Patents by Inventor Taeko Tsubokura

Taeko Tsubokura 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).

  • Patent number: 11817241
    Abstract: A magnet structure includes a first sintered magnet, a second sintered magnet, and an intermediate layer disposed between the first sintered magnet and the second sintered magnet. Each of the first sintered magnet and the second sintered magnet independently includes crystal grains containing a rare earth element, a transition metal element, and boron. The intermediate layer contains rare earth element oxide phases and crystal grains containing a rare earth element, transition metal element, and boron. Each of the transition metal elements independently includes Fe or a combination of Fe and Co. An average coverage factor of the rare earth element oxide phases measured on the basis of a cross section perpendicular to the intermediate layer of the magnet structure is within a range of 10% to 69%.
    Type: Grant
    Filed: February 26, 2021
    Date of Patent: November 14, 2023
    Assignee: TDK Corporation
    Inventors: Taeko Tsubokura, Toshihiro Kuroshima, Koji Mitake, Takeshi Masuda
  • Patent number: 11742119
    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 %.
    Type: Grant
    Filed: March 16, 2021
    Date of Patent: August 29, 2023
    Assignee: TDK Corporation
    Inventors: Masashi Miwa, Yoshitomo Tanaka, Koji Miura, Taeko Tsubokura
  • Patent number: 11636962
    Abstract: Provided is a permanent magnet including a rare-earth element R, a transition metal element T, B, Zr, and Cu. The permanent magnet contains main phase grains including Nd, T, and B, and grain boundary multiple junctions, the 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, a concentration of B in the grain boundary multiple junction containing both the ZrB2 crystal and the R—Cu-rich phase is from 5 to 20 atomic %, a concentration of Cu in the grain boundary multiple junction containing both the ZrB2 crystal and the R—Cu-rich phase is from 5 to 25 atomic %, and a surface layer part of the main phase grain includes at least one kind of heavy rare-earth element among Tb and Dy.
    Type: Grant
    Filed: March 16, 2021
    Date of Patent: April 25, 2023
    Assignee: TDK Corporation
    Inventors: Masashi Miwa, Koji Miura, Taeko Tsubokura
  • Patent number: 11404207
    Abstract: A method for manufacturing an R-T-B permanent magnet comprises a diffusion step of adhering a diffusing material to the surface of a magnet base material and heating the magnet base material with the diffusing material adhered thereto, wherein the magnet base material comprises rare-earth elements R, transition metal elements T and boron B; at least some of R are Nd; at least some of T are Fe; the diffusing material comprises a first component, a second component and a third component; the first component is at least one of a simple substance of Tb and a simple substance of Dy; the second component comprises a metal comprising at least one of Nd and Pr and not comprising Tb and Dy; and the third component is at least one selected from the group consisting of a simple substance of Cu, an alloy comprising Cu, and a compound of Cu.
    Type: Grant
    Filed: November 27, 2019
    Date of Patent: August 2, 2022
    Assignee: TDK Corporation
    Inventors: Taeko Tsubokura, Takeshi Masuda, Taku Murase
  • Patent number: 11335483
    Abstract: The present invention provides a magnet structure comprising a first magnet, a second magnet, and an intermediate layer joining the first magnet and the second magnet. In the magnet structure, each of the first magnet and the second magnet is a permanent magnet comprising a rare earth element R, a transition metal element T, and boron B. In addition, the rare earth element R comprises: a light rare earth element RL comprising at least Nd; and a heavy rare earth element RH, and the transition metal element T comprises Fe, Co, and Cu. Further, the intermediate layer comprises: an RL oxide phase comprising an oxide of the light rare earth element RL; and an RL—Co—Cu phase comprising the light rare element RL, Co, and Cu.
    Type: Grant
    Filed: October 15, 2018
    Date of Patent: May 17, 2022
    Assignee: TDK Corporation
    Inventors: Taeko Tsubokura, Takeshi Masuda, Toshihiro Kuroshima
  • Patent number: 11244777
    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.
    Type: Grant
    Filed: November 27, 2019
    Date of Patent: February 8, 2022
    Assignee: TDK Corporation
    Inventors: Takeshi Masuda, Taeko Tsubokura, Taku Murase
  • Patent number: 11242580
    Abstract: The present invention provides an R-T-B based permanent magnet having excellent magnetic properties and corrosion resistance even when Co content is small. The R-T-B based permanent magnet in which R is a rare earth element including one or more selected from Nd and Pr and one or more selected from Dy and Tb, T is a combination of Fe and Co, and B is boron. The R-T-B based permanent magnet further includes Zr. A total content of Nd, Pr, Dy, and Tb is 30.00 mass % to 32.20 mass %, Co content is 0.30 mass % to 1.30 mass %, Zr content is 0.21 mass % to 0.85 mass %, and B content is 0.90 mass % to 1.02 mass % with respect to 100 mass % of the R-T-B based permanent magnet.
