Mechanism of Reaction between Submerged-Entry Nozzle Refractory and Liquid Steel with Emphasis on Gas Generation in the SEN

Abstract

One of the causes of nozzle clogging during continuous casting of liquid steels is interfacial chemical reaction between the refractory and the liquid steels. Several researches have been conducted focusing on the interfacial reaction product. However, evaluation of the interfacial chemical reaction have been insufficient. Without the evaluation of the interfacial reaction, it is difficult to find out the refractory material capable of suppressing the nozzle clogging. Therefore, in the present study, the interfacial chemical reaction between the refractory and liquid steels was assessed in various ways: thermodynamic calculations, in-situ gas analysis using QMS (Quadrupole Mass Spectrometer), evolution of steel compositions during interfacial reaction, thickness of interfacial reaction product. Also, various nozzle refractories composed of different constituents were employed: alumina-silica-C base, SiO2-less, lime-zirconia-C base, C-less, and oxide-less refractories composed of oxynitride and nitride. Based on the evaluation results, the refractory material capable of suppressing the nozzle clogging was suggested, which can also contribute to the design direction of the nozzle material. It was found that the oxide-less refractory was efficient to suppress the clogging, followed by SiO2-less refractory.