1、Designation: B 634 88 (Reapproved 2004)e1Standard Specification forElectrodeposited Coatings of Rhodium for Engineering Use1This standard is issued under the fixed designation B 634; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、the 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.e1NOTEKeywords were added editorially in April 2004.1. Scope1.1 This specification covers requirements for electrodep
3、os-ited coatings of rhodium used for engineering purposes.1.2 Coatings of rhodium covered by this specification areusually employed for their corrosion resistance, stable electri-cal contact resistance, wear resistance, reflectivity, and heatresistance.1.3 Appendix X1 covers some typical application
4、s forelectrodeposited rhodium.1.4 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 determine the applica-bility of regulatory limitation
5、s prior to use.2. Referenced Documents2.1 The following documents form a part of this documentto the extent referenced herein.2.2 ASTM Standards:2B 183 Practice for Preparation of Low-Carbon Steel forElectroplatingB 242 Practice for Preparation of High-Carbon Steel forElectroplatingB 252 Guide for P
6、reparation of Zinc Alloy Die Castings forElectroplating and Conversion CoatingsB 254 Practice for Preparation of and Electroplating onStainless SteelB 281 Practice for Preparation of Copper and Copper-BaseAlloys for Electroplating and Conversion CoatingsB 322 Practice for Cleaning Metals Prior to El
7、ectroplatingB 343 Practice for Preparation of Nickel for Electroplatingwith NickelB 456 Specification for Electrodeposited Coatings of Cop-per Plus Nickel Plus Chromium and Nickel Plus Chro-miumB 481 Practice for Preparation of Titanium and TitaniumAlloys for ElectroplatingB 482 Practice for Prepara
8、tion of Tungsten and TungstenAlloys for ElectroplatingB 487 Test Method for Measurement of Metal and OxideCoating Thicknesses by Microscopical Examination of aCross SectionB 507 Practice for Design of Articles to Be Electroplated onRacksB 567 Test Method for Measurement of Coating Thicknessby the Be
9、ta Backscatter 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 697 Guide for Selection of Sampling Plans for Inspectionof El
10、ectrodeposited Metallic and Inorganic CoatingsB 762 Test Method of Variables Sampling of Metallic andInorganic CoatingsE 8 Test Methods of Tension Testing of Metallic Materials2.3 Military Standards:MIL-R-46085 Rhodium Plating, Electrodeposited3QQ-N-290 Nickel Plating, Electrodeposited33. Classifica
11、tion3.1 Electrodeposited coatings of rhodium on the basis ofthickness are classified as follows:Class Minimum Thickness, m0.05 0.050.25 0.250.5 0.5112.5 2.51This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the direct responsibility of Subcom
12、mitteeB08.08.02 on Precious Metal Coatings.Current edition approved April 1, 2004. Published April 2004. Originallyapproved in 1978. Last previous edition approved in 1999 as B 634 88 (1999).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serv
13、iceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.1Copyright ASTM International, 100 Barr
14、 Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.2 6.254. Ordering Information4.1 To make application of this standard complete, thepurchaser needs to supply the following information to theseller in the purchase order or other governing document:4.1.1 Name, designation,
15、 and year of issue of this standard,4.1.2 Class including a maximum thickness, if appropriate(3.1),4.1.3 Nature of substrate, for example, high strength steel,need for stress relief, undercoats, embrittlement relief (5.1, 5.2,5.3),4.1.4 Significant surfaces (6.2),4.1.5 Appearance (6.3),4.1.6 Require
16、ments and methods of testing for one or moreof the following requirements: need for and type of testspecimens (8.1); thickness (8.2); adhesion (8.3); absence ofembrittlement (8.4); reflectivity (8.5); and undercoats (S1.4),and4.1.7 Sampling plans (Section 7) and quality assurance(S1.2).5. Process Re
17、quirements5.1 Preparatory ProceduresThe basis metal shall be sub-jected to such cleaning procedures as are necessary to ensure asurface satisfactory for subsequent electroplating. Materialsused for cleaning shall have no damaging effects on the basismetal resulting in pits, intergranular attack, str
18、ess corrosioncracking, or hydrogen embrittlement.NOTE 1For basis metal 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 482.5.2 Preplating Operations:5.2.1 Electroplating shall be applied after all basis met
19、alheat treatments and mechanical operations such as forming,machining, and joining of the article have been completed.5.2.2 Stress Relief TreatmentAll steel parts having anultimate tensile strength of 1050 MPa (approximately 35 HRC)and above and that have been machined, ground, cold formed,or cold s
