The Preparation Methods And Performance Investigation Of Inert Anodes In Aluminium Electrolysis

The project of cermets, used as the inert anodes for aluminum electrolysis, has been carrying out combined with low corrosion of oxides and perfect conductivity of alloy. NiFe₂O₄-based cermets were prepared by doping the NiFe₂O₄ ceramic matrix with the mixed powders of Cu and Ni as the electrical conducting metallic elements. The effects of calcining atmosphere on synthesized condition of NiFe₂O₄ are studied with SEM and XRD. On the basis, sintering atmosphere are analyzed the oxidization of metal phase and decomposition of ceramic phase during the sintering process. The effects of technics parameters, such as the sintering time, the sintering temperature and the contents of metallic phase on the relative density and electrical conductivity of the cermets were studied. The electrical conductive mechanism of NiFe₂O₄-based cermets was investigated.The mainly conclusions and findings can be summarized as follows:1) The synthetical condition of NiFe₂O₄ is found to be suitable as Fe₂O₃ and NiO calcined at 1150°C for 6 hours;2) The sintering atmosphere has an effect on the molding performance apparently. Sintering atmosphere are efficaciously controlled at various temperature to avoid the oxidization of metal phase and decomposition of ceramic phase during the sintering process; Raising sintering temperature can increase the relative density and conductivity of cermets, however, excessively high sintering temperature may make low-melting-point metals melt and flowed out of the sample or deformation;3) Nickel is a favorable sintering aid. It can improve the wettability between Cu and NiFe₂O₄ due to a good sintering performance between NiFe₂O₄ and Ni.4) NiFe₂O₄-based cermets obey the semi-conductive mechanism. When the content of metal is less than 20%, the pyroconductivity of cermets are mainly determined by the conductivity of ceramic phase and the dispersion and content of metallic phase.5) The high density and electric conductivity are obtained when the metallic elements were added in the form of the Cu and Ni powders owing to metallic phase dispersed finely and uniformly, Ni-NiFe₂O₄ cermets were easier to obtain the compacted structure than Cu-NiFe₂O₄ and Cu-Ni-NiFe₂O₄ sintered at the same temperature and preconditioned without metal effusion from cermets and distribution homogeneousness of metal phase in cermets when the contents of addictive metal was added from 0 to 20%. The conductivity of Cu-Ni-NiFe₂O₄ cermet is at least 1～2 magnitude higher than that of nickel ferrite;...