Basic experiments were conducted on the adhesion of Al
2O
3 in molten steel when molten FeO is present in the molten steel. It was found that the adhesion and coalescence of Al
2O
3 particles are promoted when molten FeO is present in the molten steel, that FeO and FeAl
2O
4 are observed in the bond between the Al
2O
3 particles, and that this observed result agrees with the pattern of Al
2O
3 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 Al
2O
3 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 Al
2O
3 particles due to the liquid bridge force of the molten FeO is far greater than the adhesion force of the Al
2O
3 particles due to the van der Waals force or the surface tension of the molten steel. The adhesion of Al
2O
3 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 FeAl
2O
4 in a short time, the Al
2O
3 particles adhering to the nozzle interface are considered to integrate to form a network of Al
2O
3 particles faster than possible with solid-phase sintering.
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