Effect of forms of B2O3-SiO2 as an additive on magnetic properties of SrFe12O19 ferrites
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Strontium ferrites (SrO · 5.5Fe2O3) were prepared using hot-rolled mill scale as a source of iron oxides. Calcination was performed at 1200°C for 2 h. The fused B2O3-SiO2, with various mole ratios of B2O3 to SiO2, was added to the calcined ferrites during the milling stage. The ferrites were formed anisotropically. The fused additives are quite effective to enhance the magnetic properties; (BH)max can reach 3.0 MGOe for the ferrite sintered at 1220°C for 2 h. In general, (BH)max is independent of the mole ratio of B2O3 to SiO2 and dominantly influenced by the sintering temperature. The addition of 0.3 or 0.5 wt% fused additives showed no significant difference in the magnet quality. The quality of the magnet was decreased with increasing mole ratio of B2O3 to SiO2 when unfused B2O3-SiO2 was used under the same processing conditions.
KeywordsIron SiO2 Ferrite Fe2O3 Milling
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