Patents by Inventor Yoshitaka Murakawa
Yoshitaka Murakawa 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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Publication number: 20240177896Abstract: A ferrite sintered magnet represented by A1?xRx(Fe12?yCoy)zO19 in terms of atomic number ratio. A is at least one selected from a group made of Sr, Ba and Pb. R is La only or La and at least one selected from a group made of Bi and rare earth elements. 0.14?x?0.22, 11.60?(12?y)×z?11.99, and 0.13?y×z?0.17 are satisfied. 0.500?Mc?0.710 is satisfied in which Mc is CaO content in mass % converted from a content of Ca included in the ferrite sintered magnet. 0.410?Ms?0.485 is satisfied in which Ms is SiO2 content in mass % converted from a content of Si included in the ferrite sintered magnet.Type: ApplicationFiled: March 24, 2022Publication date: May 30, 2024Applicant: TDK CORPORATIONInventors: Shogo MUROYA, Yoshitaka MURAKAWA, Hiroyuki MORITA, Masanori IKEDA, Takuma ABE
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Patent number: 11688535Abstract: This ferrite sintered magnet comprises ferrite phases having a magnetoplumbite type crystal structure. This magnet comprises an element R, an element M, Fe, Co, B, Mn and Cr, the element R is at least one element selected from rare earth elements including Y, the element M is at least one element selected from the group consisting of Ca, Sr and Ba, with Ca being an essential element, and when an atomic composition of metallic elements is represented by R1-xMxFem-yCoy, x, y and m satisfy formulae: 0.2?x?0.8??(1) 0.1?y?0.65??(2) 3?m<14??(3). Additionally, a content of B is 0.1 to 0.4% by mass in terms of B2O3, a content of Mn is 0.15 to 1.02% by mass in terms of MnO, and a content of Cr is 0.02 to 2.01% by mass in terms of Cr2O3.Type: GrantFiled: March 20, 2020Date of Patent: June 27, 2023Assignee: TDK CorporationInventors: Shogo Muroya, Yoshitaka Murakawa, Hiroyuki Morita, Masanori Ikeda
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Patent number: 11664142Abstract: To provide a ferrite sintered magnet having a high residual magnetic flux density (Br), a high coercive force (HcJ), a good production stability, and also able to produce at a low cost. The ferrite sintered magnet includes a hexagonal M-type ferrite including A, R, Fe, and Co in an atomic ratio of A1-xRx(Fe12-yCoy)zO19. A is at least one selected from Sr, Ba, and Pb. R is La only or La and at least one selected from rare earth elements. 0.14?x?0.22, 11.60?(12-y)z?11.99, and 0.13?yz?0.17 are satisfied. 0.30?Mc?0.63 is satisfied in which Mc is CaO content (mass %) converted from a content of Ca included in the ferrite sintered magnet.Type: GrantFiled: March 15, 2021Date of Patent: May 30, 2023Assignee: TDK CORPORATIONInventors: Shogo Muroya, Yoshitaka Murakawa, Hiroyuki Morita, Masanori Ikeda
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Patent number: 11636964Abstract: To provide a ferrite sintered magnet having a high residual magnetic flux density (Br) and a high coercive force (HcJ), and also able to produce at a low cost. The ferrite sintered magnet includes a hexagonal M-type ferrite including A, R, Fe, and Co in an atomic ratio of A1-xRx(Fe12-yCoy)zO19. A is at least one selected from Sr, Ba, and Pb. R is La only or La and at least one selected from rare earth elements. 0.13?x?0.23, 10.80?(12?y)z?12.10, and 0.13?yz?0.20 are satisfied.Type: GrantFiled: March 11, 2021Date of Patent: April 25, 2023Assignee: TDK CORPORATIONInventors: Shogo Muroya, Yoshitaka Murakawa, Hiroyuki Morita, Masanori Ikeda
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Patent number: 11626222Abstract: A ferrite sintered magnet 100 comprises M-type ferrite crystal grains 4 and multiple-crystal grain boundaries 6b surrounded by three or more of the M-type ferrite crystal grains 4. The ferrite sintered magnet 100 contains at least Fe, Ca, B, and Si, and contains 0.005 to 0.9 mass % of B in terms of B2O3. The multiple-crystal grain boundaries 6b contain Si and Ca, and in a case where the molar ratio of Ca to Si in the multiple-crystal grain boundaries 6b is represented by (Ca/Si)G, the following formula is satisfied. 0.1<(Ca/Si)G<0.Type: GrantFiled: October 14, 2020Date of Patent: April 11, 2023Assignee: TDK CorporationInventors: Yoshitaka Murakawa, Hiroyuki Morita, Masanori Ikeda, Shogo Muroya, Tomokazu Ishikura
