YTTRIUM-ADDED RARE EARTH PERMANENT MAGNET MATERIAL AND PREPARATION METHOD THEREFOR

Abstract

The present invention discloses an yttrium-added rare earth permanent magnet material and a preparation method therefor. The chemical formula of the material is expressed as (Y.sub.xRe.sub.1-x).sub.aFe.sub.100-a-b-cM.sub.bB.sub.c according to the mass percentage, wherein 0.05≤x≤0.5, 20≤a≤28, 0.5≤b≤2, 0.5≤c≤1.5, Re is Nd and/or Pr, and M is Al and/or Nb. According to the present invention, the relatively surplus and inexpensive rare earths yttrium and cerium are used to replace Nd and/or Pr in NdFeB. By controlling the ratio of the rare earth elements such as yttrium, cerium and neodymium, and adding an appropriate amount of Nb and/or Al element, the rare earth elements are used in a comprehensive and balanced manner while better magnetic properties are maintained.

Claims

1. A yttrium-added rare earth permanent magnet material, wherein the chemical formula of the material is expressed as (Y.sub.xRe.sub.1-x).sub.aFe.sub.100-a-b-cM.sub.bB.sub.c according to the mass percentage, where 0.05≤x≤0.5, 20≤a≤28, 0.5≤b≤2, 0.5≤c≤1.5, Re is Nd and/or Pr, and M is Al and/or Nb.

2. The material according to claim 1, wherein the material has a single 2:14:1 phase structure and the proportion of yttrium in the main phase is 100%.

3. The material according to claim 1, wherein the average grain size of the material is 30 nm-45 nm, and the standard deviation is 4-9 preferably.

4. The material according to claim 1, wherein Re is partially replaced with Ce in the material; and preferably, the mass content of Ce in Re is 0-20%, excluding 0.

5. The material according to claim 1, wherein the ratio of Y:Ce is 1-2.

6. The material according to claim 1, wherein for the material, yttrium element is introduced into a NdFeB magnet with a nanocrystalline-bonded permanent magnet material preparation process.

7. A method for preparing the yttrium-added rare earth permanent magnet material according to claim 1, comprising the steps of: (1) preparing a raw material according to the composition of the permanent magnet material according to any one of claims 1 to 6, then melting the raw material into an ingot, melting the ingot at a high temperature and then casting the melted ingot onto a rotating roller, and performing rotational rapid quenching and cooling to obtain a rapidly quenched thin strip; (2) performing heat treatment on the thin strip obtained in step (1), then quenching the thin strip and pulverizing the quenched thin strip into alloy powder; and (3) bonding the alloy powder obtained in step (2) with a binder to obtain the permanent magnet material.

8. The method according to claim 7, wherein the melting in step (1) is vacuum melting; preferably, the high-temperature melting temperature is 100-300° C. above the melting point of the raw material for preparing the rapidly quenched thin strip; preferably, the casting is carried out by a high vacuum single-roller rotational quenching method; preferably, the rotational quenching roller speed is 15-45 m/s; and preferably, the cooling rate of the rotational rapid quenching and cooling is 10.sup.5-10.sup.6° C./s.

9. The method according to claim 7, wherein in step (2), the heat treatment temperature is 600-800° C., and the heat treatment time is 5-15 min; preferably, the quenching is water-cooling quenching; preferably, the quenching time is 30-60 min; and preferably, the average particle size of the alloy powder is 100 nm-200 nm.

10. The method according to claim 7, wherein in step (3), the binder is epoxy resin; preferably, the use amount of the binder is 0.5-2 wt % of the alloy powder; preferably, the bonding process comprises: mixing the alloy powder with the solution in which the binder is dissolved, and then volatilizing the solvent to obtain the permanent magnet material; and preferably, the organic solvent is one or a combination of two or more of ethanol, toluene, xylene and acetone, and is preferably acetone.

11. The material according to claim 2, wherein the average grain size of the material is 30 nm-45 nm, and the standard deviation is 4-9 preferably.

