Tdk Electronics Company, Limited

Sony Corporation

Sony Group Corporation

Kazuo Takada

Naoki Miyabayashi

Shinji Umeki

Seitoku Saito

Toshiaki Izumi

Fujio Shibata

Hiroshi Sugihara

Takayoshi Kobuke

Toshihiro Hamabata

Kazuaki Onuki

Seiji Kuroda

A magnetic recording medium comprises a magnetic alloy layer on a substrate wherein said magnetic alloy layer is made of 70-90 wt. % of Co and 30-10 wt. % of at least one of Si, Sb, Li, V, Ta, Ge and Pt and a magnetization axis of said magnetic alloy is substantially vertical to said layer.

Magnetic recording medium

A magnetic iron oxide powder which has high coercive force and stable magnetic characteristics is produced by forming a surface layer of the magnetic iron oxide powder which comprises a cobalt compound as a main component. The magnetic iron oxide powder is treated with an aqueous solution of a cobalt ion for two times or more to form at least two surfaces comprising the cobalt compound.

Process for producing magnetic powder having high coercive force

A magnetic recording medium is prepared by a tilt vapor deposition of magnetic particles from a vapor thereof on a substrate running along a peripheral surface of a cylindrical can in vacuum wherein plural cans are used to deposit said magnetic particles at substantially the same tilt angle on each of said cans.

Process for preparing magnetic recording medium

A magnetic iron oxide powder having high coercive force is produced by dispersing a magnetic iron oxide comprising a silicon component and a phosphorus component in an aqueous solution of a cobalt ion and adding a base to the dispersion to be an alkaline condition and heat-treating the dispersion whereby the cobalt ion is adsorbed and diffused in the surface layer of the magnetic iron oxide. A zinc component can be also incorporated in the crystal. The silicon component and the phosphorus component are preferably incorporated in the crystalline structure.

A magnetic recording medium is disclosed as comprising powdered magnetic particles upon which there is deposited a ferro-magnetic metal or alloy such as cobalt or a cobalt alloy. Each magnetic particle is a spiculate magnetite and the deposite of cobalt or a cobalt alloy is in the range of 0.5 wt.% to 30 wt.%. The particles are heat treated in either a reducing or inert atmosphere to a sufficient temperature to improve the magnetic characteristics of the particles including their coercive force, Br/.rho. and Bm/.rho.. A layer of the recording medium is disposed on a support layer of polyester to form a magnetic tape.

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Tokyo, Japan

Kazuo Takada