公开(公告)号：US20210304934A1

公开(公告)日：2021-09-30

申请号：US17198517

申请日：2021-03-11

Applicant: TDK CORPORATION

Inventor： Shogo MUROYA ,  Yoshitaka MURAKAWA ,  Hiroyuki MORITA ,  Masanori IKEDA

IPC: H01F1/34 ,  H02K1/02 ,  C01G51/00

Abstract: 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.

公开(公告)号：US20210118598A1

公开(公告)日：2021-04-22

申请号：US17070469

申请日：2020-10-14

Applicant: TDK Corporation

Inventor： Yoshitaka MURAKAWA ,  Hiroyuki MORITA ,  Masanori IKEDA ,  Shogo MUROYA ,  Tomokazu ISHIKURA

IPC: H01F1/03 ,  H01F1/08 ,  H01F1/11

Abstract: 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

公开(公告)号：US20210296030A1

公开(公告)日：2021-09-23

申请号：US17198542

申请日：2021-03-11

Applicant: TDK CORPORATION

Inventor： Hiroyuki MORITA ,  Masanori IKEDA ,  Yoshitaka MURAKAWA ,  Shogo MUROYA

IPC: H01F1/10 ,  C04B35/26 ,  H01F1/053

Abstract: A ferrite sintered magnet including 0.010 mass % or more and 0.090 mass % or less of Mg in terms of MgO.

公开(公告)号：US20200312497A1

公开(公告)日：2020-10-01

申请号：US16825290

申请日：2020-03-20

Applicant: TDK Corporation

Inventor： Shogo MUROYA ,  Yoshitaka MURAKAWA ,  Hiroyuki MORITA ,  Masanori IKEDA

IPC: H01F1/113 ,  C04B35/26

Abstract: 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

公开(公告)号：US20200312496A1

公开(公告)日：2020-10-01

申请号：US16826812

申请日：2020-03-23

Applicant: TDK Corporation

Inventor： Yoshitaka MURAKAWA ,  Shogo MUROYA ,  Hiroyuki MORITA ,  Masanori IKEDA

IPC: H01F1/11 ,  H02K1/02 ,  C04B35/26

Abstract: 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 μm per cross-sectional area of 76 μm2 is N, N is 7 or less.

公开(公告)号：US20200312493A1

公开(公告)日：2020-10-01

申请号：US16823871

申请日：2020-03-19

Applicant: TDK Corporation

Inventor： Yoshitaka MURAKAWA ,  Shogo MUROYA ,  Hiroyuki MORITA ,  Masanori IKEDA

IPC: H01F1/11 ,  H02K1/02 ,  C04B35/26

Abstract: 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.

公开(公告)号：US20220157498A1

公开(公告)日：2022-05-19

申请号：US17598508

申请日：2020-03-27

Applicant: TDK Corporation

Inventor： Masashi OHMURA ,  Junichi NAGAOKA ,  Shogo MUROYA ,  Takuma ABE ,  Jo SATO

IPC: H01F1/11 ,  C01G49/00 ,  C04B35/26

Abstract: A ferrite sintered magnet has a ferrite phase having a magnetoplumbite-type crystal structure, and contains at least a metal element A, a metal element R, Fe, Co, Zn, and B. The element A is at least one kind of element selected from the group consisting of Sr, Ba, Ca, and Pb, and essentially includes Ca. The element R is at least one kind of element selected from the group consisting of Bi and rare-earth elements including Y, and essentially includes La. Atomic ratios of the metal elements satisfy the following expressions. A1-rRrFexCoyZnz  (1) 0.40≤r≤0.70  (2) 8.20≤x≤9.34  (3) 0.05

公开(公告)号：US20210304935A1

公开(公告)日：2021-09-30

申请号：US17201809

申请日：2021-03-15

Applicant: TDK CORPORATION

Inventor： Shogo MUROYA ,  Yoshitaka MURAKAWA ,  Hiroyuki MORITA ,  Masanori IKEDA

IPC: H01F1/34 ,  H02K1/02 ,  C01G51/00

Abstract: 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.

公开(公告)号：US20210296032A1

公开(公告)日：2021-09-23

申请号：US17207085

申请日：2021-03-19

Applicant: TDK CORPORATION

Inventor： Masanori IKEDA ,  Hiroyuki MORITA ,  Yoshitaka MURAKAWA ,  Shogo MUROYA

IPC: H01F1/34 ,  C01G51/00

Abstract: 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.

公开(公告)号：US20200312495A1

公开(公告)日：2020-10-01

申请号：US16825717

申请日：2020-03-20

Applicant: TDK Corporation

Inventor： Yoshitaka MURAKAWA ,  Shogo MUROYA ,  Hiroyuki MORITA ,  Masanori IKEDA

IPC: H01F1/11 ,  C04B35/26

Abstract: 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].