ASTM E977-84(1999)

Standard Practice for Thermoelectric Sorting of Electrically Conductive Materials

SCOPE
1.1 This practice covers the procedure for sorting materials using the thermoelectric method, which is based on the Seebeck effect. The procedure relates to the use of direct- and comparator-type thermoelectric instruments for distinguishing variations in materials which affect the thermoelectric properties of those materials.  
1.2 While the practice is most commonly applied to the sorting of metals, it may be applied to other electrically conductive materials.  
1.3 Thermoelectric sorting may also be applied to the sorting of materials on the basis of plating thickness, case depth, and hardness.  
1.4 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 establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Dec-1999
• ICS: 29.050 - Superconductivity and conducting materials
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.10 - Specialized NDT Methods

Relations

• Replaced By: ASTM E977-05 - Standard Practice for Thermoelectric Sorting of Electrically Conductive Materials
• Effective Date: 01-Jul-2005
• Referred By: ASTM E1476-04(2022) - Standard Guide for Metals Identification, Grade Verification, and Sorting
• Effective Date: 10-Dec-1999
• Referred By: ASTM E1916-11(2019) - Standard Guide for Identification of Mixed Lots of Metals
• Effective Date: 10-Dec-1999

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:E977–84 (Reapproved 1999)
Standard Practice for
Thermoelectric Sorting of Electrically Conductive Materials
This standard is issued under the fixed designation E 977; 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 tors at two points of different temperatures. The magnitude of
this emf is a function of the chemistry of the materials, surface
1.1 This practice covers the procedure for sorting materials
metallurgical structure, and the temperature of the junction
using the thermoelectric method, which is based on the
between the two. See Fig. 1.
Seebeck effect. The procedure relates to the use of direct- and
comparator-type thermoelectric instruments for distinguishing
3. Summary of Practice
variations in materials which affect the thermoelectric proper-
3.1 The two techniques that are primarily used in thermo-
ties of those materials.
electric sorting are direct and comparative instrumentation. In
1.2 While the practice is most commonly applied to the
the direct instruments, equipment is calibrated by placing
sorting of metals, it may be applied to other electrically
standards of materials with known chemistry and metallurgical
conductive materials.
structure in the test system. The value of the thermoelectric
1.3 Thermoelectric sorting may also be applied to the
voltage (or arbitrary unit) is read on the scale of an indicator.
sorting of materials on the basis of plating thickness, case
In the comparative instruments, the thermoelectric response of
depth, and hardness.
the test piece is compared with that of a known standard(s) and
1.4 This standard does not purport to address all of the
the response indicates whether the piece is within the accep-
safety concerns, if any, associated with its use. It is the
tance limits.
responsibility of the user of this standard to establish appro-
3.1.1 Both kinds of instrumentation require comparing the
priate safety and health practices and determine the applica-
pieces to be tested with the known standard(s). Two or more
bility of regulatory limitations prior to use.
samples representing the acceptance limits may be required.
2. Terminology 3.1.2 directThermoelectricinstrumentation—aknownstan-
dard(s) is inserted in the test system and the controls of the
2.1 Descriptions of Terms:
instrument are adjusted to obtain a voltage (or arbitrary unit)
2.1.1 acceptance limits—the thermoelectric response that
reading(s). The test is then continued by inserting the pieces to
establishes the group into which the material under test
be sorted into the test system, and observing the instrument
belongs.
reading(s).
2.1.2 comparative instrumentation—a system that uses
3.1.3 Comparative Instrumentation—Known standards rep-
electrode assemblies, associated electronics, and known stan-
resenting the acceptance limits are inserted into the test system.
dards to measure a thermoelectric response from a test speci-
The instrument controls are adjusted for appropriate response.
men. This response is compared with that of the reference
The test is then continued by inserting the pieces to be sorted
standard.
in the test system, and observing the instrument response.
2.1.3 direct instrumentation—a system that specifically
3.2 In both instruments, the range of the instrument re-
measures and displays the voltage (or an arbitrary unit)
sponse must be adjusted during calibration so that any antici-
generated between the electrodes when they are at different
pated deviation from the known standard(s) will be recognized
temperatures and in contact with the material.
as within the required acceptance limits.
2.1.4 electrode—the conductors used in thermoelectric sort-
3.3 The testing process may consist of manual insertion of
ing instruments used to generate the Seebeck effect with the
one piece after another into the test system, or an automated
metal under test.
feeding and classifying mechanism may be employed.
2.1.5 Seebeckeffect—thethermoelectricelectromotiveforce
(emf) produced in a circuit connecting two dissimilar conduc-
4. Application
4.1 Thermoelectric techniques provide a method for sorting
This practice is under the jurisdiction of ASTM Committee E-7 on Nonde- large quantities of conductive materials. The ability to accom-
structive Testing and is the direct responsibility of Subcommittee E07.10 on
plishsatisfactorilythesetypesofseparationsisdependentupon
Emerging NDT Methods.
Current edition approved Jan. 27, 1984. Published May 1984.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E977–84 (1999)
FIG. 1 Typical Circuit Used in Thermoelectric Metal Sorting Instruments
the relation of the thermoelectric voltages with regard to 5.1.7 If changes in the surface chemistry of the material are
composition, condition, and structure or processing, or both. brought about due to buildup or depletion of the constituents,
4.2 Comparative instrumentation is used when high- the affected surface should be removed by grinding or other
sensitivity testing is required. The advantage of this method is means; or a known standard containing the same surface
that it reduces internal or external disturbances such as constituents should be used as comparison materials.
temperature variations of the material or probes, or both.
6. Apparatus
4.3 The success of an attempted sort will be affected by
6.1 Electronic Apparatus—The electronic apparatus shall
instrument factors such as electrode composition, electrode
be capable of maintaining a sufficient temperature differential
temperature differential, and electrode contact.
across the electrodes to produce a suitable thermoelectric
4.4 The degree of reliability of instrument readings will be
voltage. Equipment to process this voltage may include any
affected greatly by the coupling between the test electrode and
the tested part and the accuracy with which the temperature is suitable signal-processing devices (d-c amplifiers, null detec-
tors, potentiometers, etc.) and the output may be displayed by
held constant during the measuring period. The surface of the
meter, scope, recorder, signaling devices, or any suitable
test materials and of both electrodes
...