RESEARCH AND TECHNOLOGY
WANG Qin, MA Yilong, LUO Xianfu, ZHANG Yunchuan, ZHONG Yan
M-type strontium ferrite was prepared by solid-phase reaction method combined with high-energy ball milling process, and the effects of ball milling time and additive type and content on the micro-morphology, crystal structure and magnetic properties of M-type strontium ferrite were investigated. The results showed that the samples had the best magnetic properties after sintering when the secondary ball milling time was 12 h, with the maximum magnetic energy product (BH)max=32.7 kJ/m3. Effect of the addition of Co3O4, CaCO3 and SiO2 on the magnetic properties of the magnets was further investigated, and the results showed that the magnetic properties decreased with the addition of Co3O4; the increase of CaCO3 content, may result in an excessive grain growth and non-uniformity, which in turn causes a gradual decrease in its coercivity, and when the content of 0.2% CaCO3, the coercivity has a maximum value of Hcj=326.7 kA/m; with the increase in the content of SiO2, the magnetic properties of the sample show a trend of increasing and then decreasing, and when the content of 0.3% of SiO2, sintered samples have a higher densification, and at this time, the sintered samples have better overall properties: Hcj=340.5 kA/m, Br=403.0 mT, (BH)max=31.7 kJ/m3. The experimental results show that the magnetic properties of strontium ferrite can be improved by adjusting the ball milling time and the different additive type and its content.