Chemical Degradation of the Cathodic Ele

The degradation of the cathodic electrical contact between carbon and cast iron is a significant factor affecting the increase of cathode voltage drop (CVD) over the lifespan of aluminum production cells. This study aims to investigate the chemical degradation at the cast iron-carbon interface and assess the influence of various critical parameters, such as temperature and bath chemistry, through lab-scale experiments. Additionally, laboratory results were compared with industrial samples to enhance the understanding of this degradation phenomenon. A thermoelectric Ansys numerical model was applied to predict the effect of surface degradation on CVD. The findings revealed that aluminum formation on the cast iron surface and its subsequent diffusion resulted in the creation of an immiscible mixture comprising a Fe-Al metal alloy and the electrolytic bath. Differences were also observed between industrial samples derived from two distinct technologies, indicating potential strategies to slow degradation processes. Finally, thermoelectric calculations indicated that the increase in contact resistance has a far greater impact on CVD than the degradation of cast iron itself.