ASTM C657-93(2008)
(Test Method)Standard Test Method for D-C Volume Resistively of Glass
Standard Test Method for D-C Volume Resistively of Glass
SIGNIFICANCE AND USE
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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Designation: C657 − 93(Reapproved 2008)
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
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
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 April 1, 2008. Published December 2008. Originally
approved in 1970. Last previous edition approved in 2003 as C657 – 93 (2003).
the heating element. Furnaces for more than one specimen can
DOI: 10.1520/C0657-93R08.
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
Withdrawn. 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
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C657 − 93 (2008)
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
guard electrode; the other end shall be connected to the metal known and reported.
rod.
NOTE 1—The glass could be annealed or have had a special heat
6.3.2 All rods should be supported by insulation outside the
treatment which should be clearly defined.
furnace in a cool zone to minimize electrical leakage at
elevated temperatures. 7.3 Polished surfaces are preferable as they permit easier
6.3.3 Fig. 4 shows a top view of the specimen setup in the cleaning and application of metallic electrodes.
heating chamber.
7.4 Thickness of the specimen should be determined with
6.4 A Temperature-Control System should be provided so
micrometer calipers, calibrated to 0.01 mm, averaging several
that temperature-time fluctuations within the heating chamber
measurements on the specimen, as described in Test Methods
are less than 0.01 T (where T is the temperature in degrees
D374. Recommended limitations on thickness are from 1.0 to
Celsius), during the time interval when resistance measure-
4.0 mm with a maximum variation of 60.1 mm.
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
D1829. recommended cleaning procedure is: (1) trichloroethylene, (2)
detergent-water solution, (3) distilled water rinse, and (4)
7. Test Specimen
alcohol rinse, air dry. Special surface treatments, poor durabil-
ity, or the desire to include the effect of surface treatment
7.1 The Test Specimens section (Volume Resistance or
Conductance Determination) of Test Methods D257 describes require modification or elimination of the cleaning procedure.
-----------------
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
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:C657–93 (Reapproved 2003) Designation: C 657 – 93 (Reapproved 2008)
Standard Test Method for
D-C Volume Resistivity of Glass
This standard is issued under the fixed designation C 657; 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
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 10 V·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.
2. Referenced Documents
2.1 ASTM Standards:
D 257 Test Methods for DC Resistance or Conductance of Insulating Materials
D 374 Test Methods for Thickness of Solid Electrical Insulation
D 1711 Terminology Relating to Electrical Insulation
D 1829 Test Method for Electrical Resistance of Ceramic Materials at Elevated Temperatures (Discontinued 2001)
3. Summary of Test Method
3.1 The dc volume resistance is measured in accordance with Test Methods D 257, with the specimen located in a heating
chamber with adequate temperature control, electrical shielding and insulation of the sample leads as described in Test Method
D 1829.
4. 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.
5. Cautions
5.1 Thermal emfs should be avoided. Connections involving dissimilar metals can cause measurement difficulties. Even
copper-copper oxide junctions can produce high thermal emfs. Clean, similar metals should be used for electrical junctions.
Platinum is recommended. Welded or crimped connections rather than soldered joints avoid difficulties. Specimen electrodes shall
have sufficient cross section for adequate electrical conductance.
6. Apparatus
6.1 Resistance-Measuring Devices, and the possible problems associated with them are discussed thoroughly in Section 9 and
Appendixes A1 and A3 of Test Methods D 257. Further discussion of electrometer circuitry is covered in Annex A1 to this test
method.
6.2 Heating Chamber (Fig. 1) —For heating the specimen, a suitable electric furnace shall be used. The construction of the
furnace shall be such that the specimen is subjected to a uniform heat application with a minimum of temperature fluctuation.An
This test method is under the jurisdiction of ASTM Committee C14 on Glass and Glass Products and is the direct responsibility of Subcommittee C14.04 on Physical
and Mechanical Properties.
Current edition approved May 15, 1993. Published July 1993. Originally approved in 1970. Last previous edition approved in 1988 as C657–88.
