ASTM E1461-01
(Test Method)Standard Test Method for Thermal Diffusivity of Solids by the Flash Method
Standard Test Method for Thermal Diffusivity of Solids by the Flash Method
SIGNIFICANCE AND USE
Thermal diffusivity is an important property, required for such purposes as design applications under transient heat flow conditions, determination of safe operating temperature, process control, and quality assurance.
The flash method is used to measure values of thermal diffusivity, α, of a wide range of solid materials. It is particularly advantageous because of simple specimen geometry, small specimen size requirements, rapidity of measurement and ease of handling, with a single apparatus, of materials having a wide range of thermal diffusivity values over a large temperature range.
Under certain strict conditions, specific heat capacity of a homogeneous isotropic opaque solid sample can be determined when the method is used in a quantitative fashion (see Appendix X4).
Thermal diffusivity results, together with specific heat capacity (Cp) and density (ρ) values, can be used in many cases to derive thermal conductivity (λ), according to the relationship:
SCOPE
1.1 This test method covers the determination of the thermal diffusivity of primarily homogeneous isotropic solid materials. Thermal diffusivity values ranging from 10-7 to 10-3 m 2/s are readily measurable by this test method from about 75 to 2800 K.
1.2 This test method is a more detailed form of Test Method C 714, but has applicability to much wider ranges of materials, applications, and temperatures, with improved accuracy of measurements.
1.3 This test method is applicable to the measurements performed on materials opaque to the spectrum of the energy pulse, but with special precautions can be used on fully or partially transparent materials (see Appendix X1).
1.4 This test method is intended to allow a wide variety of apparatus designs. It is not practical in a test method of this type to establish details of construction and procedures to cover all contingencies that might offer difficulties to a person without pertinent technical knowledge, or to stop or restrict research and development for improvements in the basic technique.
1.5 This test method is applicable to the measurements performed on essentially fully dense materials; however, in some cases it has shown to produce acceptable results when used with porous samples. Since the magnitude of porosity, pore shapes, sizes and parameters of pore distribution influence the behavior of the thermal diffusivity, extreme caution must be exercised when analyzing data. Special caution is advised when other properties, such as thermal conductivity, are derived from thermal diffusivity obtained by this method.
1.6 This test method can be considered an absolute (or primary) method of measurement, since no reference standards are required. It is advisable to use reference materials to verify the performance of the instrument used.
1.7 This method is applicable only for homogeneous solid materials, in the strictest sense; however, in some cases it has shown to produce data which may be useful in certain applications.
1.7.1 Testing of Composite Materials--When substantial inhomogeneity and anisotropy is present in a material, the thermal diffusivity data obtained with this method may be substantially in error. Nevertheless, such data, while usually lacking absolute accuracy, may be useful in comparing materials of similar structure. Extreme caution must be exercised when related properties, such as thermal conductivity, are derived, as composites may have heat flow patterns substantially different than uniaxial.
1.7.2 Testing Liquids--This method has found an especially useful application in determining thermal diffusivity of molten materials. For this technique, specially constructed sample enclosures must be used.
1.7.3 Testing Layered Materials--This method has also been extended to test certain layered structures made of dissimilar materials, where one of the layers is considered unknown. In some cases, contact conductance of the interface may also be determined.
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Designation:E1461–01
Standard Test Method for
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Thermal Diffusivity by the Flash Method
This standard is issued under the fixed designation E1461; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 1.7.1 Testing of Composite Materials—When substantial
inhomogeneity and anisotropy is present in a material, the
1.1 Thistestmethodcoversthedeterminationofthethermal
thermal diffusivity data obtained with this method may be
diffusivity of primarily homogeneous isotropic solid materials.
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substantially in error. Nevertheless, such data, while usually
Thermal diffusivity values ranging from 10 to 10 m /s are
lacking absolute accuracy, may be useful in comparing mate-
readily measurable by this test method from about 75 to
rials of similar structure. Extreme caution must be exercised
2800K.
when related properties, such as thermal conductivity, are
1.2 ThistestmethodisamoredetailedformofTestMethod
derived, as composites may have heat flow patterns substan-
C714,buthasapplicabilitytomuchwiderrangesofmaterials,
tially different than uniaxial.
applications, and temperatures, with improved accuracy of
1.7.2 Testing Liquids—Thismethodhasfoundanespecially
measurements.
useful application in determining thermal diffusivity of molten
1.3 This test method is applicable to the measurements
materials. For this technique, specially constructed sample
performed on materials opaque to the spectrum of the energy
enclosures must be used.
pulse, but with special precautions can be used on fully or
1.7.3 Testing Layered Materials—This method has also
partially transparent materials (see Appendix X1).
been extended to test certain layered structures made of
1.4 This test method is intended to allow a wide variety of
dissimilar materials, where one of the layers is considered
apparatus designs. It is not practical in a test method of this
unknown. In some cases, contact conductance of the interface
typetoestablishdetailsofconstructionandprocedurestocover
may also be determined.
all contingencies that might offer difficulties to a person
1.8 The values stated in SI units are to be regarded as the
without pertinent technical knowledge, or to stop or restrict
standard.
research and development for improvements in the basic
1.9 This standard does not purport to address all of the
technique.
safety concerns, if any, associated with its use. It is the
1.5 This test method is applicable to the measurements
responsibility of the user of this standard to establish appro-
performed on essentially fully dense materials; however, in
priate safety and health practices and determine the applica-
some cases it has shown to produce acceptable results when
bility of regulatory limitations prior to use.
used with porous samples. Since the magnitude of porosity,
poreshapes,sizesandparametersofporedistributioninfluence
2. Referenced Documents
thebehaviorofthethermaldiffusivity,extremecautionmustbe
2.1 ASTM Standards:
exercised when analyzing data. Special caution is advised
C714 Test Method for Thermal Diffusivity of Carbon and
when other properties, such as thermal conductivity, are
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Graphite by a Thermal Pulse Method
derived from thermal diffusivity obtained by this method.
E230 Temperature-Electromotive Force (EMF) Tables for
1.6 This test method can be considered an absolute (or
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Standardized Thermocouples
primary)methodofmeasurement,sincenoreferencestandards
are required. It is advisable to use reference materials to verify
3. Terminology
the performance of the instrument used.
3.1 Definitions of Terms Specific to This Standard:
1.7 This method is applicable only for homogeneous solid
3.1.1 thermal conductivity, l, of a solid material—the time
materials, in the strictest sense; however, in some cases it has
rate of steady heat flow through unit thickness of an infinite
shown to produce data which may be useful in certain
slab of a homogeneous material in a direction perpendicular to
applications.
the surface, induced by unit temperature difference. The
property must be identified with a specific mean temperature,
since it varies with temperature.
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ThistestmethodisunderthejurisdictionofASTMCommitteeE37onThermal
Measurements and is the direct responsibility of Subcommittee E37.05 onThermo-
physical Properties.
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Current edition approved Feb. 10, 2001. Published May 2001. Originally Annual Book of ASTM Standards, Vol 05.05.
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published as E1461–92. Last previous edition E1461–92. Annual Book of ASTM Standards, Vol 14.03.
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