ASTM B772-97(2008)
(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)
SIGNIFICANCE AND USE
This guide should be used by committees or individuals in specifying the chemical composition of electrical contact materials.
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 (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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Designation: B772 − 97 (Reapproved 2008)
Standard Guide for
Specifying the Chemical Compositions for Electrical
Contact Materials (Arcing and Nonarcing)
This standard is issued under the fixed designation B772; 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 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 (MSDS) for this product/material
as provided by the manufacturer, to establish appropriate
4.2 For Impurities:
safety and health practices, and determine the applicability of
4.2.1 Specify only the tolerance limits of the elements
regulatory limitations prior to use.
commonly occurring with the major elements (for example,
copper in silver); and the tolerance limits of the detrimental
2. Referenced Documents
elements (as recognized by the industry) which may be a
2.1 ASTM Standards:
residue after fabrication (for example, sodium in Ag-CdO
E1282 GuideforSpecifyingtheChemicalCompositionsand
material by the coprecipitation method).
Selecting Sampling Practices and Quantitative Analysis
4.2.2 Specify the tolerance limits for total impurities of all
Methods for Metals, Ores, and Related Materials
the impurity elements.
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
3.1 This guide should be used by committees or individuals
specification:
in specifying the chemical composition of electrical contact
materials.
NOTE 1—Analysis is regularly made for the elements for which specific
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
4.1 For Basic Alloy Element(s) and Component(s):
impurities is not in excess of the total impurities limit.
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 shall be regularly made only for the minor elements
listed in the table. However
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