Study On New Technology Of Low Temperature Sintering NiCuZn Ferrites

Soft NiCuZn ferrites magnetic material is widely used as a functional material. It has more and more extensive application in radio,television,electronic instruments,computers and other areas.In this paper,uniform distribution of the precursor powder of NiCuZn ferrites were prepared with nickel sulfate,copper sulfate,zinc sulfate,ferrous sulfate and ammonium oxalate as raw materials by using chemical co-precipitation technique. Excellent uniformity composition NICuZn ferrite powder can be obtained after drying and calcining.Toroidal samples were obtained after being formed and sintered processes. The impact of the factors discussed above on the magnetic properties of NiCuZn ferrites was assessed by using XRD and SEM optical microscopy to investigate the microstrueture of the ferrites.Through detailed experimental conditions,it studied that sintering temperature, holding time,heating rate,additive and so on sintering process factors have effects on the microstructure and magnetic properties of NiCuzn ferrite. It found that sintering temperature can play a decisive role on the microstructure and magnetic properties of materials :the appropriate sintering temperature can promote grain size grow, reduce porosity and improve densification,which will help to improve the magnetic properties of materials;but sintering temperature is too high,it can led to abnormal grain growth and decline of magnetic properties. It was also found when the heating rate is too quick, resulting in poor magnetic properties and microstructure;while the heating rate is too slow,the magnetic properties of the material has little effect,but a waste of energy. In the sintering process,it affected the grain density when the holding time is longer.Adding the appropriate amount of V2O5 can promote the ferrite grain growth,effectively improve the saturation magnetization and thus determine the optimum sintering conditions. The results show that:sintering temperature is 910℃, heating rate of is 100℃/h and holding time is 4h,which can effectively discharge the binder PVA when holding time 2h at 350℃~ 400℃;amount of additive V2O5 is 0.3 wt%.In this condition, the sintered density is 5.15g/cm3 and saturation magnetization is 18.494emu/g. Finally,affect of Ag on the microstructure and magnetic properties of NiCuZn ferrite is investigated.It is found that a small amount of silver can promote the densification of NiCuZn ferrite and improving sintered density;too much amount of silver led to down magnetic properties of NiCuZn ferrite.