1、Designation: B634 14Standard 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 year of last revis
2、ion. 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.1.2 Coatings of r
3、hodium 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 units are to be r
4、egarded 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 practices and dete
5、rmine 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 Preparation of High-Car
6、bon 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 Conversion CoatingsB32
7、2 Guide for Cleaning Metals Prior to ElectroplatingB343 Practice for Preparation of Nickel for Electroplatingwith NickelB456 Specification for Electrodeposited Coatings of CopperPlus Nickel Plus Chromium and Nickel Plus ChromiumB481 Practice for Preparation of Titanium and TitaniumAlloys for Electro
8、platingB482 Practice for Preparation of Tungsten and TungstenAlloys for ElectroplatingB487 Test Method for Measurement of Metal and OxideCoating Thickness by Microscopical Examination ofCross SectionB507 Practice for Design of Articles to Be Electroplated onRacksB567 Test Method for Measurement of C
9、oating 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 Selection of Sampling Plan
10、s 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 Nickel Plating, Electrodep
11、osited33. 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 2.56.25 6.251This specification is under the jurisdiction of ASTM Committee B08 onMetallic and Inorganic Coatings and is the di
12、rect responsibility of SubcommitteeB08.04 on Precious Metal Coatings.Current edition approved Sept. 1, 2014. Published September 2014. Originallyapproved in 1978. Last previous edition approved in 2009 as B634 88 (2009).DOI: 10.1520/B0634-14.2For referenced ASTM standards, visit the ASTM website, ww
13、w.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.3Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094,
14、Attn: NPODS.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. 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 g
15、overning 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
16、(6.2),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)
17、 and 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 re
18、sulting in pits, intergranular attack, stress corrosioncracking, or hydrogen embrittlement.NOTE 1For basis metal preparations, the following appropriateASTMstandards are recommended: Practices B183, B242, B252, B254, B281,B322, B343, B481, and B482.5.2 Preplating Operations:5.2.1 Electroplating shal
19、l be 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 machine
20、d, 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 a
21、t 190 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 Requiremen
22、ts6.1 Nature of CoatingThe coating shall be essentially purerhodium produced by electrodeposition from aqueous electro-lytes.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 Surface
23、sSignificant 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. Whennecessa
24、ry, the 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 h
25、ave to 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 b
26、y the 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
27、 average 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 unif
28、orm appearance 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. Suc
29、h defects 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 defect
30、s. It 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 electrop-olishing. However, these are not normal
31、 in the treatment steps precedingthe application of the finish. When they are desired, they are the subject ofspecial 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 rand
32、om sample 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 requirementaccordin
33、g to 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
34、the product. 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, addition
35、al ones are given in GuideB697 which provides a large number of plans and also gives guidance inthe selection of a plan. When Guide B697 is specified, the buyer and sellerB634 142need to agree on the plan to be used.NOTE 5Test Method B762 is a variables sampling plan. Such planscan only be used when
36、 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; if
37、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 cl
38、ear. 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 unacceptabl
39、e 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 essentiall
40、y 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 Sp
41、ecial 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 o
42、r 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 the
43、 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 samemeta
44、llurgical 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 introduced
45、 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 samethick
46、ness 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 a
47、nd 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 t
48、o 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 less
49、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 relief.
