Thermo-Mechanical Characterisation of Graphitic and Graphitized Carbon Cathode Materials Used in Aluminium Electrolysis Cells

In the conventional Hall-Heroult electrolysis process, both the carbon anode and cathode operate at up to 980 degrees C and under a very, corrosive environment. Since the lifetime expectancy is an important economic point to take into consideration it is imperative that all process related phenomena present in the cells be well understood, e.g. the thermo-mechanical behaviour of carbon cathode materials used into the cell linings. To do so, an experimental program based on uniaxial compressive tests, for a temperature range from 25 degrees C to 1000 degrees C, has been conducted on graphitic and graphitized cathodes. The Young's modulus, compressive strength and damaging coefficients at various temperatures arc examples of measured properties. The properties of both cathode block types were compared and analysed. The evolution in temperature is found different according to the material, and further investigation together with tests on a new high temperature apparatus are required to confirm the experimental results and explain the behaviour.