Algorithms for thermal diffusivity measurement of heterogeneous 1D materials based on Infrared Microscopy Enhanced Angstrom Method

Abstract An infrared microscopy enhanced Angstrom method has been develpoed to measure the thermal diffusivity. Infrared microscopy technique can acquire temperatures of multiple points at one shot. Two algorithms for calculating thermal diffusivity were proposed and compared in practice. One is based on global temperature data and the other is based on local temperature data. The according calculated thermal diffusivities are denoted as α n G and α n L . Three 1D materials of different heterogeneity (Cu wire, Ni-Cu wire and PVA-CNT fiber) were measured on the experimental platform. The calculated α n G and α n L values show that for homogeneous material such as Cu, these two algorithms give similar results, while for heterogeneous ones (Ni-Cu and PVA-CNT), they come to be discrepant. The data fluctuation analysis of f n L zooms in the discrepancy and verifies that α n L is more sensitive to local property change and more competent in revealing heterogeneous properties.

Download Full-text

Thermal Diffusivity Measurement of Pure Te, (Hg1−x Cdx)1−yTey and (Hg1−xZnx)1−yTey

MRS Proceedings ◽

10.1557/proc-299-127 ◽

1994 ◽

Vol 299 ◽

Author(s):

Hossein Maleki ◽

Lawrence R. Holland

Keyword(s):

Thermal Diffusivity ◽

Melting Point ◽

Wide Temperature Range ◽

Laser Flash ◽

Thermal Diffusivity Measurement ◽

Temperature Range ◽

Diffusivity Measurement ◽

Laser Flash Technique ◽

Flash Technique ◽

Thermal Diffusivities

AbstractThe thermal diffusivities of (Hg1−xCdx)1−yTey and (Hg1−xZnx)1−yTeywith 0.55 ≤ y ≤ 1.0 and 0.0125 ≤ x ≤ 0.05465 and of pure Te are measured over a wide temperature range by the laser flash technique. The diffusivity of near pseudobinary Hg1−xCdxTe solids decrease more rapidly with temperature approaching the melting point than pseudobinary solids previously reported. The solid diffusivity for x=0.02817 is 0.83 mm2/s at 371°C, decreasing to 0.22 mm2/s at 614°C. The diffusivity of Te rich (Hg1−xCdx)1−yTey melt increases with x and with temperature. The melt diffusivity for x=0.03934 is 0.91 mm2/s at 485°C, increasing to 4.93 mm2/s at 851°C. For Te rich (Hg1−xZnx)1−yTey melt with x=0.0125 and y=0.7944 there appears to be a minimum diffusivity of about 2.6 mm2/s near 700°C. The thermal diffusivity of pure Te solid is 0.97 mm2/s at 300°C and decreases to 0.64 mm2/s at 439°C. The melt diffusivity is 1.52 mm2/s at 486°C, increasing to 3.48 mm2/s at 584°C.

Download Full-text

Application of infrared microscopy to thermal diffusivity measurement in refractories at various temperatures

High Temperatures-High Pressures ◽

10.1068/htec547 ◽

1998 ◽

Vol 30 (2) ◽

pp. 205-210 ◽

Cited By ~ 10

Author(s):

Jean-François Bisson ◽

Danièle Fournier

Keyword(s):

Thermal Diffusivity ◽

Infrared Microscopy ◽

Thermal Diffusivity Measurement ◽

Diffusivity Measurement

Download Full-text

THERMAL DIFFUSIVITY OF Bi2Sr2CaCu2O8 CERAMICS WITH NANO Ag ADDITION MEASURED USING OPEN-CELL PHOTOACOUSTIC TECHNIQUE

Modern Physics Letters B ◽

10.1142/s0217984908017473 ◽

2008 ◽

Vol 22 (30) ◽

pp. 3015-3023 ◽

Cited By ~ 1

Author(s):

M. A. B. NARRETO ◽

K. WEI ◽

R. ABD-SHUKOR ◽

H. A. ALWI

Keyword(s):

Thermal Diffusivity ◽

Electrical Resistance ◽

Photoacoustic Technique ◽

Thermal Diffusivity Measurement ◽

Metallic Behavior ◽

Open Cell ◽

Ag Addition ◽

Diffusivity Measurement ◽

Thick Region ◽

Thermal Diffusivities

This paper reports the results of thermal diffusivity measurement on nano Ag added Bi 2 Sr 2 CaCu 2 O 8- Ag x (with x = 0–1.0) ceramics using an open-cell photoacoustic instrument. The thermal diffusivities were obtained by analyzing the phase of the photo-acoustic signal of thermally thick samples using Calderon's method as well as the analysis of the phase in thermally thick region. We found that the thermal diffusivity increases with the amounts of nano Ag . The values of thermal diffusivity obtained were between 0.01250 ± 0.00128 to 0.01606 ± 0.00230 cm 2/ s for Ag 0 to Ag 1.0. The electrical resistance versus temperature measurements showed a metal-like behavior for all samples. However, a metal-like transition was observed between x = 0.5 and 0.7 when results of thermal diffusivity and electrical resistance measurements were analyzed together with samples x ≥ 0.7 showing the metallic behavior.

Download Full-text

Development of UO2 thermal diffusivity measurement with laser techniques

EPJ Web of Conferences ◽

10.1051/epjconf/202125307005 ◽

2021 ◽

Vol 253 ◽

pp. 07005

Author(s):

Thomas Doualle ◽

Vincent Le Guillous ◽

Vincent Klosek ◽

Claire Onofri-Marroncle ◽

Matthieu Reymond ◽

...

Keyword(s):

Thermal Conductivity ◽

Thermal Diffusivity ◽

Measurement Techniques ◽

Material Model ◽

Laser Flash ◽

Flash Method ◽

Infrared Microscopy ◽

Thermal Diffusivity Measurement ◽

Diffusivity Measurement ◽

Wide Range

The knowledge of the thermal conductivity of nuclear fuel and its evolution as a function of temperature and burn up is a major challenge in the context of the evaluation and understanding of irradiated fuel performances in current reactors. It is also the case for the development and qualification of fuel for future reactors. Indeed, numerical simulations of the fuel behaviour under various conditions require the accurate knowledge of thermal conductivity over a wide range of temperature (from ambient to melting point temperature) but also at the scale of few tens of micrometres to take into account the microstructural effects on the thermomechanical evolution of the fuel in normal or incidental irradiation conditions. Different methods, using laser matter interactions, can deduce the thermal conductivity from a thermal diffusivity measurement. In this paper, the potential of two techniques, which present spatial resolution from millimetre to few tens microns, are discussed in the context of the determination of the fuel thermal conductivity: laser flash method and infrared microscopy. Experiments on graphite, as material model, have been conducted and validate these two thermal diffusivity measurement techniques. We present a measurement example for both methods on graphite and then a first experiment carried out with the infrared microscopy technique on UO2.

Download Full-text