Patents by Inventor Seiichi Hosokawa
Seiichi Hosokawa has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 9601247Abstract: A sintered ferrite magnet comprising main phases of ferrite having a hexagonal M-type magnetoplumbite structure, first grain boundary phases existing between two main phases, and second grain boundary phases existing among three or more main phases, the second grain boundary phases being dispersed in its arbitrary cross section, and the second grain boundary phases having an average area of less than 0.2 ?m2, are produced by calcining, pulverizing, molding and sintering raw material powders having the general formula of Ca1-x-yLaxAyFe2n-zCoz, wherein 1?x?y, x, y and z and n representing a molar ratio are in desired ranges; 1.8% or less by mass of SiO2 and 2% or less by mass (as CaO) of CaCO3 being added to a calcined body after calcining and before molding; and the sintering step being conducted with a temperature-elevating speed of 1-4° C./minute in a range from 1100° C. to a sintering temperature, and a temperature-lowering speed of 6° C./minute or more in a range from the sintering temperature to 1100° C.Type: GrantFiled: July 24, 2013Date of Patent: March 21, 2017Assignee: HITACHI METALS, LTD.Inventors: Yoshinori Kobayashi, Seiichi Hosokawa, Etsushi Oda
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Publication number: 20150221424Abstract: A sintered ferrite magnet comprising main phases of ferrite having a hexagonal M-type magnetoplumbite structure, first grain boundary phases existing between two main phases, and second grain boundary phases existing among three or more main phases, the second grain boundary phases being dispersed in its arbitrary cross section, and the second grain boundary phases having an average area of less than 0.2 ?m2, are produced by calcining, pulverizing, molding and sintering raw material powders having the general formula of Ca1-x-yLaxAyFe2n-zCoz, wherein 1-x-y, x, y and z and n representing a molar ratio are in desired ranges; 1.8% or less by mass of SiO2 and 2% or less by mass (as CaO) of CaCO3 being added to a calcined body after calcining and before molding; and the sintering step being conducted with a temperature-elevating speed of 1-4° C./minute in a range from 1100° C. to a sintering temperature, and a temperature-lowering speed of 6° C./minute or more in a range from the sintering temperature to 1100° C.Type: ApplicationFiled: July 24, 2013Publication date: August 6, 2015Applicant: HITACHI METALS, LTD.Inventors: Yoshinori Kobayashi, Seiichi Hosokawa, Etsushi Oda
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Patent number: 8506838Abstract: A sintered ferrite magnet comprising a first granular ferrite compound phase containing Ca, La, Fe and Co and having a Curie temperature Tc1 between 415° C. and 430° C., and a second granular ferrite compound phase containing Sr, La, Fe and Co and having a Curie temperature Tc2 between 437° C. and 455° C., the volume ratio of the first ferrite compound phase being 50-90%, and the volume ratio of the second ferrite compound phase being 10-50%, with their total volume ratio being 95% or more.Type: GrantFiled: March 9, 2011Date of Patent: August 13, 2013Assignee: Hitachi Metals, Ltd.Inventors: Seiichi Hosokawa, Etsushi Oda, Hiroshi Iwasaki
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Publication number: 20120326074Abstract: A sintered ferrite magnet comprising a first granular ferrite compound phase containing Ca, La, Fe and Co and having a Curie temperature Tc1 between 415° C. and 430° C., and a second granular ferrite compound phase containing Sr, La, Fe and Co and having a Curie temperature Tc2 between 437° C. and 455° C., the volume ratio of the first ferrite compound phase being 50-90%, and the volume ratio of the second ferrite compound phase being 10-50%, with their total volume ratio being 95% or more.Type: ApplicationFiled: March 9, 2011Publication date: December 27, 2012Applicant: HITACHI METALS, LTD.Inventors: Seiichi Hosokawa, Etsushi Oda, Hiroshi Iwasaki
