Patents Assigned to Kawasaki Teitoku Co., Ltd.
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Patent number: 6103021Abstract: The present invention is directed to provide a method of preparing a raw material powder for permanent magnets superior in moldability, especially in moldability and productivity of bonded magnets. The method comprises subjecting an acicular iron powder having an aspect ratio of not smaller than 5:1 to heating at 800-900.degree. C. in fluidized state with a gas stream containing no oxygen until the acicular iron powder is transformed into a columnar shape iron powder having an aspect ratio of not larger than 3:1, a die-like shape iron powder or a spherical shape iron powder. The acicular iron powder may contain or may be attached by such a component effective for improving magnetic properties as a rare earth element metal, a rare earth element metal oxide, boron, cobalt and nickel.Type: GrantFiled: July 9, 1998Date of Patent: August 15, 2000Assignees: Kawasaki Teitoku Co., Ltd., Sanei Kasei Co., Ltd, Komeya, Inc.Inventors: Shigenobu Sekine, Hiroji Sato
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Patent number: 5650021Abstract: It is an object of the present invention to provide a method of producing sintered- or bond- rare earth element.iron.boron magnets obtainable easily and superior in magnetic properties with stable performance. The method of producing sintered rare earth element.iron.boron magnets according to the present invention is characterized by that it comprises steps of mixing in a scheduled ratio an acicular iron powder coated with a coating material, a rare earth element powder coated with a coating material and a boron powder coated with a coating material, and subjecting the mixture to compression molding followed by sintering of the molded mixture in the presence of a magnetic field. The method of producing bond rare earth element.iron.Type: GrantFiled: September 25, 1995Date of Patent: July 22, 1997Assignees: Kawasaki Teitoku Co., Ltd., Komeya Inc., Sanei Kasei Co., Ltd.Inventor: Yasunori Takahashi
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Patent number: 5580400Abstract: The present invention aims at providing a powdery raw material composition for a permanent magnet superior in the magnetic properties and easy in preparation, a magnetically anisotropic permanent magnet, and a method for producing the magnet by use of the powdery raw material composition. A powdery raw material composition for a permanent magnet according to the present invention is one prepared by subjecting a mixture composed of 13-18 weight % of a neodymium powder, 4-10 weight % of a boron powder and the rest of an acicular iron powder coated with aluminum phosphate to a temperature above 600.degree. C. in an atmosphere initially of a hydrogen-containing reducing gas followed later by an inert gas, and a magnetically anisotropic permanent magnet is prepared by compression molding a mixture obtained from the powdery composition and a binder under heating in the presence of a magnetic field.Type: GrantFiled: May 5, 1995Date of Patent: December 3, 1996Assignees: Kawasaki Teitoku Co., Ltd., Komeya Inc., Sanei Sanei Kasei Co., Ltd.Inventor: Yasunori Takahashi
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Patent number: 5569335Abstract: The material for permanent magnet according to the present invention comprises an acicular iron powder having successively on the surface (1) a coated layer of aluminum phosphate, (2) a diffused layer of rare earth element or a diffused layer of rare earth element.cndot.boron or a diffused layer of rare earth element.cndot.boron.cndot.nitrogen, and (3) a coated layer of aluminum phosphate.The material for permanent magnet can be produced by (a) a step of mixing and covering an acicular goethite (FeOOH) crystal with aluminum phosphate, (b) a step of preparing an acicular iron powder coated with a layer of aluminum phosphate by reducing under hydrogen atmosphere at 300.degree.-500.degree. C. the acicular goethite (FeOOH) crystal covered by the aluminum phosphate, (c) a step of diffusing a rare earth element or a rare earth element and boron into the surface layer of aluminum phosphate by heating under argon atmosphere at 650.degree.-1000.degree. C.Type: GrantFiled: June 2, 1995Date of Patent: October 29, 1996Assignees: Kawasaki Teitoku Co., Ltd., Komeya Inc., Sanei Kasei Co., Ltd.Inventor: Yasunori Takahashi
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Patent number: 5569336Abstract: The material for permanent magnet according to the present invention comprises an acicular iron powder having successively on the surface (1) a coated layer of aluminum phosphate, (2) a diffused, layer of rare earth element or a diffused layer of rare earth element.multidot.boron or a diffused layer of rare earth element.multidot.boron.multidot.nitrogen, and (3) a coated layer of aluminum phosphate.The material for permanent magnet can be produced by (a) a step of mixing and covering an acicular goethite (FeOOH) crystal with aluminum phosphate, (b) a step of preparing an acicular iron powder coated with a layer of aluminum phosphate by reducing under hydrogen atmosphere at 300.degree.-500.degree. C. the acicular goethite (FeOOH) crystal covered by the aluminum phosphate, (c) a step of diffusing a rare earth element or a rare earth element and boron into the surface layer of aluminum phosphate by heating under argon atmosphere at 650.degree.-1000.degree. C.Type: GrantFiled: June 2, 1995Date of Patent: October 29, 1996Assignees: Kawasaki Teitoku Co., Ltd., Komeya, Inc., Sanei Kasei Co., Ltd.Inventor: Yasunori Takahashi
