Thermodiffusion and vaporization of metal from levitated droplet V. Determination of condensation rate and thermodiffusion parameters of Mn, Fe, and Ni vapours


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Abstract

In the present paper the experimental data of vaporization from levitated droplet for Mn, Co, Ni in the flow of argon obtained from the bibliography were evaluated by means of the new method published in the previous work [Czech. J. Phys. 50 (2000) 737]. The rate constants of condensation, thermodiffusion ratios, thermodiffusion coefficients and the corresponding temperature dependencies were determined together with other physical quantities for Mn vapour at the temperature 2000 K and for Fe, Ni at 2200 K. The rate constant of condensation and the thermodiffusion ratio are higher for Ni than for Fe. The value of thermodiffusion coefficient determined for Mn is rather high and the rate constant of condensation is higher than for Ni. The increase of vaporization resulting from condensation and thermodiffusion for Mn was only 2.7-times and for Fe and Ni (5.5–5.65)-times. The process of vaporization from a levitated droplet includes molecular diffusion and convective diffusion, molecular thermodiffusion with vapour condensation and condensation without thermodiffusion. The proportions of these processes were for Mn in the range (37–29) condensation dominated and its share was over 70 accurate experimental data and this is the reason why the evaluation of the Co vaporization was unsuccessful. The work also presents some proposals of experimental procedures leading to the data accuracy improvement.

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