Influence of temperature and contact pressure between cast iron and cathode carbon on contact resistance

The contact resistance between the cathode block and cast iron, as collector bar casting agent, is said to give a significant contribution to the cathode voltage drop (CVD) measured in aluminum electrolysis cells. Five typical cathode carbon qualities were examined in this respect from room temperature to 950 C. At cell operating temperature the contact resistance in new cells is found to be usually negligible in comparison to other resistance effects. However, inadequate casting parameters and cell aging processes leading to an improper contact or contact pressure may impede the current flow between cast iron and cathode block considerably and hence result in an increasing CVD with cell age.