Abstract
The anisotropically formed BaFe12O19 ferrites were prepared from the hot-rolled mill scale and silica was added to the ferrite during fine milling in the range 0.15 to 0.50 wt%. These ferrites were sintered at 1220° C for 2 h. The grain growth of the ferrites is dominantly influenced by the sizes of the silica added. Coarse-grain (≈ 1μm) silica tends to promote discontinuous grain growth, which increases drastically with slightly increasing amounts of silica added, while fine-grain (≈ 0.013μm) silica tends to retain fine grain microstructures with the same increasing amount of silica. The average grain size of the ferrite without silica addition was 8 to 10μm. The size was increased to as large as 30μm on addition of 0.15% coarse-grain silica and the microstructure was full of extremely large grains on the addition of 0.50% coarse-grain silica.
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Chien, YT., Ko, YC. The effect of silica characterization on the microstructure of BaFe12O19 ferrites. J Mater Sci 25, 1711–1714 (1990). https://doi.org/10.1007/BF01045374
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DOI: https://doi.org/10.1007/BF01045374