    Type: Grant
    Filed: March 19, 2020
    Date of Patent: February 8, 2022
    Assignee: TDK CORPORATION
    Inventors: Taeko Tsubokura, Takeshi Masuda
  • Publication number: 20210313099
    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, a concentration of B in the one grain boundary multiple junction containing both the ZrB2 crystal and the R—Cu-rich phase is from 5 to 20 atomic %, a concentration of Cu in the one grain boundary multiple junction containing both the ZrB2 crystal and the R—Cu-rich phase is from 5 to 25 atomic %, and a surface layer part of the main phase grain includes at least one kind of heavy rare-earth element among Tb and Dy.
    Type: Application
    Filed: March 16, 2021
    Publication date: October 7, 2021
    Applicant: TDK Corporation
    Inventors: Masashi MIWA, Koji MIURA, Taeko TSUBOKURA
  • Publication number: 20210304929
    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 %.
    Type: Application
    Filed: March 16, 2021
    Publication date: September 30, 2021
    Applicant: TDK Corporation
    Inventors: Masashi MIWA, Yoshitomo TANAKA, Koji MIURA, Taeko TSUBOKURA
  • Publication number: 20210280345
    Abstract: A magnet structure includes a first sintered magnet, a second sintered magnet, and an intermediate layer disposed between the first sintered magnet and the second sintered magnet. Each of the first sintered magnet and the second sintered magnet independently includes crystal grains containing a rare earth element, a transition metal element, and boron. The intermediate layer contains rare earth element oxide phases and crystal grains containing a rare earth element, transition metal element, and boron. Each of the transition metal elements independently includes Fe or a combination of Fe and Co. An average coverage factor of the rare earth element oxide phases measured on the basis of a cross section perpendicular to the intermediate layer of the magnet structure is within a range of 10% to 69%.
    Type: Application
    Filed: February 26, 2021
    Publication date: September 9, 2021
    Applicant: TDK Corporation
    Inventors: Taeko TSUBOKURA, Toshihiro KUROSHIMA, Koji MITAKE, Takeshi MASUDA
  • Publication number: 20200299813
    Abstract: The present invention provides an R-T-B based permanent magnet having excellent magnetic properties and corrosion resistance even when Co content is small. The R-T-B based permanent magnet in which R is a rare earth element including one or more selected from Nd and Pr and one or more selected from Dy and Tb, T is a combination of Fe and Co, and B is boron. The R-T-B based permanent magnet further includes Zr. A total content of Nd, Pr, Dy, and Tb is 30.00 mass % to 32.20 mass %, Co content is 0.30 mass % to 1.30 mass %, Zr content is 0.21 mass % to 0.85 mass %, and B content is 0.90 mass % to 1.02 mass % with respect to 100 mass % of the R-T-B based permanent magnet.
    Type: Application
    Filed: March 19, 2020
    Publication date: September 24, 2020
    Applicant: TDK CORPORATION
    Inventors: Taeko Tsubokura, Takeshi Masuda
  • Publication number: 20200303100
    Abstract: To provide an R-T-B based permanent magnet having excellent magnet properties and corrosion resistance even in case Co content is too small, and also to provide R-T-B based permanent magnet suitable for a grain boundary diffusion. The R-T-B based permanent magnet in which R represents a rare earth element including at least one selected from Nd, Pr, Dy, and Tb, T represents a combination of Fe and Co, and B represents boron. The R-T-B based permanent magnet further includes Zr. A total content of Nd, Pr, Dy, and Tb is 29.5 mass % to 31.5 mass %, Co content is 0.35 mass % to 1.50 mass %, Zr content is 0.21 mass % to 0.85 mass %, B content is 0.90 mass % to 1.02 mass % with respect to 100 mass % of the R-T-B based permanent magnet.
    Type: Application
    Filed: March 19, 2020
    Publication date: September 24, 2020
    Applicant: TDK CORPORATION
    Inventors: Taeko Tsubokura, Takeshi Masuda
  • Publication number: 20200176155
    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.
    Type: Application
    Filed: November 27, 2019
    Publication date: June 4, 2020
    Applicant: TDK Corporation
    Inventors: Takeshi MASUDA, Taeko TSUBOKURA, Taku MURASE
  • Publication number: 20200176184
    Abstract: A method for manufacturing an R-T-B permanent magnet comprises a diffusion step of adhering a diffusing material to the surface of a magnet base material and heating the magnet base material with the diffusing material adhered thereto, wherein the magnet base material comprises rare-earth elements R, transition metal elements T and boron B; at least some of R are Nd; at least some of T are Fe; the diffusing material comprises a first component, a second component and a third component; the first component is at least one of a simple substance of Tb and a simple substance of Dy; the second component comprises a metal comprising at least one of Nd and Pr and not comprising Tb and Dy; and the third component is at least one selected from the group consisting of a simple substance of Cu, an alloy comprising Cu, and a compound of Cu.
