Homogeneous Nucleation of Carbon Monoxide Bubbles in Iron Drops


Wasan, D. T.


A technique has been developed for the study of the homogenous nucleation of dissolved gases in molten metal, in which levitated molten metal drops in equilibrium with dissolved gas at a high pressure become supersaturated by a sudden decrease of the pressure. The supersaturation can be determined accurately, as it is equal to the pressure drop. This technique has been applied successfully to the study of carbon monoxide gas bubble nucleation in molten iron. The first quantitative data for the critical supersaturation were obtained. The critical supersaturation was found to be strongly dependent on the oxygen activity in molten iron. A supersaturation of 10 atm was enough to initiate CO gas bubble nucleation at oxygen potentials in the melt corresponding to 8% CO2 in CO at 1600°C, and increased to 72 atm at oxygen potentials corresponding to 2% CO2 in CO. The results also showed that even higher supersaturations were required at still lower oxygen potentials; this corresponds to the behavior predicted by the classical theory. These data, together with qualitative results on nitrogen nucleation in molten iron, and the available data on the surface tension of molten iron in the presence of C, O, and N, showed that the number and nature of adsorbed molecules at the surface must play an important role in the homogeneous nucleation process.


Materials Science and Engineering

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Article - Journal

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© 1977 Elsevier, All rights reserved.

Publication Date

01 Jun 1977