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Patent number: 5569333Abstract: The material for permanent magnet according to the present invention comprises an acicular iron powder having successively on the surface (1) a coated layer of aluminum phosphate, (2) a diffused layer of rare earth element or a diffused layer of rare earth element.boron or a diffused layer of rare earth element.boron.nitrogen, and (3) a coated layer of aluminum phosphate.The material for permanent magnet can be produced by (a) a step of mixing and covering an acicular goethite (FeOOH) crystal with aluminum phosphate, (b) a step of preparing an acicular iron powder coated with a layer of aluminum phosphate by reducing under hydrogen atmosphere at 300.degree.-500.degree. C. the acicular goethite (FeOOH) crystal covered by the aluminum phosphate, (c) a step of diffusing a rare earth element or a rare earth element and boron into the surface layer of aluminum phosphate by heating under argon atmosphere at 650.degree.-1000.degree. C.Type: GrantFiled: June 2, 1995Date of Patent: October 29, 1996Assignees: Kawasaki Teitoku Co., Ltd., Komeya, Inc., Sanei Kasei Co., Ltd.Inventor: Yasunori Takahashi
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Patent number: 5562782Abstract: The present invention aims at providing a powdery raw material composition for a permanent magnet superior in the magnetic properties and easy in preparation, a magnetically anisotropic permanent magnet, and a method for producing the magnet by use of the powdery raw material composition. A powdery raw material composition for a permanent magnet according to the present invention is one prepared by subjecting a mixture composed of 13-18 weight % of a neodymium powder, 4-10 weight % of a boron powder and the rest of an acicular iron powder coated with aluminum phosphate to a temperature above 600.degree. C. in an atmosphere initially of a hydrogen-containing reducing gas followed later by an inert gas, and a magnetically anisotropic permanent magnet is prepared by compression molding a mixture obtained from the powdery composition and a binder under heating in the presence of a magnetic field.Type: GrantFiled: May 5, 1995Date of Patent: October 8, 1996Assignees: Kawasaki Teitoku Co., Ltd., Komeya Inc., Sanei Kasei Co., Ltd.Inventor: Yasunori Takahashi
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Patent number: 5478409Abstract: It is an object of the present invention to provide a method of producing sintered- or bond- rare earth element.iron.boron magnets obtainable easily and superior in magnetic properties with stable performance. The method of producing sintered rare earth element.iron.boron magnets according to the present invention is characterized by that it comprises steps of mixing in a scheduled ratio an acicular iron powder coated with a coating material, a rare earth element powder coated with a coating material and a boron powder coated with a coating material, and subjecting the mixture to compression molding followed by sintering of the molded mixture in the presence of a magnetic field. The method of producing bond rare earth element.iron.Type: GrantFiled: October 13, 1994Date of Patent: December 26, 1995Assignees: Kawasaki Teitoku Co., Ltd., Komeya Inc., Sanei Kasei Co., Ltd.Inventor: Yasunori Takahashi
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Patent number: 5453137Abstract: The material for permanent magnet according to the present invention comprises an acicular iron powder having successively on the surface (1) a coated layer of aluminum phosphate, (2) a diffused layer of rare earth element or a diffused layer of rare earth element.boron or a diffused layer of rare earth element.boron.nitrogen, and (3) a coated layer of aluminum phosphate. The material for permanent magnet can be produced by (a) a step of mixing and covering an acicular goethite (FeOOH) crystal with aluminum phosphate, (b) a step of preparing an acicular iron powder coated with a layer of aluminum phosphate by reducing under hydrogen atmosphere at 300.degree.-500.degree. C. the acicular goethite (FeOOH) crystal covered by the aluminum phosphate, (c) a step of diffusing a rare earth element or a rare earth element and boron into the surface layer of aluminum phosphate by heating under argon atmosphere at 650.degree.-1000.degree. C.Type: GrantFiled: October 5, 1994Date of Patent: September 26, 1995Assignees: Kawasaki Teitoku Co., Ltd., Komeya Inc., Sanei Kasei Co., Ltd.Inventor: Yasunori Takahashi
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Patent number: 5443617Abstract: The present invention aims at providing a powdery raw material composition for a permanent magnet superior in the magnetic properties and easy in preparation, a magnetically anisotropic permanent magnet, and a method for producing the magnet by use of the powdery raw material composition. A powdery raw material composition for a permanent magnet according to the present invention is one prepared by subjecting a mixture composed of 13-18 weight % of a neodymium powder, 4-10 weight % of a boron powder and the rest of an acicular iron powder coated with aluminum phosphate to a temperature above 600.degree. C. in an atmosphere initially of a hydrogen-containing reducing gas followed later by an inert gas, and a magnetically anisotropic permanent magnet is prepared by compression molding a mixture obtained from the powdery composition and a binder under heating in the presence of a magnetic field.Type: GrantFiled: September 30, 1994Date of Patent: August 22, 1995Assignees: Kawasaki Teitoku Co., Ltd., Komeya Inc., Sanei Kasei Co., Ltd.Inventor: Yasunori Takahashi