R-T-B SERIES PERMANENT MAGNET MATERIAL, RAW MATERIAL COMPOSITION PREPARATION METHOD AND APPLICATION

Abstract

An R-T-B series permanent magnet material, a raw material composition, a preparation method, and an application. The R-T-B series permanent magnet material comprises the following components: R: 29-31.0 wt. %, RH is greater than 1 wt. %, B: 0.905-0.945 wt. %, C: 0.04-0.15 wt. %, N: 0.1-0.4 wt. %, and Fe: 67-69 wt. %, wherein R comprises RL and RH, RL is a light rare earth element, RL comprises Nd, RH is a heavy rare earth element, a (RL.sub.1-yRH.sub.y).sub.2T.sub.17C.sub.x phase is present at the grain boundary of the R-T-B series permanent magnet material, x: 2-3, y: 0.15-0.35, and T must comprise Fe, and also comprises one or more among Co, Ti and N. The permanent magnet material retains relative high Br and Hcj under different heat treatment temperatures.

Claims

1. An R-T-B series permanent magnet material, comprising, by mass percentage, the following components: 29-31.0 wt. % of R, greater than 1 wt. % of RH, 0.905-0.945 wt. % of B, 0.04-0.15 wt. % of C, 0.1-0.4 wt. % of N, 67-69 wt. % of Fe, wherein wt. % refers to the mass percentage relative to the R-T-B series permanent magnet material; the R-T-B series permanent magnet material further comprises Co and Ti; N includes Cu and/or Ga; R includes RL and RH, wherein RL is a light rare earth element, including Nd, and RH is a heavy rare earth element; an (RL.sub.1-yRH.sub.y).sub.2Ti.sub.7C.sub.x phase is present at the grain boundary of the R-T-B series permanent magnet material, wherein x is 2-3, y is 0.15-0.35, and T necessarily includes Fe, and also includes one or more of Co, Ti and N.

2. The R-T-B series permanent magnet material according to claim 1, wherein the R-T-B series permanent magnet material further comprises the element M, and the element M includes one or more of Al, Si, Sn, Ge, Ag, Au, Bi, Mn, Cr, Zr, Nb, and Hf.

3. The R-T-B series permanent magnet material according to claim 2, wherein the range of the content of M is 0-3 wt. %, wherein wt. % refers to the mass percentage relative to the R-T-B series permanent magnet material.

4. The R-T-B series permanent magnet material according to claim 1, wherein the range of the content of R is 30.2-31.0 wt. % or 29-30.4 wt. %, wherein wt. % refers to the mass percentage relative to the R-T-B series permanent magnet material; or, the range of the content of B is 0.905-0.93 wt. % or 0.915-0.945 wt. %, wherein wt. % refers to the mass percentage relative to the R-T-B series permanent magnet material.

5. A raw material composition for an R-T-B series permanent magnet material, comprising, by mass percentage, the following components: 28.5-30.5 wt. % of R, 0.905-0.945 wt. % of B, 0.1-0.4 wt. % of N, 67-69 wt. % of Fe, wherein the raw material composition for the R-T-B series permanent magnet material comprises Ti and Co; wt. % refers to the mass percentage relative to the raw material composition for the R-T-B series permanent magnet material; N includes Cu and/or Ga; R includes RL and RH, wherein RL is a light rare earth element, including Nd, and RH is a heavy rare earth element.

6. The raw material composition for the R-T-B series permanent magnet material according to claim 5, wherein the raw material composition for the R-T-B series permanent magnet material further comprises the element M, and the element M includes one or more of Al, Si, Sn, Ge, Ag, Au, Bi, Mn, Cr, Zr, Nb, and Hf.

7. A method for preparing an R-T-B series permanent magnet material, comprising the following step: subjecting a melt of the raw material composition for the R-T-B series permanent magnet material according to claim 5 to casting, crushing, pulverization, forming, sintering, a grain boundary diffusion treatment, and a heat treatment.

8. The preparation method according to claim 7, wherein the pulverization process is carried out in an atmosphere with an oxidizing gas content of 100 ppm or less; or, after pulverization, a lubricant is added, in an amount of 0.05-0.15%, relative to the weight of the pulverized powder; or, the heat treatment temperature is 470-510° C., 460-500° C., or 480-520° C.

