ASTM C714-23

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C714 − 23
Standard Guide for
Thermal Diffusivity of Carbon and Graphite by Thermal
1
Pulse Method
This standard is issued under the fixed designation C714; 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* 3. Terminology
1.1 This guide covers the determination of the thermal 3.1 Definitions:
diffusivity of carbons and graphite at temperatures up to 3.1.1 For definitions of terms used in this guide, refer to
500 °C. It is applicable only to small easily fabricated speci-
Terminology D4175.
2
mens. Thermal diffusivity values in the range from 0.04 cm /s
3.1.2 thermal conductivity, n—the rate at which heat passes
2
to 2.0 cm /s are readily measurable by this guide; however, for
through a material, expressed as the amount of heat that flows
the reason outlined in Section 7, for materials outside this
per unit time through a unit area with a temperature gradient of
range this guide may not be applicable.
one degree per unit distance.
1.2 Units—The values stated in SI units are to be regarded 3.1.3 thermal diffusivity, n—a measure of the ability of a
as the standard. No other units of measurement are included in
material to conduct thermal energy relative to its ability to store
this standard. thermal energy; it is equal to the thermal conductivity divided
by density and specific heat capacity at constant pressure.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Summary of Guide
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
4.1 A high-intensity short-duration thermal pulse from a
mine the applicability of regulatory limitations prior to use.
flash lamp is absorbed on the front surface of a specimen; and
1.4 This international standard was developed in accor-
the rear surface temperature change as a function of time is
dance with internationally recognized principles on standard-
recorded. The pulse raises the average temperature of the
ization established in the Decision on Principles for the
specimen only a few degrees above its initial value. The
Development of International Standards, Guides and Recom-
ambient temperature of the specimen is controlled by a furnace
mendations issued by the World Trade Organization Technical
or cryostat. Thermal diffusivity is calculated from the specimen
Barriers to Trade (TBT) Committee.
thickness and the time required for the temperature of the back
3
surface to rise to one half of its maximum value (1).
2. Referenced Documents
2
4.2 The critical factors in this guide are:
2.1 ASTM Standards:
1
4.2.1 τ/t ⁄2 must be 0.02 or less. τ is the pulse time as defined
C781 Practice for Testing Graphite Materials for Gas-Cooled
1
in Fig. 1 and t ⁄2 is the time for the rear surface temperature to
Nuclear Reactor Components
rise to one half of its maximum value (see Fig. 2).
D4175 Terminology Relating to Petroleum Products, Liquid
4.2.2 Heat losses from the specimen via radiation,
Fuels, and Lubricants
convection, or conduction to the specimen holder must be
D7775 Guide for Measurements on Small Graphite Speci-
small. Whether or not this condition is violated can be
mens
determined experimentally from the data output, an example of
E1461 Test Method for Thermal Diffusivity by the Flash
1 1
which is shown in Fig. 2. If ΔT(10 t ⁄2 )/ΔT(t ⁄2 ) > 1.98, the heat
Method
losses are assumed to be zero.
1
1 4.2.3 The measurement must be such that ΔT , ΔT(10t ⁄2 ),
This guide is under the jurisdiction of ASTM Committee D02 on Petroleum
max
1
Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-
and t ⁄2 can be determined to 62 %.
mittee D02.F0 on Manufactured Carbon and Graphite Products.
4.2.4 The other conditions are less critical, and the experi-
Current edition approved Oct. 1, 2023. Published October 2023. Originally
menter is left to their discretion.
approved in 1972. Last previous edition approved in 2017 as C714 – 17. DOI:
10.1520/C0714-23.
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
3
Standards volume information, refer to the standard’s Document Summary page on The boldface numbers in parentheses refer to the list of references at the end of
the ASTM website. this guide.
*A Summary of Changes section appears at the end of this s
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