MAGNETIC POWDER FOR MAGNETIC RECORDING

摘要

PURPOSE:To improve the transfer characteristics of magnetic powder by setting the ratio of coercive force measured at -196 deg.C to coercive force measured at ambient temperature to less than specific value and setting the coercive force measured at the ambient temperature to a value higher than the specific value for cobalt coating ferromagnetic oxidized iron. CONSTITUTION:Cobalt coating ferromagnetic oxidized iron in which the ratio of coercive force measured at -196 deg.C to coercive force measured at ambient temperature (25 deg.C) is set less than 2.5 and the coercive force measured at the ambient temperature is higher than 1,000 oersted is used as magnetic powder for magnetic recording, more than 20% by weight of ferrous salt of F<2+> and more than 6% by weight of cobalt salt of Co<2+> are contained in gamma-Fe2O3 so that the ratio of the ferrous salt to the cobalt salt is set by weight to 3-4.5, thereby obtaining cobalt coating ferromagnetic oxidized rion. Thus, the transfer characteristics can be improved with thermal stability.