scholarly journals HIGH TEMPERATURE THERMAL DIFFUSIVITY MEASUREMENTS BY THE FLASH TECHNIQUE

1965 ◽  
Author(s):  
B.H. Morrison ◽  
D.J. Klein ◽  
L.R. Cowder
Keyword(s):  
High Temperature ◽  
Thermal Diffusivity ◽  
Diffusivity Measurements ◽  
Flash Technique

scholarly journals Uncertainty Assessment for Very High Temperature Thermal Diffusivity Measurements on Molybdenum, Tungsten and Isotropic Graphite

2021 ◽  
Vol 43 (1) ◽  
Author(s):  
Bruno Hay ◽  
Olivier Beaumont ◽  
Guillaume Failleau ◽  
Nolwenn Fleurence ◽  
Marc Grelard ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Diffusivity ◽  
Laser Flash ◽  
Uncertainty Assessment ◽  
National Metrology Institute ◽  
Thermal Diffusivity Measurement ◽  
Uncertainty In Measurement ◽  
Diffusivity Measurements ◽  
Very High ◽  
Isotropic Graphite

AbstractThe French National Metrology Institute LNE has improved its homemade laser flash apparatus in order to perform accurate and reliable measurements of thermal diffusivity of homogeneous solid materials at very high temperature. The inductive furnace and the associated infrared (IR) detection systems have been modified and a specific procedure for the in situ calibration of the used radiation thermometers has been developed. This new configuration of the LNE’s diffusivimeter has been then applied for measuring the thermal diffusivity of molybdenum up to 2200 °C, tungsten up to 2400 °C and isotropic graphite up to 3000 °C. Uncertainties associated with these high temperature thermal diffusivity measurements have been assessed for the first time according to the principles of the “Guide to the Expression of Uncertainty in Measurement” (GUM). Detailed uncertainty budgets are here presented in the case of the isotropic graphite for measurements performed at 1000 °C, 2000 °C and 3000 °C. The relative expanded uncertainty (coverage factor k = 2) of the thermal diffusivity measurement is estimated to be between 3 % and 5 % in the whole temperature range for the three investigated refractory materials.

scholarly journals Effect of radiative heat loss on thermal diffusivity evaluated using normalized logarithmic method in laser flash technique

2020 ◽  
Vol 39 (1) ◽  
pp. 390-394
Author(s):  
Tsuyoshi Nishi ◽  
Naoyoshi Azuma ◽  
Hiromichi Ohta
Keyword(s):  
High Temperature ◽  
Thermal Diffusivity ◽  
Heat Loss ◽  
Radiative Heat ◽  
Laser Flash ◽  
Solid Samples ◽  
Radiative Heat Loss ◽  
Logarithmic Method ◽  
Laser Flash Technique ◽  
Flash Technique

AbstractThe laser flash technique is a standard method to measure the thermal diffusivity of solid samples especially at high temperatures. To understand the reliability of thermal diffusivity evaluation at high temperature for solid samples with low-thermal-diffusivity values, we analyzed the effect of radiative heat loss using the logarithmic method. The results revealed that when the Biot number was 0.1, the deviation from the input thermal diffusivity value was approximately −1.6%. In addition, when an aluminum silicate (AS) sample was heated to 1,273 K, the maximum deviation was approximately −0.35%. In contrast, the difference between the input value and the thermal diffusivity evaluated by the halftime method when AS was heated to 1,273 K was approximately 2.38%. Thus, since the effect of radiative heat loss was found to be negligible, it is concluded that the normalized logarithmic method should be very useful for the thermal diffusivity analysis of low-thermal-diffusivity solid samples at high temperature.

Dynamic Thermal Diffusivity Measurements – A Tool for Studying Gas-Solid Reactions

2011 ◽  
Vol 312-315 ◽  
pp. 217-222
Author(s):  
Hesham M. Ahmed ◽  
Nurini N. Viswanathan ◽  
Seshadri Seetharaman
Keyword(s):  
Thermal Diffusivity ◽  
Laser Flash ◽  
Diffusivity Measurements ◽  
Calculated Activation Energy ◽  
Laser Flash Technique ◽  
Flash Technique ◽  
The Difference ◽  
Increasing Temperature ◽  
Cold Pressed ◽  
Calculated Activation

In the present work, the thermal diffusivity measurements of uniaxially cold pressed NiWO4 has been carried out. The measurements were performed isothermally at temperatures between 973 and 1273 K under H2 gas using the laser flash technique. The experimental thermal diffusivity values were found to increase with the reduction progress as well as with increasing temperature. The calculated activation energy was found to be higher than that for chemically controlled reaction. The difference has been attributed to factors like agglomeration of the product as well as sintering of the precursor along with the chemical reaction. In order to sort out the sintering effect on the thermal diffusivity values, complementary experiments have been done on pressed NiWO4 and Ni-W, produced by the reduction of NiWO4 at 1123K, under Argon gas. The porosity change and its effect on thermal diffusivity values have been studied.

Thermal diffusivity measurements on a single fiber with microscale diameter at very high temperature

2006 ◽  
Vol 45 (5) ◽  
pp. 443-451 ◽  
Author(s):  
C. Pradère ◽  
J.M. Goyhénèche ◽  
J.C. Batsale ◽  
S. Dilhaire ◽  
R. Pailler
Keyword(s):  
High Temperature ◽  
Thermal Diffusivity ◽  
Single Fiber ◽  
Diffusivity Measurements ◽  
Very High
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