CaOおよびSiO₂添加によるSrフェライト磁石の高性能化

抄録

Effects of CaO and SiO₂ additives on the magnetic properties, density and microstructures of the sintered compacts of Sr-ferrite were investigated. It was revealed that CaO and SiO₂ additives play important roles of rapid densification and grain growth controll through the sintering process of Sr-ferrite compacts. EPMA, microstructure observation and temperature dependence of the densification showed that the densification of Sr-ferrite containing CaO and SiO₂ additives was promoted by liquid phase with low melting point along the grain boundaries. The liquid phase was composed of CaO-SiO₂-SrO-6Fe₂O₃ ternary solid solution. Magnetic properties of the sintered Sr-ferrite were strongly dependent on the amount of CaO and SiO₂ additives and, in the case of CaO=0.45% and CaO/SiO₂=1.25, a high quality permanent magnet (Br=4.4 KG and iHc=2.8 KOe) was obtained for an electronic oven.