Standard Specification for Electrodeposited Coatings of Rhodium for Engineering Use

ABSTRACT
This specification covers the requirements for electrodeposited rhodium coatings for engineering applications, usually employed for their corrosion resistance, stable electrical contact resistance, wear resistance, reflectivity, and heat resistance. Coating shall be classified based on their thickness. Specimens shall undergo preparatory preplating procedures such as surface cleaning and stress relief treatment, as well as post-plating embrittlement relief process. Coatings shall be sampled, tested, and conform accordingly to specified requirements as to purity, appearance, adhesion, hydrogen embrittlement, reflectivity, and thickness (to be measured either nondestructively by beta backscatter method or X-ray fluorescence, or destructively by microscopical cross sectioning method).
SCOPE
1.1 This specification covers requirements for electrodeposited coatings of rhodium used for engineering purposes.
1.2 Coatings of rhodium covered by this specification are usually employed for their corrosion resistance, stable electrical contact resistance, wear resistance, reflectivity, and heat resistance.
1.3 Appendix XI covers some typical applications for electrodeposited rhodium.
1.4 This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

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31-Mar-2004
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ASTM B634-88(2004)e1 - Standard Specification for Electrodeposited Coatings of Rhodium for Engineering Use
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: B634 – 88 (Reapproved 2004)
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.
´ NOTE—Keywords were added editorially in April 2004.
1. Scope B456 Specification for Electrodeposited Coatings of Cop-
per Plus Nickel Plus Chromium and Nickel Plus Chro-
1.1 This specification covers requirements for electrodepos-
mium
ited coatings of rhodium used for engineering purposes.
B481 Practice for Preparation of Titanium and Titanium
1.2 Coatings of rhodium covered by this specification are
Alloys for Electroplating
usually employed for their corrosion resistance, stable electri-
B482 Practice for Preparation of Tungsten and Tungsten
cal contact resistance, wear resistance, reflectivity, and heat
Alloys for Electroplating
resistance.
B487 Test Method for Measurement of Metal and Oxide
1.3 Appendix X1 covers some typical applications for
CoatingThicknessbyMicroscopicalExaminationofCross
electrodeposited rhodium.
Section
1.4 This standard does not purport to address all of the
B507 Practice for Design ofArticles to Be Electroplated on
safety concerns, if any, associated with its use. It is the
Racks
responsibility of the user of this standard to establish appro-
B567 Test Method for Measurement of Coating Thickness
priate safety and health practices and determine the applica-
by the Beta Backscatter Method
bility of regulatory limitations prior to use.
B568 Test Method for Measurement of Coating Thickness
2. Referenced Documents by X-Ray Spectrometry
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
2.2 ASTM Standards:
Inorganic Coatings
B183 Practice for Preparation of Low-Carbon Steel for
B697 Guide for Selection of Sampling Plans for Inspection
Electroplating
of Electrodeposited Metallic and Inorganic Coatings
B242 Guide for Preparation of High-Carbon Steel for Elec-
B762 Test Method of Variables Sampling of Metallic and
troplating
Inorganic Coatings
B252 Guide for Preparation of ZincAlloy Die Castings for
E8 Test Methods for Tension Testing of Metallic Materials
Electroplating and Conversion Coatings
2.3 Military Standards:
B254 Practice for Preparation of and Electroplating on
MIL-R-46085 Rhodium Plating, Electrodeposited
Stainless Steel
QQ-N-290 Nickel Plating, Electrodeposited
B281 Practice for Preparation of Copper and Copper-Base
Alloys for Electroplating and Conversion Coatings
3. Classification
B322 Guide for Cleaning Metals Prior to Electroplating
3.1 Electrodeposited coatings of rhodium on the basis of
B343 Practice for Preparation of Nickel for Electroplating
thickness are classified as follows:
with Nickel
Class Minimum Thickness, µm
0.05 0.05
This specification is under the jurisdiction of ASTM Committee B08 on
0.25 0.25
Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee
0.5 0.5
B08.08.02 on Precious Metal Coatings.
Current edition approved April 1, 2004. Published April 2004. Originally 2.5 2.5
approved in 1978. Last previous edition approved in 1999 as B634 – 88 (1999). 6.2 6.25
DOI: 10.1520/B0634-88R04E01.
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.
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B634 – 88 (2004)
4. Ordering Information to the serviceability or function of the article or which can be
the source of corrosion products or tarnish films that interfere
4.1 To make application of this standard complete, the
with the function or desirable appearance of the article. When
