Standard Test Method for Electrical Resistivity of Manufactured Carbon and Graphite Articles at Room Temperature

SIGNIFICANCE AND USE
This test method provides a means of determining the electrical resistivity of carbon or graphite specimens. The use of specimens that do not conform to the specimen size limitations described in the test method may result in an alteration of test method accuracy.
SCOPE
1.1 This test method covers the determination of the electrical resistivity of manufactured carbon and graphite articles at room temperature.
1.2 The values stated in SI units are to be regarded as the standard.
1.3This 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.

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Historical
Publication Date
30-Apr-2005
Current Stage
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ASTM C611-98(2005)e1 - Standard Test Method for Electrical Resistivity of Manufactured Carbon and Graphite Articles at Room Temperature
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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
AnAmerican National Standard
´1
Designation:C611–98 (Reapproved 2005)
Standard Test Method for
Electrical Resistivity of Manufactured Carbon and Graphite
Articles at Room Temperature
This standard is issued under the fixed designation C611; 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.
´ NOTE—Editorial changes were made to Figure 3 in May 2005.
1. Scope 4. Apparatus
1.1 This test method covers the determination of the elec- 4.1 The means for applying current and potential terminals
tricalresistivityofmanufacturedcarbonandgraphitearticlesat to the specimen is specified in 5.2.3.1. A typical specimen
room temperature. holder is shown in Fig. 1.
1.2 The values stated in SI units are to be regarded as the 4.2 Bridge, Potentiometer,or Suitable Digital Voltmeter,
standard. with necessary accessories for making resistance measure-
1.3 This standard does not purport to address all of the ments with a limit of error of less than 0.5 %. Fig. 2
safety concerns, if any, associated with its use. It is the schematically depicts two wiring diagrams that have been
responsibility of the user of this standard to establish appro- found satisfactory for this purpose.
priate safety and health practices and determine the applica- 4.3 The means for measuring the dimensions of the speci-
bility of regulatory limitations prior to use. men should be adequate to determine its gage length and its
mean area of cross section, each within 0.5 %.
2. Terminology
5. Test Specimen
2.1 Definition:
2.1.1 resistivity—the property of a material that determines 5.1 Thetestspecimenmaybeintheformofastrip,rod,bar,
its resistance to the flow of an electrical current. It is defined as or tube.
the value of r, in milliohm metres, as follows: 5.2 In order to determine the resistivity, each specimen shall
conform to the following:
r5 ~R·A!/L
5.2.1 The cross-sectional area shall be uniform within
where: 0.75 %.Ingeneral,thediameterofcircularcrosssection,orthe
R = resistance of a specimen of the material of uniform
thickness and width of a strip specimen shall be determined by
cross section, ohms,
micrometer measurements, and a sufficient number of mea-
A = uniform cross section, mm , and
surements shall be made to obtain a mean cross-sectional area
L = distance between potential contacts, mm.
to within 0.5 %. The test specimen shall be machined to yield
2.1.1.1 In cases where resistivity is requested in ohm-
planar and parallel end faces. These faces shall be perpendicu-
inches, multiply r in milliohm metres by 0.03937.
lar to the specimen length to within 0.001 mm/mm. All
surfaces shall have a surface finish visually comparable to 0.8
3. Significance and Use
µm (32 µin.) rms. Reasonable care should be exercised to
3.1 This test method provides a means of determining the
assure that all edges are sharp and without chips or other flaws.
electrical resistivity of carbon or graphite specimens. The use
5.2.2 The test specimen shall show no defects observable
of specimens that do not conform to the specimen size
with normal vision and shall be free of surface deposits.
limitations described in the test method may result in an
5.2.3 The minimum ratio of specimen length to maximum
alteration of test method accuracy.
cross-sectional dimension (width or diameter) shall be 6 : 1.
5.2.3.1 The gage length may be measured by any scale that
will give an accuracy of 60.5 % in the length measured. In the
direction of the length of the specimen, the dimension of each
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
potential contact shall be not more than 0.5 % of the distance
D02.F0 on Manufactured Carbon and Graphite Products .
betweenthepotentialcontacts.Theminimumdistancebetween
Current edition approved May 1, 2005. Published May 2005. Originally
each potential contact and the adjacent current contact shall be
approved in 1969. Last previous edition approved in 1998 as C611 – 98. DOI:
10.1520/C0611-98R05E01. the maximum cross-sectional dimension (width or diameter) of
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959, United States.
´1
C611–98 (2005)
1—Base block 12—Wire gauze holder
2—Pivot block 13—Pivot red
3—Current block adjustable 14—Screw: sockethead
4—Current block stationary 15—Roundhead screw
5—Clamp block 16—Roundhead screw
6—Clamp screw 17—Roundhead screw
7—Brush holder 18—Screw, sockethead
8—Contacts 19—Set screw
9—Current block support 20—Neoprene
10—Current block guide 21—Wire gauze
11—Pivot bracket 22—Set screw
NOTE—Contacts for the voltage and current probes may be made through channels drilled in the brush holders (7) and the current blocks (3 and 4),
respectively.
FIG. 1 Typical Test Apparatus
the specimen. If knife edges are used, they shall be parallel to 7.1.1 Clean the surface of the specimen at current and
each other and perpendicular to the longitudinal direction of potential contact points to obtain good electrical contact.
the sample. The minimum ratio of gage length to maximum Mount the sample in the test apparatus, apply current, and
cross-sectional dimension (width or diameter) shall be 4 : 1. measure the voltage. Take four measurements, on each side of
5.2.4 No dimension shall be smaller than five times the arectangularspecimen,orat90°(p/2radians)apartonaround
length of the largest visible particle.
specimen. Reverse the current direction and take four measure-
5.2.5 No joints or splices are permissible, unless this is the ments again. Remove the specimen from the test apparatus,
variable under study.
turn it end for end, replace it in the apparatus, and repeat the
measurements. The total of 16 measurements is recommended
6. Conditioning
to minimize errors due
...

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