1、Designation: B 635 00 (Reapproved 2004)e1Standard Specification forCoatings of Cadmium-Tin Mechanically Deposited1This standard is issued under the fixed designation B 635; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f 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.e1NOTEUpdated warning note in 7.2 and added keywords editorially in August 2004.1. Scope1.1 This specification covers the requi
3、rements for a coatingthat is a mixture of cadmium and tin mechanically deposited onmetal products. The coating is provided in various thicknessesup to and including 12 m.1.2 Mechanical deposition greatly reduces the risk of hy-drogen embrittlement and is suitable for coating bores andrecesses in man
4、y parts that cannot be conveniently platedelectrolytically. (See Appendix X1.)1.3 This standard 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 deter
5、mine the applica-bility of regulatory limitations prior to use. For specific hazardsstatements, see Section 7.2. Referenced Documents2.1 ASTM Standards:2B 117 Practice for Operating Salt Spray (Fog) ApparatusB 183 Practice for Preparation of Low-Carbon Steel forElectroplatingB 201 Practice for Testi
6、ng Chromate Coatings on Zinc andCadmium SurfacesB 242 Guide for Preparation of High-Carbon Steel forElectroplatingB 322 Guide for Cleaning Metals Prior to ElectroplatingB 487 Test Method for Measurement of Metal and OxideCoating Thicknesses by Microscopical Examination of aCross SectionB 499 Test Me
7、thod for Measurement of Coating Thick-nesses by the Magnetic Method: Nonmagnetic Coatings onMagnetic Basis MetalsB 567 Test Method for Measurement of Coating Thicknessby the Beta Backscatter MethodB 571 Practice for Adhesion of Metallic CoatingsB 602 Test Method for Attribute Sampling of Metallic an
8、dInorganic CoatingsB 697 Guide for Selection of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic CoatingsB 762 Test Method of Variables Sampling of Metallic andInorganic CoatingsE 87 Methods for Chemical Analysis of Lead, Tin, Anti-mony, and Their Alloys (Photometric Methods)3
9、E 396 Test Methods for Chemical Analysis of CadmiumF 1470 Guide for Fastener Sampling for Specified Mechani-cal Properties and Performance Inspection2.2 U.S. Federal Standard:FED-STD-141 Paint, Varnish, Lacquer, and Related Mate-rials; Methods of Inspection, Sampling and Testing42.3 U.S. Military St
10、andard:MIL-L-7808J Lubricating Oil, Aircraft Turbine Engine,Synthetic Base43. Classification3.1 ClassesCadmium-tin coatings are classified on thebasis of thickness, as follows:Class Minimum Thickness, m12 1288553.2 TypesCadmium-tin coatings are identified by types onthe basis of supplementary treatm
11、ent required, as follows:3.2.1 Type IAs coated, without supplementary chromatetreatment (see X1.1).3.2.2 Type IIWith supplementary chromate treatment (seeX1.2).1This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of Su
12、bcommitteeB08.08.04 on Soft Metals.Current edition approved Aug. 1, 2004. Published August 2004. Originallyapproved in 1978. Last previous edition approved in 2000 as B 635 00.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. Fo
13、r Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.4Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.1Copyright ASTM International, 100 Barr Har
14、bor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Ordering Information4.1 To make the application of this specification complete,the purchaser needs to supply the following information to thesupplier in the purchase order or other governing document:4.1.1 Class, including a
15、maximum thickness, if appropriate,type, and need for supplemental lubricant (3.1, 3.2, and5.2.4.2).4.1.2 Nature of substrate, for example, high-strength steel,need for stress-relief, and cleaning precautions to be followed(5.2.2).4.1.3 Significant surfaces (5.3).4.1.4 Requirements and methods of tes
16、ting for one or moreof the following requirements: need for and type of testspecimens (8.1), composition (8.2), thickness (8.4), adhesion(8.6), and absence of hydrogen embrittlement and the waitingperiod prior to testing and testing loads (8.8) and lubricatingresistance (S2).4.1.5 Sampling plan for
17、each inspection criterion and re-sponsibility for inspection, if necessary (Section 6 and Supple-mentary Requirement S1).4.1.6 Requirements for certified report of test results (Sec-tion 10).5. Requirements5.1 Nature of FinishThe coating shall be 45 to 75 mass %cadmium, the remainder tin.5.2 Process
18、:5.2.1 Stress Relief TreatmentAll steel parts that haveultimate tensile strength of 1000 MPa and above and thatcontain tensile stresses caused by machining, grinding,straightening, or cold forming operation shall be given a stressrelief heat treatment prior to cleaning and metal deposition.The tempe
