ASTM C408-88(1999)

Standard Test Method for Thermal Conductivity of Whiteware Ceramics

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

• Status: Historical
• Publication Date: 09-Oct-1999
• ICS: 81.060.20 - Ceramic products
• Technical Committee: C21 - Ceramic Whitewares and Related Products
• Drafting Committee: C21.03 - Methods for Whitewares and Environmental Concerns

Relations

• Replaced By: ASTM C408-88(2006) - Standard Test Method for Thermal Conductivity of Whiteware Ceramics
• Effective Date: 15-Feb-2006
• Referred By: ASTM C1470-20 - Standard Guide for Testing the Thermal Properties of Advanced Ceramics
• Effective Date: 10-Oct-1999
• Referred By: ASTM D2442-75(2020) - Standard Specification for Alumina Ceramics for Electrical and Electronic Applications
• Effective Date: 10-Oct-1999
• Referred By: ASTM D116-86(2020) - Standard Test Methods for Vitrified Ceramic Materials for Electrical Applications
• Effective Date: 10-Oct-1999

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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 1999)
Standard Test Method for
Thermal Conductivity of Whiteware Ceramics
This standard is issued under the fixed designation C 408; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 3.1.1 Heating Unit—The heating unit, shown in detail in
2 Fig. 1, shall consist of a 500-W Nichrome element helically
1.1 This test method covers a general procedure for deter-
supported by ceramic insulators inside a 2-in. (50.8-mm)
mining the thermal conductivity of whiteware ceramics over
diameter brass cylinder. This brass cylinder shall be highly
the temperature range from 100 to 300°F (40 to 150°C).
polished to serve also as a reflector, since heat transmission to
1.2 The values stated in inch-pound units are to be regarded
the upper thermode is primarily by radiation. Line voltage to
as the standard. The SI (metric) units given in parentheses are
the heater circuit shall be held constant to within 60.1 % by
for information purposes only.
means of an electronic voltage regulator, and power input to
1.3 This standard does not purport to address all of the
the heater shall be controlled by a variable transformer.
safety concerns, if any, associated with its use. It is the
3.1.2 Thermodes—The thermodes to which the ceramic test
responsibility of the user of this standard to establish appro-
specimen is soldered shall be machined from electrolytically
priate safety and health practices and determine the applica-
deposited pure copper to tolerances of 60.001 in. (0.03 mm)
bility of regulatory limitations prior to use.
on diameters. Thermodes of diameters from 0.250 to 0.500 in.
2. Significance and Use (6.50 to 12.70 mm) may be used, but in all cases the diameters
of the specimen, and that portion of the upper and lower
2.1 This test method provides information useful in under-
thermodes incorporating the thermocouple shall be equal in
standing and quantifying such parameters as thermal shock
diameter to within 60.001 in. (0.03 mm). The section of the
resistance and ability to conduct or dissipate heat.
upper thermode above the upper cooling jacket shall be coated
3. Apparatus
with carbon black to increase its emissivity.
3.1.3 Cooling Jackets—Details of the lower cooling jacket
3.1 Essentially,theapparatus shallconsistofaheatingunit,
are shown in Fig. 1. The lower thermode makes contact with
upper and lower copper “thermodes” (bars that serve to
the lower cooling jacket by means of a tapered fit. The upper
introduce heat) to which the ceramic test specimen is soldered,
⁄8-in. (3.2-mm) brass plate which supports the heating unit
and a cooling jacket. The foregoing set of parts shall be
shall also be water-cooled for the purpose of eliminating
enclosed by a 5-in. (127-mm) diameter brass cylinder, 12 in.
radiation from the heating unit to the thermodes and test
(305 mm) long, which is sealed to the base with a rubber
specimen below. In addition, the upper thermode shall be fitted
gasket. With the exception of the copper thermodes and the
with a copper reflecting shield to prohibit any direct radiation
coppercoolingjackets,theinstrumentshallbemadeentirelyof
from striking the thermodes and specimen in the chamber
brass with all joints silver soldered. During operation, the
below. A water-circulating system shall be provided for sup-
system shall be evacuated to a pressure of approximately 1 µm
plying the cooling jackets with water at constant pressure and
of mercury with an oil-diffusion pump which is backed up with
temperature. The water temperatures shall not vary at a rate
a mechanical vacuum pump.
greater than 1°F (0.5°C)/h.
3.1.4 Thermocouples—Calibrated glass-asbestos insulated
iron-constantan thermocouples shall be permanently attached
This test method is under the jurisdiction of ASTM Committee C-21 on
Ceramic Whitewares and Related Products and is the direct responsibility of to the thermodes in positions 1.75 in. (44.4 mm) apart as noted
Subcommittee C21.03 on Test Methods for Whiteware Properties.
in Fig. 2. The diameter of the thermocouple wires used shall
Current edition approved Sept. 30, 1988. Published November 1988. Originally
not exceed the diameter of No. 28 AWG (0.321 mm). The
published as C 408 – 57 T. Last previous edition C 408 – 88 (1994).
thermocouple wires shall be permanently attached to the
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
thermode by silver-soldering each wire of the thermocouple
Development Center, OH.
into No. 70 (0.028-in. diameter) (0.71-mm) holes drilled in the
A suitable type of apparatus is described by Edwin Ruh in “Improved Method
thermode to a depth of ⁄32 in. (0.8 mm) on opposite ends of a
of Measuring Thermal Conductivity of Dense Ceramics,” Journal, Am. Ceramic
Society, Vol 37, 1954, No. 5, pp. 224–229. diameter. All thermocouple wires shall be taken through the
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C408
FIG. 1 Thermal Conductivity Apparatus
base plate without any break in the continuity of the wire. An perpendicular to the axis of the cylinder within 615 min. The
ice-water bath shall be used for cold junction reference. The
length of the cylinder shall be equal to its diameter within
instrument for measuring emf shall not have an instrument
61%.
error greater than 60.001 mV.
5. Preparation of Test Specimens
4. Test Specimens
5.1 Metallize the plane faces of the specimen to be evalu-
4.1 The ceramic test specimens used in the thermal c
...