The Research Of Chemical Co-precipitation Synthesis NiCuZn Ferrite And Low Temperature Sintering Process

Soft magnetic NiCuZn ferrite materials is a wide used functional materials.It is wider and wider used in many fields,for example broadcast,television,electronic meter and computer etc,what more the apparatus will be come less and more diminutive.So the study of NiCuZn ferrite materials is an important way.In this paper,nano-particles of NiCuZn ferrites powders were prepared with nickel nitrate,zinc sulfate,copper sulfate and ferrous sulfate as starting materials and ammonium oxalate as the precipitator by employing co-precipitation technique using oxalate precursors.Excellent composition uniformity NiCuZn ferrite powder can be obtained after drying and calcination.Toroidal samples were obtained after being formed and sintered.The impact of the factors discussed above on the magnetic properties of NiCuZn ferrites was assessed by using DSC,TEM, EDS,XRD,VSM,SEM and optical microscopy to investigate the microstructure of the ferrites.Test conditions detailed studies to determine the precursor powder in the process of reaction temperature,reaction time,stirring speed and reaction ratio control factors such as the optimum reaction conditions:reaction temperature 50℃,stirring speed 300 r/min, reaction time 2 h,reactant ratio(COO)^2-:Me²⁺=1.2.Under the best conditions in the above, the precursor powder products which have a good dispersion,particle size of 20～30 nm and yield 97.1%can be obtained.The prepared precursor powder take calcining experiments to determine the course of precursor powder calcined time.The best calcination temperature of calcination conditions: calcination temperature 800℃,calcination time 2 h.The saturation magnetization of NiCuZn ferrite can be available for 52emu/g and the particle size of 50 nm products is around the ferrite conditions.NiCuZn ferrite sintering experiment has been taken.Add trace additives on the H₃BO₃,forming process and sintering conditions were studied,to draw the best sintering conditions.The results showed that:the best pressure-type pressure is 300 MPa and pressure time is 4 min;the samples should be heat treated at 350～400℃for 2 hours in order to completely eliminate the PVA and take warming rate of 100℃/h;the sintering temperature and the sintering time have been taken that is 900℃and 4 h,cooling with the furnace;additives H₃BO₃ of its adding is 1%.Under the conditions of this process the density of sintered bodies is 4.52g/cm³ and the Saturation magnetization can be for 65.55emu/g.