12. The material according to claim 2, wherein Re is partially replaced with Ce in the material; and preferably, the mass content of Ce in Re is 0-20%, excluding 0.

13. The material according to claim 3, wherein Re is partially replaced with Ce in the material; and preferably, the mass content of Ce in Re is 0-20%, excluding 0.

14. The material according to claim 2, wherein the ratio of Y:Ce is 1-2.

15. The material according to claim 3, wherein the ratio of Y:Ce is 1-2.

16. The material according to claim 4, wherein the ratio of Y:Ce is 1-2.

17. The material according to claim 2, wherein for the material, yttrium element is introduced into a NdFeB magnet with a nanocrystalline-bonded permanent magnet material preparation process.

18. The material according to claim 3, wherein for the material, yttrium element is introduced into a NdFeB magnet with a nanocrystalline-bonded permanent magnet material preparation process.

19. The material according to claim 4, wherein for the material, yttrium element is introduced into a NdFeB magnet with a nanocrystalline-bonded permanent magnet material preparation process.

20. The material according to claim 5, wherein for the material, yttrium element is introduced into a NdFeB magnet with a nanocrystalline-bonded permanent magnet material preparation process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The accompanying drawings illustrate one or more embodiments of the present invention and, together with the written description, serve to explain the principles of the invention. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like elements of an embodiment.

[0061] FIG. 1 is a TEM image of a permanent magnet material with an alloy component (Nd(Pr)).sub.25Fe.sub.ba1M.sub.1.2B.sub.0.8 (wt %).

[0062] FIG. 2 is a TEM image of an yttrium-containing permanent magnet material with an alloy component (Y.sub.0.2Nd(Pr).sub.0.8).sub.25Fe.sub.ba1M.sub.1.2B.sub.0.8 (wt %).

DETAILED DESCRIPTION

[0063] In order for the convenience of understanding the present invention, the embodiments of the present invention are listed as follows. It should be understood by those skilled in the art that the embodiments are merely intended to understand the present invention instead of specific limitation to the present invention.

Embodiment 1

[0064] The permanent magnet material prepared in the present embodiment has the following alloy component: the permanent magnet of (Y.sub.0.1(Nd, Pr, Ce).sub.0.9).sub.27Fe.sub.ba1M.sub.1.45B.sub.1 (M is Al and Nb) (wt %), and the specific steps are as follows.

[0065] (1) A master alloy with the above alloy component is prepared, wherein the ratio of Nd to Pr to Ce in mass percentage in the raw material is 70:20:10, the phase forms of M and B are respectively iron alloys with the iron contents of 35% and 80%, Y is added in the form of a pure metal, and the remaining amount is blended in the form of pure iron metal. The NdFeB rare earth permanent magnet material is then manufactured with the following process steps.

[0066] (2) The prepared raw material is placed in a vacuum arc furnace to be uniformly melted, and the current is turned off until the alloy liquid is cooled to obtain a master alloy ingot. The prepared ingot is placed in a high-vacuum single-roller rotational quenching device, melted at a high temperature, cast onto a rotating roller, and subjected to rotational rapid quenching cooling at a cooling rate of 3*10.sup.5K/s, wherein the rapid quenching process is carried out under a protective atmosphere. The molten steel is sprayed onto a roller rotating at a roller speed of 20 m/s to obtain a rapidly quenched thin strip.

[0067] (3) Heat treatment is performed on the above rapidly quenched strip, wherein the heat treatment temperature is 750° C., and the heat treatment time is 15 min.

[0068] (4) After the above heat treatment, the rapidly quenched strip is subjected to water-cooling quenching for 30 min, and then is crushed into alloy powder having an average particle size of 100 nm by coarse pulverization and grinding.

