日本金属学会誌

J. Japan Inst. Metals, Vol. 59, No. 8 (1995),
pp. 814-820

Evaporation Rate of Molten Iron in Argon Stream and Characteristics ofFormed Ultrafine Iron Particle

Seiji Yokoyama, Katsuyoshi Saito,Naoto Ito and Masahiro Kawakami

Department of Production Systems Engineering, Toyohashi University of Technology, Toyohashi

Abstract:

As a fundamental study of evaporation rate of molten metal in cold gas stream, molten iron was evaporated in argon flow with the levitation melting method. In this experiment, an ultrafine particle was formed in vaporizing the molten iron. Therefore, the effects of temperature (2173{~}2273 K) of the molten iron and gas flow rate (0.167{~}2.50{×}10-4 m3⋅s-1 (STP) on the evaporation rate and the distribution of particle size were investigated.
Since a temperature gradient existed around levitated iron under the present experimental conditions, the evaporation rate was analyzed by the model that iron vapor was nucleated homogeneously in the boundary layer. Furthermore, the absorption of impurities in argon, such as oxygen, was also discussed because the content of oxygen in the levitated iron increased.

The results obtained were summarized as follows:

(1) The evaporation rate increased with increasing temperature and gas flow rate. The rate was well explained by the model.

(2) The ultrafine particles were of α-Fe and Fe3O4. Its mean particle size was ca. 50 nm and unaffected by the experimental conditions.

(3) Since the iron vapor and/or condensed particle reacted with the impurities in the boundary layer, the partial pressure of oxygen on the levitated iron had a tendency to decrease with increasing evaporation rate.


(Received February 13, 1995)

Keywords:

iron, evaporation rate, ultrafine particle, nucleation, oxygen absorption, particle size, variance, α-iron, Fe3O4


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