NL2031758B1 - METHOD FOR PROMOTING MAGNETIC PROPERTIES OF SINTERED NEODYMIUM-IRON-BORON (Nd-Fe-B) MAGNET - Google Patents
METHOD FOR PROMOTING MAGNETIC PROPERTIES OF SINTERED NEODYMIUM-IRON-BORON (Nd-Fe-B) MAGNET Download PDFInfo
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- NL2031758B1 NL2031758B1 NL2031758A NL2031758A NL2031758B1 NL 2031758 B1 NL2031758 B1 NL 2031758B1 NL 2031758 A NL2031758 A NL 2031758A NL 2031758 A NL2031758 A NL 2031758A NL 2031758 B1 NL2031758 B1 NL 2031758B1
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- rare earth
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- 238000000034 method Methods 0.000 title claims abstract description 22
- 229910001172 neodymium magnet Inorganic materials 0.000 title claims abstract description 22
- 230000001737 promoting effect Effects 0.000 title claims abstract description 13
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 title description 4
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 46
- 238000002844 melting Methods 0.000 claims abstract description 28
- 150000002910 rare earth metals Chemical class 0.000 claims abstract description 24
- 239000002184 metal Substances 0.000 claims abstract description 19
- 229910052751 metal Inorganic materials 0.000 claims abstract description 17
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 9
- 239000000956 alloy Substances 0.000 claims abstract description 9
- 238000010438 heat treatment Methods 0.000 claims abstract description 8
- 238000000151 deposition Methods 0.000 claims description 21
- 230000008021 deposition Effects 0.000 claims description 17
- 238000001755 magnetron sputter deposition Methods 0.000 claims description 9
- 229910052692 Dysprosium Inorganic materials 0.000 claims description 8
- 229910052771 Terbium Inorganic materials 0.000 claims description 8
- 238000001704 evaporation Methods 0.000 claims description 7
- 238000005496 tempering Methods 0.000 claims description 7
- 230000008020 evaporation Effects 0.000 claims description 6
- 229910018565 CuAl Inorganic materials 0.000 claims description 3
- -1 CuMg Inorganic materials 0.000 claims description 3
- 229910016347 CuSn Inorganic materials 0.000 claims description 3
- 229910002535 CuZn Inorganic materials 0.000 claims description 3
- 229910020068 MgAl Inorganic materials 0.000 claims description 3
- 229910017706 MgZn Inorganic materials 0.000 claims description 3
- 229910005728 SnZn Inorganic materials 0.000 claims description 3
- OWXLRKWPEIAGAT-UHFFFAOYSA-N [Mg].[Cu] Chemical compound [Mg].[Cu] OWXLRKWPEIAGAT-UHFFFAOYSA-N 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- 229910052802 copper Inorganic materials 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 238000001652 electrophoretic deposition Methods 0.000 claims description 3
- 229910052749 magnesium Inorganic materials 0.000 claims description 3
- 230000008018 melting Effects 0.000 claims description 3
- 238000005507 spraying Methods 0.000 claims description 3
- 229910052725 zinc Inorganic materials 0.000 claims description 3
- 229910052774 Proactinium Inorganic materials 0.000 claims description 2
- 229910052718 tin Inorganic materials 0.000 claims description 2
- 238000004544 sputter deposition Methods 0.000 claims 1
- 238000009792 diffusion process Methods 0.000 abstract description 28
- 239000002344 surface layer Substances 0.000 abstract description 8
- 238000005324 grain boundary diffusion Methods 0.000 abstract description 2
- 229910000743 fusible alloy Inorganic materials 0.000 description 20
- 230000000052 comparative effect Effects 0.000 description 9
- 230000000694 effects Effects 0.000 description 7
- 239000010410 layer Substances 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 4
- 150000002739 metals Chemical class 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000005238 degreasing Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910001092 metal group alloy Inorganic materials 0.000 description 2
- 102100040190 ADP-ribosylation factor-binding protein GGA2 Human genes 0.000 description 1
- 229910016943 AlZn Inorganic materials 0.000 description 1
- 101001037082 Homo sapiens ADP-ribosylation factor-binding protein GGA2 Proteins 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000000779 depleting effect Effects 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
- H01F41/0293—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D13/00—Electrophoretic coating characterised by the process
- C25D13/02—Electrophoretic coating characterised by the process with inorganic material
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D13/00—Electrophoretic coating characterised by the process
- C25D13/12—Electrophoretic coating characterised by the process characterised by the article coated
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D13/00—Electrophoretic coating characterised by the process