20、traightened shall have heat treatment to 190 6 15Cfor a minimum of 5 h before cleaning and electroplating.5.3 Post-Plating Procedures:5.3.1 Embrittlement ReliefSteel parts having an ultimatetensile strength of 1200 MPa (approximately 38 HRC) orgreater shall be baked at 190 6 15C for a minimum of 8 h
21、within 4 h after electroplating to provide hydrogen embrittle-ment relief. Steel parts having an ultimate tensile strengthgreater than 1300 MPa (approximately 40 HRC) shall be bakedat 190 6 15C for a minimum of 23 h within 4 h afterelectroplating.6. Coating Requirements6.1 Nature of CoatingThe coati
22、ng shall be essentiallypure rhodium produced by electrodeposition from aqueouselectrolytes.6.2 ThicknessThe rhodium coating thickness on all sig-nificant surfaces shall conform to the requirements of thespecified class as defined in Section 3.6.3 Significant SurfacesSignificant surfaces are defined
23、asthose normally visible (directly or by reflection) or are essentialto the serviceability or function of the article or which can bethe source of corrosion products or tarnish films that interferewith the function or desirable appearance of the article. Whennecessary, the significant surfaces shall
24、 be indicated on thedrawings of the parts, or by the provision of suitably markedsamples.NOTE 2Variation in the coating thickness from point-to-point on acoated article is an inherent characteristic of electroplating processes.Therefore, the coating thickness will have to exceed the specified value
25、atsome points on the significant surfaces to ensure that the thickness equalsor exceeds the specified value at all points. Therefore, the average coatingthickness on an article will usually be greater than the specified value; howmuch greater is largely determined by the shape of the article (see Pr
26、acticeB 507) and the characteristics of the electroplating process. Additionally,the average coating thickness on an article will vary from article to articlewithin a production lot. If all of the articles in a production lot are to meetthe thickness requirement, the average coating thickness of the
27、 productionlot as a whole will be greater than the average necessary to ensure that asingle article meets the requirements.6.4 Appearance:6.4.1 Electroplated coatings shall completely cover all sur-faces as specified in the manufacturing document and shallhave a uniform appearance to the extent that
28、 the nature of thebasis metal and good commercial practices permit.6.4.2 Defects in the surface of the basis metal such asscratches, pits, nonconducting inclusions, and roll and diemarks, may adversely affect the appearance and performanceof the applied coatings. Such defects that persist in the fin
29、ishdespite the observance of good metal finishing practices shallnot be cause for rejection.NOTE 3Applied finishes generally perform better in service when thesubstrate over which they are applied is smooth and free from torn metal,inclusions, pores, and other defects. It is recommended that the spe
30、cifi-cations covering the unfinished product provide limits for those defects. Ametal finisher often can remove defects through special treatments such asgrinding, polishing, abrasive blasting, chemical treatments, and elec-tropolishing. However, these are not normal in the treatment stepspreceding
31、the application of the finish. When they are desired, they are thesubject of special agreement between the purchaser and the supplier.6.5 AdhesionThe rhodium coatings shall be free of blis-ters and peeled areas when tested in accordance with 8.3.7. Sampling7.1 A random sample of the size required by
32、 Test MethodsB 602 or B 762 shall be selected from the inspection lot (see7.2). The articles in the lot shall be inspected for conformanceto the requirements of this specification and the lot shall beclassified as conforming or nonconforming to each requirementaccording to the criteria of the sampli
33、ng plans in Test MethodB 602.NOTE 4Test Method B 602 contains four sampling plans, three foruse with nondestructive test methods. The fourth is to be used withdestructive test methods. The three methods for nondestructive tests differin the quality level they require of the product. Test Method B 60
34、2requires use of the plan with the intermediate quality level unless thepurchaser specifies otherwise. It is recommended that the purchasercompare the plans with his needs and state which plan is to be used. If theplans in Test Method B 602 do not serve the needs, additional ones areB 634 88 (2004)e