purchaser needs to supply the following information to the
necessary, the significant surfaces shall be indicated on the
seller in the purchase order or other governing document:
drawings of the parts, or by the provision of suitably marked
4.1.1 Name, designation, and year of issue of this standard,
samples.
4.1.2 Class including a maximum thickness, if appropriate
(3.1),
NOTE 2—Variation in the coating thickness from point-to-point on a
4.1.3 Nature of substrate, for example, high strength steel, coated article is an inherent characteristic of electroplating processes.
Therefore, the coating thickness will have to exceed the specified value at
needforstressrelief,undercoats,embrittlementrelief(5.1,5.2,
some points on the significant surfaces to ensure that the thickness equals
5.3),
or exceeds the specified value at all points.Therefore, the average coating
4.1.4 Significant surfaces (6.2),
thicknessonanarticlewillusuallybegreaterthanthespecifiedvalue;how
4.1.5 Appearance (6.3),
muchgreaterislargelydeterminedbytheshapeofthearticle(seePractice
4.1.6 Requirements and methods of testing for one or more
B507) and the characteristics of the electroplating process. Additionally,
of the following requirements: need for and type of test
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
the thickness requirement, the average coating thickness of the production
embrittlement (8.4); reflectivity (8.5); and undercoats (S1.4),
lot as a whole will be greater than the average necessary to ensure that a
and
single article meets the requirements.
4.1.7 Sampling plans (Section 7) and quality assurance
6.4 Appearance:
(S1.2).
6.4.1 Electroplated coatings shall completely cover all sur-
5. Process Requirements
faces as specified in the manufacturing document and shall
have a uniform appearance to the extent that the nature of the
5.1 Preparatory Procedures—The basis metal shall be sub-
basis metal and good commercial practices permit.
jected to such cleaning procedures as are necessary to ensure a
6.4.2 Defects in the surface of the basis metal such as
surface satisfactory for subsequent electroplating. Materials
scratches, pits, nonconducting inclusions, and roll and die
used for cleaning shall have no damaging effects on the basis
marks, may adversely affect the appearance and performance
metal resulting in pits, intergranular attack, stress corrosion
of the applied coatings. Such defects that persist in the finish
cracking, or hydrogen embrittlement.
despite the observance of good metal finishing practices shall
NOTE 1—For basis metal preparations, the following appropriate
not be cause for rejection.
ASTM standards are recommended: Practices B183, B242, B252, B254,
B281, B322, B343, B481, and B482.
NOTE 3—Applied finishes generally perform better in service when the
substrate over which they are applied is smooth and free from torn metal,
5.2 Preplating Operations:
inclusions, pores, and other defects. It is recommended that the specifi-
5.2.1 Electroplating shall be applied after all basis metal
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 elec-
5.2.2 Stress Relief Treatment—All steel parts having an tropolishing. However, these are not normal in the treatment steps
precedingtheapplicationofthefinish.Whentheyaredesired,theyarethe
ultimatetensilestrengthof1050MPa(approximately35HRC)
subject of special agreement between the purchaser and the supplier.
and above and that have been machined, ground, cold formed,
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
7.1 A random sample of the size required by Test Methods
tensile strength of 1200 MPa (approximately 38 HRC) or
greater shall be baked at 190 6 15°C for a minimum of 8 h B602 or B762B602B762 shall be selected from the inspection
lot (see 7.2). The articles in the lot shall be inspected for
within 4 h after electroplating to provide hydrogen embrittle-
ment relief. Steel parts having an ultimate tensile strength conformance to the requirements of this specification and the
lot shall be classified as conforming or nonconforming to each
greaterthan1300MPa(approximately40HRC)shallbebaked
requirement according to the criteria of the sampling plans in
at 190 6 15°C for a minimum of 23 h within 4 h after
Test Method B602.
electroplating.
NOTE 4—Test Method B602 contains four sampling plans, three for use
6. Coating Requirements
withnondestructivetestmethods.Thefourthistobeusedwithdestructive
6.1 Nature of Coating—The coating shall be essentially test methods. The three methods for nondestructive tests differ in the
quality level they require of the product. Test Method B602 requires use
pure rhodium produced by electrodeposition from aqueous
of the plan with the intermediate quality level unless the purchaser
electrolytes.
specifies otherwise. It is recommended that the purchaser compare the
6.2 Thickness—The rhodium coating thickness on all sig-
plans with his needs
...

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