19、rature and time at temperature shall be 190 6 15Cfor a minimum of3hsothat maximum stress relief is obtainedwithout reducing the hardness below the specified minimum.5.2.2 High-strength steels that have heavy oxide or scaleshall be cleaned before application of the coating in accordancewith Guide B 2
20、42. In general, non-electrolytic alkaline, anodic-alkaline, and some inhibited acid cleaners are preferred toavoid the risk of producing hydrogen embrittlement from thecleaning procedure.5.2.3 For preparation of low-carbon steels, see PracticeB 183. For cleaning, useful guidelines are also given in
21、GuideB 322.5.2.4 Supplementary Treatments:5.2.4.1 Chromate treatment for Type II shall be done in asolution containing hexavalent chromium. This solution shallproduce a bright or semi-bright continuous, smooth, protectivefilm. This film may have a slight yellowish or iridescent color.The absence of
22、color shall not be considered evidence of theabsence of a Type II film or as a basis for rejection of the parts.Only post treatments that contain salts that yield films contain-ing hexavalent chromium are permitted as treatments forproducing Type II coatings.5.2.4.2 Waxes, lacquers, or other organic
23、 coatings may beused to improve lubricity, and the need for them should besupplied in the purchase order or other governing document(4.1.1). Such supplemental lubrication treatments shall not beused to ensure conformance to the salt spray corrosion resistantrequirements or to enhance the test result
24、s of the lead acetatespot test (8.5.2).5.3 Thickness:5.3.1 The thickness of the coating everywhere on thesignificant surfaces shall be at least that of the specified classas defined in 3.1.5.3.2 Significant surfaces are defined as those normallyvisible (directly or by reflection) that are essential
25、to theappearance or serviceability of the article when assembled innormal position; or which can be the source of corrosionproducts that deface visible surfaces on the assembled article.When necessary, the significant surfaces shall be indicated onthe drawing of the article, or by the provision of s
26、uitablymarked samples.NOTE 1The thickness of mechanically-deposited coatings varies frompoint-to-point on the surface of a product, characteristically tending to bethicker on flat surfaces and thinner at exposed edges, sharp projections,shielded or recessed areas, interior corners and holes, with su
27、ch thinnerareas often being exempted from thickness requirement.5.3.3 When significant surfaces are involved on which thespecified thickness of deposit cannot readily be controlled, thepurchaser and manufacturer should recognize the necessity foreither thicker or thinner deposits. For example, to re
28、ducebuildup in thread roots, holes, deep recesses, bases of angles,and similar areas, the deposit thickness on the more accessiblesurfaces will have to be reduced proportionately.NOTE 2The coating thickness requirement of this specification is aminimum requirement; that is, the coating thickness is
29、required to equal orexceed the specified thickness everywhere on the significant surfaces.Variation in the coating thickness from point to point on a coated articleis an inherent characteristic of mechanical deposition processes. There-fore, the coating thickness will have to exceed the specified va
30、lue at somepoints on the significant surfaces to ensure that the thickness equals orexceeds the specified value at all points. Thus, in most cases, the averagecoating thickness on an article will be greater than the specified value;how much greater is largely determined by the shape of the article a
31、nd thecharacteristics of the deposition process. In addition, the average coatingthickness on articles will vary from article to article within a productionlot. Therefore, if all of the articles in a production lot are to meet thethickness requirement, the average coating thickness for the productio
32、n lotas a whole will be greater than the average necessary to ensure that asingle article meets the requirement.5.4 AdhesionThe cadmium-tin coating shall be suffi-ciently adherent to the basis metal to pass the tests specified in8.6.5.5 Corrosion Resistance:5.5.1 The presence of corrosion products v
33、isible to theunaided eye at normal reading distance at the end of thespecified test period as stated in Table 1 shall constitute failure,except that corrosion products at the edges of specimens shallnot constitute failure. Slight “wisps” of white corrosion, asopposed to obvious accumulations, shall
