• Journal of the Korean Magnetics Society
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• v.3 no.2
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• pp.108-114
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• 1993

This paper presents a study on the effects of silica coating in the production of ${\gamma}-Fe_{2}O_{3}$ powders suitable for magnetic recording media. Emphasis has been put on investigating the relationship between the powder characteristics and the effects of silica coating in the heat-treatment stage of ${\gamma}-Fe_{2}O_{3}$ production. After we prepared non-coated ${\gamma}-Fe_{2}O_{3}$ and silica coated ${\gamma}-Fe_{2}O_{3}$ with coating water glass on the surface of goethite and heattreatment process, we compared and investigated powder characteristics. As silica coated layer played a role of preventing the powders from overreduction to metal iron and rapid oxidation, silica coated ${\gamma}-Fe_{2}O_{3}$ showed superior magnetization value due to inhibiting t!1e adulteration of ${\alpha}-Fe_{2}O_{3}$ into the final product. When silica coated layer acted as a sintering restrainer, silica coated ${\gamma}-Fe_{2}O_{3}$ showed high coercivity and specific sur-face area due to good acicularity.