- C25D13/22—Servicing or operating apparatus or multistep processes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
- H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
- H01F1/047—Alloys characterised by their composition
- H01F1/053—Alloys characterised by their composition containing rare earth metals
- H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
- H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
- H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
- H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
- H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
Abstract
A method for promoting magnetic properties of a sintered Nd-Fe-B magnet is provided. The method is suitable for sintered Nd-Fe-B magnets with various 5 components; the method includes: grain boundary repairing via a low-melting metal or alloy, grain boundary diffusion via a heavy rare earth element and the corresponding heat treatment process. In the present invention, low-melting properties of alloys are utilized to preferably diffuse and repair the discontinuous grain boundary rare earth phase on the surface layer of the magnet, thus obtaining a continuous low-melting rare 10 earth phase; the continuous low-melting rare earth phase serves as a rapid diffusion path for the heavy rare earth element to effectively promote the diffusion depth of the heavy rare earth element in the magnet and reduce the use amount of the heavy rare earth element, thus achieving the promotion in coercive force of the magnet. Therefore, the present invention has wide application prospects. 15
Description
METHOD FOR PROMOTING MAGNETIC PROPERTIES OF SINTERED
NEODYMIUM-IRON-BORON (Nd-Fe-B) MAGNET
[OI] The present invention relates to the technical field of rare-earth permanent magnetic materials, and in particular to a method for promoting magnetic properties of a sintered neodymium-iron-boron (Nd-Fe-B) magnet.
[02] Neodymium-Iron-Boron (Nd-Fe-B) permanent magnet is called “king of magnet” by virtue of excellent magnetic properties, and widely applied in the fields such as, aerospace, wind power generation, energy-efficient home appliances, electronics and new energy automobile. Moreover, with the continuous improvement in manufacturing technologies and the promotion of people’s environmental awareness,
Nd-Fe-B permanent magnet has been highly concerned on the market in the three major categories of energy conservation and environment protection, new energy and new energy automobile to be a key material to achieve the “Made in China 2025” development planning. The use amount of Nd-Fe-B permanent magnet achieves rapid growth with a rate of 10-20 % per vear and shows good application prospects.
[03] Directed to magnets, coercive force is an important indicator to evaluate the magnetic properties of the Nd-Fe-B permanent magnet materials. Heavy rare earth elements Dy and Tb, as the important elements to promote coercive force, can effectively promote the magneto-crystalline anisotropy constant of the 2:14:1 phase, but are very expensive. Therefore, coercive force is generally promoted by the surface deposition-diffusion way of heavy rare earth elements Dy and Tb to reduce the manufacturing cost of the magnet. But the heavy rare earth element has a greater decreasing amplitude in concentration from the surface to the inner portion, a shallow diffusion depth and thus, has a limited improvement amplitude in properties.
[04] The objective of the present invention is to provide a method for promoting magnetic properties of a sintered Nd-Fe-B magnet. The properties of low-melting metals or alloys are utilized to repair the grain boundary of the surface layer on a magnet to form a uniform, continuous and low-melting rare earth-rich phase; the uniform, continuous and low-melting rare earth-rich phase serves as a heavy rare earth diffusion path to promote the diffusion depth and rate of the element, enhance coercive force and to save manufacturing costs.
[05] To achieve the above objective, the present invention provides the following technical solution:
[06] A method for promoting magnetic properties of a sintered Nd-Fe-B magnet includes the following steps:
[07] 1) depleting oxide skin on a surface of a magnet and drying;
[08] 2) depositing a low-melting pure metal or low-melting alloy on the surface of the magnet at a condition of a vacuum degree lower than 2x 10° Pa, where the deposited layer has a thickness of 5-10 um;
[09] 3) depositing a heavy rare earth Dy or Tb on the surface of the magnet, where the deposition layer has a thickness;
[10] 4) putting the treated magnet to a tempering furnace, vacuumizing and heating up to 660-880°C and maintaining for 3-8 h when the vacuum degree is lower than 1x10 Pa;
[11] 5) heating up to 850-950°C and maintaining for 5-10 h.
[12] Further, the low-temperature metal is one of Cu, Al, Zn, Mg and Sn.
[13] Further, the low-temperature metal is one of CuAl, CuSn, CuZn, CuMg, SnZn,
MgAl, MgCu, MgZn, AIMgZn and CuAlMg.
