Interfacial tension between aluminum and

The interfacial tension between aluminum and cryolite melts containing different salt additions has been measured by the capillary depression method. This technique involves measuring the capillary depression that occurs when a capillary is moved vertically down through the molten salt layer, passing through the salt/metal interface. The interfacial tension demonstrated a strong dependency on the n(NaF)/n(AlF3) ratio (cryolite ratio, CR). At a cryolite ratio of 2.28 (80 wt.% Na3AlF6 + 10 wt.% AlF3 + 10 wt.% Al2O3 // Al, t = 1000 /C176C), the interfacial tension was measured at 546 mN m )1, reducing to 450 mN m )1 at a cryolite ratio of 4.43 (80 wt.% Na3AlF6 + 10 wt.% NaF + 10 wt.% Al2O3 // Al, t = 1000 /C176C). Under current flow conditions, the tension at the n(NaF)/n(AlF3) ratio of 2.28 decreased from 546 mN m )1 at zero current to 518 mN m )1 at 0.112 A cm )2, and a similar trend was noted for the cryolite ratio of 4.43, decreasing from 450 mN m )1 to 400 mN m )1 at the same current density. Conversely, the interruption of electrolysis resulted in an increase in interfacial tension for these systems.