    Type: Application
    Filed: November 27, 2019
    Publication date: June 4, 2020
    Applicant: TDK Corporation
    Inventors: Taeko TSUBOKURA, Takeshi Masuda, Taku Murase
  • Patent number: 10546672
    Abstract: The present invention provides a rare earth based magnet that inhibits the high temperature demagnetization rate even when less or no heavy rare earth elements such as Dy, Tb and the like are used. The rare earth based magnet according to the present invention includes R2T14B main phase crystal grains and grain boundary phases between adjacent main phase crystal grains. In any cross-section of the rare earth based magnet, when evaluating the circular degree of the main phase crystal grains with Wadell's Roundness A, the shape of the main phase crystal grains is controlled such that the Roundness A becomes 0.24 or more.
    Type: Grant
    Filed: March 28, 2014
    Date of Patent: January 28, 2020
    Assignee: TDK CORPORATION
    Inventors: Eiji Kato, Yoshinori Fujikawa, Taeko Tsubokura, Chikara Ishizaka, Katsuo Sato
  • Publication number: 20190255618
    Abstract: A method of processing a rare earth magnet comprises: a step of irradiating an R-T-B-based rare earth magnet with laser light to process; and a step of performing heat treatment on the magnet after the irradiating. The heat treatment includes: a step A of bringing the temperature of the magnet to 400° C. or less, a step B of holding the magnet at a temperature T1 in a range of 400 to 700° C. after the step A, and a step C of bringing the temperature of the magnet to less than 400° C. after the step B. The temperature of the magnet is made not to exceed 700° C. between the step A and the step B. The temperature of the magnet is made not to exceed 700° C. between the step B and the step C. A step of setting the magnet at a temperature higher than 700° C. after the step C is not included.
    Type: Application
    Filed: February 19, 2019
    Publication date: August 22, 2019
    Applicant: TDK Corporation
    Inventors: Takeshi MASUDA, Taeko TSUBOKURA, Hiroshi MIYASAKA, Yutaka HATAKEYAMA, Toshihiro KUROSHIMA
  • Publication number: 20190115125
    Abstract: The present invention provides a magnet structure comprising a first magnet, a second magnet, and an intermediate layer joining the first magnet and the second magnet. In the magnet structure, each of the first magnet and the second magnet is a permanent magnet comprising a rare earth element R, a transition metal element T, and boron B. In addition, the rare earth element R comprises: a light rare earth element RL comprising at least Nd; and a heavy rare earth element RH, and the transition metal element T comprises Fe, Co, and Cu. Further, the intermediate layer comprises: an RL oxide phase comprising an oxide of the light rare earth element RL; and an RL—Co—Cu phase comprising the light rare element RL, Co, and Cu.
    Type: Application
    Filed: October 15, 2018
    Publication date: April 18, 2019
    Applicant: TDK Corporation
    Inventors: Taeko TSUBOKURA, Takeshi MASUDA, Toshihiro KUROSHIMA
  • Patent number: 10109402
    Abstract: The present invention provides a rare earth based magnet that inhibits the high temperature demagnetization rate even when less or no heavy rare earth elements such as Dy, Tb and the like than before are used. The rare earth based magnet according to the present invention is a sintered magnet which includes R2T14B crystal grains as main phase and grain boundary phases between the R2T14B crystal grains. When the grain boundary phase surrounded by three or more main phase crystal grains is regarded as the grain boundary multi-point, the microstructure of the sintered body is controlled so that the ratio of the grain boundary triple-point surrounded by three main phase crystal grains in all grain boundary multi-points to be specified value or less.
    Type: Grant
    Filed: July 16, 2014
    Date of Patent: October 23, 2018
    Assignee: TDK CORPORATION
    Inventors: Eiji Kato, Yoshinori Fujikawa, Taeko Tsubokura, Chikara Ishizaka, Katsuo Sato
  • Patent number: 10096412
    Abstract: The present invention provides a rare earth based magnet including R2T14B main-phase crystal grains, and two-grain boundary phases between adjacent two R2T14B main-phase crystal grains, the two-grain boundary phases are controlled such that the thickness thereof is 5 nm or more and 500 nm or less, and it is composed of a phase with a magnetism different from that of a ferromagnet.
    Type: Grant
    Filed: March 28, 2014
    Date of Patent: October 9, 2018
    Assignee: TDK CORPORATION
    Inventors: Eiji Kato, Yoshinori Fujikawa, Taeko Tsubokura, Chikara Ishizaka, Katsuo Sato
  • Patent number: 10020099
    Abstract: The present invention provides a rare earth based magnet that inhibits the high temperature demagnetization rate even when less or no heavy rare earth elements such as Dy, Tb and the like than before are used. The rare earth based magnet according to the present invention is a sintered magnet which includes R2T14B crystal grains as main phase and grain boundary phases between the R2T14B crystal grains. when evaluating the cross-sectional area distribution of the main phase crystal grains by histogram in any cross-section of the rare earth based magnet, the crystal grains with large particle size and the crystal grains with small particle size are controlled so that the cross-sectional area distribution becomes the one which respectively has at least one peak at two sides of the average value of the cross-sectional area.
    Type: Grant
    Filed: July 16, 2014
    Date of Patent: July 10, 2018
    Assignee: TDK CORPORATION
    Inventors: Eiji Kato, Yoshinori Fujikawa, Taeko Tsubokura, Chikara Ishizaka, Katsuo Sato