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Patent number: 11615901Abstract: A ferrite sintered magnet comprises a plurality of main phase grains containing a ferrite having a hexagonal structure, wherein at least some of the main phase grains are core-shell structure grains each having a core and a shell covering the core; and wherein the minimum value of the content of La in the core is [La]c atom %; the minimum value of the content of Co in the core is [Co]c atom %; the maximum value of the content of La in the shell is [La]s atom %; the maximum value of the content of Co in the shell is [Co]s atom %; [La]c+[Co]c is 3.08 atom % or more and 4.44 atom % or less; and [La]s+[Co]s is 7.60 atom % or more and 9.89 atom % or less.Type: GrantFiled: January 31, 2020Date of Patent: March 28, 2023Assignee: TDK CorporationInventors: Hiroyuki Morita, Masanori Ikeda, Yoshitaka Murakawa, Shogo Muroya
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Patent number: 11610705Abstract: A ferrite sintered magnet comprising an M type Sr ferrite having a hexagonal structure as a main phase, wherein the ferrite sintered magnet does not substantially comprise a rare earth element and Co, a content of B is 0.005 to 0.9% by mass in terms of B2O3, and a content of Zn is 0.01 to 1.2% by mass in terms of ZnO.Type: GrantFiled: March 19, 2020Date of Patent: March 21, 2023Assignee: TDK CorporationInventors: Yoshitaka Murakawa, Shogo Muroya, Hiroyuki Morita, Masanori Ikeda
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Patent number: 11600412Abstract: A ferrite sintered magnet 100 comprises M-type ferrite crystal grains 4 and multiple-crystal grain boundaries 6b surrounded by three or more of the M-type ferrite crystal grains 4. The ferrite sintered magnet 100 contains at least Fe, Ca, B, and Si, and contains 0.005 to 0.9 mass % of B in terms of B2O3. The multiple-crystal grain boundaries 6b contain Si and Ca, and in a case where the molar ratio of Ca to Si in the multiple-crystal grain boundaries 6b is represented by (Ca/Si)G, the following formula is satisfied. 0.1<(Ca/Si)G<0.Type: GrantFiled: October 14, 2020Date of Patent: March 7, 2023Assignee: TDK CorporationInventors: Yoshitaka Murakawa, Hiroyuki Morita, Masanori Ikeda, Shogo Muroya, Tomokazu Ishikura
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Patent number: 11557412Abstract: A ferrite sintered magnet comprising an M type Sr ferrite having a hexagonal structure as a main phase, wherein the ferrite sintered magnet comprises La and Co, a content of B is 0.005 to 0.9% by mass in terms of B2O3, a content of Zn is 0.01 to 1.2% by mass in terms of ZnO, and the ferrite sintered magnet satisfies [La]/[Zn]?0.79 and [Co]/[Zn]?0.67 when an atomic concentration of La is represented by [La], an atomic concentration of Co is represented by [Co], and an atomic concentration of Zn is represented by [Zn].Type: GrantFiled: March 20, 2020Date of Patent: January 17, 2023Assignee: TDK CorporationInventors: Yoshitaka Murakawa, Shogo Muroya, Hiroyuki Morita, Masanori Ikeda
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Patent number: 11532413Abstract: A ferrite sintered magnet 100 comprises M-type ferrite crystal grains 4 having a hexagonal structure, two-crystal grain boundaries 6a formed between two of the M-type ferrite crystal grains 4, and multiple-crystal grain boundaries 6b surrounded by three or more of the M-type ferrite crystal grains 4. This ferrite sintered magnet 100 contains at least Fe, Ca, B, and Si, and contains B in an amount of 0.005 to 0.9 mass % in terms of B2O3, the two-crystal grain boundaries 6a and the multiple-crystal grain boundaries 6b contain Si and Ca, and in a cross-section parallel to a c-axis of the ferrite sintered magnet, when the number of multiple-crystal grain boundaries 6b having a maximum length of 0.49 to 5 ?m per cross-sectional area of 76 ?m2 is N, N is 7 or less.Type: GrantFiled: March 23, 2020Date of Patent: December 20, 2022Assignee: TDK CorporationInventors: Yoshitaka Murakawa, Shogo Muroya, Hiroyuki Morita, Masanori Ikeda
