PRODUCTION OF MAGNETIC POWDER AND MAGNETIC RECORDING

摘要

PURPOSE:To obtain a high-density perpendicular magnetic recording medium having a high C/N characteristic by subjecting a leaf-like amorphous body to a heat treatment to precipitate hexagonal ferrite in the form of fine particles and removing the coarse particles precipitated on the leaf surfaces by a heat treatment. CONSTITUTION:The basic components of the hexagonal ferrite as well as a substituting component for decreasing coercive force and glass forming material are mixed and after the mixture is melted, the mixture is subjected to rapid cooling to prepare the leaf-like amorphous body. The amorphous body is subjected to the heat treatment to precipitate the hexagonal ferrite in the form of fine particles. The leaves after the crystallization are sized to about 5mm square and are immersed into a weakly acidic soln. of CH3COOH or HNO3. The soln. is stirred to about the extent that the leaves move gently in the bottom of a container and never move vertically within the container; thereafter, the soln. is poured onto a sieve of the opening smaller than the leaves and the large particles are flushed away by rinsing. The packing rate of the magnetic powder in the medium is thereby improved and the output is improved as well. The magnetic recording medium improved in the C/N characteristic is thus obtd.