ANODE BEHAVIOR OF NIO–FE2O3–CR2O3–CU COMPOSITE AT LOW-TEMPERATURE ELECTROLYSIS OF ALUMINUM

Abstract

To produce 25,3NiO–41,2Fe2O3–13,5Cr2O3–20Cu oxide-metal composite (wt.%), the temperature and sintering duration (1350 °С, 30 min.) have been determined, which provide the formation of chromium oxide solid solution in nickel ferrite phase. The composite has been tested as an anode during low-temperature (800 °C) alumina saturated 12,0NaF–36,8KF–51,2AlF3 (wt.%) melt electrolysis. The amount of oxygen gas evolved from the anode was measured. The oxygen gas evolution is shown to be the main reaction on the anode at current density of 0,015 to 1,0 A·сm–2, and a substantial increase in the oxidation rate of the composite anode is observed at i = 0,015÷1,0 A·сm–2. The electrolyzer voltage (4,5±0,5 V) and the anode potential (2,43±0,2 relatively to the Al-reference electrode) during a long-term experiment (89 h, i = 0,4 A·сm–2) show stable and admissible composite electric conductivity; and the dissolution rate calculated from the mass loss (0,6 cm/year) and volume loss (0,7 cm/year) meets the requirements to inert anodes.