Effect of sintering oxygen partial pressure on microstructure and its mechanical and electrical properties of 25(20Ni-Cu)/(10NiO-NiFe2O4)cermets
In order to improve the relative density and optimize the phase composition of cermets,the cermets with a nominal composition of 25(20Ni-Cu)/(10NiO-NiFe2O4)were prepared by controlled oxygen partial pressure sintering.Based on the thermodynamics of ternary phase equilibrium of Fe-Ni-O,the influence of the sintering oxygen partial pressure on the microstructure,mechanical and electrical properties of the materials was explored,and the effect of different oxygen partial pressures on the sintered cermets was revealed.Under different sintering oxygen partial pressures,the oxygen loss reaction and organization evolution mechanism of cermets were revealed.The results show that the sintering oxygen partial pressure affects the decomposition of the spinel phase and the oxidation process of the metal phase,which in turn determines the equilibrium phase composition of the cermet.NiFe2O4 phase is partially decomposed,and the metal phase is higher than the standard content when the oxygen partial pressure is in the range of 2.1-12.1 Pa,and the equilibrium phase composition of the cermet after sintering at 1 250℃is CuNiFe-NiO-NiαFe3-αO4.The mechanical properties and electrical conductivity of the cermets decrease with the increase of oxygen partial pressure,and the samples has the highest relative density of 99.7％,flexural strength of 176.86 MPa,and room temperature conductivity of 14 S·cm-1 when the oxygen partial pressure is 2.1 Pa.
metal ceramicsaluminum electrolysismechanical propertieselectrical propertiessintering atmosphere
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