practices, where a
43、ppropriatefor cleaning, be used: B 183, B 242, B 252, B 281, and B 322.7.3 Thickness:7.3.1 The thickness of the coating everywhere on thesignificant surfaces shall conform to the requirements in Tables1-3 as to minimum thickness.NOTE 6The thickness of electrodeposited coatings varies from pointto po
44、int on the surface of the product. (See Practice B 507.) The thicknessis less in interior corners and holes. Such surfaces are often exempt fromthickness requirements. If the full thickness is required in those locations,the electroplater will have to use special techniques that will probablyraise t
45、he cost of the process.NOTE 7The coating thickness requirement of this specification is aminimum. Variation in the thickness from point to point on an article andfrom article to article in a production lot is inherent in electroplating.Therefore, if all of the articles in a production are to meet th
46、e thicknessrequirement, the average coating thickness for the production lot as awhole will be greater than the specified minimum.7.4 AdhesionThe coatings shall be adherent to the basismetal when subject to either test, in accordance with 8.5.2 and8.5.3. There shall be no separation of the coating f
47、rom thesubstrate.7.5 Integrity of the Coating:7.5.1 Gross Defects/Mechanical Damage The coatingsshall be free of mechanical damage, large pores, and similargross defects. For some applications this requirement may berelaxed to allow for a small number of such defects (per unitarea), especially if th
48、ey are outside the significant surfaces.7.5.2 PorosityAlmost all as-plated electrodeposits containsome porosity. The amount of porosity that may be tolerabledepends on the severity of the environment that the article islikely to encounter during service or storage. If the pores arefew in number or a
49、way from significant surfaces, their pres-ence can often be tolerated. Such acceptance (or pass-fail)criteria shall be part of the product specification for theparticular article or coating requiring the porosity test (see 8.6for porosity test methods).7.6 Pre-Treatments of Iron and Steel for Reducing the Riskof Hydrogen EmbrittlementParts that are made of steels withultimate tensile strengths of 1000 MPa (hardness of 31 HRC)or greater that have been machined, ground, cold formed, orcold straightened subsequent to heat treatment shall be heattr