[0069] (5) Epoxy resin in an amount of 1 wt % of the selected magnetic powder is weighed and dissolved in acetone to prepare an epoxy resin acetone solution. The above preferred rapidly quenched magnetic powder is slowly poured into the epoxy resin acetone solution, and stirred until the acetone is completely volatilized, and the mixture is crushed to obtain mixed powder. Zinc stearate (playing a role of surface lubrication, and being favorable for demolding) in an amount of 0.05 wt % of the selected mixed powder is added, uniform mixing is performed to form a blank, and the blank is mechanically pressed into a billet in a specific mold. The billet is placed in an oven for solidification treatment, wherein the heat treatment is thermal insulation at 150° C. for 1 h, so that an yttrium-containing NdFeB-bonded permanent magnet material is obtained.

[0070] By testing, the magnetic properties of the magnet are as shown in Table 1.

TABLE-US-00001 TABLE 1 Magnetic properties of the yttrium-containing NdFeB-bonded permanent magnet material according to Embodiment 1. Magnetic flux loss Average after thermal crystal Crystal demagnetization phase grain at 120° C. Component name (wt %) Br Hcj (BH).sub.max size deviation for 100 h (Y.sub.0.1(Nd, Pr, Ce).sub.0.9).sub.27Fe.sub.balM.sub.1.45B.sub.1 6.64 KGs 12.05 KOe 9.08 MGOe 34.65 nm 8.73 1.4%

Embodiment 2

[0071] The permanent magnet material prepared in the present embodiment has the following alloy component: the permanent magnet of (Y.sub.0.2(Nd, Pr, Ce).sub.0.8).sub.25Fe.sub.ba1M.sub.1.2B.sub.0.8 (M is Nb) (wt %), and the specific steps are as follows.

[0072] (1) A master alloy with the above alloy component is prepared, wherein the ratio of Nd to Pr to Ce in mass percentage in the raw material is 70:20:10, the phase forms of M and B are respectively iron alloys with the iron contents of 35% and 80%, Y is added in the form of a pure metal, and the remaining amount is blended in the form pure iron metal.

[0073] (2) The prepared raw material is placed in a vacuum arc furnace to be uniformly melted, and the current is turned off until the alloy liquid is cooled to obtain a master alloy ingot. The prepared ingot is placed in a high-vacuum single-roller rotational quenching device, melted at a high temperature, cast onto a rotating roller, and subjected to rotational rapid quenching cooling at a cooling rate of 8*10.sup.5K/s, wherein the rapid quenching process is carried out under a protective atmosphere. The molten steel is sprayed onto a roller rotating at a roller speed of 30 m/s to obtain a rapidly quenched thin strip.

[0074] (3) Heat treatment is performed on the above rapidly quenched thin strip, wherein the heat treatment temperature is 700° C., and the heat treatment time is 12 min.

[0075] (4) After the above heat treatment, the rapidly quenched strip is subjected to water-cooling quenching for 40 min, and is crushed into alloy powder having an average particle size of 150 nm by coarse pulverization and grinding.

[0076] (5) The epoxy resin in an amount of 0.8 wt % of the selected magnetic powder is weighed and dissolved in acetone to prepare an epoxy resin acetone solution. The above preferred rapidly quenched magnetic powder is slowly poured into the epoxy resin acetone solution, and stirred until the acetone is completely volatilized, and the mixture is crushed to obtain mixed powder. The zinc stearate in an amount of 0.05 wt % of the selected mixed powder is added, uniform mixing is performed to form a blank, and the blank is mechanically pressed into a billet in a specific mold. The billet is placed in an oven for solidification treatment, wherein the heat treatment is thermal insulation at 150° C. for 1 h, so that an yttrium-containing NdFeB-bonded permanent magnet material is obtained.

[0077] By testing, the magnetic properties of the magnet are as shown in Table 2.

