Bar to Block Contact Resistance in Aluminum Reduction Cell Cathode Assemblies

Abstract

Contact resistance between the collector bar and cathode block has been previously estimated at 10 Ωmm²contributing roughly 100 mV to cell voltage. This paper proposes four mechanisms as contributors to high contact resistance through low contact pressure and large scale intermittent contact. These mechanisms are: temporary bowing of the bar during solidification of cast iron joints, shrinkage of the bar during the phase change from ferrite to austenite, mismatch of iron and carbon surface texture due to axial thermal expansion, and reduced contact pressure due to creep in the steel bar.