A Study On Oxidation And Molten Salt Corrosion Behavior Of Cu-Ni/（10NiO-NiFe₂O₄）Cermets

NiFe2O4based cermets were one of the most promising industrial inert anode materials for aluminum electrolysis at present. The high sintering density, good conductivity and excellent corrosion resistance in high temperature molten salt were required for this kind of materials. Supported by the National Basic Research Program (973Program) and the National High-Tech Research and Development Program (863Program), the effect of sintering temperature, the metal phase composition and content on the cermets sintering densification and mechanical properties has been studied mainly in this paper. Besides, the oxidation behavior in air and molten salt corrosion behavior of Cu-Ni/(10NiO-NiFe2O4) at880and960"C has also been discussed. The main works were summarized as followed:(1) The10NiO-NiFe2O4ceramic powders and Ni coated Cu metal powders were synthesied by solid-state reaction method and chemical plating, and the cermets samples were prepared by isostatic pressing-atmosphere sintering method. It was found that increasing the sintering temperature and metal phase content of Cu contributes to the cermets sintering densification, but at the same time, easy to cause the metal phase overflow; The bending strength, thermal shock resistance and fracture toughness are improved obviously with the increasing content of the metal phase.(2) The oxidation behavior in air at880℃of40(50Cu-Ni)/(10NiO-NiFe2O4) cermets has been studied and the effect of the metal phase composition and content on it were discussed. The results show that the oxidation process was conducted by the external oxidation of Cu and in situ oxidation of Ni while the oxide film could be divided into three layers.With the increasing metal phase content of Cu or the oxide temerature,antioxidant properties of materials decresed and pores and even cracks could be found in the oxide film.(3) The molten salt corrosion behavior of40(50Cu-Ni)/(10NiO-NiFe2O4) cermets in different electrolysis temperature has been studied. It was found that the electrolysis at960℃could do favor to the electrolytic stability and the formation of the dense surface layer,while at880℃, the loss of outer layer metal phase became serious and the infiltration of electrolyte into anode aggravated the intergranular corrosion which decreased the anode corrosion resistance.