Current edition approved April 1, 2008. Published December 2008. Originally approved in 1970. Last previous edition approved in 2003 as C 657 – 93 (2003).
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book ofASTM Standards
, Vol 10.01.volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C 657 – 93 (2008)
NOTE 1—Heating elements attached to fused alumina core—covered with baked-on refractory cement.
FIG. 1 Heating Chamber
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 equivalent.Agrounded metallic shield shall also be provided within the furnace, preferably
of silver, stainless steel, or equivalent, to isolate electrically the specimen test circuit from the heating element. Furnaces for more
thanonespecimencanbeconstructed.Thecontrolthermocouplemaybelocatedintheheatingchamberoutsidethemetallicshield,
as shown in Fig. 1, or inside the metallic shield.
6.3 Two Flat Contacting Electrodes , smaller in diameter than the specimen electrodes (see 7.6), shall be used to sandwich the
specimen. Sufficient thickness should be used to maintain an adequate pressure and to provide heat equalization between the
specimen and the contacting electrodes.
6.3.1 Fig. 2 shows the specimen setup in the heating chamber. The bottom electrode shall be placed at the end of a metal rod
and shall support the specimen in the center of the furnace. The unguarded specimen electrode, No. 3 of Fig. 3, shall be placed
in contact with this bottom contacting electrode. The top contacting electrode shall be placed on the guarded, specimen electrode,
No. 1 of Fig. 3. This top contacting electrode has leads connected to an off-center metal rod. The specimen guard electrode, No.
2 of Fig. 3, shall be connected to the second off-center metal rod with platinum wire or strap. One end shall be connected to the
specimen guard electrode; the other end shall be connected to the metal rod.
6.3.2 All rods should be supported by insulation outside the furnace in a cool zone to minimize electrical leakage at elevated
temperatures.
6.3.3 Fig. 4 shows a top view of the specimen setup in the heating chamber.
6.4 ATemperature-ControlSystem shouldbeprovidedsothattemperature-timefluctuationswithintheheatingchamberareless
than 0.01 T(where Tis the temperature in degrees Celsius), during the time interval when resistance measurements are made.Two
thermocouples should be used for accurate temperature readings, one in the heating chamber, supplying the emf to the temperature
controller and the other on the guard ring of the specimen. The latter should be used to measure the specimen temperature as
instructed in the Apparatus section (Temperature-Control Device) of Test Method D 1829.
7. Test Specimen
7.1 The Test Specimens section (Volume Resistance or Conductance Determination) of Test Methods D 257 describes in detail
the specimen requirements. To quote in part, “The test specimen may have any practical form that allows the use of a third
electrode, when necessary, to guard against error from surface effects.” For practical reasons, a flat disk or square that is easy to
set up in a furnace box is recommended. Other configurations are possible. The descriptions will apply to flat samples but can be
modified for other configurations. Recommended limitations in the diameter of a disk are 40 to 130 mm. This is not a critical
dimension as the effective area of measurements is defined by the area of the applied electrodes, as stated in 7.7.
7.2 As the electrical properties of glass are dependent on the thermal condition of the specimen, this condition should be known
and reported.
NOTE 1—The glass could be annealed or have had a special heat treatment which should be clearly defined.
7.3 Polished surfaces are preferable as they permit easier cleaning and application of metallic electrodes.
7.4 Thickness of the specimen should be determined with micrometer calipers, calibrated to 0.01 mm, averaging several
measurements on the specimen, as described in Test Methods D 374. Recommended limitations on thickness are from 1.0 to 4.0
C 657 – 93 (2008)
FIG. 2 Specimen Setup for Heating Chamber
FIG. 3 Glass Specimen with Three-Terminal Electrodes
mm with a maximum variation of 60.1 mm.
7.5 There are two main reasons for cleaning a specimen: (1) to assure better contact between an applied electrode and the
surface of the specimen and (2) to remove contaminants that may lower the surface resistivity, thereby introducing an error in the
measurements. If the glass is chemically durable, a recommended cleaning procedure is: (1) trichloroethylene, (2) detergent-water
solutio
...
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