35、12given in Guide B 697 which provides a large number of plans and alsogives guidance in the selection of a plan. When Guide B 697 is specified,the buyer and seller need to agree on the plan to be used.NOTE 5Test Method B 762 is a variables sampling plan. Such planscan only be used when a test yields
36、 a measured quantity, such as thickness,and when the requirements are stated as a numerical limit also such asthickness. Test Method B 762 contains several plans and gives instructionsfor calculating plans for special needs. Buyer and seller may agree on theplan or plans to be used; if not Test Meth
37、od B 762 identifies the plan to beused.NOTE 6When both destructive and nondestructive tests exist for themeasurement of a characteristic, the purchaser needs to state which is tobe used so that the proper sampling plan is selected. Whether or not a testis destructive may not always be clear. A test
38、may destroy the coating butin a noncritical area. The purchaser needs to state whether the test is to beconsidered destructive or nondestructive. The decision is importantbecause the plans for destructive tests are significantly less able todiscriminate between acceptable and unacceptable lots. This
39、 is becausefewer parts are tested.7.2 An inspection lot shall be defined as a collection ofcoated articles that are of the same kind, that have beenproduced to the same specifications, that have been coated bya single supplier at one time or at approximately the same timeunder essentially identical
40、conditions, and that are submittedfor acceptance or rejection as a group.7.3 If special test specimens are used to represent the coatedarticles in a test, the specimens shall be of the nature, size, andnumber, and shall be processed as required in accordance with8.1.8. Test Methods8.1 Special Test S
41、pecimens:8.1.1 Special test specimens are used to represent the coatedarticles in a test if the articles are of a size, shape, or materialthat is not suitable for the test, or if it is preferred not to submitarticles to a destructive test because, for example, the articlesare expensive or few in num
42、ber. The permission or therequirement to use special test specimens, their number, thematerial from which they are to be made, and their shape andsize shall be stated by the purchaser.8.1.2 The special test specimen shall duplicate those char-acteristics of the article that influence the property be
43、ing tested,and it shall be processed with the article through those processsteps that influence the property.8.1.2.1 The special test specimens used to represent anarticle in an adhesion, corrosion resistance, or appearance testshall be made of the same material, shall be in the samemetallurgical co
44、ndition, and shall have the same surfacecondition as the articles they represent; they shall be placed inthe production lot of and be processed along with the articlesthey represent.8.1.2.2 Special test specimens used to represent an article ina coating thickness test shall be introduced into the pr
45、ocess atthe point where the coating or coatings are applied and shall becarried through all steps that have a bearing on the coatingthickness.NOTE 7When special test specimens are used to represent a coatedarticle in a thickness test, the specimens will not necessarily have the samethickness and thi
46、ckness distribution as the article unless the specimens andthe article are of the same general size and shape. Therefore, before coatedarticles may be accepted on the basis of a thickness test performed on testspecimens, the relationship between the thickness on special test speci-mens and the thick
47、ness on the part needs to be established. The criterionof acceptance is that thickness on the specimen that corresponds to therequired thickness on the article.8.2 Thickness:8.2.1 The coating thickness shall be measured at locationson the significant surfaces where it would be expected to be aminimu
48、m.8.2.2 Use Test Method B 567 for beta backscatter or TestMethod B 568 for X-ray fluorescence (as applicable) fornondestructive methods.8.2.3 Rhodium thickness can be measured destructively byMethod B 487 for microscopical cross sectioning. This methodshall not be used for thicknesses less than 2.5
49、m.8.3 AdhesionDetermine adhesion in accordance with oneof the procedures given in Practice B 571, Bend Tests and HeatQuench Test.8.4 Hydrogen Embrittlement Relief:8.4.1 Steel products that are required by 5.3 to be heattreated to remove hydrogen embrittlement shall be subjectedfor 200 6 8 h to a sustained tensile load equal to 75 6 2%ofthe ultimate tensile notch strength of the material. If theproduct fractures during the test or is found, when examinedafter the test, to have cracks, it does not conform to therequirement for hydrogen embrittlement relief.8.4.2 Se
