The effect of pressure on the viscosity of the molten alkali nitrates
The effect of pressure on the viscosity of the molten alkali nitrates
The variation of the shear viscosities of the molten alkali nitrates has been measured as a function of pressure to 1.5 x 108 Pascal for fixed temperatures to 715K. This was achieved using a falling weight, viscometer, the sinker being raised electromagnetically by a set of 15 coils and the fall times subsequently timed by monitoring the change in inductance of a group of 4 of these coils. From the results obtained, Arrhenius plots of inn vs P were made, the slopes of which gave aVn,T, the activation volumes. These have been interpreted as an indication of the effect of cation size upon viscosity through the alkali nitrate series being 2.5 ± 0.9x 10-6 m3 mo1-1 for LiN03 rising to 7.2 ± 0.8 x 10-6 m3 moll for CsN03. The values obtained here discriminate between temperature and density effects and have been compared with those of similar transport studies involving conductivity and diffusion, thereby giving an indication of the differences in the mechanism of movement during these processes for individual ions. It is also apparent from the trend in viscous activation volumes through the alkali nitrate series that Frenkel's hypothesis is confirmed in that the larger particle, in this case the nitrate ion, tends to dominate the extent to which shear forces are resisted in a liquid.
University of Southampton
Divine, Paul Christopher John
1981
Divine, Paul Christopher John
Divine, Paul Christopher John
(1981)
The effect of pressure on the viscosity of the molten alkali nitrates.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The variation of the shear viscosities of the molten alkali nitrates has been measured as a function of pressure to 1.5 x 108 Pascal for fixed temperatures to 715K. This was achieved using a falling weight, viscometer, the sinker being raised electromagnetically by a set of 15 coils and the fall times subsequently timed by monitoring the change in inductance of a group of 4 of these coils. From the results obtained, Arrhenius plots of inn vs P were made, the slopes of which gave aVn,T, the activation volumes. These have been interpreted as an indication of the effect of cation size upon viscosity through the alkali nitrate series being 2.5 ± 0.9x 10-6 m3 mo1-1 for LiN03 rising to 7.2 ± 0.8 x 10-6 m3 moll for CsN03. The values obtained here discriminate between temperature and density effects and have been compared with those of similar transport studies involving conductivity and diffusion, thereby giving an indication of the differences in the mechanism of movement during these processes for individual ions. It is also apparent from the trend in viscous activation volumes through the alkali nitrate series that Frenkel's hypothesis is confirmed in that the larger particle, in this case the nitrate ion, tends to dominate the extent to which shear forces are resisted in a liquid.
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Published date: 1981
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Local EPrints ID: 462914
URI: http://eprints.soton.ac.uk/id/eprint/462914
PURE UUID: 7421edf5-2af0-4025-871c-d32e35ba710a
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Date deposited: 04 Jul 2022 20:22
Last modified: 04 Jul 2022 20:22
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Author:
Paul Christopher John Divine
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