ASTM B634-14a(2021)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B634 −14a (Reapproved 2021)
Standard Specification for
Electrodeposited Coatings of Rhodium for Engineering Use
This standard is issued under the fixed designation B634; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope B242 Guide for Preparation of High-Carbon Steel for Elec-
troplating
1.1 This specification covers requirements for electrodepos-
B252 Guide for Preparation of Zinc Alloy Die Castings for
ited coatings of rhodium used for engineering purposes.
Electroplating and Conversion Coatings
1.2 Coatings of rhodium covered by this specification are
B254 Practice for Preparation of and Electroplating on
usually employed for their corrosion resistance, stable electri-
Stainless Steel
cal contact resistance, wear resistance, reflectivity, and heat
B281 Practice for Preparation of Copper and Copper-Base
resistance.
Alloys for Electroplating and Conversion Coatings
1.3 Appendix X1 covers some typical applications for B322 Guide for Cleaning Metals Prior to Electroplating
B343 Practice for Preparation of Nickel for Electroplating
electrodeposited rhodium.
with Nickel
1.4 The values stated in SI units are to be regarded as
B456 Specification for Electrodeposited Coatings of Copper
standard. No other units of measurement are included in this
Plus Nickel Plus Chromium and Nickel Plus Chromium
standard.
B481 Practice for Preparation of Titanium and Titanium
1.5 This standard does not purport to address all of the
Alloys for Electroplating
safety concerns, if any, associated with its use. It is the
B482 Practice for Preparation of Tungsten and Tungsten
responsibility of the user of this standard to establish appro-
Alloys for Electroplating
priate safety, health, and environmental practices and deter-
B487 Test Method for Measurement of Metal and Oxide
mine the applicability of regulatory limitations prior to use.
Coating Thickness by Microscopical Examination of
1.6 This international standard was developed in accor-
Cross Section
dance with internationally recognized principles on standard-
B507 Practice for Design of Articles to Be Electroplated on
ization established in the Decision on Principles for the
Racks
Development of International Standards, Guides and Recom-
B567 Test Method for Measurement of Coating Thickness
mendations issued by the World Trade Organization Technical
by the Beta Backscatter Method
Barriers to Trade (TBT) Committee.
B568 Test Method for Measurement of Coating Thickness
by X-Ray Spectrometry
2. Referenced Documents
B571 Practice for Qualitative Adhesion Testing of Metallic
2.1 The following documents form a part of this document
Coatings
to the extent referenced herein.
B602 Test Method for Attribute Sampling of Metallic and
Inorganic Coatings
2.2 ASTM Standards:
B697 Guide for Selection of Sampling Plans for Inspection
B183 Practice for Preparation of Low-Carbon Steel for
of Electrodeposited Metallic and Inorganic Coatings
Electroplating
B762 Test Method of Variables Sampling of Metallic and
Inorganic Coatings
This specification is under the jurisdiction of ASTM Committee B08 on
E8 Test Methods for Tension Testing of Metallic Materials
Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee
[Metric] E0008_E0008M
B08.04 on Precious Metal Coatings.
2.3 Military Standards:
Current edition approved Oct. 1, 2021. Published October 2021. Originally
approved in 1978. Last previous edition approved in 2014 as B634 – 14a. DOI:
MIL-R-46085 Rhodium Plating, Electrodeposited
10.1520/B0634-14AR21. 3
QQ-N-290 Nickel Plating, Electrodeposited
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on AvailablefromStandardizationDocumentsOrderDesk,Bldg.4SectionD,700
the ASTM website. Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B634 − 14a (2021)
3. Classification greaterthan1300MPa(approximately40HRC)shallbebaked
at 190 6 15°C for a minimum of 23 h within 4 h after
3.1 Electrodeposited coatings of rhodium on the basis of
electroplating.
thickness are classified as follows:
Class Minimum Thickness, µm
6. Coating Requirements
0.05 0.05
0.25 0.25
6.1 Nature of Coating—Thecoatingshallbeessentiallypure
0.5 0.5
rhodium produced by electrodeposition from aqueous electro-
lytes.
2.5 2.5
6.25 6.25
6.2 Thickness—The rhodium coating thickness on all sig-
NOTE 1—Previous revisions of B634 included Class 6.2. Any require-
nificant surfaces shall conform to the requirements of the
ments for B634 Class 6.2 shall be required to meet the same requirements
specified class as defined in Section 3.
now within Class 6.25.