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Patent number: 8206606Abstract: An oxide magnetic material includes a ferrite with a hexagonal structure as its main phase. Metallic elements included in the oxide magnetic material are represented by the formula: Ca1-x-x?LaxSrx?Fe2n-yCoy, where atomic ratios x, x? and y and a molar ratio n satisfy 0.4?x?0.6, 0.01?x??0.3, 0.2?y?0.45 and 5.2?n?5.8, respectively.Type: GrantFiled: June 25, 2008Date of Patent: June 26, 2012Assignee: Hitachi Metals, Ltd.Inventors: Seiichi Hosokawa, Yoshinori Kobayashi, Yasunobu Ogata, Etsushi Oda
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Publication number: 20100237273Abstract: An oxide magnetic material according to the present invention is represented by the formula: (1?x)CaO.(x/2)R2O3.(n?y/2)Fe2O3.yMO, where R is at least one element selected from the group consisting of La, Nd and Pr and always includes La, M is at least one element selected from the group consisting of Co, Zn, Ni and Mn and always includes Co, and the mole fractions x, y and n satisfy 0.4?x?0.6, 0.2?y?0.35, 4?n?6, and 1.4?x/y?2.5. The oxide magnetic material includes a ferrite having a hexagonal M-type magnetoplumbite structure as a main phase.Type: ApplicationFiled: June 4, 2010Publication date: September 23, 2010Applicant: NEOMAX CO., LTD.Inventors: Yoshinori KOBAYASHI, Seiichi HOSOKAWA, Sachio TOYOTA
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Patent number: 7758767Abstract: An oxide magnetic material according to the present invention is represented by the formula: (1?x)CaO.(x/2)R2O3.(n?y/2)Fe2O3.yMO, where R is at least one element selected from the group consisting of La, Nd and Pr and always includes La, M is at least one element selected from the group consisting of Co, Zn, Ni and Mn and always includes Co, and the mole fractions x, y and n satisfy 0.4?x?0.6, 0.2?y?0.35, 4?n?6, and 1.4?x/y?2.5. The oxide magnetic material includes a ferrite having a hexagonal M-type magnetoplumbite structure as a main phase.Type: GrantFiled: September 8, 2005Date of Patent: July 20, 2010Assignee: Neomax Co., Ltd.Inventors: Yoshinori Kobayashi, Seiichi Hosokawa, Sachio Toyota
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Publication number: 20090261288Abstract: An oxide magnetic material includes a ferrite with a hexagonal structure as its main phase. Metallic elements included in the oxide magnetic material are represented by the formula: Ca1-x-x?LaxSrx?Fe2n-yCoy, where atomic ratios x, x? and y and a molar ratio n satisfy 0.4?x?0.6, 0.01?x??0.3, 0.2?y?0.45 and 5.2?n?5.8, respectively.Type: ApplicationFiled: June 25, 2008Publication date: October 22, 2009Applicant: HITACHI METALS, LTD.Inventors: Seiichi Hosokawa, Yoshinori Kobayashi, Yasunobu Ogata, Etsushi Oda
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Publication number: 20070194269Abstract: An oxide magnetic material according to the present invention is represented by the formula: (1?x)CaO.(x/2)R2O3.(n?y/2)Fe2O3.yMO, where R is at least one element selected from the group consisting of La, Nd and Pr and always includes La, M is at least one element selected from the group consisting of Co, Zn, Ni and Mn and always includes Co, and the mole fractions x, y and n satisfy 0.4?x?0.6, 0.2?y?0.35, 4?n?6, and 1.4?x/y?2.5. The oxide magnetic material includes a ferrite having a hexagonal M-type magnetoplumbite structure as a main phase.Type: ApplicationFiled: September 8, 2005Publication date: August 23, 2007Applicant: Neomax Co., Ltd.Inventors: Yoshinori Kobayashi, Seiichi Hosokawa, Sachio Toyota
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Patent number: 7144642Abstract: A ferrite magnet obtained by adding a ferrite having a hexagonal W-type magnetoplumbite structure to a ferrite having a hexagonal M-type magnetoplumbite structure, in which a portion of Sr, Ba, Pb or Ca is replaced with at least one element that is selected from the group consisting of the rare-earth elements (including Y) and Bi and that always includes La, during the fine pulverization process thereof. By adding a small amount of the element such as Co, Ni, Mn or Zn to the ferrite already having the hexagonal M-type magnetoplumbite structure during the fine pulverization process thereof, the magnetic properties can be improved.Type: GrantFiled: February 6, 2002Date of Patent: December 5, 2006Assignee: Neomax Co., Ltd.Inventors: Etsushi Oda, Seiichi Hosokawa, Sachio Toyota
