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CN-115938778-B - Preparation method of sintered NdFeB permanent magnet material with high temperature stability

CN115938778BCN 115938778 BCN115938778 BCN 115938778BCN-115938778-B

Abstract

The invention provides a preparation method of a high-temperature-stability sintered neodymium-iron-boron permanent magnet material, which takes main phase alloy powder with a chemical component shown as a formula RE x B y Co a M b Fe 100‑x‑y‑a‑b and auxiliary phase alloy powder with a chemical component shown as a formula Re c B d Co e M f Fe 100‑c‑d‑e‑f as raw materials, and the main phase alloy powder and the auxiliary phase alloy powder are mixed and then sequentially subjected to orientation molding, sintering and tempering to obtain the high-temperature-stability sintered neodymium-iron-boron material. The invention uses double alloy to introduce auxiliary phase and boron-rich phase in grain boundary to generate alloying reaction, regenerates new main phase shell layer, uses cobalt concentration difference between two phases to stabilize main phase and inhibit generation of impurity phase, can prepare high cobalt sintered NdFeB magnet with high temperature stability, and the process of the method is easy to control and is suitable for batch production.

Inventors

  • JIA ZHI
  • CAO SHUAI
  • DING GUANGFEI
  • Jin Mengxin
  • FAN XIAODONG
  • GUO SHUAI
  • CHEN RENJIE
  • YAN ARU

Assignees

  • 中国科学院宁波材料技术与工程研究所

Dates

Publication Date
20260508
Application Date
20221223

Claims (8)

  1. 1. A preparation method of a sintered NdFeB permanent magnet material with high temperature stability comprises the following steps: Mixing main phase alloy powder with a component shown in a formula (I) and auxiliary phase alloy powder with a component shown in a formula (II), and then sequentially carrying out orientation profiling, sintering and tempering to obtain a sintered NdFeB permanent magnet material with high temperature stability; the auxiliary phase alloy powder is 1-20wt% of the total of the main phase alloy powder and the auxiliary phase alloy powder; the sintering process comprises the following steps: sintering the oriented magnet at 900-1100 ℃ for 1-6 hours, reducing the temperature to 800-1000 ℃ and preserving heat for 0.5-2 hours, and finally raising the temperature to 900-1100 ℃ and preserving heat for 0.5-2 hours; RE x B y Co a M b Fe 100-x-y-a-b (I), in the formula (I), RE is selected from one or more of Dy, tb, pr, nd, la, ce, Y and Ho; M is selected from one or more of Al, cu, ga, si, sn, ge, zr, ti and Zn; 29≤x≤34,1.2≤y≤1.8,10≤a≤30,0.1≤b≤2.0; RE c B d Co e M f Fe 100-c-d-e-f (II), in the formula (II), RE is selected from one or more of Dy, tb, pr, nd, la, ce, Y and Ho; M is selected from one or more of Al, cu, ga, si, sn, ge, zr, ti and Zn; 29≤c≤70,0≤d≤2,0≤e<a≤20,0.1≤f≤50。
  2. 2. The method of claim 1, wherein the main phase of the sintered NdFeB has RE 2 (Fe,Co) 14 B.
  3. 3. The method according to claim 1, wherein the main phase alloy powder has a particle size of 1 to 5 μm and the auxiliary phase alloy powder has a particle size of 1 to 5 μm.
  4. 4. The method according to claim 1, wherein the magnetic field strength of the orientation profiling is 1.0 to 2.0t and the pressure is 100 to 200mpa.
  5. 5. The preparation method according to claim 1, wherein the preparation method of the main phase alloy powder and the auxiliary phase alloy powder specifically comprises: the main phase alloy cast sheet and the auxiliary phase alloy Jin Zhu sheet are respectively subjected to hydrogen crushing and then air flow grinding.
  6. 6. The method according to claim 5, wherein the hydrogen pressure of the hydrogen crushing is independently selected from 0.1 to 0.5mpa, the hydrogen absorption time is independently selected from 2 to 5 hours, the dehydrogenation temperature is independently selected from 300 to 500 ℃, and the dehydrogenation time is independently selected from 4 to 8 hours.
  7. 7. The method according to claim 5, wherein the hydrogen content in the powder obtained by hydrogen crushing is independently lower than 1500ppm, and the average particle size of the powder is independently selected from 100-250 μm.
  8. 8. The method according to claim 1, wherein the tempering treatment is performed at 800-1000 ℃ for 2-4 hours and then at 450-600 ℃ for 2-4 hours.

