The Rate of Nitrogen Desorption from Liquid Iron by Blowing Argon Gas under the Condition of Non-inductive Stirring

Abstract

The nitrogen desorption reaction by blowing argon gas onto the surface of liquid iron containing various oxygen contents has been studied in a resistance furnace. Using a periscopic high temperature lens the Marangoni convection was qualitatively observed in the process of nitrogen desorption. In terms of the experimental results and gas-liquid metal reaction kinetic theory, the procedure of the nitrogen desorption is discussed. The nitrogen desorption from liquid iron under the condition of non-inductive stirring exhibits a 1.5^th order dependence with respect to the nitrogen concentration in the melt regardless of oxygen content. The rate of nitrogen desorption is controlled by three mixed rate-controlling steps of gas-and liquid-phase mass transfers and chemical reaction at the gas-metal interface and mainly by the latter two steps. It was deduced that the decrease of the nitrogen desorption rate which accompanies the increment of oxygen concentration was mainly attributed to the attenuation of Marangoni convection and the increase of chemical reaction resistance at the interface in the present study.