Abstract:
An extensive laboratory study has been undertaken to determine the effect of changes in internal structure on graphitized and graphitic cathode blocks used in aluminium reduction cells. Research has focused on sub-surface chemical and electrochemical wear. Previous work on graphitized material (published in Light Metals 2005) showed increasing the total porosity leads to uneven wear with pitting due to particle detachment becoming a noticeable feature of the surface topography. Results also showed that wear is dependant on the combined interaction of multiple variables, in particular the interaction between current density, bath chemistry and porosity. This paper focuses on recent work with a graphitic material. Compared to the graphitized materials, the graphitic cathodes show even wear phenomena with less surface pitting; this is due to the reduction in porosity in the graphitic material. The effect of variables such as current density, bath chemistry and porosity will also be addressed.
