| As the development of miniaturization of electronic chip components, monolithic components of chip material performance put forward higher requestion.NiCuZn ferrite magnets in monolithic inductance of the development of the chip inductance development becomes bottleneck.This is the NiCuZn ferrite materials on improving comprehensive performance this center, through theory analysis, preparation technology of optimization and performance testing, analysis and material properties of realization was adopted to develop high performance NiCuZn ferrite, which were very suitable to produce multilayer chip inductors.In this paper,NiCuZn ferrites have been prepared using the traditional solid-state mixing method. Samples were obtained after being ball-milled,calcined, granulation, forming and sintering process. The analytical reagent-grade powders of Fe203, NiO, CuO and ZnO were chosen as the precursor materials to prepare the ferrites.HP4294A Impedance Analyzer was used for evaluating magnetic properties of samples; SEM were used for observing sample microstructure.It was studied systematically that factors influent on the microstructure and properties of samples by changing the formula of Fe/Ni, main parameters and doping sequence,and proposed new doping process.First, Determined the Fe/Ni the formula.The influences of the properties of different Fe/Ni in the formula of NiCuZn ferrite was investigated.The results show that:when Fe2O3 is 51.50mol%, NiO is 28.59mol%, it obtained maximum sintering density(5.05g/cm3) and proper shrinkage of inside and outside diameter and obtained maximum initial permeability for 87.Thus we confirmed with the formula as Ni0.57 Cu0.19 Zn0.21 Fe2.06 O3.97.Secondly, The effect of calcining, the time of second ball-milled and sintering temperature on the microstructure and electromagnetic properties of NiCuZn ferrite were investigated. The study found:raising the calcining temperature is favorable to the grain growth and few porosity so as to the improvement of magnetic properties of the NiCuZn ferrites. However, with further improving calcinations temperature, the reatibe ability of calcining powders can be decreased and leaded the decrease of magnetie properties. With the prolonging of second ball-milled, Average grain size decreases slightly;The singtering temperature apporpiately will be benefit of grain growth and densification so as to the improvement of magnetic properties of the NiCuZn ferrites.But the magnetic properties could be deteriored by more porosity and abnomal grain growth. To determine the optimize technical parameters:calcining temperature at 850℃,second ball-milled time being 6h,sintering at 1100℃.Finally,effect of doping with Co2O3,MnCO3 and combined addition on electromagnetic properties and microstructure of NiCuZn ferrite were investigated. Results showed that:it can obtain optimal performance by doping 0.75 wt% MnCO3 before calcining alone or doping 0.80 wt% Co2O3 after calcining alone.Then effect of MnCO3+Co2O3 composite doped on properties ferrite were investigated. To give attention to both permeability and quality factor, the optimal additives was:before calcining doped 0.25wt%MnCO3+1.00wt%Co2O3 after calcining,μi for 82, Q for 95. In this paper, effect of different calcining activity powder (750℃and 900℃calcined) to quantitative proportion on microstructure and electromagnetic properties of NiCuZn ferrite were studied. Results show that:the ratio of powder of 750℃calcined 10wt%+ powder of 900℃calcined 90wt% to get better microstructure and electromagnetic properties,μi for 63, Q for 92.
|
PDF Full Text Request