Sintering of Soft Magnetic Material under Microwave Magnetic Field

We have developed a simple process for sintering of soft magnetization materials using microwave sintering. The saturated magnetization (Ms) of sintered magnetite was 85.6 emu/g, which was as high as 95% of magnetite before heating (90.4 emu/g). On the other hand, the averaged remanence (Mr) and coercivity (Hc) of the magnetite after heating were 0.17 emu/g and 1.12 Oe under measuring limit of SQUID, respectively. For the sintering process of soft magnetic materials, magnetic fields of microwave have been performed in nitrogen atmosphere. Therefore, a microwave single-mode system operating at a frequency of 2.45 GHz and with a maximum power level of 1.5 kW was used. We can sinter the good soft magnetic material in microwave magnetic field. The sample shrank to 82% theoretical density (TD) from 45%TD of green body. The sintered sample was observed the microstructure by TEM and the crystal size was estimated the approximate average size is 10 nm.