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Patent number: 6994797Abstract: A ferrite magnet obtained by adding at least one element selected from the group consisting of Co, Ni, Mn and Zn to a ferrite having a hexagonal M-type magnetoplumbite structure, in which a portion of Sr, Ba, Pb or Ca is replaced with at least one element that is selected from the group consisting of the rare-earth elements (including Y) and Bi and that always includes La, during the fine pulverization process thereof, and then subjecting the mixture to re-calcining and/or sintering process(es). By adding a small amount of the element such as Co, Ni, Mn or Zn to the ferrite already having the hexagonal M-type magnetoplumbite structure during the fine pulverization process thereof, the magnetic properties can be improved.Type: GrantFiled: February 6, 2002Date of Patent: February 7, 2006Assignee: Neomax Co., Ltd.Inventors: Etsushi Oda, Sachio Toyota, Seiichi Hosokawa
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Patent number: 6955768Abstract: A ferrite magnet obtained by adding a ferrite having a spinel-type structure to a ferrite having a hexagonal M-type magnetoplumbite structure, in which a portion of Sr, Ba, Pb or Ca is replaced with at least one element that is selected from the group consisting of the rare-earth elements (including Y) and Bi and that always includes La, during the fine pulverization process thereof. By adding a small amount of the element such as Co, Ni, Mn or Zn to the ferrite already having the hexagonal M-type magnetoplumbite structure during the fine pulverization process thereof, the magnetic properties can be improved.Type: GrantFiled: February 6, 2002Date of Patent: October 18, 2005Assignee: Neomax Co., Ltd.Inventors: Etsushi Oda, Seiichi Hosokawa, Sachio Toyota
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Patent number: 6929758Abstract: A ferrite magnet obtained by adding either an oxide of Mn or oxides of Mn and Co to a ferrite having a hexagonal M-type magnetoplumbite structure, in which a portion of Sr, Ba, Pb or Ca is replaced with at least one element that is selected from the group consisting of the rare earth elements (including Y) and Bi and that always includes La, during the fine pulverization process thereof, and then subjecting the mixture to re-calcining and/or sintering process(es). By adding a small amount of the element Mn or elements Mn and Co to the ferrite already having the hexagonal M-type magnetoplumbite structure during the fine pulverization process thereof, the magnetic properties can be improved.Type: GrantFiled: December 6, 2001Date of Patent: August 16, 2005Assignee: Neomax Co., Ltd.Inventors: Etsushi Oda, Sachio Toyota, Seiichi Hosokawa
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Patent number: 6758986Abstract: The production is performed by calcining ferrite magnetic powder in which La is substituted for part of Sr and Ti, Zn, and Co are substituted for part of Fe at temperatures of 1100° C. to 1450° C. The magnetization is improved by substituting Zn for part of Fe, and by substituting Ti for part of Fe for the purpose of charge compensation. In addition, the coercive force is improved by substituting Co for part of Fe, and by substituting La for part of Sr for the purpose of charge compensation. Ti is used for the charge compensation, so that it is possible to reduce the cost.Type: GrantFiled: April 30, 2001Date of Patent: July 6, 2004Assignee: Sumitomo Special Metals Co., Ltd.Inventors: Seiichi Hosokawa, Sachio Toyota
