Method for manufacturing magnetic powder for high density magnetic recording
AssigneeTokyo Shibaura Denki Kabushiki Kaisha
InventorsOsamu Kubo, Tadashi Ido, Tutomu Nomura, Koichiro Inomata
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Abstract
A method for preparing a magnetic powder for high density magnetic recording includes melting a mixture containing the fundamental component of a hexagonal ferrite, a substituting component for reducing the coercive force, and a glass forming material. The resultant molten material is rapidly cooled to obtain an amorphous body which is then heat-treated to produce desired substituted type hexagonal ferrite particles in the glass matrix.
Claims12
A method for manufacturing a magnetic powder for high density magnetic recording having a particle size within the range of 0.01 to 0.3 microns, comprising:
- mixing, together with a glass forming substance, metal oxide or metal oxide precursor components of a substituted ferrite having the formula:
- AFe.sub.12-2x Co.sub.x M.sub.x O.sub.19 or AFe.sub.12-3/2x Co.sub.x M.sub.1/2x O.sub.19
- wherein A is at least one element selected from the group consisting of barium, strontium, lead and calcium, M is at least one tetravalent element selected from the group consisting of titanium and germanium or at least one pentavalent element selected from the group consisting of vanadium, niobium, antimony and tantalum, and x is a value from 0.5 to 1.1;
- melting the mixture into a molten material;
- rapidly cooling the molten material to obtain an amorphous material;
- heat-treating the amorphous material in the range between 700.degree. and 850.degree. C. to precipitate a substituted hexagonal ferrite as mutually separated fine particles in the amorphous material;
- and
- separating the fine particles from the amorphous material wherein said metal oxide or metal oxide precursor components are mixed in an amount sufficient to provide, as said fine particles, a substituted ferrite of said formulation.
Dependencies are inferred from the claim text.