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    R-T-B BASED PERMANENT MAGNET
    1.
    发明申请
    R-T-B BASED PERMANENT MAGNET 有权

    公开(公告)号：US20250014792A1

    公开(公告)日：2025-01-09

    申请号：US18702173

    申请日：2022-11-02

    Applicant: TDK CORPORATION

    Inventor： Hiroki KAWAMURA ,  Hikaru KUDO ,  Masashi MIWA

    IPC: H01F1/057

    Abstract: An R-T-B based permanent magnet contains Al, Ga, and Zr. The R content is greater than or equal to 30.00 mass % and less than or equal to 33.00 mass %, the B content is greater than or equal to 0.70 mass % and less than or equal to 0.88 mass %, the Al content is greater than 0 mass % and less than or equal to 0.07 mass %, the Ga content is greater than or equal to 0.40 mass % and less than or equal to 1.00 mass %, and the Zr content is greater than 0.10 mass % and less than or equal to 1.60 mass %.

    R-T-B BASED PERMANENT MAGNET AND MOTOR
    2.
    发明申请
    R-T-B BASED PERMANENT MAGNET AND MOTOR 有权

    公开(公告)号：US20210407714A1

    公开(公告)日：2021-12-30

    申请号：US17356178

    申请日：2021-06-23

    Applicant: TDK CORPORATION

    Inventor： Koji MIURA ,  Masashi MIWA

    IPC: H01F1/057 ,  C22C38/00

    Abstract: To provide an R-T-B based permanent magnet having a high residual magnetic flux density Br at room temperature and a high coercivity HcJ at high temperature. In the R-T-B based permanent magnet, R is a rare earth element, T is an iron group element, and B is boron, and the R-T-B based permanent magnet includes a light rare earth element and a heavy rare earth element as R. The R-T-B based permanent magnet further includes Al, Ga, and Zr. With respect to 100 mass % of the R-T-B based permanent magnet, a total content of R is 28.50 mass % to 30.25 mass % (not including 28.50 mass %), B content is 0.93 mass % to 0.98 mass %, Al content is 0.03 mass % to 0.19 mass %, Ga content is 0.03 mass % to 0.15 mass %, and Zr content is 0.30 mass % to 0.50 mass %.

    R-T-B BASED SINTERED MAGNET
    3.
    发明申请
    R-T-B BASED SINTERED MAGNET 审中-公开

    公开(公告)号：US20180301256A1

    公开(公告)日：2018-10-18

    申请号：US15939719

    申请日：2018-03-29

    Applicant: TDK CORPORATION

    Inventor： Yoshinori FUJIKAWA ,  Masashi MIWA

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

    CPC classification number: H01F1/0577 ,  C22C38/002 ,  C22C38/005 ,  C22C38/06 ,  C22C38/10 ,  C22C38/14 ,  C22C38/16 ,  C22C2202/02 ,  H01F41/0266 ,  H01F41/0293

    Abstract: An R-T-B based sintered magnet including main phase particles having an R2T14B type crystal structure. R is at least one rare earth element essentially including a heavy rare-earth element RH. T is at least one transition metal element essentially including Fe or Fe and Co. B is boron. At least one of the main phase particles includes low RH crystal phases inside the main phase particle. The low RH crystal phases include the R2T14B type crystal structure, wherein an RH concentration in the low RH crystal phases is relatively lower than the RH concentration in the whole main phase particles. The R-T-B based sintered magnet may satisfy rs−rc≥20% when an existence ratio of the main phase particles including the low RH crystal phases in a magnet surface layer part is rs (%) and the same in a magnet central part is rc (%).

    R-T-B BASED PERMANENT MAGNET
    5.
    发明申请
    R-T-B BASED PERMANENT MAGNET 审中-公开

    公开(公告)号：US20200303102A1

    公开(公告)日：2020-09-24

    申请号：US16819071

    申请日：2020-03-14

    Applicant: TDK Corporation

    Inventor： Masashi MIWA

    IPC: H01F1/057 ,  H01F41/02 ,  H01F7/02 ,  C22C38/00

    Abstract: A permanent magnet 2 includes Nd, Fe, and B, the permanent magnet 2 contains a plurality of main phase grains; and grain boundaries positioned between the main phase grains, the main phase grains include Nd, Fe, and B, at least a portion of the grain boundaries contains an R′—O—C phase, the R′—O—C phase includes a rare earth element R′, O, and C, the concentration of each of R′, O, and C in the R′—O—C phase is higher compared to the main phase grains, the permanent magnet 2 comprises a surface layer portion 21 and a central portion 22, the surface layer portion 21 is positioned on the surface side of the permanent magnet 2, the central portion 22 is positioned on the inner side of the permanent magnet 2, the proportion of the area of the R′—O—C phase occupying in a cross-section of the surface layer portion 21 is S1 %, the proportion of the area of the R′—O—C phase occupying in a cross-section of the central portion 22 is S2%, and S1 is higher than S2.