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Publication number: 20040121188Abstract: A ferrite magnet obtained by adding at least one element selected from the group consisting of Co, Ni, Mn and Zn to a ferrite having a hexagonal M-type magnetoplumbite structure, in which a portion of Sr, Ba, Pb or Ca is replaced with at least one element that is selected from the group consisting of the rare-earth elements (including Y) and Bi and that always includes La, during the fine pulverization process thereof, and then subjecting the mixture to re-calcining and/or sintering process(es). By adding a small amount of the element such as Co, Ni, Mn or Zn to the ferrite already having the hexagonal M-type magnetoplumbite structure during the fine pulverization process thereof, the magnetic properties can be improved.Type: ApplicationFiled: July 24, 2003Publication date: June 24, 2004Inventors: Etsushi Oda, Sachio Toyota, Seiichi Hosokawa
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Publication number: 20040061090Abstract: A ferrite magnet obtained by adding a ferrite having a spinel-type structure to a ferrite having a hexagonal M-type magnetoplumbite structure, in which a portion of Sr, Ba, Pb or Ca is replaced with at least one element that is selected from the group consisting of the rare-earth elements (including Y) and Bi and that always includes La, during the fine pulverization process thereof. By adding a small amount of the element such as Co, Ni, Mn or Zn to the ferrite already having the hexagonal M-type magnetoplumbite structure during the fine pulverization process thereof, the magnetic properties can be improved.Type: ApplicationFiled: July 22, 2003Publication date: April 1, 2004Inventors: Etsushi Oda, Seiichi Hosokawa, Sachio Toyota
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Publication number: 20040053075Abstract: A ferrite magnet obtained by adding a ferrite having a hexagonal W-type magnetoplumbite structure to a ferrite having a hexagonal M-type magnetoplumbite structure, in which a portion of Sr, Ba, Pb or Ca is replaced with at least one element that is selected from the group consisting of the rare-earth elements (including Y) and Bi and that always includes La, during the fine pulverization process thereof. By adding a small amount of the element such as Co, Ni, Mn or Zn to the ferrite already having the hexagonal M-type magnetoplumbite structure during the fine pulverization process thereof, the magnetic properties can be improved.Type: ApplicationFiled: June 27, 2003Publication date: March 18, 2004Inventors: Etsushi Oda, Seiichi Hosokawa, Sachio Toyota
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Publication number: 20040028946Abstract: A ferrite magnet obtained by adding either an oxide of Mn or oxides of Mn and Co to a ferrite having a hexagonal M-type magnetoplumbite structure, in which a portion of Sr, Ba, Pb or Ca is replaced with at least one element that is selected from the group consisting of the rare earth elements (including Y) and Bi and that always includes La, during the fine pulverization process thereof, and then subjecting the mixture to re-calcining and/or sintering process(es). By adding a small amount of the element Mn or elements Mn and Co to the ferrite already having the hexagonal M-type magnetoplumbite structure during the fine pulverization process thereof, the magnetic properties can be improved.Type: ApplicationFiled: June 13, 2003Publication date: February 12, 2004Inventors: Etsushi Oda, Sachio Toyota, Seiichi Hosokawa
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Patent number: 6419847Abstract: An La—Co ferrite magnet powder, in which Sr and Fe are replaced with La and Co, respectively, is made by carrying out a calcination process at a temperature higher than 1300° C. and equal to or lower than 1450° C. Fe has a magnetic moment oriented upwardly with respect to a crystal c-axis at a number of sites thereof, and also has an opposite magnetic moment oriented downwardly with respect to the crystal c-axis at another number of sites thereof. And Fe is replaced with Co at the greater number of sites thereof. As a result, high coercivity is attained. In this manner, coercivity can be increased while suppressing decrease in saturation magnetization &sgr;s.Type: GrantFiled: July 19, 2000Date of Patent: July 16, 2002Assignee: Sumitomo Special Metals Co., Ltd.Inventors: Sachio Toyota, Seiichi Hosokawa, Shuji Anamoto, Isamu Furuchi