1、Designation: B605 95a (Reapproved 2015)Standard Specification forElectrodeposited Coatings of Tin-Nickel Alloy1This standard is issued under the fixed designation B605; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st 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 This specification covers the requirements for electrode-posited tin-nickel alloy coatings from aqueous solutions in-ten
3、ded 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 to
4、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 because
5、 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 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard
6、does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user 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 S
7、tandards:2B183 Practice for Preparation of Low-Carbon Steel forElectroplatingB242 Guide for Preparation of High-Carbon Steel for Elec-troplatingB246 Specification for Tinned Hard-Drawn and Medium-Hard-Drawn Copper Wire for Electrical PurposesB252 Guide for Preparation of Zinc Alloy Die Castings forE
8、lectroplating and Conversion CoatingsB281 Practice for Preparation of Copper and Copper-BaseAlloys for Electroplating and Conversion CoatingsB322 Guide for Cleaning Metals Prior to ElectroplatingB374 Terminology Relating to ElectroplatingB487 Test Method for Measurement of Metal and OxideCoating Thi
9、ckness by Microscopical Examination ofCross SectionB499 Test Method for Measurement of Coating Thicknessesby the Magnetic Method: Nonmagnetic Coatings onMagnetic Basis MetalsB504 Test Method for Measurement of Thickness of Metal-lic Coatings by the Coulometric MethodB507 Practice for Design of Artic
10、les to Be Electroplated onRacksB567 Test Method for Measurement of Coating Thicknessby the Beta Backscatter MethodB568 Test Method for Measurement of Coating Thicknessby X-Ray SpectrometryB571 Practice for Qualitative Adhesion Testing of MetallicCoatingsB602 Test Method for Attribute Sampling of Met
11、allic andInorganic CoatingsB634 Specification for Electrodeposited Coatings of Rho-dium for Engineering UseB697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic CoatingsB762 Test Method of Variables Sampling of Metallic andInorganic CoatingsB765 Guide fo
12、r Selection of Porosity and Gross Defect Testsfor Electrodeposits and Related Metallic CoatingsB809 Test Method for Porosity in Metallic Coatings byHumid Sulfur Vapor (“Flowers-of-Sulfur”)B849 Specification for Pre-Treatments of Iron or Steel forReducing Risk of Hydrogen EmbrittlementB850 Guide for
13、Post-Coating Treatments of Steel for Reduc-ing the Risk of Hydrogen EmbrittlementD3951 Practice for Commercial Packaging3. Terminology3.1 Definitions:3.1.1 Many terms used in this standard are defined inTerminology B374.1This specification is under the jurisdiction of ASTM Committee B08 onMetallic a
14、nd Inorganic Coatings and is the direct responsibility of SubcommitteeB08.06 on Soft Metals.Current edition approved March 1, 2015. Published April 2015. Originallyapproved in 1975. Last previous edition approved in 2009 as B605 95a (2009).DOI: 10.1520/B0605-95AR15.2For referenced ASTM standards, vi
15、sit the ASTM website, www.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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2
16、959. United States13.1.2 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. Significantsurfaces are those that are essential to the serviceability orfunction of the article, or which c
17、an be a source of corrosionproducts or tarnish films that interfere with the function ordesirable appearance of 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
18、 the product.3.1.3 undercoatinga metallic coating layer between thebasis metal or substrate and the topmost metallic 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 Gr
19、adesSix grades of coatings, designated byservice condition numbers, are covered by this specification.For each coating grade a coating thickness grade is specified(see Tables 1-3).4.2 Service Condition NumberThe service condition num-ber indicates the severity of exposure for which the grade ofcoati
20、ng is intended.SC5extended severe serviceSC4very severe serviceSC3severe serviceSC2moderate serviceSC1mild serviceSC0mild 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 Nota
21、tionThe coating thickness isspecified for each service condition in the following manner:Basis metal/Undercoating (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 notatio
22、ns are minimum thick-nesses.5. Ordering Information5.1 To make the application of this standard complete, thepurchaser 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 Locat
23、ion of significant surface(s) (see section 3.1.2),5.1.3 The service number or coating thickness notation (see4.2 and 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
24、to be defined(see 7.2.1),5.1.7 Any requirement for porosity testing and the criteriafor acceptance (see 7.5.2),5.1.8 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 pa