Description

Preparation method of sintered NdFeB permanent magnet material with high temperature stability Technical Field The invention relates to the technical field of rare earth permanent magnet materials, in particular to a preparation method of a sintered NdFeB permanent magnet material with high temperature stability. Background Since the 60 th century of 20 th, the rare earth permanent magnet material has been developed at high speed in scientific research, production and application, and has been developed to the third generation rare earth permanent magnet neodymium iron boron. Compared with the first two generations of rare earth permanent magnet materials, the neodymium iron boron permanent magnet material has the characteristics of high remanence, high magnetic energy product and high intrinsic coercivity, and is the strongest magnetic property in the permanent magnet materials found in the world at present. However, the application in the fields of high-temperature motors, precise meters and the like is greatly limited due to the poor temperature stability. In order to meet the application requirements of industries such as new energy automobiles, national defense and military industry and the like on high temperature stability, the temperature stability of the neodymium iron boron is improved, and the development of the neodymium iron boron permanent magnet material with high temperature stability has important significance. The research shows that Co is added into the magnet to replace Fe and preferentially occupy 8j 1 crystal position of RE 2Fe14 B compound, so that negative exchange effect is reduced, 3d-3d metal atom exchange effect is enhanced, 3d-3d exchange coupling effect in RE 2Co14 B is 3 times of that of RE 2Fe14 B, and the effect of raising Curie temperature and reducing remanence temperature coefficient is achieved, and the method becomes an important means for raising temperature stability of the magnet. However, when the Co content is high, a hetero-phase such as RE (Fe, co) 2、RE(Fe,Co)3、RE(Fe,Co)4B、RE2(Fe,Co)17 occurs. The coercive force of the sintered NdFeB is a structural sensitive parameter, and the ideal tissue structure of the sintered NdFeB material is that uniform thin-area grain boundaries wrap RE 2Fe14 B main phase grains, and the grains are fine and uniformly distributed. The presence of the impurity phase deteriorates the microstructure of the magnet, wherein RE (Fe, co) 2 is a soft magnetic phase, precipitates along grain boundaries, weakens the magnetic isolation between grains of the main phase, and is detrimental to the coercive force of the magnet. In addition, the presence of the impurity phase reduces the main phase ratio and reduces the remanence of the magnet. Therefore, how to suppress the impurity phase in the high cobalt magnet, it is a challenge to prepare a magnet having both high performance and high temperature stability. Disclosure of Invention The application solves the technical problem of providing a preparation method of a sintered neodymium-iron-boron magnet, and the prepared neodymium-iron-boron permanent magnet material has high temperature stability, high coercivity and high remanence. In view of the above, the application provides a preparation method of a sintered NdFeB permanent magnet material with high temperature stability, which comprises the following steps: Mixing main phase alloy powder with a component shown in a formula (I) and auxiliary phase alloy powder with a component shown in a formula (II), and then sequentially carrying out orientation profiling, sintering and tempering to obtain a sintered NdFeB permanent magnet material with high temperature stability; RExByCoaMbFe100-x-y-a-b(I), in the formula (I), RE is selected from one or more of Dy, tb, pr, nd, la, ce, Y and Ho; M is selected from one or more of Al, cu, ga, si, sn, ge, zr, ti and Zn; 29≤x≤34,1.0≤y≤1.8,10≤a≤30,0.1≤b≤2.0; REcBdCoeMfFe100-c-d-e-f(II), in the formula (II), RE is selected from one or more of Dy, tb, pr, nd, la, ce, Y and Ho; M is selected from one or more of Al, cu, ga, si, sn, ge, zr, ti and Zn; 29≤c≤70,0≤d≤2,0≤e<a≤20,0.1≤f≤50。 Preferably, the main phase molecule of the high-temperature stability sintered NdFeB is RE 2(Fe,Co)14 B. Preferably, the auxiliary phase alloy powder is 0.5-30wt% of the total of the main phase alloy powder and the auxiliary phase alloy powder. Preferably, the particle size of the main phase alloy powder is 1-5 μm, and the particle size of the auxiliary phase alloy powder is 1-5 μm. Preferably, the magnetic field strength of the orientation profiling is 1.0-2.0T, and the pressure is 100-200 MPa. Preferably, the sintering process specifically comprises the following steps: sintering the oriented magnet at 900-1100 ℃ for 1-6 hours, reducing the temperature to 800-1000 ℃ and preserving heat for 0.5-2 hours, and finally raising the temperature to 900-1100 ℃ and preserving heat for 0.5-2 hours. Preferably, the preparation method of the main pha