Abstract: An aspect of the present invention relates to a method of manufacturing a hexagonal ferrite magnetic powder comprising discharging a melt of a starting material mixture comprising a glass-forming component and a hexagonal ferrite-forming component through an outlet provided in the bottom surface of the melting vat and supplying it between a pair of rotating milling rolls positioned beneath the melting vat; discharging an amorphous material from between the rolls by roll quenching the melt that has been supplied between the milling rolls, wherein at least an outermost layer portion of the milling rolls is comprised of a material with a Young's modulus of 500 GPa or higher and a Rockwell hardness of 85.0 HRA or higher, and the outermost layer portion has a thickness of 5 mm or greater and a surface roughness of 0.5 ?m or less.
Abstract: A method for manufacturing magnetic metal powder is provided. In the method, a powdered magnetic metal oxide is supplied to a heat treatment furnace with a carrier gas composed of a reducing gas. The heat treatment furnace is maintained at temperatures above a reducing action starting temperature for the powdered magnetic metal oxide and above a melting point of the magnetic metal in the powder. The powdered magnetic metal oxide is subject to a reducing process, and then magnetic metal particles, the resultant reduced product, is melted to form a melt. The melt is re-crystallized in a succeeding cooling step, to obtain single crystal magnetic metal power in substantially spherical form.
Abstract: A fine magnetic powder suitable for magnetic tape capable of high-density magnetic recording is provided that helps to prevent degradation of tape surface property and durability with increasing fineness of the magnetic powder particles, which magnetic powder consists of particles composed chiefly of Fe whose surface layer contains an oxide of at least one of Al, Si and Ra (where Ra represents one or more rare earth elements, defined as including Y), has an average particle diameter of less than 70 nm, the number of basic sites on the particle surface of not greater than 0.85 sites/nm2, and the number of acid sites on the particle surface of not greater than 0.75 sites/nm2.
Abstract: A PCB that can transmit a high frequency signal of a GHz band with a low loss includes an insulator and magnetic nanoparticles dispersed in the insulator.
Abstract: Provided is a magnetic recording medium capable of achieving higher density recording. The magnetic recording medium comprises a magnetic layer formed on a non-magnetic base through vacuum oblique evaporation. The magnetic layer includes a plurality of columns in which 3 to 7 ferromagnetic particles with an average diameter of 5 to 10 nm are arranged in a line, and non-magnetic particles are disposed between columns so as to separate the columns from one another. A value Y/X defined as a ratio of an average value Y of a distance between the centers of adjacent columns in a film in-plane direction to an average value X of a distance between the centers of adjacent columns in a film thickness direction is preferably 0.5 or more.
Type:
Grant
Filed:
July 6, 2004
Date of Patent:
July 10, 2007
Assignee:
Sony Corporation
Inventors:
Junichi Tachibana, Yuichi Arisaka, Hiroshi Mizuno, Takuya Ito
Abstract: A magnetic material having a structure of a material having a ferromagnetic phase at ordinary temperature as a core and a material having an antiferromagnetic phase at ordinary temperature surrounding the periphery of the core in the form of a shell, wherein a ratio between a volume of the ferromagnetic phase material and the volume of the antiferromagnetic phase material in the magnetic material is in a range where no exchange biasing field of the magnetic material appears and a rotational hysteresis loss of the magnetic material is made the maximum, a method of producing the same, and a magnetic recording medium using the same.
Abstract: A magnetic recording medium comprising a non-magnetic support and a magnetic layer containing a ferromagnetic metal powder and a binder, wherein the ferromagnetic metal powder comprises an oxide layer and a metal portion surrounded by the oxide layer, and the ferromagnetic metal powder has an average long axis length of from 30 nm to 55 nm, a coefficient of variation of long axis length of not more than 25%, a coefficient of variation of axial ratio of not more than 20%, and a coefficient of variation of a thickness of the oxide layer of not more than 15%.