Abstract:NiFe₂O₄-Cu cermet inert anodes containing 5%-20% Cu were prepared by cold pressing-sintering NiFe₂O₄ ceramic powder synthesized by solid state reaction and Cu metal powder. The effects of sintering atmosphere and temperature on the phase compositions, microstructure and morphology, physical properties of the cermet products were studied. The results show that the NiFe₂O₄-Cu cermet with the desired phase composition can be obtained by controlling the partial oxygen pressure between the decomposition oxygen pressures of NiO and Cu₂O; sintering temperature and holding time are vital for the relative density of the NiFe₂O₄-Cu cermets; the improvement of sintering temperature and prolonging of holding time are limited due to the low melting point and poor wetting characteristics of copper towards the NiFe₂O₄ phases, thus the relative density of NiFe₂O₄-Cu cermets obtained is less to assure its compositions uniformity and without metallic protrusion on the surface; the more the metal content of NiFe₂O₄-Cu cermet, the lower the maximum sintering temperature and the shorter the longest holding time, so its relative density is lower and its apparent porosity is higher. Besides decreasing the metal content, other metals with better wetting characteristics and higher melting point, such as nickel and cobalt, may be added to the NiFe₂O₄-Cu cermets to increase its sintering temperature, relative density and resistance.

Key words: NiFe₂O₄-Cu cermet; inert anode; preparation technics; aluminium electrolysis