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Title:
PROCESS FOR PRODUCING FERROMAGNETIC PARTICULATE POWDER, AND ANISOTROPIC MAGNET, BONDED MAGNET, AND COMPACTED MAGNET
Document Type and Number:
WIPO Patent Application WO/2012/147833
Kind Code:
A1
Abstract:
The present invention provides: a ferromagnetic particulate powder which has an industrially high purity and shows excellent magnetic properties; a process for producing the powder; and an anisotropic magnet, a bonded magnet, and a compacted magnet which comprise or contain the ferromagnetic particulate powder. This ferromagnetic particulate powder is a ferromagnetic particulate powder which gives a Mossbauer spectrum showing that 80% or more of the ferromagnetic particles are accounted for by an Fe16N2 compound phase, the ferromagnetic particles each including FeO as a shell, the FeO having a film thickness of 5 nm or less. The ferromagnetic particulate powder can be obtained using, as a starting material, an iron compound in which the primary particles have a value of (average deviation of major-axis lengths)/(average major-axis length) of 50% or less, a Uc of 1.55 or less, a Cg of 0.95 or more, a Cg2 of 0.40 or more, an average major-axis length of 40-5,000 nm, and an aspect ratio (major-axis length/minor-axis length) of 1-200, by subjecting the iron compound to a treatment for disaggregating the aggregate particles, subsequently passing the treated particles through a mesh, reducing the obtained iron-compound particulate powder at 160-420ºC, and nitriding the powder at 130-170ºC.

Inventors:
TAKAHASHI MIGAKU (JP)
OGAWA TOMOYUKI (JP)
OGATA YASUNOBU (JP)
KOBAYASHI NAOYA (JP)
POLWATTA GALLAGE CHAMMIKA RUWAN (JP)
KOHARA KAORI (JP)
Application Number:
PCT/JP2012/061176
Publication Date:
November 01, 2012
Filing Date:
April 26, 2012
Export Citation:
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Assignee:
TODA KOGYO CORP (JP)
UNIV TOHOKU (JP)
TAKAHASHI MIGAKU (JP)
OGAWA TOMOYUKI (JP)
OGATA YASUNOBU (JP)
KOBAYASHI NAOYA (JP)
POLWATTA GALLAGE CHAMMIKA RUWAN (JP)
KOHARA KAORI (JP)
International Classes:
C01B21/06; H01F1/11; H01F1/24; H01F41/02
Foreign References:
JP2010147079A2010-07-01
JP2012069811A2012-04-05
JPH11340023A1999-12-10
JP2000277311A2000-10-06
JP2009084115A2009-04-23
JP2008108943A2008-05-08
JP2008103510A2008-05-01
JP2007335592A2007-12-27
JP2007258427A2007-10-04
JP2007134614A2007-05-31
JP2007036027A2007-02-08
JP2009249682A2009-10-29
Other References:
TAKESHI HATTORI ET AL.: "Magnetic Properties of Fe16N2 Fine Particles", JOURNAL OF MAGNETICS SOCIETY OF JAPAN, vol. 25, no. 4-2, 2001, pages 927 - 930, XP009114659
YUKI ONUMA ET AL.: "Humidity effects in Fe16N2 fine powder preparation by low-temperature nitridation", ABSTRACTS OF MEETING OF JAPAN SOCIETY OF POWDER AND POWDER METALLURGY, vol. 2006, 5 December 2006 (2006-12-05), pages 123, XP055106705
M. TAKAHASHI; H. SHOJI; H. TAKAHASHI; H. NASHI; T. WAKIYAMA; M. DOI; M. MATSUI, J. APPL. PHYS., vol. 76, 1994, pages 6642 - 6647
Y. TAKAHASHI; M. KATOU; H. SHOJI; M. TAKAHASHI, J. MAGN. MAGN. MATER., vol. 232, 2001, pages 18 - 26
"Study on synthesis and magnetism of non-equilibrium a',a'',y phases in (C, N)-added Fe-based alloy thin layer", DOCTORIAL THESIS OF GRADUATE SCHOOL OF TOHOKU UNIVERSITY, SCHOOL OF ENGINEERING, ELECTRICAL ENGINEERING, 2001
K. H. JACK: "The iron-nitrogen system: the preparation and the crystal structures of nitrogen-austenite (y) and nitrogen-martensite (a", PROC. ROY. SOC., vol. A208, 1951, pages 216
Attorney, Agent or Firm:
OKADA, KAZUHIKO (JP)
Kazuhiko Okada (JP)
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