ASTM B631-93(2021)
(Specification)Standard Specification for Silver-Tungsten Electrical Contact Materials
Standard Specification for Silver-Tungsten Electrical Contact Materials
ABSTRACT
This specification covers electrical contact components made from silver-tungsten by powder-metallurgical procedures. The material shall conform to composition limits specified. The material shall be finished by braze alloy backing, tumbling to polish surfaces, special surface finish, silver-rich surface layer, cleaning, etc. Chemical analysis and physical test shall be made to conform to the specified requirements.
SIGNIFICANCE AND USE
9.1 Proprietary methods for manufacture of these materials vary significantly among suppliers, and these methods influence such properties as arc erosion, contact resistance, and tendency to weld in service. Since the performance of contacts in a device depends on numerous factors outside the contact itself (opening speed, closing speed, contact pressure, contact bounce, environmental variations, assembly technique and variations, etc.) this specification cannot ensure performance control in the application. As part of the qualification on initial samples it is recommended that the user functionally electrically test the materials for all devices applicable to the material's use. This specification will provide a means for the contact manufacturer and contact user to reach agreement on the details of material to be supplied for a specific use and reasonable assurance that future lots will be similar in properties and microstructure to the initial test or sample contacts supplied.
SCOPE
1.1 This specification covers electrical contact components made from silver-tungsten by powder-metallurgical procedures.
1.2 This specification covers compositions within the silver-tungsten system normally specified by users of contacts.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to become familiar with all hazards including those identified in the appropriate Data Safety Sheet (SDS) for this product/material as provided by the manufacturer, to establish appropriate safety, health, and environmental practices, and determine the applicability of regulatory limitations prior to use.
1.4 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.
General Information
Standards Content (Sample)
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: B631 −93 (Reapproved 2021)
Standard Specification for
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Silver-Tungsten Electrical Contact Materials
This standard is issued under the fixed designation B631; 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 3.1.2 Chemical composition (see reference tables in the
Appendix X1 as a possible guide).
1.1 This specification covers electrical contact components
3.1.3 Physicalproperties(seeSection6andAppendixX1as
made from silver-tungsten by powder-metallurgical proce-
guideline).
dures.
3.1.4 Certification (see Section 13).
1.2 This specification covers compositions within the silver-
3.1.5 Other features as agreed upon between the purchaser
tungsten system normally specified by users of contacts.
and manufacturer.
1.3 This standard does not purport to address all of the
4. Chemical Composition
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to become familiar 4.1 The material shall conform to composition limits as
with all hazards including those identified in the appropriate
agreed upon between the manufacturer and purchaser.
Data Safety Sheet (SDS) for this product/material as provided
4.2 The chemical analysis shall be made in accordance with
by the manufacturer, to establish appropriate safety, health,
the methods prescribed in the newest edition of the Annual
and environmental practices, and determine the applicability
Book of ASTM Standards, or by any other approved method
of regulatory limitations prior to use.
agreed upon between the manufacturer and purchaser.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard- 5. Other Requirements
ization established in the Decision on Principles for the
5.1 The manufacturer and purchaser shall agree on qualifi-
Development of International Standards, Guides and Recom-
cation tests for determination of physical properties.
mendations issued by the World Trade Organization Technical
5.2 The tests shall be performed on production parts,
Barriers to Trade (TBT) Committee.
wherever practical or applicable (small size contacts do not
lend themselves to accurate conductivity measurement).
2. Referenced Documents
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5.3 The tests shall be determined after consideration of the
2.1 ASTM Standards:
function of the part.
B328 Test Method for Density, Oil Content, and Intercon-
nected Porosity of Sintered Metal Structural Parts and
5.4 The typical properties of the four most common types of
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Oil-Impregnated Bearings (Withdrawn 2009)
silver-tungsten contacts are given in the appendix.
6. Finishing of Contacts
3. Ordering Information
6.1 The material shall be finished by such operations as
3.1 Orders for this material under this specification shall
necessary to meet requirements agreed upon by the maker and
include the following information:
user of the contacts (braze alloy backing, tumbling to polish
3.1.1 Dimensions (see Section 7).
surfaces, special surface finish, silver-rich surface layer,
cleaning, etc.).
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This specification is under the jurisdiction of ASTM Committee B02 on
7. Permissible Variations in Dimensions
Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee
B02.05 on Precious Metals and Electrical Contact Materials.
7.1 Permissible variations in dimensions shall be within the
Current edition approved Nov. 1, 2021. Published December 2021. Originally
limits specified on drawings describing the contacts and
approved in 1977. Last previous edition approved in 2016 as B631 – 93 (2016).
accompanying the order, or shall be within the limits specified
DOI: 10.1520/B0631-93R21.
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or in the purchase order.
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 8. Workmanship
the ASTM website.
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8.1 The parts shall be free of defects in material or process-
The last approved version of this historical standard is referenced on
www.astm.org. ing that would seriously affect their performance.
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B631 − 93 (2021)
9. Significance and Use additives. Analysis shall be regularly made only for the minor
elements listed in the table. H
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