ASTM B63-90(1995)e1

Standard Test Method for Resistivity of Metallically Conducting Resistance and Contact Materials

SCOPE
1.1 This test method covers the determination, to a precision of 2%, of the electrical resistivity of materials used in resistors, heating elements, and electrical contacts, as well as products of powder metallurgy processes which are used for other purposes.
Note 1--For determining the resistivity of electrical conductors, see Test Method B193.
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 establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Dec-2000
• Technical Committee: B02 - Nonferrous Metals and Alloys
• Drafting Committee: B02.10 - Thermostat Metals and Electrical Resistance Heating Materials

Relations

• Replaced By: ASTM B63-90(2001) - Standard Test Method for Resistivity of Metallically Conducting Resistance and Contact Materials
• Effective Date: 01-Jan-2001

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NOTICE: This standard has either been superseded and replaced by a new version or
withdrawn.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.
e1
Designation: B 63 – 90 (Reapproved 1995) An American National Standard
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Resistivity of Metallically Conducting Resistance and
Contact Materials
This standard is issued under the fixed designation B 63; 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.
e NOTE—Section 14 was added editorially in June 1995.
1. Scope section and length will have a required resistance. It serves as
one basis for the selection of materials for specific applications
1.1 This test method covers the determination, to a precision
and its measurement is a necessary acceptance test for
of 2 %, of the electrical resistivity of materials used in
resistance materials.
resistors, heating elements, and electrical contacts, as well as
4.2 In the case of materials for electrical contacts, the
products of powder metallurgy processes which are used for
measurement of resistivity can serve as a test for uniformity of
other purposes.
materials of nominally the same composition and structure.
NOTE 1—For determining the resistivity of electrical conductors, see
Test Method B 193.
5. Apparatus
1.2 This standard does not purport to address all of the 5.1 Means for applying current and voltage terminals to the
safety concerns, if any, associated with its use. It is the
specimen are specified in Section 9. An optional suitable
responsibility of the user of this standard to establish appro- specimen holder for nonductile materials is shown in Fig. 1.
priate safety and health practices and determine the applica-
5.2 A suitable bridge, potentiometer, digital ohmmeter, or
bility of regulatory limitations prior to use. equivalent, with necessary accessories for making resistance
measurements with a limit of error of less than 0.5 %.
2. Referenced Documents
5.3 Means for measuring the dimensions of the specimen,
2.1 ASTM Standards: adequate to determine its length and its mean area of cross
B 193 Test Method for Resistivity of Electrical Conductor
section, each within 0.5 %.
Materials
6. Test Specimen
3. Terminology
6.1 Ductile Materials—The test specimen for ductile
materials, including those used for contacts, shall be in the
3.1 Definitions:
3.1.1 resistivity—that property of a material which deter- form of a wire or a strip. In order to determine the resistivity
with a precision of 2 %, it is necessary that the resistance,
mines its resistance to the flow of an electric current, expressed
as: cross-sectional area, and length shall be measured with a limit
of error within 0.5 %. To ensure this limit of error each test
r5 RA/L (1)
specimen shall conform to the following:
where R is the resistance in ohms of a specimen of the
6.1.1 It shall have a length of at least 30 cm (1 ft),
material of uniform cross section A and of a length L.In
6.1.2 It shall have a resistance of at least 0.001 V,
reporting values of resistivity under this test A shall be
6.1.3 If the cross section is to be determined by direct
expressed in square centimetres and L in centimetres.
measurement, the diameter of a wire specimen or the thickness
of a strip specimen shall not be less than the limits defined by
4. Significance and Use
the 0.5 % criteria of 6.1, and this dimension throughout the
4.1 In the case of materials for resistors and heating
length of the specimen shall not vary by more than 3 %, and
elements, a knowledge of resistivity is important in
6.1.4 It shall show no surface cracks or other defects
determining whether wire or strip of a specified area of cross
observable with normal vision, and shall be free from surface
oxide.
1 6.2 Nonductile Materials—The test specimen for nonductile
This test method is under the jurisdiction of ASTM Committee B-4 on Metallic
Materials for Thermostats and for Electrical Resistance, Heating, and Contacts and materials shall be made in accordance with Fig. 2 if the
is the direct responsibility of Subcommittee B04.01 on Electrical Heating and
material is readily machinable. For materials which are not
Resistance.
readily machinable, such as those containing graphite, a flat
Current edition approved May 25, 1990. Published July 1990. Originally
strip may be used as a test specimen. In order to determine the
published as B 63 – 26 T. Last previous edition B 63 – 81.
Annual Book of ASTM Standards, Vol 02.03. resistivity with a precision of 2 %, each specimen shall
B63
Description Dimensions, in. (mm) Material Number
Item
Required
1 Base block ⁄2 by 3 by 4 (12.7 by 76.2 by 101.6) micarta 1
2 Clamp block ⁄4 by 1 by 1 (19.0 by 25.4 by 25.4) copper 2
10 3
3 Current lead clamp screw, knurled head ⁄32 by ⁄16 brass 2
4 Specimen clamp screw, knurled head ⁄4 in. by 40 by 1 in. brass 2
1 15 7
5 Pivot bracket ⁄2 by ⁄16 by 1 ⁄16 (12.7 by 23.8 by 36.5) steel 2
6 Pivot . steel 2
1 3
7 Pivot block ⁄2 by 2 ⁄32by 3 (12.7 by 53.2 by 76.2) micarta 1
8 Potential knife-edge . steel 2 sets
9 Specimen being tested . . .
NOTE 1—Contact surfaces must be clean and free of visible oxide.
FIG. 1 Specimen Holder for Nonductile Materials
conform to the following:
6.2.1 The diameter of a specimen (Fig. 2), or the thickness
and width of a strip specimen, shall be uniform within 1 %, and
6.2.2 It shall show no surface cracks or other defects
observable with normal vision, and shall be free from surface
oxide.
7. Length Measurements
7.1 The length may be measured by any scale which will
give an accuracy of 0.5 % in the length measured. In case
NOTE—Metric equivalents are as follows.
potential leads are used, the length shall be taken between the
potential contacts. In the direction of the length of specimen,
in. mm in. mm
the dimension of each potential contact, including soldering
0.010 0.25 0.438 11.12
surface or clamp contact area, shall not be more than 0.5 % of
0.012 0.30 2.000 50.80
the distance between the potential contacts. In the case of the 0.187 4.75 2.375 60.32
0.188 4.78 3.250 82.55
specimen holder for nonductile materials shown in Fig. 1, the
0.237 6.01
distance between the potential contacts may be found by
FIG. 2 Resistivity Test Specimen for Machinable Nonductile
measuring from the outside flat of one potential knife edge to
Materials
the outside flat of the other. A micrometer shall be used for
...