TABLE-US-00002 TABLE 2 Magnetic properties of the yttrium-containing NdFeB-bonded permanent magnet material according to Embodiment 2. Magnetic flux loss Average after thermal crystal Crystal demagnetization phase grain at 120° C. Component name (wt %) Br Hcj (BH).sub.max size deviation for 100 h (Y.sub.0.2(Nd, Pr, Ce).sub.0.8).sub.25Fe.sub.balM.sub.1.2B.sub.0.8 6.74 KGs 9.85 KOe 8.76 MGOe 38.44 nm 4.62 1.3%

[0078] FIG. 1 shows an initial TEM image without yttrium. According to the statistical calculation of the grain size, the average grain size is 85.57 nm and the standard deviation of the grain size is 15.74. FIG. 2 shows a TEM image of the magnet added with yttrium in the present embodiment. According to the statistical calculation of the grain size, the average grain size is 38.44 nm and the standard deviation of the grain size is 4.62.

[0079] By comparing the grain sizes of the two TEM images, the crystal grain refinement of the bonded magnet after the addition of yttrium can be seen: after the addition of yttrium, the crystal grains are remarkably refined, and the standard deviation is reduced, indicating that the morphology distribution is more uniform.

Embodiment 3

[0080] The permanent magnet material prepared in the present embodiment has the following alloy component: the permanent magnet of (Y.sub.0.5(Nd, Pr, Ce).sub.0.5).sub.28Fe.sub.ba1M.sub.1.4B.sub.1.5 (M is Nb) (wt %), and the specific steps are as follows.

[0081] (1) A master alloy with the above alloy component is prepared, wherein the ratio of Nd to Pr to Ce in mass percentage in the raw material is 70:20:10, the phase forms of M and B are respectively iron alloys with the iron contents of 35% and 80%, Y is added in the form of a pure metal, and the remaining amount is blended in the form pure iron metal.

[0082] (2) The prepared raw material is placed in a vacuum arc furnace to be uniformly melted, and the current is turned off until the alloy liquid is cooled to obtain a master alloy ingot. The prepared ingot is placed in a high-vacuum single-roller rotational quenching device, melted at a high temperature, cast onto a rotating roller, and subjected to rotational rapid quenching cooling at a cooling rate of 4*10.sup.5K/s, wherein the rapid quenching process is carried out under a protective atmosphere. The molten steel is sprayed onto a roller rotating at a roller speed of 25 m/s to obtain a rapidly quenched thin strip.

[0083] (3) Heat treatment is performed on the above rapidly quenched thin strip, wherein the heat treatment temperature is 730° C., and the heat treatment time is 13 min.

[0084] (4) After the above heat treatment, the rapidly quenched strip is subjected to water-cooling quenching for 50 min, and is crushed into alloy powder having an average particle size of 200 nm by coarse pulverization and grinding.

[0085] (5) The epoxy resin in an amount of 1.2 wt % of the selected magnetic powder is weighed and dissolved in acetone to prepare an epoxy resin acetone solution. The above preferred rapidly quenched magnetic powder is slowly poured into the epoxy resin acetone solution, and stirred until the acetone is completely volatilized, and the mixture is crushed to obtain mixed powder. The zinc stearate in an amount of 0.05 wt % of the selected mixed powder is added, uniform mixing is performed to form a blank, and the blank is mechanically pressed into a billet in a specific mold. The billet is placed in an oven for solidification treatment, wherein the heat treatment is thermal insulation at 150° C. for 1 h, so that an yttrium-containing NdFeB-bonded permanent magnet material is obtained.

[0086] By testing, the magnetic properties of the magnet are as shown in Table 3.

TABLE-US-00003 TABLE 3 Magnetic properties of the yttrium-containing NdFeB-bonded permanent magnet material according to Embodiment 3. Magnetic flux loss Average after thermal crystal Crystal demagnetization phase grain at 120° C. Component name (wt %) Br Hcj (BH).sub.max size deviation for 100 h (Y.sub.0.5(Nd, Pr, Ce).sub.0.5).sub.28Fe.sub.balM.sub.1.4B.sub.1.5 6.55 KGs 10.84 KOe 8.30 MGOe 43.40 nm 6.45 1.2%

Embodiments 4-6

[0087] The operation is performed according to the steps of Embodiment 1, except that the component and operation conditions are as shown in Table 4 below, and by testing, the results of the magnetic properties of the obtained products are shown in Table 5.

