ASTM E1225-04
(Test Method)Standard Test Method for Thermal Conductivity of Solids by Means of the Guarded-Comparative-Longitudinal Heat Flow Technique
Standard Test Method for Thermal Conductivity of Solids by Means of the Guarded-Comparative-Longitudinal Heat Flow Technique
SIGNIFICANCE AND USE
The comparative method of measurement of thermal conductivity is especially useful for engineering materials including ceramics, polymers, metals and alloys, refractories, carbons, and graphites including combinations and other composite forms of each.
Proper design of a guarded-longitudinal system is difficult and it is not practical in a method of this type to try to establish details of construction and procedures to cover all contingencies that might offer difficulties to a person without technical knowledge concerning theory of heat flow, temperature measurements, and general testing practices. Standardization of this test method is not intended to restrict in any way the future development by research workers of new or methods or improved procedures. However, new or improved techniques must be thoroughly tested. Requirements for qualifying an apparatus are outlined in Section 10.
SCOPE
1.1 This test method describes a steady state technique for the determination of the thermal conductivity, , of homogeneous-opaque solids (see Note 1 and Note 2). This test method is for materials with effective thermal conductivities in the approximate range 0.2 200 W/(mK) over the approximate temperature range between 90 and 1300 K. It can be used outside these ranges with decreased accuracy. Note 0For purposes of this technique, a system is homogeneous if the apparent thermal conductivity of the specimen, A, does not vary with changes of thickness or cross-sectional area by more than 5 %. For composites or heterogeneous systems consisting of slabs or plates bonded together, the specimen should be more than 20 units wide and 20 units thick, respectively, where a unit is the thickness of the thickest slab or plate, so that diameter or length changes of one-half unit will affect the apparent A by less than 5 %. For systems that are non-opaque or partially transparent in the infrared, the combined error due to inhomogeneity and photon transmission should be less than 5 %. Measurements on highly transparent solids must be accompanied with infrared absorption coefficient information, or the results must be reported as apparent thermal conductivity, A.Note 2
This test method may also be used to evaluate the contact thermal conductance/resistance of materials.
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.
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Standards Content (Sample)
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Designation:E1225–04
Standard Test Method for
Thermal Conductivity of Solids by Means of the Guarded-
1
Comparative-Longitudinal Heat Flow Technique
This standard is issued under the fixed designation E1225; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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 C177 Test Method for Steady-State Heat Flux Measure-
ments and Thermal Transmission Properties by Means of
1.1 This test method describes a steady state technique for
the Guarded-Hot-Plate Apparatus
the determination of the thermal conductivity, l,of
C408 Test Method for Thermal Conductivity of Whiteware
homogeneous-opaque solids (see Notes 1 and 2). This test
Ceramics
methodisformaterialswitheffectivethermalconductivitiesin
C1045 PracticeforCalculatingThermalTransmissionProp-
the approximate range 0.2 < l < 200 W/(m·K) over the
erties Under Steady-State Conditions
approximate temperature range between 90 and 1300 K. It can
D4351 Test Method for Measuring the Thermal Conductiv-
be used outside these ranges with decreased accuracy.
ity of Plastics by the Evaporation-Calorimetric Method
NOTE 1—For purposes of this technique, a system is homogeneous if
E220 Test Method for Calibration of Thermocouples By
the apparent thermal conductivity of the specimen, l , does not vary with
A
Comparison Techniques
changes of thickness or cross-sectional area by more than 65%. For
E230 Specification and Temperature-Electromotive Force
composites or heterogeneous systems consisting of slabs or plates bonded
(EMF) Tables for Standardized Thermocouples
together, the specimen should be more than 20 units wide and 20 units
F433 Practice for EvaluatingThermal Conductivity of Gas-
thick, respectively, where a unit is the thickness of the thickest slab or
plate, so that diameter or length changes of one-half unit will affect the
ket Materials
apparent l by less than 65%. For systems that are non-opaque or
A
partially transparent in the infrared, the combined error due to inhomo- 3. Terminology
geneityandphotontransmissionshouldbelessthan 65%.Measurements
3.1 Descriptions of Terms and Symbols Specific to This
onhighlytransparentsolidsmustbeaccompaniedwithinfraredabsorption
Standard:
coefficientinformation,ortheresultsmustbereportedasapparentthermal
3.1.1 Terms:
conductivity, l .
A
3.1.1.1 thermal conductivity, l—the time rate of heat flow,
NOTE 2—This test method may also be used to evaluate the contact
understeadyconditions,throughunitarea,perunittemperature
thermal conductance/resistance of materials.
gradient in the direction perpendicular to the area;
3.1.1.2 apparent thermal conductivity—when other modes
1.2 This standard does not purport to address all of the
of heat transfer through a material are present in addition to
safety concerns, if any, associated with its use. It is the
conduction,theresultsofthemeasurementsperformedaccord-
responsibility of the user of this standard to establish appro-
ing to this test method will represent the apparent or effective
priate safety and health practices and determine the applica-
thermal conductivity for the material tested.
bility of regulatory limitations prior to use.
3.1.2 Symbols:
2. Referenced Documents
2
2.1 ASTM Standards:
l (T) = thermalconductivityofmeterbars(reference
M
materials) as a function of temperature, (W/
1
ThistestmethodisunderthejurisdictionofASTMCommitteeE37onThermal
(m·K)),
1
Measurements and is the direct responsibility of Subcommittee E37.05 onThermo-
l = thermal conductivity of top meter bar (W/
M
physical Properties.
(m·K)),
Current edition approved May 1, 2004. Published June 2004. Originally
2
l = thermal conductivity of bottom meter bar
approved in 1987. Last previous edition approved in 1999 as E1225–99. DOI: M
10.1520/E1225-04. (W/(m·K)),
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
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
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1
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E1225–04
l (T) = thermal conductivity of specimen corrected
S
for heat exchange where necessary, (W/(
m·K)),
l8 (T) = thermal conductivity of specimen calculated
S
by ignoring heat exchange correction, (W/
(m·K)),
l (T) = thermal conductivity of insulation as a func-
I
tion of temperature, (W/(m·K)),
T = absolute temperature (K),
Z = position as measured from t
...
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