• Lathabai, Sri
• Vecchio-Sadus, Angelica
• Dorin, R.
• Constable, Duncan
• Fernandez, Irene
• Frazer, Eric
• Neal, Graeme
• Tomsett, Alan
• Trigg, Mark
• Johnson, John

Abstract

The behaviour of tin dioxide-based ceramics as inert anodes was examined in a laboratory-scale aluminium smelting cell over a range of electrolyte compositions with operating temperatures between 830 -975°C. Anodes of a nominal composition Sn02 (96 wt%), Sb203 (2 wt%) and CuO (2 wt%), were electrolyzed for 90 min at a current density of ~1 A cm"2. The corrosion rate was determined from the tin and copper concentrations in the recovered electrolyte, aluminium metal and the fume. The corrosion rates were 12.5, 1.6 and 6.5 mg (Ah)"1 in electrolytes with bath ratios 1.5 (975°C), 0.89 (903°C) and 0.74 (830°C), respectively. A four-fold increase in corrosion rate was obtained at open-circuit demonstrating the protection provided by oxygen evolution during electrolysis. A preliminary investigation of the dependence of corrosion rate on firing temperatures and additive (Sb203 and CuO) concentrations was conducted using a part-factorial design experiment. Post-electrolysis examination of the anodes using scanning electron microscopy coupled with energy dispersive spectroscopy analysis revealed a depletion of copper from the anode and a build-up of an alumina-rich surface layer under certain conditions.

Topics

• density
• surface
• corrosion
• scanning electron microscopy
• experiment
• Oxygen
• aluminium
• copper
• current density
• ceramic
• tin
• spectroscopy