ASTM D6120-97(2007)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D6120 − 97(Reapproved 2007)
Standard Test Method for
Electrical Resistivity of Anode and Cathode Carbon Material
at Room Temperature
This standard is issued under the fixed designation D6120; 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 between two points along its length. The resistivity is calcu-
latedbasedonthevoltagedroporelectricalresistance,distance
1.1 This test method covers the determination of the elec-
between the two points, and the cross-sectional area of the
trical resistivity at room temperature of solid cylindrical
cylinder.
specimens cored from commercial sized carbon anodes and
cathodes.This test method also applies to samples from carbon 4.2 This test method are used to determine electrical resis-
blocks prepared in a laboratory. tivity for various carbon materials typically found in the
aluminum industry. Electrical resistivity of other carbon arti-
1.2 This standard does not purport to address all of the
facts such as graphite and specialty carbons is more appropri-
safety concerns, if any, associated with its use. It is the
ately determined by Test Method C611.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. Significance and Use
bility of regulatory limitation prior to use. For specific safety
5.1 The electrical resistivity of anode and cathode carbon
information, see 8.2.3.
material is important for efficient aluminum cell operation. It is
2. Referenced Documents
a quality parameter that determines the suitability of an
anode/cathode for operation in an aluminum cell.
2.1 ASTM Standards:
C611 TestMethodforElectricalResistivityofManufactured
5.2 The electrical resitivity may be selected as a require-
Carbon and Graphite Articles at Room Temperature
ment in a customer specification.
D5502 Test Method for Apparent Density by Physical Mea-
6. Apparatus
surements of Manufactured Anode and Cathode Carbon
Used by the Aluminum Industry
6.1 Specimen Holder (Fig. 1), a device for holding a
specimen of 50 mm diameter and a minimum of 120 mm in
3. Terminology
length between two flat copper plates. One of the plates is
3.1 Definitions:
swivel mounted to ensure good contact in case the ends of the
3.1.1 electrical resistivity, n—the electrical resistance of-
specimen are not perfectly parallel. The plates shall be as large
fered by a material to the flow of current, times the cross-
astheendsofthespecimenandelectricallyinsulatedfromeach
sectional area of current flow and per unit length of current
other.
path, the reciprocal of conductivity. It is also known as
6.1.1 Voltage Drop Contact Points—The contact points
resistivity, or specific resistance.
shall be conical or knife edge in shape and securely fastened to
rigid insulatig material with a minimum spacing of 50 mm and
4. Summary of Test Method
amaximumspacingof80 %ofthelengthofthespecimen.The
4.1 An electrical current is passed through a carbon cylinder
distance (L) in millimetres (mm) betweeen the center of the
and the voltage drop or electrical resistance is measured
conical points or knife edges is used when calculating the
electrical resistivity.
This test method is under the jurisdiction of ASTM Committee D02 on
6.2 Apparatus for Indirect Resistance Measurement (per-
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee
D02.05 on Properties of Fuels, Petroleum Coke and Carbon Material.
mits measurement of voltage and current needed for calculat-
Current edition approved May 1, 2007. Published June 2007. Originally
ing electrical resistivity):
approved in 1997. Last previous edition approved in 2002 as D6120 – 97 (2002).
6.2.1 dc Power Supply—The power supply shall be capable
DOI: 10.1520/D6120-97R07.
of supplying a minimum DC current of 10 amps at an electrical
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
potential of up to 5V.The line and load regulation shall be less
Standards volume information, refer to the standard’s Document Summary page on
than 0.1 % and background noise less than or equal to 0.1 %.
the ASTM website.
6.2.2 dc Voltage Measuring Instrument, high-impedance
Parker, Sybil P., Ed in Chief, Dictionary of Scientific and Technical Terms,
McGraw Hill Book Co., Fourth Ed., 1989, p 615. device capable of measuring a minimum of 5 V to 0.01 mV.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6120 − 97 (2007)
8.2.1 Mount the test specimen in the holder and tighten
contact plates firmly to the ends of the specimen.
8.2.2 Apply voltage and adjust current to about
6 amps 63A.
8.2.3 Center the contact points longitudinally on top of this
specimen and measure the voltage drop. Move the contact
points around the curcumference of the cylinder a distance
equivalent to an arc length of the circumference subtended by
a45°angle.Makesurecontactsarestilllongitudinallycentered
and take a voltage reading. Continue moving in the same
directionaroundthecircumferenceuntilatotalofeightequally
spaced voltage readings are recorded. (Warning—Passing a
current through a test specimen for an extended period of time
can increase the temperature and consequently lower the
resistance of the specimen.)
8.3 Direct Resistance Measurement :
FIG. 1 Schematic of Specimen Holder
8.3.1 Mount the test specimen in the holder and tighten
contact plates firmly to the ends of the specimen.
8.3.2 Center the contact points longitudinally on top of the
6.2.3 dc Current Measuring Device, a device capable of
specimen and measure the resistance. Move the contact points
measuring a current of 10 to 0.01 A.
around the circumference of the cyinder a distance equivalent
6.3 Apparatus for Direct Resistance Measurement:
to an arc length of the circumference subtended by 45° angle.
6.3.1 Electrical Resistance Measuring Device—A device
Make sure contacts are still longitudinally centered and take a
capable of measuring electrical resistan
...