Development of porous refractory ceramic plugs: Will the next generation be 3D printed?

Bubble generation in refractory porous plugs: The role of the ceramic surface composition

“…For the steel–argon system, the ceramic plug material plays a major role for D O ≤ 250 μm so that no pore‐dominated region is expected. Although the current commercial plugs based on Al₂O₃ and MgO show a good performance regarding the resistance to infiltration, 29 these compositions result in the largest bubble diameters. For instance, the ideal D B value to withdraw silica inclusions from liquid steel ranges within 1 and 5 mm based on kinetic aspects, which is restricted within the 1.5–2 mm range when the thermodynamic aspects are coupled 8,17 .…”

“…Thus, the surface wettability establishes a trade‐off between the resistance to infiltration of liquid metal in the purging plug and the generation of small bubbles capable of removing inclusions as these targets are better addressed with high and low contact angles, respectively. However, it is worth noting that the wettability acts at different moments for each effect because the bubble spreads over the horizontal surface of the ceramic plug during bubbling, whereas the infiltration is controlled by the capillary wall underneath the pore 29 . Coupled with cutting edge manufacturing techniques (i.e., additive manufacturing), these fundamentals could be further applied to develop infiltration‐delayed ceramic plugs, also able to generate small bubbles.…”

“…However, it is worth noting that the wettability acts at different moments for each effect because the bubble spreads over the horizontal surface of the ceramic plug during bubbling, whereas the infiltration is controlled by the capillary wall underneath the pore. 29 Coupled with cutting edge manufacturing techniques (i.e., additive manufacturing), these fundamentals could be further applied to develop infiltration-delayed ceramic plugs, also able to generate small bubbles.…”

“…In summary, applying Equation () to ceramic plugs underestimates the bubble size for non‐wetting surface compositions, commonly used to limit the liquid steel infiltration 29 . Consequently, the plug would generate larger bubbles than predicted, displacing their size distribution out of the optimum range for inclusion capturing and removal.…”