| The new technology for aluminum smelting based on inert anodeand wettable cathode, which can reduce production cost, cut down energyconsumption and is environmentally friendly, means a technologicalrevolution of the traditional aluminum electrolysis industry. Founded bythe State Key Project of Fundamental Research (973 project), and withthe aim of realizing low-temperature sintering densification of10NiO-NiFe204 cermet. The cold pressing-sintering process is used and10NiO-NiFe2O4 based ceramic and cermet with high densification areprepared at low sintering temperature by doping sintering assistants. Anideal sintering assistant is ascertained for 10NiO-NiFe2O4 based ceramic,Effect of the sintering assistant on densification, mechanical property andelectrical conductivity of ceramic is studied, and the sintering theory isdicussed. The main results are summarized as follows:1) Effect of ZnO, Bi2O3, CaO and content on sintering densificationof 10NiO-NiFe2O4 composite ceramic is studied, the problems of highsintering temperature and difficultly densifying are resolved,low-temperature sintering densification of 10NiO-NiFe2O4 ceramic isrealized, and the sintering temperature is reduced 200℃. CaO isascertained as ideal sintering assistant: When sintered at 1200℃, thesamples doped with 2％CaO have the maximum relative density of98.75％, which increases about 20％compared to the undoped samplessintered at same temperature, and higher than relative density(97.3％) ofthe undoped samples sintered at 1400℃. The sintering is promoted byZnO and Bi2O3 doping, but the high relative density can not obtained atlow temperature, ZnO and Bi2O3 are not the ideal sintering assistant.2) When samples sintered at 1200℃, bending strength increasesobviously with CaO doping, the samples doped with 2％CaO have themaximum bending strength of 185MPa, and is two times than that(60MPa) of the samples without CaO doping; Fracture toughness isimproved obviously with CaO doping, the samples doped with 2％CaOhave the maximum fracture toughness of 2.12 MPa.m1/2, which improved about one time than that of undoping ceramics, but fracture toughness isreduced when CaO is over-doped(4％), CaO doping is not well to thermalshock resistance of 10NiO-NiFe2O4 composite ceramics. Otherwise,electrical conductivity is improved with CaO doping because of theincrease of relative density Therefore, when the samples doped with 2％CaO, the relative density, electrical conductivity, bending strength andfracture toughness of material are well.3) The low temperature sintering densification ofxM/(10NiO-NiFe2O4) cermet is realized by 2％CaO doping, overflow ofCu during sintering process of xCu/(10NiO-NiFe2O4) cermet is impeded,and the sintering temperature is reduced 50℃. Sintering temperature ofxNi/(10NiO-NiFe2O4) cermet is reduced 150℃. Mechanical property ofcermet is not affected obviously by 2％CaO doping. Metal phases areconglobated and insulation in ceramic by 2％CaO doping, and bad forcontinuous reticular distribution of metal phase, so the electricalconductivity is reduced. |
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