Investigation of the Cathode Wear Mechanism in a Laboratory Test Cell

Abstract

Cathode wear has become one of the major challenges for the life time of high amperage aluminum reduction cells due to the use of graphitized cathodes. The fundamentals of the cathode wear are still a matter of debate, and a laboratory procedure for testing of cathode materials is desired. Here, we present a laboratory electrolysis cell, which has been designed for cathode wear tests of industrial cathode materials. The formation and transport of aluminum carbide have been considered to be an important factor for cathode wear, and the laboratory test cell was designed in such a way that the cathode is exposed directly to the electrolyte. Aluminum carbide formed at the cathode may dissolve directly into the electrolyte. Here we present the study of the cathode wear of a commercial high density graphitic material, where the influence of the cathode surface morphology, diffusion and hydrodynamics in the electrolyte, have been in focus. The cathode wear and the penetration of electrolyte into the cathode were investigated by optical and electron microscopy. The influence of current density, hydrodynamics and transport of carbide in the electrode are discussed in relation to the experimental results.