公开(公告)号：US20200176155A1

公开(公告)日：2020-06-04

申请号：US16698019

申请日：2019-11-27

Applicant: TDK Corporation

Inventor： Takeshi MASUDA ,  Taeko TSUBOKURA ,  Taku MURASE

IPC: H01F1/057 ,  C22C38/16 ,  C22C38/14 ,  C22C38/06 ,  C22C38/00 ,  C22C38/10

Abstract: An R-T-B permanent magnet comprises rare-earth elements R, transition metal elements T, and boron B; wherein at least some of the rare-earth elements R is Nd and at least one of Tb and Dy; at least some of the transition metal elements T are Fe; the R-T-B permanent magnet comprises a plurality of main phase grains and grain boundary triple points each surrounded by the main phase grains; the grain boundary triple points comprise at least one of Nd and Pr, at least one of Tb and Dy, at least one of Fe and Co, and copper; the average contents of Nd, Pr, Tb, Dy, Fe, Co and Cu each (unit: atom %) are represented by [Nd], [Pr], [Tb], [Dy], [Fe], [Co] and [Cu]; ([Fe]+[Co])/([Nd]+[Pr]) is 2 or more and 5 or less; and [Cu]/([Tb]+[Dy]) is 1 or more and 4 or less.

公开(公告)号：US20190304643A1

公开(公告)日：2019-10-03

申请号：US16295156

申请日：2019-03-07

Applicant: TDK Corporation

Inventor： Hiroyuki MORITA ,  Masanori IKEDA ,  Yoshitaka MURAKAWA ,  Hiroyuki ONO ,  Taku MURASE

IPC: H01F1/11

Abstract: 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).

公开(公告)号：US20190304642A1

公开(公告)日：2019-10-03

申请号：US16269612

申请日：2019-02-07

Applicant: TDK Corporation

Inventor： Masanori IKEDA ,  Hiroyuki MORITA ,  Yoshitaka MURAKAWA ,  Taku MURASE

IPC: H01F1/11 ,  H01F41/02 ,  C22C38/10 ,  C22C38/00 ,  B22F9/04 ,  B22F3/16

Abstract: A ferrite sintered magnet comprising ferrite particles having a hexagonal structure is provided. 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 rare-earth elements and Bi, and comprises at least La. In formula (1), w, x, z and m satisfy formulae (2) to (5). The above-mentioned ferrite sintered magnet comprises 0.037 to 0.181% by mass of B in terms of H3BO3. 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≤0.269   (5)

公开(公告)号：US20190304641A1

公开(公告)日：2019-10-03

申请号：US16267400

申请日：2019-02-05

Applicant: TDK Corporation

Inventor： Hiroyuki MORITA ,  Masanori IKEDA ,  Yoshitaka MURAKAWA ,  Taku MURASE

IPC: H01F1/10 ,  C04B35/26

Abstract: 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.