EFFECT OF MnO2 ADDITIVE ON PERFORMANCES OF NiFe2O4 SPINEL BASED INERT ANODE
Pages: 603-608
Year: 2005 Issue: 5
Journal: ACTA METALLURGICA SINICA
Keyword: nickel ferrite spinel; inert anode; corrosion resistance; aluminum electrolysis;
Abstract: The NiFe2O4 inert anode is synthesized by high-temperature solid-state reaction method using NiO and Fe2O3 as main raw materials and adding MnO2 powder as additive. Archimedes method using water immersion technique is used to measure the sintering performances of samples. The static thermal corrosion rates of samples are measured by weight loss. SEM is employed for the observation of material microstructure, and phase structure of the sample surface after corrosion is determined by XRD. The experimental results indicate that a suitable MnO2additive content is 2%, while the sintering performance is the best, and the static thermal corrosion rate is the lowest. Because of MnO2 dopant enriching at crystal boundary, the corrosion reaction of molten salt to crystal grain creates Mn2AlO4 phase, which is denser than NiFe2O4phase, and prevents the cryolite molten salt to penetrate into the inert anode, thus reducing the corrosion.
Year: 2005 Issue: 5
Journal: ACTA METALLURGICA SINICA
Keyword: nickel ferrite spinel; inert anode; corrosion resistance; aluminum electrolysis;
Abstract: The NiFe2O4 inert anode is synthesized by high-temperature solid-state reaction method using NiO and Fe2O3 as main raw materials and adding MnO2 powder as additive. Archimedes method using water immersion technique is used to measure the sintering performances of samples. The static thermal corrosion rates of samples are measured by weight loss. SEM is employed for the observation of material microstructure, and phase structure of the sample surface after corrosion is determined by XRD. The experimental results indicate that a suitable MnO2additive content is 2%, while the sintering performance is the best, and the static thermal corrosion rate is the lowest. Because of MnO2 dopant enriching at crystal boundary, the corrosion reaction of molten salt to crystal grain creates Mn2AlO4 phase, which is denser than NiFe2O4phase, and prevents the cryolite molten salt to penetrate into the inert anode, thus reducing the corrosion.
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