9. An R-T-B series permanent magnet material prepared by the preparation method according to claim 7.

10. An application of the R-T-B series permanent magnet material according to claim 1 as an electronic component.

11. The R-T-B series permanent magnet material according to claim 1, wherein, when N includes Cu, the range of the content of Cu is 0.05-0.20 wt. %, wherein wt. % refers to the mass percentage relative to the R-T-B series permanent magnet material; or, when N includes Ga, the range of the content of Ga is 0.05-0.20 wt. %, wherein wt. % refers to the mass percentage relative to the R-T-B series permanent magnet material.

12. The R-T-B series permanent magnet material according to claim 1, wherein the R-T-B series permanent magnet material further comprises 0, the range of the content of 0 is 0.08-0.12 wt. %, wherein wt. % refers to the mass percentage relative to the R-T-B series permanent magnet material.

13. The R-T-B series permanent magnet material according to claim 1, wherein the type of RH includes Dy and/or Tb.

14. The R-T-B series permanent magnet material according to claim 1, wherein the range of the content of RH is 1-2.5 wt. %, exclusive of 1 wt. %, wherein wt. % refers to the mass percentage relative to the R-T-B series permanent magnet material.

15. The R-T-B series permanent magnet material according to claim 1, wherein the range of the content of C is 0.1-0.15 wt. % or 0.04-0.12 wt. %, wherein wt. % refers to the mass percentage relative to the R-T-B series permanent magnet material.

16. The R-T-B series permanent magnet material according to claim 1, wherein the range of the content of Ti is 0.05-0.2 wt. % or 0.1-0.25 wt. %, wherein wt. % refers to the mass percentage relative to the R-T-B series permanent magnet material; or, the range of the content of Co is 0.5-1.5 wt. % or 1-2 wt. %, wherein wt. % refers to the mass percentage relative to the R-T-B series permanent magnet material.

17. The raw material composition for the R-T-B series permanent magnet material according to claim 5, wherein, when N includes Cu, the range of the content of Cu is 0.05-0.20 wt. %, wherein wt. % refers to the mass percentage relative to the raw material composition for the R-T-B series permanent magnet material; or, when N includes Ga, the range of the content of Ga is 0.05-0.20 wt. %, wherein wt. % refers to the mass percentage relative to the raw material composition for the R-T-B series permanent magnet material.

18. The raw material composition for the R-T-B series permanent magnet material according to claim 5, wherein, the type of RH includes Dy and/or Tb; or, the range of the content of RH is 0.5-2 wt. %, exclusive of 0.5 wt. %, wherein wt. % refers to the mass percentage relative to the raw material composition for the R-T-B series permanent magnet material.

19. The raw material composition for the R-T-B series permanent magnet material according to claim 5, wherein, the range of the content of Ti is 0.05-0.2 wt. % or 0.1-0.25 wt. %, wherein wt. % refers to the mass percentage relative to the raw material composition for the R-T-B series permanent magnet material; or, the range of the content of Co is 0.5-1.5 wt. % or 1-2 wt. %, wherein wt. % refers to the mass percentage relative to the raw material composition for the R-T-B series permanent magnet material.

20. An application of the R-T-B series permanent magnet material according to claim 9 as an electronic component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0078] FIG. 1 is an FE-EPMA surface distribution diagram of the element Nd in the R-T-B series permanent magnet material prepared in Example 1, wherein point 1 is (RL.sub.0.77RH.sub.0.23).sub.2-T.sub.17-C.sub.2.7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0079] The present disclosure is further described below by way of examples; however, the present disclosure is not limited to the scope of the described examples. For the experimental methods in which no specific conditions are specified in the following examples, selections are made according to conventional methods and conditions or according to the product instructions.

TABLE-US-00001 TABLE 1 Formula of raw material composition for R-T-B series permanent magnet material and contents (wt. %) RL RH No. R PrNd Nd Dy Tb B Cu Ga Ti Fe Zr Nb Co Example 1 29.8 / 28.5 0 1.3 0.93 0.12 0.12 0.16 68.07 / / 0.8 Example 2 30.5 29 / 1.5 0 0.905 0.2 0.2 0.08 66.92 / / 1.2 Example 3 28.5 / 27.5 1 0 0.945 0.05 0.12 0.05 69.34 / / 1 Example 4 30.5   29.5 / 1 0 0.905 0.08 0.1 0.1 66.82 / / 1.5 Example 5 29.5 / 28.5 1 0 0.915 0.15 0.05 0.2 67.19 / / 2 Comparative 31 30 / 1 0 0.96 0.08 0.07 0.1 66.79 / / 1 Example 1 Comparative 30.1   29.1 / 1 0 0.89 0.04 0.03 0.1 67.84 / / 1 Example 2 Comparative 30.4   29.4 / 1 0 0.97 0.25 0.3 0.1 66.98 / / 1 Example 3 Comparative 29 / 28   1 0 0.945 0.05 0.25 0.02 68.74 / / 1 Example 4 Comparative 28.5 / 27.5 1 0 0.945 0.05 0.12 0.05 69.35 / / 1 Example 5 Comparative 30.5 29 / 1.5 0 0.905 0.2 0.2 / 67.12 0.08 / 1 Example 6 Comparative 30.5 29 / 1.5 0 0.905 0.2 0.2 / 67.12 / 0.08 1 Example 7 Note: “/” refers to being free of the element.

