異方性BaFe2-W型フェライト磁石の磁気特性−第2報−

概要

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An experiment was carried out to investigate the effect of Co-Stearate as a reducing agent on the magnetic and physical properties of anisotropic BaFe2-W type ferrite magnets. It was found that the magnetic properties of BaO·8.5Fe2O3 were improved by adding 0.3 wt% of Co-Stearate, 0.5 wt% of SiO2, and 0.5 wt% of CaO together. The optimum conditions for making magnets were as follows: Chemical composition Ba0.975Ca0.129Si0.144Co0.010C0.075Fe2+2.627Fe3+15.215O27, semisintering condition 1350°C × 4.0 h in nitrogen gas atmosphere, drying condition 180°C × 2.0 h in air, sintering condition 1180°C × 1.5 h in nitrogen gas atmosphere. The magnetic and physical properties of a typical sample were Jm=0.48 T, Jr=0.44 T, HcJ=199.7 kA/m, HcB=196.2 kA/m, (BH)max=34.4 kJ/m3, Tc=497°C. The lattice constants of this compound were a=5.893 × 10−10m, c=32.86 × 10−10m, and c/a=5.577.