    R-T-B BASED PERMANENT MAGNET
    8.
    发明申请
    R-T-B BASED PERMANENT MAGNET 有权

    公开(公告)号：US20210304929A1

    公开(公告)日：2021-09-30

    申请号：US17202424

    申请日：2021-03-16

    Applicant: TDK Corporation

    Inventor： Masashi MIWA ,  Yoshitomo TANAKA ,  Koji MIURA ,  Taeko TSUBOKURA

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

    Abstract: Provided is a permanent magnet including a rare-earth element R (such as Nd), a transition metal element T (such as Fe), B, Zr, and Cu. The permanent magnet contains a plurality of main phase grains including Nd, T, and B, and grain boundary multiple junctions, the one grain boundary multiple junction is a grain boundary surrounded by three or more of the main phase grains, one of the grain boundary multiple junctions contains a ZrB2 crystal and an R—Cu-rich phase including R and Cu, Fe is contained in the ZrB2 crystal, a total concentration of Nd and Pr in the one grain boundary multiple junction containing both the ZrB2 crystal and the R—Cu-rich phase is higher than a total concentration of Nd and Pr in the main phase grain, a concentration of Cu in the one grain boundary multiple junction containing both the ZrB2 crystal and the R—Cu-rich phase is higher than a concentration of Cu in the main phase grain, and a unit of the concentration of each of Nd, Pr, and Cu is atomic %.

    R-T-B BASED PERMANENT MAGNET
    9.
    发明申请
    R-T-B BASED PERMANENT MAGNET 审中-公开

    公开(公告)号：US20190304638A1

    公开(公告)日：2019-10-03

    申请号：US16367650

    申请日：2019-03-28

    Applicant: TDK CORPORATION

    Inventor： Yuki NAGAMINE ,  Masashi MIWA ,  Yoshinori FUJIKAWA

    IPC: H01F1/055 ,  C22C38/16 ,  C22C38/10 ,  C22C38/06 ,  C22C38/00

    Abstract: An R-T-B based permanent magnet excellent in magnetic properties relatively reduces the amount of a heavy rare earth element used. An R-T-B based permanent magnet, wherein R represents a rare earth element, T an iron group element and B boron, includes main phase grains including an R2T14B crystal phase and grain boundaries formed between main phase grains. Grain boundaries include R-O-C-N concentrated parts where concentrations of R, O, C and N are all higher than those in main phase grains. C/R(S)>C/R(C) is satisfied in which C/R(S) represents a C/R ratio (atomic ratio) in R-O-C-N concentrated parts present in a surface of a R-T-B based permanent magnet and C/R(C) represents a C/R ratio (atomic ratio) in the R-O-C-N concentrated parts present in the center of a R-T-B based permanent magnet, and a heavy rare earth element RH is included in the R-T-B based permanent magnet.

    R-T-B BASED SINTERED MAGNET
    10.
    发明申请
    R-T-B BASED SINTERED MAGNET 审中-公开

    公开(公告)号：US20180286545A1

    公开(公告)日：2018-10-04

    申请号：US15939778

    申请日：2018-03-29

    Applicant: TDK CORPORATION

    Inventor： Yoshinori FUJIKAWA ,  Masashi MIWA

    IPC: H01F1/057 ,  H01F41/02 ,  C22C38/00

    CPC classification number: H01F1/0577 ,  C22C38/005 ,  H01F41/0293

    Abstract: An R-T-B based sintered magnet including a plural number of main phase particles having an R2T14B type crystal structure. R is at least one rare earth element essentially including heavy rare earth elements RH, T is at least one transition metal element essentially including Fe or Fe and Co, and B is boron. At least one of the main phase particles is a reverse core-shell main phase particle including a core part and a shell part, in which CRC/CRS>1.0 is satisfied when a total RH concentration (at %) in the core part is defined as CRC and a total RH concentration (at %) in the shell part is defined as CRS. An existence ratio of the reverse core-shell main phase particles is larger in a surface layer part of the magnet than in a central part of the magnet.

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