Contact Line Undulation Induced Capillary Interaction Between Micron-Sized Ce2O3 Inclusions at the Ar Gas/Liquid Steel Interface

The behavior of Ce2O3 inclusions was observed in-situ at the argon gas/liquid steel interface. A fast agglomeration of inclusions was frequently observed. It is found that inclusions usually have rough surfaces and surface chemical heterogeneities, suggesting an undulating contact line around the inclusions on the liquid steel surface. In this work, both the undulating contact line induced capillary force and the resistive drag force on inclusions are considered. In calculations, the inclusions are treated as capillary 'charges' or 'multipoles' through the analogy with electrostatics. The results show that the capillary 'quadrupole' assumption best represents the strong pairwise attractive force between inclusions. The resistive drag force is dominant compared to the net (inertial) force on the particles by 5 or 6 orders of magnitude. We can conclude that the contact line undulation provides a sufficient attraction for inclusion agglomeration, even for particles smaller than 10 mu m.