ASTM C657-93(2013)
(Test Method)Standard Test Method for D-C Volume Resistivity of Glass
Standard Test Method for D-C Volume Resistivity of Glass
SIGNIFICANCE AND USE
4.1 This experimental procedure yields meaningful data for the dc volume resistivity of glass. It is designed to minimize space charge, buildup polarization effects, and surface conductances. The temperature range is limited to room temperature to the annealing point of the specimen glass.
SCOPE
1.1 This test method covers the determination of the dc volume resistivity of a smooth, preferably polished, glass by measuring the resistance to passage of a small amount of direct current through the glass at a voltage high enough to assure adequate sensitivity. This current must be measured under steady-state conditions that is neither a charging current nor a space-charge, buildup polarization current.
1.2 This test method is intended for the determination of resistivities less than 1016 Ω·cm in the temperature range from 25°C to the annealing point of the glass.
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 and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 5.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: C657 − 93 (Reapproved 2013)
Standard Test Method for
D-C Volume Resistivity of Glass
This standard is issued under the fixed designation C657; 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 heating chamber with adequate temperature control, electrical
shielding and insulation of the sample leads as described in
1.1 This test method covers the determination of the dc
Test Method D1829.
volume resistivity of a smooth, preferably polished, glass by
measuring the resistance to passage of a small amount of direct
4. Significance and Use
current through the glass at a voltage high enough to assure
4.1 This experimental procedure yields meaningful data for
adequate sensitivity. This current must be measured under
the dc volume resistivity of glass. It is designed to minimize
steady-state conditions that is neither a charging current nor a
space charge, buildup polarization effects, and surface conduc-
space-charge, buildup polarization current.
tances. The temperature range is limited to room temperature
1.2 This test method is intended for the determination of
to the annealing point of the specimen glass.
resistivities less than 10 Ω·cm in the temperature range from
25°C to the annealing point of the glass.
5. Cautions
1.3 This standard does not purport to address all of the
5.1 Thermal emfs should be avoided. Connections involv-
safety concerns, if any, associated with its use. It is the
ing dissimilar metals can cause measurement difficulties. Even
responsibility of the user of this standard to establish appro-
copper-copper oxide junctions can produce high thermal emfs.
priate safety and health practices and determine the applica-
Clean, similar metals should be used for electrical junctions.
bility of regulatory limitations prior to use. For specific hazard
Platinum is recommended. Welded or crimped connections
statements, see Section 5.
rather than soldered joints avoid difficulties. Specimen elec-
trodes shall have sufficient cross section for adequate electrical
2. Referenced Documents
conductance.
2.1 ASTM Standards:
D257 Test Methods for DC Resistance or Conductance of 6. Apparatus
Insulating Materials
6.1 Resistance-Measuring Devices, and the possible prob-
D374 Test Methods for Thickness of Solid Electrical Insu-
lems associated with them are discussed thoroughly in Section
lation (Withdrawn 2013)
9 and Appendixes A1 and A3 of Test Methods D257. Further
D1711 Terminology Relating to Electrical Insulation
discussion of electrometer circuitry is covered in AnnexA1 to
D1829 Test Method for Electrical Resistance of Ceramic
this test method.
Materials at Elevated Temperatures (Withdrawn 2001)
6.2 Heating Chamber (Fig. 1)—For heating the specimen, a
suitable electric furnace shall be used. The construction of the
3. Summary of Test Method
furnace shall be such that the specimen is subjected to a
3.1 The dc volume resistance is measured in accordance
uniform heat application with a minimum of temperature
with Test Methods D257, with the specimen located in a
fluctuation. An adequate muffle should be provided to shield
the specimen from direct radiation by the heating elements.
