ANISOTROPIC COMPLEX SINTERED MAGNET COMPRISING MnBi WHICH HAS IMPROVED MAGNETIC PROPERTIES AND METHOD OF PREPARING THE SAME

Patent metadata

Field	Value
Publication number	US-2016168660-A1
Application number	US-201514837800-A
Country	US
Kind code	A1
Filing date	Aug 27, 2015
Priority date	Dec 15, 2014
Publication date	Jun 16, 2016
Grant date	—

Abstract

The present invention relates to a method of preparing an anisotropic complex sintered magnet having MnBi, that includes: (a) preparing a non-magnetic phase MnBi-based ribbon by a rapidly solidification process (RSP); (b) heat treating the non-magnetic phase MnBi-based ribbon to convert the non-magnetic phase MnBi-based ribbon into a magnetic phase MnBi-based ribbon; (c) grinding the magnetic phase MnBi-based ribbon to form a MnBi hard magnetic phase powder; (d) mixing the MnBi hard magnetic phase powder with a rare-earth hard magnetic phase powder; (e) magnetic field molding the mixture obtained in step (d) by applying an external magnetic field to form a molded article; and (f) sintering the molded article.

First claim

What is claimed is:

1 . A method of preparing an anisotropic complex sintered magnet comprising MnBi, the method comprising:
(a) preparing a non-magnetic phase MnBi-based ribbon by a rapidly solidification process (RSP); (b) heat treating the non-magnetic phase MnBi-based ribbon to convert the non-magnetic phase MnBi-based ribbon into a magnetic phase MnBi-based ribbon; (c) grinding the magnetic phase MnBi-based ribbon to form a MnBi hard magnetic phase powder; (d) mixing the MnBi hard magnetic phase powder with a rare-earth hard magnetic phase powder; (e) magnetic field molding the mixture obtained in step (d) by applying an external magnetic field to form a molded article; and (f) sintering the molded article.

2 . The method of claim 1 , wherein the MnBi-based ribbon prepared in step (a) has a crystal grain size of 50 to 100 nm.

3 . The method of claim 1 , wherein the MnBi-based ribbon is further prepared using a cooling wheel during the rapidly solidification process, and wherein the cooling wheel has a circumference speed of 10 to 300 m/s.

4 . The method of claim 1 , wherein the MnBi-based ribbon in step (a) is represented by Mn x Bi 100 −x , where X is 50 to 55.

5 . The method of claim 1 , wherein the heat treating of step (b) is performed at a temperature of 280 to 340° C.

6 . The method of claim 1 , wherein the MnBi hard magnetic phase powder has a diameter of 0.5 to 5 μm and the rare-earth hard magnetic phase powder has a diameter of 1 to 5 μm.

7 . The method of claim 1 , wherein the rare-earth hard magnetic phase is represented by R—Co or R—Fe—B, wherein R is a rare-earth element selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

8 . The method of claim 1 , wherein the rare-earth hard magnetic phase is SmFeN, NdFeB, or SmCo.

9 . The method of claim 1 , wherein a dispersing agent is added during the grinding the magnetic phase MnBi-based ribbon of step (c), wherein the dispersing agent is selected from the group consisting of oleic acid (C 18 H 34 O 2 ), oleylamine (C 18 H 37 N), polyvinylpyrrolidone, and polysorbate.

10 . The method of claim 1 , wherein a lubricant is added during the mixing of step (d), wherein the lubricant is selected from the group consisting of ethyl butyratebutyrate, methyl caprylatecaprylate, ethyl laurate, and stearate.

11 . The method of claim 1 , wherein the grinding the magnetic phase MnBi-based ribbon of step (c) is performed for 3 to 8 hours.

12 . The method of claim 1 , wherein the mixing of step (d) is rapidly performed within 1 minute to 1 hour for preventing the powders from being crushed.

13 . The method of claim 1 , wherein the sintering of step (f) is performed by a process selected from the group consisting of a hot press sintering, a hot isotactic press sintering, a spark plasma sintering, a furnace sintering, and a microwave sintering.

14 . An anisotropic complex sintered magnet prepared by the method of claim 1 , comprising:
MnBi; and a rare-earth hard magnetic phase, wherein the MnBi-based ribbon prepared in step (a) has a crystal grain size of 50 to 100 nm.

15 . The anisotropic complex sintered magnet of claim 14 , wherein the anisotropic complex sintered magnet comprises 55 to 99 wt % of the MnBi and 1 to 45 wt % of the rare-earth hard magnetic phase.

16 . The anisotropic complex sintered magnet of claim 14 , wherein the anisotropic complex sintered magnet has a maximum magnetic energy product (BH max ) of 5 to 15 MGOe at a temperature from 25° C. to 150° C.

17 . A product comprising the anisotropic complex sintered magnet of claim 14 , wherein the product is selected from the group consisting of a compressor motor for refrigerator or air conditioner, a washing machine driving motor, a mobile handset vibration motor; a speaker, a voice coil motor, a linear motor, a zoom, an iris diaphragm, and a shutter of a camera, an actuator of a precision machine, a dual clutch transmission (DCT), an anti-lock brake system (ABS), an electric power steering (EPS) motor, and a fuel pump.

18 . The method of claim 3 , wherein the cooling wheel has a circumference speed of 30 to 100 m/s.

19 . The method of claim 3 , wherein the cooling wheel has a circumference speed of 60 to 70 m/s.

20 . The method of claim 1 , wherein the magnetic field molding is performed under a magnetic field of 0.1 to 5.0 T.

Assignees

• Lg Electronics Inc

Inventors

• Kim Jinbae
• Byun Yangwoo
• Cho Sanggeun

Classifications

• B22F2301/355

  Rare Earth - Fe intermetallic alloys · CPC title

• B22F3/087

  using high energy impulses, e.g. magnetic field impulses · CPC title

• B22F2301/30

  Low melting point metals, i.e. Zn, Pb, Sn, Cd, In, Ga · CPC title

• B22F1/0059

  Operations & Transport · mapped topic

• B22F2009/043

  by ball milling · CPC title