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Patent number: 11521769Abstract: A ferrite sintered magnet 100 comprises M-type ferrite crystal grains 4 having a hexagonal crystal structure, two-crystal grain boundaries 6a formed between two of the M-type ferrite crystal grains 4, and multiple-crystal grain boundaries 6b surrounded by three or more of the M-type ferrite crystal grains 4. This ferrite sintered magnet 100 contains at least Fe, Ca, B, and Si, and contains B in an amount of 0.005 to 0.9 mass % in terms of B2O3, the two-crystal grain boundaries 6a and the multiple-crystal grain boundaries 6b contain Si and Ca, and in a cross-section parallel to a c-axis of the ferrite sintered magnet, when the number of multiple-crystal grain boundaries having a maximum length of 0.088 or more and less than 0.49 ?m per cross-sectional area of 76 ?m2 is P, P is 8 or more.Type: GrantFiled: March 20, 2020Date of Patent: December 6, 2022Assignee: TDK CorporationInventors: Yoshitaka Murakawa, Shogo Muroya, Hiroyuki Morita, Masanori Ikeda
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Patent number: 11488752Abstract: The present invention provides a ferrite sintered magnet comprising ferrite crystal grains having a hexagonal structure, wherein the ferrite sintered magnet comprises metallic elements at an atomic ratio represented by formula (1). In formula (1), R is at least one element selected from the group consisting of Bi and rare-earth elements, and R comprises at least La. In formula (1), w, x, z and m satisfy formulae (2) to (5). The above-mentioned ferrite sintered magnet further has a coefficient of variation of a size of the crystal grains in a section parallel to a c axis of less than 45%. Ca1-w-xRwSrxFezCom??(1) 0.360?w?0.420??(2) 0.110?x?0.173??(3) 8.51?z?9.71??(4) 0.208?m?0.Type: GrantFiled: September 21, 2020Date of Patent: November 1, 2022Assignee: TDK CorporationInventors: Tomokazu Ishikura, Masanori Ikeda, Yoshitaka Murakawa, Hiroyuki Morita, Shogo Muroya
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Patent number: 11476023Abstract: A ferrite sintered magnet including ferrite grains having a hexagonal crystal structure. The ferrite grains satisfy 0.56?W?0.68 where W is an average value of circularities of the ferrite grains in a cross section parallel to an axis of easy magnetization.Type: GrantFiled: March 19, 2021Date of Patent: October 18, 2022Assignee: TDK CORPORATIONInventors: Masanori Ikeda, Hiroyuki Morita, Yoshitaka Murakawa, Shogo Muroya
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Patent number: 11456096Abstract: There is provided a ferrite sintered magnet having a high residual magnetic flux density. A ferrite sintered magnet 2 includes a plurality of main phase particles 5 including ferrite having a hexagonal structure, the number of core-shell structured particles 5A having a core 7 and a shell 9 covering the core 7, among the main phase particles 5, is smaller than the number of the main phase particles 5 other than the core-shell structured particles 5A.Type: GrantFiled: February 5, 2019Date of Patent: September 27, 2022Assignee: TDK CorporationInventors: Hiroyuki Morita, Masanori Ikeda, Yoshitaka Murakawa, Taku Murase
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Patent number: 11440848Abstract: This ferrite sintered magnet comprises metallic elements at an atomic ratio represented by formula (1): Ca1-w-xRwSrxFezCom??(1) in formula (1), R is at least one element selected from the group consisting of rare-earth elements and Bi, and R comprises at least La, in formula (1), w, x, z and m satisfy formulae (2) to (5): 0.360?w?0.420??(2) 0.110?x?0.173??(3) 8.51?z?9.71??(4) 0.208?m?0.269??(5), and in a section parallel to an axis of easy magnetization, when the number of total ferrite grains is N and the number of ferrite grains having a stacking fault is n, 0?n/N?0.20 is satisfied.Type: GrantFiled: February 5, 2020Date of Patent: September 13, 2022Assignee: TDK CorporationInventors: Masanori Ikeda, Hiroyuki Morita, Yoshitaka Murakawa, Shogo Muroya