TABLE-US-00002 TABLE 2 Process conditions for Examples 1-5 and Comparative Examples 1-7 Does grain Grain boundary Heat Zinc boundary diffused treatment stearate diffusion heavy rare temperature No. (%) occur? earth element (° C.) Example 1 0.12% Yes Dy 470-510 Example 2 0.06% Yes Tb 460-500 Example 3 0.15% Yes Tb 480-520 Example 4 0.08% Yes Tb 480-520 Example 5 0.08% Yes Tb 460-500 Comparative 0.08% Yes Tb 480-500 Example 1 Comparative 0.08% Yes Tb 460-470 Example 2 Comparative 0.08% Yes Tb 480-500 Example 3 Comparative 0.2% Yes Tb 480-490 Example 4 Comparative 0.16% No / 480-490 Example 5 Comparative 0.06% Yes Tb 480-500 Example 6 Comparative 0.06% Yes Tb 480-500 Example 7 Note: % with regard to zinc stearate refers to the mass percentage in the powder after mixing; “/” refers to being free of the element.

The Preparation Method for the R-T-B Series Permanent Magnet Materials in Examples 1-5 and Comparative Examples 1-7 was as Follows:

[0080] (1) Smelting process: According to the formula shown in Table 1 and the corresponding process conditions in Table 2, the prepared raw materials were placed in a crucible made of aluminum oxide, and vacuum smelting was carried out in a high-frequency vacuum induction smelting furnace in a vacuum of 5×10.sup.−2 Pa at a temperature of 1500° C. or lower.

[0081] (2) Casting process: Ar gas was introduced into the smelting furnace after vacuum smelting to make the gas pressure reach 55,000 Pa, casting was then carried out, and a quenched alloy was obtained at a cooling rate of 10.sup.2 to 10.sup.4° C./sec.

[0082] (3) Hydrogen-decrepitation-based pulverization process: A hydrogen decrepitation furnace, in which the quenched alloy was placed, was evacuated at room temperature, hydrogen with a purity of 99.9% was then introduced into the hydrogen decrepitation furnace, and the hydrogen pressure was maintained at 0.15 MPa; after full hydrogen absorption, the furnace was heated up while being evacuated, and full dehydrogenation was carried out; after cooling, a powder pulverized by hydrogen decrepitation was taken out.

[0083] (4) Micro-pulverization process: The powder pulverized by hydrogen decrepitation was subjected to jet mill pulverization for 3 hours under the conditions of an oxidizing gas content of 100 ppm or less in a nitrogen atmosphere and a pulverization chamber pressure of 0.38 MPa to obtain a fine powder. The oxidizing gas referred to oxygen or moisture.

[0084] (5) Zinc stearate was added to the powder resulting from jet mill pulverization in an amount as shown in Table 2, and then fully mixed by means of a V-type mixer.

[0085] (6) Magnetic field forming process: The above-mentioned powder, to which zinc stearate had been added, was subjected to primary formation into a cube with a side length of 25 mm by means of a right-angle alignment magnetic field forming machine in a 1.6 T alignment magnetic field at a forming pressure of 0.35 ton/cm.sup.2, and after the primary formation, the powder was demagnetized in a 0.2 T magnetic field. The formed body resulting from primary formation was sealed so that it did not come into contact with air, and secondary formation was then carried out at a pressure of 1.3 ton/cm.sup.2 by means of a secondary formation machine (an isostatic pressing machine).

[0086] (7) Sintering process: Each formed body was moved to a sintering furnace for sintering in a vacuum of 5×10.sup.−3 Pa and at temperatures of 300° C. and 600° C., each for 1 hour, and then for sintering at a temperature of 1040° C. for 2 hours, Ar gas was then introduced to make the gas pressure reach 0.1 MPa, and the formed body was then cooled to room temperature.

