| The Hall-Heroult process is universally used in aluminum industry and has many disadvantages because of using carbon anode. Inert anode has been studied since late of1860s to reduce carbon dioxide emissions. NiFe2O4spinel has high-stability, small-coefficient at high temperature and excellent corrosion-resistance which makes it rank top materials for inert anode. In this work, the Kinetics of solid-phase synthesis NiFe2O4and the influence of additives on the kinetics are studied.NiFe2O4was synthesized by high-temperature solid-state reaction method. The effect of factors such as raw material ratio, synthesizing temperature, synthesizing time and press pressure on the sintering performance and electric conductivity of NiFe2O4have been investigated detailly and the most suitable synthesizing technology is obtained. The results show, the synthesizing reaction of NiFe2O4was completely after heating for6h at900-1000℃in case that raw materials ratio of NiO and Fe2O3is1.5:1. The best preparation condition of sample is as:ball mill24h and pressed at160MPa.The sintering thermodynamics and kinetics of NiFe2O4are also investigated, and diffusion sintering is introduced for the first time to study the initial stage sintering mechanism of different spinel powder synthesized at different synthesizing temperature. The experimental results show that the thermodynamic conditions are available to the solid-phase reaction of NiO with Fe2O3, and the synthesis of NiFe2O4pinel powder is controlled by diffusion and meet the first order kinetic equation.The microstructure and components of intert anode are analyzed by SEM and X-ray analysis. The influences of additives and additive content on the performance of NiFe2O4have been studied. The results show that TiO2and MnO2additives increase the conductivity of4. The synthesizing activation energy of NiFe2O4is53.1kJ·mol-1and greater than that with1wt%TiO2(45.5kJ·mol-1) and1wt%MnO2(39.7kJ·mol-1). TiO2and MnO2additives improved the sintering property... |
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