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Patent number: 11407686Abstract: This ferrite sintered magnet comprises metallic elements at an atomic ratio represented by formula (1): Ca1-w-xRwSrxFezCom??(1) in formula (1), R is at least one element selected from the group consisting of rare-earth elements and Bi, and R comprises at least La, in formula (1), w, x, z and m satisfy formulae (2) to (5): 0.360?w?0.420??(2) 0.110?x?0.173??(3) 8.51?z?9.71??(4) 0.208?m?0.269??(5), and in a section parallel to an axis of easy magnetization, when the number of total ferrite grains is N and the number of ferrite grains having a stacking fault is n, 0?n/N?0.20 is satisfied.Type: GrantFiled: February 5, 2020Date of Patent: August 9, 2022Assignee: TDK CorporationInventors: Masanori Ikeda, Hiroyuki Morita, Yoshitaka Murakawa, Shogo Muroya
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Patent number: 11380466Abstract: The present invention provides a ferrite sintered magnet comprising (1) main phase grains containing a ferrite having a hexagonal structure, (2) two-grain boundaries formed between two of the main phase grains, and (3) multi-grain boundaries surrounded by three or more of the main phase grains. The above ferrite sintered magnet comprises Ca, R, Sr, Fe and Co, with R being at least one element selected from the group consisting of rare earth elements and Bi, and comprising at least La. The number Nm of the above main phase grains and the number Ng of the above multi-grain boundaries in the cross section including the direction of the easy magnetization axis of the above ferrite sintered magnet satisfy the formula (1A): 50%?Nm/(Nm+Ng)?65%??(1A).Type: GrantFiled: March 7, 2019Date of Patent: July 5, 2022Assignee: TDK CorporationInventors: Hiroyuki Morita, Masanori Ikeda, Yoshitaka Murakawa, Hiroyuki Ono, Taku Murase
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Publication number: 20210304934Abstract: To provide a ferrite sintered magnet having a high residual magnetic flux density (Br) and a high coercive force (HcJ), and also able to produce at a low cost. The ferrite sintered magnet includes a hexagonal M-type ferrite including A, R, Fe, and Co in an atomic ratio of A1-xRx(Fe12-yCoy)zO19. A is at least one selected from Sr, Ba, and Pb. R is La only or La and at least one selected from rare earth elements. 0.13?x?0.23, 10.80?(12?y)z?12.10, and 0.13?yz?0.20 are satisfied.Type: ApplicationFiled: March 11, 2021Publication date: September 30, 2021Applicant: TDK CORPORATIONInventors: Shogo MUROYA, Yoshitaka MURAKAWA, Hiroyuki MORITA, Masanori IKEDA
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Publication number: 20210304935Abstract: To provide a ferrite sintered magnet having a high residual magnetic flux density (Br), a high coercive force (HcJ), a good production stability, and also able to produce at a low cost. The ferrite sintered magnet includes a hexagonal M-type ferrite including A, R, Fe, and Co in an atomic ratio of A1-xRx(Fe12-yCoy)zO19. A is at least one selected from Sr, Ba, and Pb. R is La only or La and at least one selected from rare earth elements. 0.14?x?0.22, 11.60?(12-y)z?11.99, and 0.13?yz?0.17 are satisfied. 0.30?Mc?0.63 is satisfied in which Mc is CaO content (mass %) converted from a content of Ca included in the ferrite sintered magnet.Type: ApplicationFiled: March 15, 2021Publication date: September 30, 2021Applicant: TDK CORPORATIONInventors: Shogo MUROYA, Yoshitaka MURAKAWA, Hiroyuki MORITA, Masanori IKEDA
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Publication number: 20210296030Abstract: A ferrite sintered magnet including 0.010 mass % or more and 0.090 mass % or less of Mg in terms of MgO.Type: ApplicationFiled: March 11, 2021Publication date: September 23, 2021Applicant: TDK CORPORATIONInventors: Hiroyuki MORITA, Masanori IKEDA, Yoshitaka MURAKAWA, Shogo MUROYA