25、ckaging requirement (see section 7.8),5.1.11 Inspection procedure to be used (see Section 9),5.1.12 Any requirement 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
26、 producing Sn-Ni alloy deposits includecyanide, fluoborate, pyrophosphate, and acetate, but the onlyone in general commercial use is the fluoride-chloride formu-lation.3The deposit contains 35 6 5 % nickel with the remain-der tin (see Note 2).NOTE 2The electrodeposited tin-nickel coating is a single
27、-phase,metastable compound, corresponding approximately to the formula SnNi.It is stable at ordinary temperatures 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 is3Lowenheim, F
28、. 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-Ni 8 8ACopper undercoat shall be at
29、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 specifiedB(above 45) (above 45)4 Cu/S
30、n-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 alloys toserve as a zinc diffusion barrier.BThickness of Sn-Ni shall be stated in a Thickness Notation. A statement ofService Condition 5 is not sufficient.TABLE 3 Tin-Nickel
31、 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 plating bath and to serve as a diffusion
32、barrier.B605 95a (2015)2hard (700HV100). Like many such compounds, it is inherently somewhatbrittle, but if it is free of internal stresses, the brittleness is not sufficientto impair its serviceability or to cause the coating to flake under impact.Because of the brittleness of the tin-nickel, howev
33、er, it is not possible tofabricate parts by bending coated sheet material, because the compressivestresses in the coating on the inside of the bend usually cause some of thecoating to flake off. To provide serviceability, the coating must bedeposited in a stress-free condition. In addition, it is ge
34、nerally inadvisableto specify tin-nickel finish for parts subject to deformation in service.6.2 Basis MetalTin-nickel 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 co
35、nditions:6.2.1 On steel, a copper undercoating with a minimumthickness of 4 m, shall be used for Service Conditions 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 al
36、loys shall have an undercoating of aminimum of 4 m of copper to prevent diffusion of the zincinto the deposit and 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
37、 tin.7. Coating Requirements7.1 Composition of CoatingThe deposit shall contain65 6 5 % tin, 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, excessi
38、vebuildup, staining, and other defects. All tin-nickel coatedarticles shall be clean and undamaged. 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 Defect
39、s and variations in appearance in the coatingthat arise from surface conditions of the substrate (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 pe
40、rform better in service when thesubstrate over which they are applied is smooth and free of 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, s
41、uch as grinding,polishing, abrasive blasting, chemical etches, and electropolishing.However, these are not normal in the treatment steps preceding theapplication of the coating. When they are desired, they are the subject ofspecial agreement between the purchaser and the seller.NOTE 5Proper preparat
42、ory procedures and thorough cleaning areessential to ensure satisfactory adhesion and corrosion 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 unwa
43、rranted hydrogen embrittle-ment. It is recommended that the following Practices, where appropriatefor cleaning, be used: B183, B242, B252, B281, and B322.7.3 Thickness:7.3.1 The thickness of the coating everywhere on thesignificant surfaces shall conform to the requirements in Tables1-3 as to minimu
44、m thickness.NOTE 6The thickness of electrodeposited coatings varies from pointto point on the surface of the product. (See Practice B507.) The thicknessis less in interior corners and holes. Such surfaces are often exempt fromthickness requirements. If the full thickness is required in those locatio
45、ns,the electroplater will have to use special techniques that will probablyraise the 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
46、in electroplating.Therefore, if all of the articles in a production are to meet the 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
47、, in accordance with 8.5.2 and8.5.3. There shall be no separation of the coating from thesubstrate.7.5 Integrity of the Coating:7.5.1 Gross Defects/Mechanical DamageThe coatingsshall be free of mechanical damage, large pores, and similargross defects. For some applications this requirement may berel
48、axed to allow for a small number of such defects (per unitarea), especially if they 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 is
49、likely to encounter during service or storage. If the pores arefew in number or away 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, gro
