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

Abstract:

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.

• Periodical: Defect and Diffusion Forum (Volumes 312-315)
• Pages: 217-222
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.312-315.217
• Online since: April 2011
• Authors: Hesham M. Ahmed, Nurni N. Viswanathan, Seshadri Seetharaman
• Keywords: Gas-Solid Reactions, Laser-Flash, NiWO₄, Reduction by Hydrogen, Thermal Diffusivity

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DOI: 10.1016/0017-9310(68)90144-0

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