Characteristics of Agglomeration of Various Inclusion Particles on Molten Steel Surface.

Abstract

The behavior of various inclusion particles at inert gas/molten steel interface was "in-situ" studied with a confocal scanning laser microscope. Solid CaO-Al₂O₃ and solid CaO-Al₂O₃-SiO₂ inclusion particles were subjected to quick agglomeration to form clusters which densified and deformed later. Capillary attraction was found responsible for the agglomeration and densification. The capillary effect also operated between solid CaO-Al₂O₃ inclusion particle and liquid CaO-Al₂O₃ inclusion particle pairs, making the densification and deformation of the solid inclusion particles much easier. The attraction force was found to be in the range of 10^-16- 10^-13 N for different particles and extended to a distance of up to 100 μm. However, such capillary attraction was not at all found between liquid CaO-Al₂O₃-SiO₂ inclusion particles. Even when the two liquid particles came in touch, merger took place only after contacting for a while. The merger of liquid CaO-Al₂O₃ particles was even more difficult for small particles of less than 7μm, but easier for particles larger than 24 μm. These phenomena are discussed in terms of inert gas/oxide inclusions/liquid steel three-phase interfacial interaction.