This may be made of a ceramic such as aluminum oxide or
This test method is under the jurisdiction of ASTM Committee C14 on Glass
equivalent. A grounded metallic shield shall also be provided
and Glass Products and is the direct responsibility of Subcommittee C14.04 on
within the furnace, preferably of silver, stainless steel, or
Physical and Mechanical Properties.
equivalent, to isolate electrically the specimen test circuit from
Current edition approved Oct. 1, 2013. Published October 2013. Originally
approved in 1970. Last previous edition approved in 2008 as C657 – 93 (2008).
the heating element. Furnaces for more than one specimen can
DOI: 10.1520/C0657-93R13.
be constructed. The control thermocouple may be located in
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
the heating chamber outside the metallic shield, as shown in
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Fig. 1, or inside the metallic shield.
the ASTM website.
6.3 Two Flat Contacting Electrodes, smaller in diameter
The last approved version of this historical standard is referenced on
www.astm.org. than the specimen electrodes (see 7.6), shall be used to
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C657 − 93 (2013)
NOTE 1—Heating elements attached to fused alumina core—covered with baked-on refractory cement.
FIG. 1 Heating Chamber
sandwich the specimen. Sufficient thickness should be used to in detail the specimen requirements.To quote in part, “The test
maintain an adequate pressure and to provide heat equalization specimen may have any practical form that allows the use of a
between the specimen and the contacting electrodes. third electrode, when necessary, to guard against error from
6.3.1 Fig. 2 shows the specimen setup in the heating surface effects.” For practical reasons, a flat disk or square that
chamber. The bottom electrode shall be placed at the end of a is easy to set up in a furnace box is recommended. Other
metal rod and shall support the specimen in the center of the configurations are possible. The descriptions will apply to flat
furnace. The unguarded specimen electrode, No. 3 of Fig. 3, samples but can be modified for other configurations. Recom-
shall be placed in contact with this bottom contacting elec- mended limitations in the diameter of a disk are 40 to 130 mm.
trode. The top contacting electrode shall be placed on the This is not a critical dimension as the effective area of
guarded, specimen electrode, No. 1 of Fig. 3. This top measurements is defined by the area of the applied electrodes,
contacting electrode has leads connected to an off-center metal as stated in 7.7.
rod. The specimen guard electrode, No. 2 of Fig. 3, shall be
7.2 Astheelectricalpropertiesofglassaredependentonthe
connected to the second off-center metal rod with platinum
thermal condition of the specimen, this condition should be
wire or strap. One end shall be connected to the specimen
known and reported.
guard electrode; the other end shall be connected to the metal
rod.
NOTE 1—The glass could be annealed or have had a special heat
treatment which should be clearly defined.
6.3.2 All rods should be supported by insulation outside the
furnace in a cool zone to minimize electrical leakage at
7.3 Polished surfaces are preferable as they permit easier
elevated temperatures.
cleaning and application of metallic electrodes.
6.3.3 Fig. 4 shows a top view of the specimen setup in the
7.4 Thickness of the specimen should be determined with
heating chamber.
micrometer calipers, calibrated to 0.01 mm, averaging several
6.4 A Temperature-Control System should be provided so
measurements on the specimen, as described in Test Methods
that temperature-time fluctuations within the heating chamber
D374. Recommended limitations on thickness are from 1.0 to
are less than 0.01 T (where T is the temperature in degrees
4.0 mm with a maximum variation of 60.1 mm.
Celsius), during the time interval when resistance measure-
ments are made. Two thermocouples should be used for 7.5 There are two main reasons for cleaning a specimen:(1)
accurate temperature readings, one in the heating chamber, to assure better contact between an applied electrode and the
supplying the emf to the temperature controller and the other surface of the specimen and (2) to remove contaminants that
on the guard ring of the specimen. The latter should be used to may lower the surface resistivity, thereby introducing an error
measure the specimen temperature as instructed in the Appa- in the measurements. If the glass is chemically durable, a
ratus section (Temperature-Control Device) of Test Method recommended cleaning procedure is: (1) trichloroethylene, (2)
D1829. detergent-water solution, (3) distilled water rinse, and (4)
alcohol rinse, air dry. Special surface treatments, poor
7. Test Specimen
durability, or the desire to include the effect of surface
7.1 The Test Specimens section (Volume Resistance or treatment require modification or elimination of the cleaning
Conductance Determination) of Test Methods D257 describes procedure.
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