Standard Specification for 75 % Silver-25 % % Graphite Sliding Contact Material

ABSTRACT
This specification defines the criteria for the chemical composition and other requirements (including physical properties, microstructure, superficial hardness, and specific resistance ) for silver-graphite brushes for sliding electrical contacts. The percentage of silver, graphite, ash in graphite, and total metal impurities are prescribed. The minimum acceptable values for the physical properties such as density, determined by measurement and weight method, and shear strength are given. Typical Rockwell hardness and specific resistance for the material are also specified.
SCOPE
1.1 This specification defines the criteria for composition and other requirements for brushes with a nominal silver content of 75 weight % with the balance being substantially graphite.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
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 Material Safety Data Sheet (MSDS) for this product/material as provided by the manufacturer, to establish appropriate safety and health practices, and determine the applicability of regulatory limitations prior to use.

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Historical
Publication Date
30-Apr-2012
Current Stage
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Technical specification
ASTM B692-90(2012) - Standard Specification for 75 % Silver-25 % % Graphite Sliding Contact Material
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:B692 −90 (Reapproved 2012)
Standard Specification for
1
75% Silver-25 % Graphite Sliding Contact Material
This standard is issued under the fixed designation B692; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Requirements
1.1 This specification defines the criteria for composition 3.1 Chemical Composition shall be as follows:
and other requirements for brushes with a nominal silver
Silver 75 ± 3 % (weight)
content of 75 weight% with the balance being substantially Graphite balance
Total metal impurities 1 % max
graphite.
Percent ash in graphite (ANSI C64.1) 5 % max
1.2 The values stated in inch-pound units are to be regarded
3.2 Physical Properties—The following lot average proper-
as standard. The values given in parentheses are mathematical
ties must be met. Unless otherwise agreed between the pro-
conversions to SI units that are provided for information only
ducer and the user, the number of samples shall be five.
and are not considered standard.
3.2.1 Density—The minimum acceptable density shall be
3
1.3 This standard does not purport to address all of the 4.6 g/cm as determined by the measurement and weight
safety concerns, if any, associated with its use. It is the method defined by ANSI C64.1.
responsibility of the user of this standard to become familiar 3.2.2 Shear Strength:
with all hazards including those identified in the appropriate 3.2.2.1 The shear strength for the normal and transverse
Material Safety Data Sheet (MSDS) for this product/material directions shall be measured for rectangular parallelepipeds
as provided by the manufacturer, to establish appropriate and shall be 2000 psi (14 MPa), minimum.
safety and health practices, and determine the applicability of 3.2.2.2 The shear strength for the longitudinal shear direc-
regulatory limitations prior to use. tion shall be measured for cylinders and shall be 1000 psi (6.9
MPa), minimum.
2. Referenced Documents
3.3 Microstructure—Partsshallbevisuallyfreeofstructural
2
2.1 ASTM Standards:
defects, cracks, etc., upon examination at 50×. The press
B613 Guide for Preparing Specifications for Miniature
direction, as evidenced by laminations, shall be as defined by
Brushes of Composite Materials for Sliding Electric
the purchase order. Also the brush material shall not contain
Contacts
abrasive particles that will sliver a metal-alloy ring with a
E18Test Methods for Rockwell Hardness of Metallic Ma-
hardness≥110 HK when the brush force is equal to 30 g or
100
terials
that necessary for 5.0 psi (34 kPa) pressure, whichever is
2.2 ANSI Standard:
greater. A sliver is defined as a loose wear particle with one
3
C64.1 Brushes for Electrical Machines
dimension ≥50× the next smaller dimension. Although sliver-
ing can be caused by coarse abrasive particles, other param-
1
eters can contribute to slivering (for example, very high brush
This specification is unde
...

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