[0087] (8) Grain boundary diffusion treatment process: The metal Dy or Tb and the sintered R-T-B series permanent magnet material were placed in a furnace and heated at a high temperature, such that the metal Dy or Tb was evaporated at the high temperature, deposited on the surface of the magnet under the induction of a foreign rare gas, and diffused into the interior of the magnet along the grain boundaries (specifically according to the conditions shown in Table 2).

[0088] (9) Heat treatment process: The sintered body was heat treated for 3 hours in high-purity Ar gas at the heat treatment temperature shown in Table 2, then cooled to room temperature, and then taken out to obtain the R-T-B series permanent magnet material.

Effect Example

[0089] The R-T-B series permanent magnet materials prepared in Examples 1-5 and Comparative Examples 1-7 were separately taken to measure the magnetic performance and compositions thereof, and the phase compositions of the magnets thereof were observed by means of FE-EPMA.

[0090] (1) The compositions of the R-T-B series permanent magnet materials were measured using a high-frequency inductively coupled plasma optical emission spectrometer (ICP-OES), wherein an (RL.sub.1-yRH.sub.y).sub.2Ti.sub.7C.sub.x (x: 2-3, and y: 0.15-0.35) phase was obtained according to an FE-EPMA test. Table 3 below showed the composition test results.

TABLE-US-00003 TABLE 3 Composition of R-T-B series permanent magnet material and contents (wt. %) Is RL RH (RL.sub.1−yRH.sub.y).sub.2T.sub.17C.sub.x No. R PcNd Nd Dy Tb B C Cu Ga Ti Fe Zr Nb Co O phase generated? Example 1 30.4 / 28.5 0.6 1.3 0.93 0.12 0.12 0.12 0.16 67.27 / / 0.8 0.08 Yes Example 2 31 29 / 1.5 0.5 0.905 0.04 0.2 0.2 0.08 66.29 / / 1.2 0.09 Yes Example 3 29 / 27.5 1 0.5 0.945 0.15 0.05 0.12 0.05 68.59 / / 1 0.1 Yes Example 4 31   29.5 / 1 0.5 0.905 0.07 0.08 0.1 0.1 66.13 / / 1.5 0.12 Yes Example 5 30 / 28.5 1 0.5 0.915 0.1 0.15 0.05 0.2 66.49 / / 2 0.1 Yes Comparative 31.5 30 / 1 0.5 0.96 0.07 0.08 0.07 0.1 66.14 / / 1 0.08 Yes Example 1 Comparative 30.6   29.1 / 1 0.5 0.89 0.07 0.04 0.03 0.1 67.19 / / 1 0.08 No Example 2 Comparative 30.9   29.4 / 1 0.5 0.97 0.07 0.25 0.3 0.1 66.33 / / 1 0.08 No Example 3 Comparative 29.5 / 28   1 0.5 0.945 0.2 0.05 0.25 0.02 67.92 / / 1 0.12 No Example 4 Comparative 28.5 / 27.5 1 0.5 0.945 0.15 0.05 0.12 0.05 68.57 / / 1 0.12 No Example 5 Comparative 31 29 / 1.5 0.5 0.905 0.04 0.2 0.2 / 66.49 0.08 / 1 0.09 No Example 6 Comparative 31 29 / 1.5 0.5 0.905 0.04 0.2 0.2 / 66.49 / 0.08 1 0.09 No Example 7 Note: The above-mentioned permanent magnet materials were all prepared under the process conditions with an oxygen content of 100 ppm or less, and the difference in the O content in the final product could be regarded as a regular fluctuation; Note: “/” referred to being free of the element.

[0091] (2) FE-EPMA detection: A vertical alignment plane of the permanent magnet material was polished, and detected by means of a field emission-electron probe micro-analyser (FE-EPMA) (JEOL, 8530F). Surface scanning was firstly performed, and phases with different contrasts were then quantitatively analyzed to determine the phase composition, wherein the test conditions were an accelerating voltage of 15 kV and a probe beam current of 50 nA.

[0092] FE-EPMA detection was carried out on the R-T-B series permanent magnet materials prepared in Examples 1-5, and the results were as shown in Table 4 below, wherein FIG. 1 corresponded to the R-T-B series permanent magnet material prepared in Example 1 (wherein the composition of point 1 was as shown in Table 4 with respect to Example 1).

