A new numerical method and modified apparatus for the simultaneous evaluation of thermo-physical properties above 1500 K: A case study on isostatically pressed graphite

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Title: A new numerical method and modified apparatus for the simultaneous evaluation of thermo-physical properties above 1500 K: A case study on isostatically pressed graphite
Author(s): Pavlov, T
Vlahovic, L
Staicu, D
Konings, RJM
Wenman, MR
Van Uffelen, P
Grimes, RW
Item Type: Journal Article
Abstract: This paper presents a new numerical inverse method coupled with an improved apparatus based on the laser flash (LF) technique for the measurement of thermo-physical properties of materials at high temperatures. Using this thermal conductivity, specific heat capacity, thermal diffusivity and spectral emissivity have been measured at temperatures above 1500 K. The method improves the characterization of input parameters such as laser power profile, which was shown to impact thermal conductivity and specific heat capacity by 15–20%. Convective heat losses are characterized semi-empirically and are not fitted. The apparatus has been enhanced via the adoption of a spectropyrometer for the simultaneous measurement of spectral emissivity within an uncertainty of 5% (equivalent to 0.3–0.7% error in temperature in the range 1500–3000 K) The results obtained on isotropic, isostatically pressed, graphite are in good agreement with literature values (around 1500 K) and extend the available data up to 2800 K. Additionally, a model has been developed based on the theory of Debye and Klemens for predicting the temperature dependence of thermal conductivity, specific heat capacity and thermal diffusivity of isotropic graphite. The model is in good agreement with the new experimental data and previous lower temperature data and therefore provides confidence in the new experimental approach.
Publication Date: 10-Mar-2017
Date of Acceptance: 7-Mar-2017
URI: http://hdl.handle.net/10044/1/49145
DOI: https://dx.doi.org/10.1016/j.tca.2017.03.004
ISSN: 0040-6031
Publisher: Elsevier
Start Page: 39
End Page: 52
Journal / Book Title: Thermochimica Acta
Volume: 652
Copyright Statement: © 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Keywords: Science & Technology
Physical Sciences
Thermodynamics
Chemistry, Analytical
Chemistry, Physical
Chemistry
Thermal conductivity
Specific heat
Laser flash
Isotropic graphite
DIFFERENTIAL SCANNING CALORIMETRY
HEAT-CAPACITY
HIGH-TEMPERATURES
THERMODYNAMIC PROPERTIES
ADIABATIC CALORIMETER
LASER POLARIMETRY
FLASH METHOD
DIFFUSIVITY MEASUREMENTS
EMISSIVITY MEASUREMENTS
ELECTRICAL-RESISTIVITY
Physical Chemistry
0301 Analytical Chemistry
Publication Status: Published
Appears in Collections:Faculty of Engineering
Materials
Faculty of Natural Sciences



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