Materials Fabrication and Corrosion Behavior ofNiFe_2O_4 Cermet Inert Anodes

The cermet inert anodes with the compositions of Cu-NiFe_2O_4 and Ni-NiFe_2O_4 were developed by classical powder metallurgical technique respectively. The corrosion behaviors of NiFe_2O_4-based inert anodes in Na_3AlF_6-Al_2O_3 melts were investigated. The results show that the corrosion behavior of cermet materials is consistent with thermodynamic calculations. To improve densification and electrical conductivity are difficult because copper has poor wetting characteristics to NiFe_2O_4 phase. The relative high porosity can lead to the oxidation of metals in Cu-NiFe_2O_4 cermets and electrolyte penetration into the anodes. The anode was badly swollen at the end of testing. The materials do not degrade during electrolysis via anodic dissolution of copper phase. Preliminary testing of 5%Ni-NiFe_2O_4 cermet materials show that the anodes have excellent performance in cryolite-based melts. Nickel has the tendency to anodic dissolve and ferrite has the tendency of incongruent dissolution.