TABLE-US-00004 TABLE 4 R T C No. Nd Pr Tb Dy Fe Co Ga Cu Ti C Phase composition Example 1 7.11 0 0.2 1.9 76.83 1.32 0.02 0.08 0.01 12.21 (RL.sub.0.77RH.sub.0.23).sub.2-T.sub.17-C.sub.2.7 Example 2 5.92 1.3 1.7 0.3 76.94 1.52 0..05 0.1 0.02 12.15 (RL.sub.0.78RH.sub.0.22).sub.2-T.sub.17-C.sub.2.6 Example 3 7.06 0 1.89 0.2 76.36 1.48 0.03 0.07 0.02 12.89 (RL.sub.0.77RH.sub.0.23).sub.2-T.sub.17-C.sub.2.8 Example 4 5.88 1.6 1.5 0.2 76.51 1.65 0.06 0.02 0.05 12.53 (RL.sub.0.81RH.sub.0.18).sub.2-T.sub.17-C.sub.2.7 Example 5 6.58 0 2.4 0.2 76.51 1.52 0.02 0.06 0.04 12.67 (RL.sub.0.72RH.sub.0.28).sub.2-T.sub.17-C.sub.2.8

[0093] (3) Magnetic performance evaluation: The permanent magnet material was tested for magnetic performance by NIM-10000H BH bulk rare earth permanent magnet nondestructive measurement system from The National Institute of Metrology of China, and the magnetic performance test results were as shown in Table 5 below. In Table 5, “Br” referred to residual magnetic flux density, “Hcj” referred to intrinsic coercivity, “BHmax” referred to maximum energy product, and “BHH” referred to the sum of BHmax and Hcj.

TABLE-US-00005 TABLE 5 Performance of R-T-B series permanent magnet materials Br Hcj BHmax Heat treatment No. (kGs) (kOe) (MGOe) BHH temperature (° C.) Example 1 14.05 26.5 47.4 73.9 470-510 Example 2 13.92 28.3 46.4 74.7 460-500 Example 3 14.31 25.7 49.2 74.9 480-520 Example 4 13.98 27.1 47.0 74.1 480-520 Example 5 14.02 26.6 47.1 73.7 460-500 Comparative 13.51 26.8 43.7 70.5 480-500 Example 1 Comparative 14.03 25.8 47.1 72.9 460-470 Example 2 Comparative 13.58 27.0 44.1 71.1 480-500 Example 3 Comparative 14.28 24.1 48.9 73.0 480-490 Example 4 Comparative 14.33 17.5 49.1 66.6 480-490 Example 5 Comparative 13.88 26.4 46.1 72.5 480-500 Example 6 Comparative 13.81 26.8 45.6 72.4 480-500 Example 7

[0094] As can be seen from Table 5,

1) the R-T-B series permanent magnet material of the present application has an excellent performance, maintains relatively high Br and Hcj at various heat treatment temperatures: Br≥13.92 kGs and Hcj≥25.7 kOe (Examples 1-5);
2) based on the formula of the present application, even if the contents of R, B, Cu, and Ga are adjusted, no (RL.sub.1-yRH.sub.y).sub.2T.sub.17C.sub.x (x: 2-3, and y: 0.15-0.35) phase can be generated, the Br and Hcj of the R-T-B series permanent magnet material cannot be both maintained at higher values, and the heat treatment temperature range is reduced significantly (Comparative Example 1 and Comparative Example 3);
3) based on the formula of the present application, even if the contents of C, Ti and Ga are adjusted, the Hcj of the R-T-B series permanent magnet material is reduced and at the same time the heat treatment temperature range will also decrease when the contents of the other compositions are not within the ranges defined in the present application (Comparative Example 4);
4) based on the formula of the present application, where the content of RH remains constant and no grain boundary diffusion is performed during preparation, no (RL.sub.1-yRH.sub.y).sub.2T.sub.17C.sub.x (x: 2-3, and y: 0.15-0.35) phase can be generated without introduction of RH, the Hcj significantly decreases, and the heat treatment temperature range also decreases (Comparative Example 5);
5) based on the formula of the present application, where the high melting point metal Ti is replaced with Zr and Nb respectively and the content remains unchanged, the Br and Hcj of the R-T-B series permanent magnet material decrease, and the heat treatment temperature range also decreases (Comparative Examples 6 and 7).