Image Analysis Investigating Porous Structures of Carbon Cathodes Materials and Melts Penetration

During aluminum electrolysis, the cryolitic melts will penetrate into the carbon cathode block through porous structure. Na generated from the cryolitic melts will lead cathode expansion and deterioration. This work is aimed to give a better understanding of the relationship between the pore structure and the cryolitic melts penetration. Image analysis was applied to characterize the porous structures of the virgin cathode. Penetration experiments with carbon cathode materials were carried out and the penetrated melts distribution in the cathode samples were analyzed by SEM-EDS. The quantitative information of porous structures shows 50–80% pores in cathode external areas filled by melts after 180 min electrolysis tests. Most of melts penetrated into the narrow open pores. Selective mechanism of the melts penetration into pores was discussed. The information obtained could be useful for improving control of the cathode quality through quantitative image analysis.