34、be acceptable.NOTE 3The hours given in Table 1 are the minimums required toguarantee satisfactory performance. Longer periods before the appearanceof white corrosion products and rust are possible, but salt spray resistancedoes not vary in exact proportion with increased plating thickness. Thehours
35、given for Type II reflect the added protection of chromate treatmentswithout requiring impractical testing periods.B 635 00 (2004)e125.5.2 There are no requirements for corrosion of base metalsother than steels.NOTE 4Mechanical deposition is exclusively a barrel-finishing pro-cess. It is recognized
36、that mechanical deposition on parts may thereforeproduce surfaces which have a different characteristic from those on partswhich are finished exclusively by racking. Similarly, corrosion testing ofactual parts may produce different results from those on test panels. Saltspray requirements that are a
37、ppropriate to indicate the technical qualitywith which a process is carried out may be impractical for acceptance ofactual parts. In such cases the purchaser should indicate his requirementson the purchase order (see 4.1.4).NOTE 5In many instances, there is no direct relation between theresults of a
38、n accelerated corrosion test and the resistance to corrosion inother media, because several factors that influence the progress ofcorrosion, such as the formation of protective films, vary greatly with theconditions encountered. The results obtained in the test should not,therefore, be regarded as a
39、 direct guide to the corrosion resistance of thetested materials in all environments where these materials may be used.Also, performance of different materials in the test cannot always be takenas a direct guide to the relative corrosion resistance of these materials inservice.5.6 Absence of Hydroge
40、n Embrittlement Steel springs andother high-strength steel parts subject to flexure shall be heldfor a minimum of 48 h at room temperature after coating,before being loaded, flexed, or used. Such parts shall be freefrom hydrogen embrittlement. When specified in the purchaseorder, freedom from embrit
41、tlement shall be determined by thetest specified herein (see 4.1.4 and 8.8).5.7 WorkmanshipThe coating shall be uniform in appear-ance and substantially free of blisters, pits, nodules, flaking andother defects that can adversely affect the function of thecoating. The coating shall cover all surface
42、s as stated in 5.3,including thread roots, thread peaks, corners, recesses, andedges. The coating shall not be stained or discolored through-out to an extent that would adversely affect appearance as afunctional requirement. However, superficial staining that re-sults from rinsing or drying, and var
43、iations in color or lustershall not be cause for rejection.NOTE 6The nature of the mechanical plating process is such thatcoatings characteristically will not be as smooth or as bright as someelectroplated coatings.5.8 Surface DefectsDefects and variations in appearancein the coating that arise from
44、 surface conditions of the substrate(scratches, pores, roll marks, inclusions, etc.) and that persist inthe finish despite the observance of good metal finishingpractices shall not be cause for rejection.NOTE 7Applied finishes generally perform better in service when thesubstrate over which they are
45、 applied is smooth and free of torn metal,inclusions, pores, and other defects. It is recommended that the specifi-cations covering the unfinished product provide limits for these defects. Ametal finisher can often remove defects through special treatments, suchas grinding, polishing, abrasive blast
46、ing, chemical treatments, and elec-tropolishing. However, these are not normal in the treatment stepspreceding the application of the finish. When desired, they must bespecified on the purchase order (see 4.1.2).6. Sampling6.1 The purchaser and producer are urged to employ statis-tical process contr
47、ol in the coating process. Properly per-formed, statistical process control will assure coated productsof satisfactory quality and will reduce the amount of accep-tance inspection. The sampling plan used for the inspection ofthe quality coated article shall be agreed upon between thepurchaser and pr
48、oducer.6.1.1 When a collection of coated articles (inspection lot,see 6.2) 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 complying with the requ
49、irements 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 B 602, Guide B 697, and Test MethodB 762 contain sampling plans that are designed for samplinginspection of coatings.6.1.2 Test Method B 602 contains four sampling plans, threefor use with tests that are nondestructive and one when they aredestructive. Test Method B 602 provides a default plan if oneis not specified.6.1.3 Guide B 697 provides a