[14] Further, the low-melting pure metal or low-melting alloy is deposited on the surface of the magnet by evaporation or magnetron sputtering in the step 2).
[15] Further, the heavy rare earth Dy or Tb is deposited on the surface of the magnet by evaporation or magnetron sputtering at a condition of a vacuum degree lower than
2x10 Pa in the step 3).
[16] Further, a Dy or Tb oxide is deposited on the surface of the magnet by spraying or electrophoretic deposition in a non-vacuum environment in the step 3).
[17] In the technical solution of the present invention, low-melting properties of a metal or alloy are utilized to preferably diffuse and repair the discontinuous grain boundary rare earth phase on the surface layer of the magnet, thus obtaining a continuous low-melting rare earth phase; the continuous low-melting rare earth phase serves as a rapid diffusion path for the heavy rare earth element to effectively promote the diffusion depth of the heavy rare earth element in the magnet and reduce the use amount of the heavy rare earth element, thus achieving the promotion in coercive force of the magnet and reducing the use amount of the heavy rare earth element significantly.
The method 1s simple in process and easy to achieve and thus, has wide application prospects.
[18] The present invention will be described more comprehensively by the following examples. The present invention may be embodied in multiple different forms, and not construed as being limited to the exemplary embodiments described herein.
[19] For the sake of description, spatially relative terms such as, “above”, “below”, “left” and “right” may be used herein to specify a relation of one element or feature illustrated in the drawings relative to another element or feature. It should be understood that spatial terms are intended to include different directions/positions of a device in use or operation besides the direction/position illustrated in the drawings. For example, if the device in the drawings is inverted, the element described located “below” other elements or features will be located “above” other elements or features. Therefore, the exemplary term “below” may contain the upper and lower directions/positions. The device may be located in other ways (rotated 90° or located at other positions), and the spatially relative description may be interpreted correspondingly.
[20] Example 1
[21] (1) Sintered Nd-Fe-B magnet was cut into 20%30*5 mm blocks.
[22] (2) The magnet was subjected ultrasonic degreasing for 3 min in a 50°C degreasing solution, and then subjected to secondary washing; each washing time was 5-15 s.
[23] (3) The magnet was placed to a nitric acid solution having a concentration of 3% for shake cleaning for 10-20 s, then taken out and subjected to secondary washing; each washing time was 5-15 s, afterwards, subjected to ultrasonic oscillation till observed that the oxide skin on the surface layer of the magnet fell off, and the obtained magnet was taken and dried for 20 min with a drying temperature of 40°C. Other ways may be also used to make the oxide skin on the surface layer of the magnet falling off.
[24] (4) A low-melting alloy AlZn was subjected to magnetron sputtering at a vacuum degree lower than 2107 Pa; and the deposition layer had a thickness of 10 um.
The deposition may be also performed by an evaporation method. The magnetron sputtering power and time were controlled to 60-90 W and 30-60 min, thus controlling the thickness of the deposited layer within 5 um to 10 um. The low-melting metal refers to metals and its alloys which have a melting point at 300°C or below; Cu, Al, Zn, Mg,
Sn and other metals or CuAl, CuSn, CuZn, CuMg, SnZn, MgAl, MgCu, MgZn,
AlMgZn, CuAlMg and other low-melting alloys composed of the above metals.
[25] (5) A heavy rare earth Dy was deposited on the surface of the magnet by evaporation or magnetron sputtering technology at a condition of a vacuum degree lower than 2x107 Pa; the deposition time was 1-3 min. A heavy rare earth Tb may be also deposited on the surface of the magnet. An oxide Dy20:; or oxide of Tb may be also deposited on the surface of the magnet by spraying or electrophoretic deposition in a non-vacuum environment; the deposition time was 1-3 min.
[26] (6) The magnet was heat preserved for 8 h at 680°C under a condition of a vacuum degree lower than 1x10~ Pa; and then heat preserved for 5 h at 900°C, and finally tempered at 500°C; the tempering time was 2 h. In the tempering process, the primary tempering temperature should be controlled with 660-880°C and time was controlled within 3-8 h; and the secondary tempering temperature should be controlled with 850-950°C and time was controlled within 5-10 h. The step achieves the grade diffusion: the internal layer of the low-melting metal is facilitated to be diffused preferably at a lower temperature to repair the grain boundary of the surface layer on the magnet to obtain a continuous low-melting rare earth phase; then the external layer of 5 heavy rare earth element was induced via high-temperature heat treatment to achieve rapid diffusion by means of the repaired low-melting grain boundary path, thus promoting the diffusion rate and depth. The consumption of rare earth in this example was 8.8 mg (magnetron sputtering).
