ASTM C611-21

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C611 − 98 (Reapproved 2016) C611 − 21
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.
1. Scope 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 standard. No other units of measurement are included in this standard.
1.3 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Terminology
2.1 Definitions:
2.1.1 resistivity—resistivity, n—the property of a material that determines its resistance to the flow of an electrical current. It is
defined as the value of ρ, in milliohm metres, as follows:
ρ5 ~R·A!/L
where:
R = resistance of a specimen of the material of uniform cross section, ohms,
A = uniform cross section, mm , and
L = distance between potential contacts, mm.
3. Significance and Use
3.1 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.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.F0 on Manufactured Carbon and Graphite Products.
Current edition approved Oct. 1, 2016May 1, 2021. Published November 2016May 2021. Originally approved in 2005. Last previous edition approved in 20102016 as
ε1
C611 – 98 (2010)(2016). . DOI:10.1520/C0611-98R16. DOI:10.1520/C0611-21.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C611 − 21
4. Apparatus
4.1 The means for applying current and potential terminals to the specimen is specified in 5.2.3.1. A typical specimen holder is
shown in Fig. 1.
4.2 Bridge, Potentiometer, or Suitable Digital Voltmeter, with necessary accessories for making resistance measurements with a
limit of error of less than 0.5 %. Fig. 2 schematically depicts two wiring diagrams that have been found satisfactory for this
purpose.
4.3 The means for measuring the dimensions of the specimen should be adequate to determine its gage length and its mean area
of cross section, each within 0.5 %.
5. Test Specimen
5.1 The test specimen may be in the form of a strip, rod, bar, or tube.
5.2 In order to determine the resistivity, each specimen shall conform to the following:
5.2.1 The cross-sectional area shall be uniform within 0.75 %. In general, the diameter of circular cross section, or the thickness
and width of a strip specimen shall be determined by micrometer measurements, and a sufficient number of measurements shall
be made to obtain a mean cross-sectional area to within 0.5 %. The test specimen shall be machined to yield planar and parallel
end faces. These faces shall be perpendicular to the specimen length to within 0.001 mm ⁄mm. All surfaces shall have a surface
finish visually comparable to 0.8 μm rms. Reasonable care should be exercised to assure that all edges are sharp and without chips
or other flaws.
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 1—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
C611 − 21
NOTE 1—Adjustable, regulated dc power supply—line and load regulation to 0.1 % and ripple and noise ≤0.1 %.
FIG. 2 Typical Schematic for Resistivity Measurements
5.2.2 The test specimen shall show no defects observable with normal vision and shall be free of surface deposits.
5.2.3 The minimum ratio of specimen length to maximum 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 potential contact shall be not more than 0.5 % of the distance
between the potential contacts. The minimum distance between each potential contact and the adjacent current contact shall be the
maximum cross-sectional dimension (width or diameter) of the specimen. If knife edges are used, they shall be parallel to each
other and perpendicular to the longitudinal direction of the sample. The minimum ratio of gage length to maximum cross-sectional
dimension (width or diameter) shall be 4 : 1.
5.2.4 No dimension shall be smaller than five times the length of the largest visible particle.
5.2.5 No joints or splices are permissible, unless this is the variable under study.
6. Conditioning
6.1 The specimen shall be dried for a minimum of 2 h at 110 °C, cooled to room temperature in a desiccator, and stored in a
desiccator until tested.
C611 − 21
7. Procedure
7.1 Resistance Measurement—Measure resistance with instruments accurate to 60.5 % or less (see Note 1). To ensure a correct
reading, the reference standard and the test specimen must be allowed to come to the same temperature as the surrounding medium.
NOTE 1—For resistance below 10 Ω, a Kelvin bridge meth
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