高磁导率MnZn铁氧体的氧化还原度调控与磁性能提升

采用氧化物陶瓷工艺制备MnZn铁氧体材料,研究了烧结过程氧分压及热处理氧分压对于其电磁性能的影响。实验表明,烧结过程中的氧分压P(O_2)越高,材料中的Fe²⁺含量越低,烧结体晶粒越大;氧分压的最佳范围在4~7%附近,过高或过低均会降低材料的磁性能。对于因氧分压偏离最佳范围导致磁性能低下的MnZn烧结体,可以通过后续的热处理工艺调节Fe²⁺含量以恢复其磁性能。根据这些结果,综合烧结工艺和热处理工艺的优势,采用21%的氧分压烧结获得较大的晶粒之后再在0.1%的氧分压气氛中热处理的方法调节铁氧体的Fe²⁺含量,获得了25℃时μi=10600,Bs=427 mT,μi(200 kHz)/μi(10 kHz)=98%,综合性能良好的高磁导率MnZn铁氧体磁芯。

Improvement of magnetic properties of high-permeability MnZn ferrite through the adjustment of oxidation states

MnZn ferrites were prepared by conventional ceramics technique. Effects of partial pressure of oxygen in the sintering and annealing processes on the magnetic properties of MnZn ferrites were studied. It was revealed that higher sintering P(O2) leads to larger grain and lower Fe2+concentration. The optimal range of sintering P(O2) is 4-7 %, higher or lower sintering P(O2) will reduce the permeability. For MnZn ferrite cores with bad magnetic properties derived from the failure in P(O2) control during sintering, the Fe2+content could be adjusted by subsequent annealing process to recover their magnetic properties. The samples with larger grain size and optimal Fe2+content were achieved by sintering at P(O2)=21 % and subsequently annealing at P(O2)=0.1 % which exhibits excellent magnetic properties with μi=10600, Bs=427 mT and μi (200 kHz)/μi(10 kHz)=98 % at 25℃.