Research Of High B_s Manganese Zinc Ferrite Electromagnetic Properties And Low Temperature Sintering

As an important soft magnetic material,MnZn ferrite is widely used in electronic components due to its high saturation magnetic flux density,high permeability and low loss.Especially high B_s MnZn ferrite has been a hot research.In addition,due to the integration and miniaturization of electronic components,the chip components be composed of low-temperature co-fired ferrite become increasingly important.The chip transformers and other components utilized MnZn ferrite require to ensure a higher B_s under the premise of the same time to achieve low-temperature sintering.In this paper,the electromagnetic properties of high B_s MnZn ferrite have been studied systematically,and the low temperature sintering characteristics have been studied.In the first part,the influence of preparation process is discussed.The results show that with the increase of calcination temperature,the activity of powder decreases gradually,and the saturation magnetic induction and magnetic permeability of the material decrease,The optimum pre-calcination temperature is 900℃.The appropriate two-milling process can effectively control the reactivity of the powder,make the grain growth uniform,inhibit the abnormal grain growth,and reduce the porosity and increase sintering density.As a result,the magnetic properties of ferrite are improved.Moreover,the compositions was discussed.The results show that when the content of ZnO is between 2 mol%and 14 mol%,with the increase of ZnO content,the saturation magnetic flux density B_s first decreases and then increases,and the initial permeability increases monotonously,The magnetic loss decreases gradually.When the content of Fe₂O₃ is between 53 mol%and 56 mol%,the saturation magnetic induction Bs increases monotonously with the increase of Fe₂O₃content,and the initial permeabilityμi increases and then decreases.Furthermore,the influence of Co₂O₃ additive was discussed.The experimental results showed that the addition of Co₂O₃ could improve the initial magnetic permeability and saturation magnetic induction effectively,and the loss could be reduced.The suitable addition amount was 0.01wt%.At last,high B_s MnZn ferrite with Bs of 565 mT（at room temperature）,B_s of 463 mT（at 100℃）and magnetic permeability of 1689 was prepared by orthogonal experiment taking into account main factors such as main formula and sintering temperature.In the second part of the article,the low temperature sintering of high B_s MnZn ferrite has been studied.The results show that the addition of Bi-B-Si to the MnZn ferrite can promote the sintering of the material at low temperature（1020℃）.The glass with low softening point contributes to the densification and the inhibition of grain of the abnormal growth.When the content of Bi-B-Si glass is 1.0 wt%,MnZn ferrite is sintered at 1020℃,the permeability is 715,the saturation magnetic induction is 288 mT and the resistivity is520Ω·m.