TABLE-US-00004 TABLE 4 Components and preparation conditions of the permanent magnet materials according to Embodiments 4-6 Mass ratio of Component name (wt %) Nd to Pr to Ce Embodiment 4 (Y.sub.0.05(Nd, Pr, Ce) .sub.0.95).sub.20Fe.sub.balAl.sub.0.5B.sub.0.5 60:20:20 Embodiment 5 (Y.sub.0.3(Nd, Pr, Ce) .sub.0.7).sub.26Fe.sub.balAl.sub.2B.sub.1.5 75:20:5  Embodiment 6 (Y.sub.0.3(Nd, Pr, Ce) .sub.0.7).sub.23Fe.sub.balNb.sub.1.2B.sub.0.8 65:20:15

[0088] Following table 4

TABLE-US-00005 Cooling Average rate of Rotational Heat particle Addition rotational quenching treatment size of amount of rapid quenching roller condition Quenching alloy epoxy resin cooling (° C./s) speed (m/s) (° C., min) time(min) powder(nm) (wt %) Embodiment 4 2*10.sup.5 15 800, 5  60 150 0.5 Embodiment 5  10.sup.6 30 600, 10 50 100 1 Embodiment 6 5*10.sup.5 45 700, 15 35 200 2

TABLE-US-00006 TABLE 5 Magnetic properties of the yttrium-containing NdFeB-bonded permanent magnet materials according to Embodiments 4-6 Magnetic flux loss Average after thermal crystal Crystal demagnetization phase grain at 120° C. Br/KGs Hcj/KOe (BH)max/MGOe size/nm deviation for 100 h Embodiment 4 6.98 10.65 8.73 44.78 4.56 1.5% Embodiment 5 6.54 10.76 8.21 36.64 12.67 1.9% Embodiment 6 6.62 11.40 8.39 40.36 7.44 1.8%

[0089] It can be seen from the above embodiments that the above embodiments according to the present invention achieve the following technical effects: the rare earth permanent magnet material prepared by changing the use amounts of Nd(Pr, Ce), Fe and B, and further combining the Y and Ce elements with the conventional Nd(Pr)FeB rare earth permanent magnet material has an average grain size of 30-45 nm and the minimum standard deviation of 4.62. When the rare earth permanent magnet material of the present invention is compared with the initial NdFeB of which the average grain size of the crystal phase is 80-120 nm, and the standard deviation is 14-20, the crystal grains are obviously refined, and the morphology distribution is more uniform; and while good magnetic properties are maintained, the temperature coefficient is lower and the temperature resistance is better. Since the relatively-abundant light rare earth elements Y and Ce are used to replace Nd and Pr, the production cost is also greatly reduced.

Comparative Example 1

[0090] Comparative example 1 is the same as Embodiment 1 except that the mass ratio of Nd to Pr to Ce is 60:10:30, and the content of Ce in mass percentage exceeds 20%.

Comparative Example 2

[0091] Comparative example 2 is the same as Embodiment 1 except that the component is (Y.sub.0.1(Nd, Pr, Ce).sub.0.9).sub.32Fe.sub.ba1M.sub.1.45B.sub.1.

Comparative Example 3

[0092] Comparative example 3 is the same as Embodiment 1 except that the component is (Y.sub.0.1(Nd, Pr, Ce).sub.0.9).sub.20Fe.sub.ba1M.sub.1.45B.sub.1.

Comparative Example 4

[0093] Comparative example 4 is the same as Embodiment 1 except that the rotational rapid quenching cooling rate is 10.sup.4° C./s.

Comparative Example 5

[0094] Comparative example 5 is the same as Embodiment 1 except that the rotational rapid quenching cooling rate is 10.sup.7° C./s.

Comparative Example 6

[0095] Comparative example 6 is the same as Embodiment 1 except that the rotational quenching roller speed is 10 m/s.

