Effect of Ba Strate Addition on Magnetic Properties of Ba-System W-Type Ferrite Magnets

摘要

Experiment was carried out to investigate the effect of Ba Stearate as a reducing agent on the magnetic and physical properties of anisotropic BaFe_2-W type ferrite magnets. It was found that the magnetic properties of BaO·8.5Fe_2O_3 were improved by adding 0.3 wt% of Ba Stearate, 0.5 wt% of SiO_2, and 0.5 wt% of CaO together. The optimum conditions for making magnets were as follows; chemical composition: Ba_(1.029)Ca_(0.127)Si_(0.097)C_(0.053)Fe_(2.456)~(2+)Fe_(15.392)~(3+)O_(27), semisintering condition: 1350 ℃×4.0 h in nitrogen gas atmosphere, drying condition: 180 ℃×2.0 h in air, sintering condition: 1160 ℃×1.5 h in nitrogen gas atmosphere. Magnetic and physical properties of a typical sample were J_m = 0.46 T, J_r = 0.43 T, H_(cJ) = 182.3 kA/m, H_(cB) = 177.2 kA/m, (BH)_(max) = 33.8 kJ/m~3, T_c = 495 ℃ and K_A = 2.65 × 10~5 J/m~3 and H_A = 1332 kA/m. The lattice constants of this compound were a = 5.883 × 10~(-10) m, c = 32.92 × 10~(-10) m, and c/a = 5.596.