ASTM B772-97(2003)
(Guide)Standard Guide for Specifying the Chemical Compositions for Electrical Contact Materials (Arcing and Nonarcing)
Standard Guide for Specifying the Chemical Compositions for Electrical Contact Materials (Arcing and Nonarcing)
SCOPE
1.1 This guide provides suggested methods for users and producers of electrical contact materials to specify the chemical compositions of these materials.
1.2 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 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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Designation:B772–97(Reapproved2003)
Standard Guide for
Specifying the Chemical Compositions for Electrical
Contact Materials (Arcing and Nonarcing)
This standard is issued under the fixed designation B 772; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4.1.2 One of these elements may be chosen to be specified
by “report by difference.” List the minimum value of this
1.1 This guide provides suggested methods for users and
element in a pair of parentheses before the clause “report by
producers of electrical contact materials to specify the chemi-
difference.” Select this element or component according to one
cal compositions of these materials.
or more of the following considerations:
1.2 This standard does not purport to address all of the
4.1.2.1 Least precious,
safety concerns, if any, associated with its use. It is the
4.1.2.2 Widest tolerance, and
responsibility of the user of this standard to become familiar
4.1.2.3 Requiring the least precise or most costly method to
with all hazards including those identified in the appropriate
analyze.
Material Safety Data sheet for this product/material as pro-
4.2 For Impurities:
vided by the manufacturer, to establish appropriate safety and
4.2.1 Specify only the tolerance limits of the elements
health practices, and determine the applicability of regulatory
commonly occurring with the major elements (for example,
limitations prior to use.
copper in silver); and the tolerance limits of the detrimental
2. Referenced Documents elements (as recognized by the industry) which may be a
residue after fabrication (for example, sodium in Ag-CdO
2.1 ASTM Standards:
material by the coprecipitation method).
E 1282 Guide for Specifying the Chemical Compositions
4.2.2 Specify the tolerance limits for total impurities of all
and Selecting Sampling Practices and Quantitative Analy-
the impurity elements.
sis Methods for Metals, Ores, and Related Material
4.3 Place the following note under the Table of Chemical
3. Significance and Use
Compositions (see Table 1 for example) in the text of each
specification:
3.1 This guide should be used by committees or individuals
in specifying the chemical composition of electrical contact
NOTE 1—Analysis is regularly made for the elements for which specific
materials.
limitsarelisted.If,however,thepresenceof“other”elementsissuspected
or indicated in the course of routine analysis, further analysis shall be
4. Procedure
made to determine that the total of these “other” elements and the listed
impurities is not in excess of the total impurities limit.
4.1 For Basic Alloy Element(s) and Component(s):
4.1.1 Specify the numerical limits of the elements as fol-
4.4 State under the section of Chemical Composition in the
lows:
text of each specification a clause as follows:
4.1.1.1 Major fractions of the alloy,
4.4.1 These specification limits do not preclude the possible
4.1.1.2 Tighter tolerances, or
presence of other unnamed elements, impurities, or additives.
4.1.1.3 Higher unit cost(s) or combination thereof.
Analysis shal
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