ASTM C408-88(2006)
(Test Method)Standard Test Method for Thermal Conductivity of Whiteware Ceramics
Standard Test Method for Thermal Conductivity of Whiteware Ceramics
SIGNIFICANCE AND USE
This test method provides information useful in understanding and quantifying such parameters as thermal shock resistance and ability to conduct or dissipate heat.
SCOPE
1.1 This test method covers a general procedure for determining the thermal conductivity of whiteware ceramics over the temperature range from 100 to 300°F (40 to 150°C).
1.2 The values stated in inch-pound units are to be regarded as the standard. The SI (metric) units given in parentheses are for information purposes only.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems 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
Relations
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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
Designation:C408–88(Reapproved 2006)
Standard Test Method for
Thermal Conductivity of Whiteware Ceramics
This standard is issued under the fixed designation C408; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope of mercury with an oil-diffusion pump which is backed up with
2 a mechanical vacuum pump.
1.1 This test method covers a general procedure for deter-
3.1.1 Heating Unit—The heating unit, shown in detail in
mining the thermal conductivity of whiteware ceramics over
Fig. 1, shall consist of a 500-W Nichrome element helically
the temperature range from 100 to 300°F (40 to 150°C).
supported by ceramic insulators inside a 2-in. (50.8-mm)
1.2 The values stated in inch-pound units are to be regarded
diameter brass cylinder. This brass cylinder shall be highly
as the standard. The SI (metric) units given in parentheses are
polished to serve also as a reflector, since heat transmission to
for information purposes only.
the upper thermode is primarily by radiation. Line voltage to
1.3 This standard does not purport to address all of the
the heater circuit shall be held constant to within 60.1 % by
safety concerns, if any, associated with its use. It is the
means of an electronic voltage regulator, and power input to
responsibility of the user of this standard to establish appro-
the heater shall be controlled by a variable transformer.
priate safety and health practices and determine the applica-
3.1.2 Thermodes—The thermodes to which the ceramic test
bility of regulatory limitations prior to use.
specimen is soldered shall be machined from electrolytically
2. Significance and Use deposited pure copper to tolerances of 60.001 in. (0.03 mm)
on diameters. Thermodes of diameters from 0.250 to 0.500 in.
2.1 This test method provides information useful in under-
(6.50 to 12.70 mm) may be used, but in all cases the diameters
standing and quantifying such parameters as thermal shock
of the specimen, and that portion of the upper and lower
resistance and ability to conduct or dissipate heat.
thermodes incorporating the thermocouple shall be equal in
3. Apparatus
diameter to within 60.001 in. (0.03 mm). The section of the
upper thermode above the upper cooling jacket shall be coated
3.1 Essentially,theapparatus shallconsistofaheatingunit,
with carbon black to increase its emissivity.
upper and lower copper “thermodes” (bars that serve to
3.1.3 Cooling Jackets—Details of the lower cooling jacket
introduce heat) to which the ceramic test specimen is soldered,
are shown in Fig. 1. The lower thermode makes contact with
and a cooling jacket. The foregoing set of parts shall be
the lower cooling jacket by means of a tapered fit. The upper
enclosed by a 5-in. (127-mm) diameter brass cylinder, 12 in.
⁄8-in. (3.2-mm) brass plate which supports the heating unit
(305 mm) long, which is sealed to the base with a rubber
shall also be water-cooled for the purpose of eliminating
gasket. With the exception of the copper thermodes and the
radiation from the heating unit to the thermodes and test
coppercoolingjackets,theinstrumentshallbemadeentirelyof
specimen below. In addition, the upper thermode shall be fitted
brass with all joints silver soldered. During operation, the
with a copper reflecting shield to prohibit any direct radiation
system shall be evacuated to a pressure of approximately 1 µm
from striking the thermodes and specimen in the chamber
below. A water-circulating system shall be provided for sup-
plying the cooling jackets with water at constant pressure and
ThistestmethodisunderthejurisdictionofASTMCommitteeC21onCeramic
temperature. The water temperatures shall not vary at a rate
Whitewares and Related Products and is the direct responsibility of Subcommittee
C21.03 on Methods for Whitewares and Environmental Concerns.
greater than 1°F (0.5°C)/h.
Current edition approved Feb. 15, 2006. Published February 2006. Originally
3.1.4 Thermocouples—Calibrated glass-asbestos insulated
approved in 1957. Last previous edition approved in 1999 as C408 – 88 (1999).
iron-constantan thermocouples shall be permanently attached
DOI: 10.1520/C0408-88R06.
to the thermodes in positions 1.75 in. (44.4 mm) apart as noted
This work was done under the sponsorship of the U.S. Signal Corps., Squier
Signal Laboratory, Ft. Monmouth, NJ, and the U.S.Air Force, Wright-PattersonAir
in Fig. 2. The diameter of the thermocouple wires used shall
Development Center, OH.
not exceed the diameter of No. 28 AWG (0.321 mm). The
A suitable type of apparatus is described by Edwin Ruh in “Improved Method
thermocouple wires shall be permanently attached to the
of Measuring Thermal Conductivity of Dense Ceramics,” Journal, Am. Ceramic
Society, Vol 37, 1954, No. 5, pp. 224–229. thermode by silver-soldering each wire of the thermocouple
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C408–88 (2006)
FIG. 1 Thermal Conductivity Apparatus
into No. 70 (0.028-in. diameter) (0.71-mm) holes drilled in the the specimens shall be ground to within 60.001 in. (0.03 mm)
thermode to a depth of ⁄32 in. (0.8 mm) on opposite ends of a of the diameter of the thermodes being used.The bases shall be
diameter. All thermocouple wires shall be taken through the perpendicular to the axis of the cylinder within 615 min. The
base plate without any break in the continuity of the wire. An length of the cylinder shall be equal to its diameter within
ice-water bath shall be used for cold junction reference. The 61%.
instrument for measuring emf shall not have an instrument
5. Preparation of Test Specimens
error greater than 60.001 mV.
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.