1、Designation: B634 88 (Reapproved 2009)Standard Specification forElectrodeposited Coatings of Rhodium for Engineering Use1This standard is issued under the fixed designation B634; 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers requirements for electrodepos-ited coatings of rhodium used for engineering purposes
3、.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 applications forelectrodeposited rhodium.1.4 The values stated in SI
4、 units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 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
5、practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 The following documents form a part of this documentto the extent referenced herein.2.2 ASTM Standards:2B183 Practice for Preparation of Low-Carbon Steel forElectroplatingB242 Guide for Prepa
6、ration of High-Carbon Steel for Elec-troplatingB252 Guide for Preparation of Zinc Alloy Die Castings forElectroplating and Conversion CoatingsB254 Practice for Preparation of and Electroplating onStainless SteelB281 Practice for Preparation of Copper and Copper-BaseAlloys for Electroplating and Conv
7、ersion CoatingsB322 Guide for Cleaning Metals Prior to ElectroplatingB343 Practice for Preparation of Nickel for Electroplatingwith NickelB456 Specification for Electrodeposited Coatings of Cop-per Plus Nickel Plus Chromium and Nickel Plus Chro-miumB481 Practice for Preparation of Titanium and Titan
8、iumAlloys for ElectroplatingB482 Practice for Preparation of Tungsten and TungstenAlloys for ElectroplatingB487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination of CrossSectionB507 Practice for Design of Articles to Be Electroplated onRacksB567 Test Method
9、 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 Metallic andInorganic CoatingsB697 Guide for Selec
10、tion of Sampling Plans for Inspectionof Electrodeposited Metallic and Inorganic CoatingsB762 Test Method of Variables Sampling of Metallic andInorganic CoatingsE8 Test Methods for Tension Testing of Metallic Materials2.3 Military Standards:MIL-R-46085 Rhodium Plating, Electrodeposited3QQ-N-290 Nicke
11、l Plating, Electrodeposited33. Classification3.1 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 on and isthe direct responsibility
12、of Subcommittee B08.08.02 on Precious Metal Coatings.Current edition approved Sept. 1, 2009. Published November 2009. Originallyapproved in 1978. Last previous edition approved in 2004 as B634 88 (2004)1.DOI: 10.1520/B0634-88R09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, o
13、rcontact ASTM Customer Service at serviceastm.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.1
14、Copyright ASTM International, 100 Barr 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 gover
15、ning document:4.1.1 Name, designation, 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
16、),4.1.5 Appearance (6.3),4.1.6 Requirements 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
17、 quality assurance(S1.2).5. Process Requirements5.1 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 result
18、ing in pits, intergranular attack, stress corrosioncracking, or hydrogen embrittlement.NOTE 1For basis metal preparations, the following appropriateASTM standards are recommended: Practices B183, B242, B252, B254,B281, B322, B343, B481, and B482.5.2 Preplating Operations:5.2.1 Electroplating shall b
19、e applied after all basis metalheat 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,
20、ground, cold formed,or cold straightened 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 1
21、90 6 15C for a minimum of 8 hwithin 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
22、.1 Nature of CoatingThe coating 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 SurfacesSign
23、ificant surfaces are defined 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, t
24、he significant surfaces shall 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 t
25、o exceed the specified value 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
26、 shape of the article (see PracticeB507) 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 aver
27、age coating thickness of the 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 a
28、ppearance to the extent that 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 def
29、ects that persist in the finishdespite 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
30、 is recommended that the specifi-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 t
31、he treatment stepspreceding 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 sa
32、mple of the size required by Test MethodsB602 or B762 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
33、the criteria of the sampling plans in Test MethodB602.NOTE 4Test Method B602 contains four sampling plans, three for usewith nondestructive test methods. The fourth is to be used with destructivetest methods. The three methods for nondestructive tests differ in thequality level they require of the p
34、roduct. Test Method B602 requires useof the plan with the intermediate quality level unless the purchaserspecifies otherwise. It is recommended that the purchaser compare theplans with his needs and state which plan is to be used. If the plans in TestMethod B602 do not serve the needs, additional on
35、es are given in GuideB634 88 (2009)2B697 which provides a large number of plans and also gives guidance inthe selection of a plan. When Guide B697 is specified, the buyer and sellerneed to agree on the plan to be used.NOTE 5Test Method B762 is a variables sampling plan. Such planscan only be used wh
36、en a test yields a measured quantity, such as thickness,and when the requirements are stated as a numerical limit also such asthickness. Test Method B762 contains several plans and gives instructionsfor calculating plans for special needs. Buyer and seller may agree on theplan or plans to be used; i
37、f not Test Method B762 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
38、clear. A test 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 unaccepta
39、ble lots. This 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 essentia
40、lly identical 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
41、Special Test Specimens: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
42、 or few in number. 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 t
43、he property being 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 sameme
44、tallurgical condition, 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 introduc
45、ed into the process 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 samethi
46、ckness and thickness 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
47、 and the thickness 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
48、 to be aminimum.8.2.2 Use Test Method B567 for beta backscatter or TestMethod B568 for X-ray fluorescence (as applicable) fornondestructive methods.8.2.3 Rhodium thickness can be measured destructively byMethod B487 for microscopical cross sectioning. This methodshall not be used for thicknesses les
49、s than 2.5 m.8.3 AdhesionDetermine adhesion in accordance with oneof the procedures given in Practice B571, 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 reli
