DYNAMIC YOUNGS MODULUS AS A FUNCTION OF SOFT THERMAL-SHOCK TEMPERATURES FOR CATHODE BLOCK MATERIALS FOR ALUMINUM REDUCTION CELLS

The purpose of this work was to investigate the variations in Young's modulus of anthracite cathode blocks with soft thermal shock temperatu res during two repeated heating-cooling cycles at a constant rate (i.e . 120 +/- 20 degrees C/h). The vibrated anthracite cathode block conta ins 20 (wt%) graphite, with a 7 mm maximum grain size. Such blocks are currently used in aluminum reduction cells. The measurements were car ried out using acoustic transmission in two directions, i.e., parallel and perpendicular to the aggregate grain alignment. The results show that aggregate grain alignment, grain size, thermal expansion/contract ion behaviour, aggregate/binder interface, coupled with heating-coolin g temperatures (degrees C) are the most important factors affecting th e Young's modulus at high temperatures.