Interfacial wetting mechanisms of Al liquid on cathode carbon blocks of aluminum reduction cell for developing wettable cathode materials

Abstract

Molecular dynamics simulation had been performed to investigate the wetting properties of Al droplets on amorphous carbon surfaces and graphite surfaces. The effects of temperature, graphitization of substrate and roughness were considered. Our results show that the contact angles can be improved effectively with the increased temperature. Furthermore, the Al droplet on graphite surface has a better wettability than that on amorphous carbon surface. Similarly, the contact angle will also reduce with the increased degree of graphitization and the wetting state will change from the transition wetting state to the Cassie state when the roughness increases. In addition to the contact angles on the rough surface, the remaining contact angles are less than 90°, which is different from the previous reports. The free energy and thermodynamic properties analysis were applied to character the solid-liquid interface properties and explain the wettability. Another interesting finding is that the study reveals the reason of the poor wettability between Al liquid and cathode carbon blocks of aluminum electrolytic cell. These findings improve our understandings of the wetting behaviors of Al droplets on cathode carbon block surfaces at the atomistic level, which is profitable to develop the wettable cathode materials for aluminum electrolysis.