Mechanism of alumina adhesion to continuous caster nozzle with reoxidation of molten steel

\Basic experiments were conducted on the adhesion of Al2O3 in molten steel when molten FeO is present in the molten steel. It was found that the adhesion and coalescence of Al2O3 particles are promoted when molten FeO is present in the molten steel, that FeO and FeAl2O4 are observed in the bond between the Al2O3 particles, and that this observed result agrees with the pattern of Al2O3 adhesion to the continuous caster nozzle when the molten steel is reoxidized. Based on these experimental results, a study was made of the mechanism whereby Al2O3 adheres to the continuous caster nozzle when the molten steel is reoxidized. When the oxygen concentration in the molten steel is locally raised by the reoxidation of the molten steel, the adhesion force of the Al2O3 particles due to the liquid bridge force of the molten FeO is far greater than the adhesion force of the Al2O3 particles due to the van der Waals force or the surface tension of the molten steel. The adhesion of Al2O3 to the nozzle interface is thus considered to proceed mainly with the molten FeO serving as binder. Since the molten FeO binder changes into a solid bridge of FeAl2O4 in a short time, the Al2O3 particles adhering to the nozzle interface are considered to integrate to form a network of Al2O3 particles faster than possible with solid-phase sintering.