CaOおよびSiO2添加によるSrフェライト磁石の高性能化

概要

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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.