Comparative Example 7

[0096] Comparative example 7 is the same as Embodiment 1 except that the rotational quenching roller speed is 55 m/s.

Comparative Example 8

[0097] Comparative example 8 is the same as Embodiment 1 except that the heat treatment temperature is 500° C. and the heat treatment time is 25 min.

Comparative Example 9

[0098] Comparative example 9 is the same as Embodiment 1, except that the heat treatment temperature is 900° C. and the heat treatment time is 3 min.

Comparative Example 10

[0099] Comparative example 10 is the same as Embodiment 1 except that the quenching time is 20 min.

Comparative Example 11

[0100] Comparative example 11 is the same as Embodiment 1 except that the quenching time is 80 min.

Comparative Example 12

[0101] Comparative example is the same as Embodiment except that the average particle size of the alloy powder is nm.

Comparative Example 14

[0102] Comparative example 14 is the same as Embodiment 1 except that the average particle size of alloy powder is 300 nm.

Comparative Example 15

[0103] Comparative example 15 is the same as Embodiment 1 except that the addition amount of the epoxy resin is 0.3 wt %.

Comparative Example 16

[0104] Comparative example 16 is the same as Embodiment 1, except that the addition amount of the epoxy resin is 3 wt %.

[0105] The test results of magnetic properties of the permanent magnet materials prepared in Comparative examples 1-16 are shown in Table 6 below.

TABLE-US-00007 TABLE 6 Magnetic properties of yttrium-containing NdFeB-bonded permanent magnet materials of Comparative examples 1-16. Magnetic flux loss Average after thermal crystal Crystal demagnetization (BH)max phase grain at 120° C. Br/KGs Hcj/KOe ZMGOe size/nm deviation for 100 h Comparative example 1 5.78 7.84 6.10 52.07 50.09 2.1% Comparative example 2 5.82 7.96 6.45 62.88 48.16 2.3% Comparative example 3 4.37 7.22 6.62 54.68 50.31 2.5% Comparative example 4 4.68 7.84 6.76 48.89 51.37 2.5% Comparative example 5 4.73 7.96 6.58 52.24 51.16 2.3% Comparative example 6 4.67 7.22 6.23 54.71 50.40 2.5% Comparative example 7 4.73 7.84 6.47 52.15 56.12 2.8% Comparative example 8 4.95 7.96 6.40 55.27 53.17 2.4% Comparative example 9 5.16 7.22 6.23 69.87 48.23 2.2% Comparative example 10 4.63 7.84 6.40 50.42 50.30 2.7% Comparative example 11 4.80 7.96 6.45 74.12 50.31 2.5% Comparative example 12 4.96 7.2 6.59 60.25 50.23 2.6% Comparative example 13 5.08 7.84 6.24 57.23 48.12 2.4% Comparative example 14 4.98 7.96 6.44 67.25 51.15 2.6% Comparative example 15 5.42 7.22 6.32 54.68 49.30 2.4% Comparative example 16 5.29 7.22 6.68 49.23 48.78 2.3%

[0106] By comparing the product performance data of the comparative examples in Table 6 with the performance data of the embodiments, it can be seen that if the raw material component or content, the particle size, and the preparation process parameters are not within the scope of the present invention, the comprehensive magnetic properties of the prepared permanent magnet material are significantly reduced.

[0107] It is apparent that the above embodiments are merely intended for clear description, instead of limiting the implementations. Other variations or modifications of the various forms may also be made by those skilled in the art based on the above description. There is no need and no way to exhaust all of the embodiments, and obvious changes or variations resulting therefrom are still within the protection scope of the present invention.

[0108] The foregoing description of the exemplary embodiments of the present invention has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching.

[0109] The embodiments were chosen and described in order to explain the principles of the invention and their practical application so as to activate others skilled in the art to utilize the invention and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the present invention pertains without departing from its spirit and scope. Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing description and the exemplary embodiments described therein.