Inorganic Compound Encapsulated Or Coated Magnetic Particles (e.g., Co Oxide Coated Fe Particles, Etc.) Patents (Class 428/842.4)
  • Publication number: 20110244271
    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.
    Type: Application
    Filed: March 31, 2011
    Publication date: October 6, 2011
    Applicant: FUJIFILM Corporation
    Inventor: Takeshi KAKUTA
  • Patent number: 7416795
    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.
    Type: Grant
    Filed: September 22, 2004
    Date of Patent: August 26, 2008
    Assignee: TDK Corporation
    Inventors: Minoru Takaya, Yoshiaki Akachi, Hisashi Kobuke, Hiroyuki Uematsu
  • Patent number: 7344779
    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.
    Type: Grant
    Filed: August 6, 2004
    Date of Patent: March 18, 2008
    Assignee: Dowa Electronics Materials Co., Ltd.
    Inventor: Kimitaka Sato
  • Patent number: 7297423
    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.
    Type: Grant
    Filed: February 25, 2005
    Date of Patent: November 20, 2007
    Assignees: Sony Corporation, Migaku Takahashi
    Inventors: Mikihisa Mizuno, Yuichi Sasaki, Makoto Inoue, Kenji Yazawa, Migaku Takahashi, Yasuo Tateno, Teiichi Miyauchi
  • Patent number: 7241519
    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
  • Patent number: 7147916
    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.
    Type: Grant
    Filed: August 29, 2002
    Date of Patent: December 12, 2006
    Assignee: Sony Corporation
    Inventors: Yoh Iwasaki, Yuichi Sasaki, Mikihisa Mizuno
  • Patent number: 7041398
    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%.
    Type: Grant
    Filed: March 25, 2005
    Date of Patent: May 9, 2006
    Assignee: Fuji Photo Film Co., Ltd.
    Inventor: Hiroaki Doushita