6.3 Significant Surfaces—Significant surfaces are defined as
4. Ordering Information
thosenormallyvisible(directlyorbyreflection)orareessential
to the serviceability or function of the article or which can be
4.1 To make application of this standard complete, the
the source of corrosion products or tarnish films that interfere
purchaser needs to supply the following information to the
with the function or desirable appearance of the article. When
seller in the purchase order or other governing document:
necessary, the significant surfaces shall be indicated on the
4.1.1 Name, designation, and year of issue of this standard,
drawings of the parts, or by the provision of suitably marked
4.1.2 Class including a maximum thickness, if appropriate
samples.
(3.1),
4.1.3 Nature of substrate, for example, high strength steel,
NOTE 3—Variation in the coating thickness from point-to-point on a
need for stress relief, undercoats, embrittlement relief (5.1, 5.2,
coated article is an inherent characteristic of electroplating processes.
Therefore, the coating thickness will have to exceed the specified value at
5.3),
some points on the significant surfaces to ensure that the thickness equals
4.1.4 Significant surfaces (6.2),
or exceeds the specified value at all points. Therefore, the average coating
4.1.5 Appearance (6.3),
thicknessonanarticlewillusuallybegreaterthanthespecifiedvalue;how
4.1.6 Requirements and methods of testing for one or more
muchgreaterislargelydeterminedbytheshapeofthearticle(seePractice
of the following requirements: need for and type of test B507) and the characteristics of the electroplating process. Additionally,
the average coating thickness on an article will vary from article to article
specimens (8.1); thickness (8.2); adhesion (8.3); absence of
within a production lot. If all of the articles in a production lot are to meet
embrittlement (8.4); reflectivity (8.5); and undercoats (S1.4),
the thickness requirement, the average coating thickness of the production
and
lot as a whole will be greater than the average necessary to ensure that a
4.1.7 Sampling plans (Section 7) and quality assurance
single article meets the requirements.
(S1.2).
6.4 Appearance:
6.4.1 Electroplated coatings shall completely cover all sur-
5. Process Requirements
faces as specified in the manufacturing document and shall
5.1 Preparatory Procedures—The basis metal shall be sub-
have a uniform appearance to the extent that the nature of the
jected to such cleaning procedures as are necessary to ensure a
basis metal and good commercial practices permit.
surface satisfactory for subsequent electroplating. Materials
6.4.2 Defects in the surface of the basis metal such as
used for cleaning shall have no damaging effects on the basis
scratches, pits, nonconducting inclusions, and roll and die
metal resulting in pits, intergranular attack, stress corrosion
marks, may adversely affect the appearance and performance
cracking, or hydrogen embrittlement.
of the applied coatings. Such defects that persist in the finish
despite the observance of good metal finishing practices shall
NOTE2—Forbasismetalpreparations,thefollowingappropriateASTM
standards are recommended: Practices B183, B242, B252, B254, B281, not be cause for rejection.
B322, B343, B481, and B482.
NOTE 4—Applied finishes generally perform better in service when the
5.2 Preplating Operations:
substrate over which they are applied is smooth and free from torn metal,
5.2.1 Electroplating shall be applied after all basis metal inclusions, pores, and other defects. It is recommended that the specifi-
cations covering the unfinished product provide limits for those defects.A
heat treatments and mechanical operations such as forming,
metal finisher often can remove defects through special treatments such as
machining, and joining of the article have been completed.
grinding, polishing, abrasive blasting, chemical treatments, and electro-
5.2.2 Stress Relief Treatment—All steel parts having an
polishing. However, these are not normal in the treatment steps preceding
ultimatetensilestrengthof1050MPa(approximately35HRC)
the application of the finish.When they are desired, they are the subject of
and above and that have been machined, ground, cold formed, special agreement between the purchaser and the supplier.
or cold straightened shall have heat treatment to 190 6 15°C
6.5 Adhesion—The rhodium coatings shall be free of blis-
for a minimum of 5 h before cleaning and electroplating.
ters and peeled areas when tested in accordance with 8.3.
5.3 Post-Plating Procedures:
7. Sampling
5.3.1 Embrittlement Relief—Steel parts having an ultimate
tensile strength of 1200 MPa (approximately 38 HRC) or 7.1 A random sample of the size required by Test Methods
greater shall be baked at 190 6 15°C for a minimum of 8 h B602 or B762 shall be selected from the inspection lot (see
within 4 h after electroplating to provide hydrogen embrittle- 7.2). The articles in the lot shall be inspected for conformance
ment relief. Steel parts having an ultimate tensile strength to the requirements of this specification and the lot shall be
B634 − 14a (2021)
...