[27] NIM-2000HF rare-earth permanent magnet measuring equipment was used to detect the magnetic properties of the test sample prepared by the above process. The change situation of the magnetic properties of the magnet before and after being repaired by the low-melting alloy is shown in Table 1.
[28]
Test sample Br Hoi (BH)max Hx/Hgj (kGs) (kOe) (MGOe) (%0)
Low-melting 12.83 18.29 39.89 89.40 diffusion magnet
[29] Table 1 Change situation of the magnetic properties of the magnet before and after being repaired by the low-melting alloy
[30] Comparative Example 1
[31] The repair effect of a low-melting alloy on the grain boundary on the surface of a magnet to achieve the rapid diffusion of the heavy rare earth element along the grain.
As shown in Example 1, the magnet test sample was prepared by deposition and diffusion. The difference lies in that the magnet was prepared directly by the deposition and diffusion of the heavy rare earth Dy or its oxide Dy20: instead of the deposition of the low-melting metal or low-melting alloy in the step (4); the consumption of the rare earth was 12.6 mg (magnetron sputtering) and more 30% than that of Example 1. The magnetic properties of the magnet test sample prepared without the repair of the low-melting alloy are shown in Table 2.
[32]
Test sample Br Hej (BH)max Hi/Hoj (kGs) (kOe) (MGOe) (©)
Non-repaired 12.7 17.59 39.41 90.70 magnet
[33] Table 2 The magnetic properties of the magnet not repaired by the low-melting alloy
[34] It can be seen from the magnetic properties in Example 1 and Comparative
Example 1 that for the test sample on the surface layer of the magnet not repaired by the low-melting metal or alloy, even though there is no marked change in the residual magnetism and magnetic energy product, the promotion amplitude of the coercive force is lower than that of the magnet repaired by the low-melting alloy.
[35] Comparative Example 2
[36] The repair effect of a low-melting alloy on the grain boundary on the surface of a magnet to achieve the rapid diffusion of the heavy rare earth element along the grain.
As shown in Example 1, the magnet test sample was prepared by deposition and diffusion. The difference lies in that no step (4) was taken in the Comparative Example 2, namely, no evaporation or magnetron sputtering was performed at a vacuum degree lower than 6107 Pa. The magnetic properties of the test sample prepared by the low-melting alloy at a low vacuum degree are shown in Table 3.
[37]
Test sample Br Hej (BH)max Hx/Hcj (kGs) (kOe) (MGOe) (%)
Low vacuum | 12.78 16.92 38.82 91.60 deposited magnet
[38] Table 3 The magnetic properties of the test sample prepared by the low-melting alloy at a low vacuum degree
[39] It can be seen from the magnetic properties in Example 1 and Comparative
Example 2 that the magnetic properties decrease to some extent under the environment of poor vacuum degree; this is because the low-melting alloy is oxidized in the deposition process, which is against the repair of the grain boundary, and hinders the diffusion of the subsequent heavy rare earth elements, resulting in the decrease of the magnetic properties.
[40] Comparative Example 3
[41] The repair effect of a low-melting alloy on the grain boundary on the surface of a magnet to achieve the rapid diffusion of the heavy rare earth element along the grain.
As shown in Example 1, the magnet test sample was prepared by deposition and diffusion. The difference lies in that the deposition thickness is respectively 5 um and um. The magnetic properties of the prepared test sample are shown in Table 4. 15 [42]
Test sample Br Hej (BH)max Hx/Hcj (kGs) (kOe) (MGOe) (%0)
Deposition 12.75 17.56 38.05 86.90 thickness 5 um
Deposition 12.66 15.68 38.57 92.30 thickness 15 um
[43] Table 4 The magnetic properties of the magnet deposited by different thickness of low-melting alloys
[44] It can be seen from the magnetic properties in Example 1 and Comparative
Example 3 that the deposition thickness of the low-melting alloy obviously influences the magnetic properties; when the thickness is 10 um, the repair effect is proper; when the thickness is lower, the repair effect is not significant because there is a low content of low-melting alloy; and coercive force is not obviously improved; when the thickness is greater, the coercive force is reduced to some extent because the thickness hinders the diffusion of the subsequent heavy rare earth element.
[45] Comparative Example 4
[46] The repair effect of a low-melting alloy on the grain boundary on the surface of a magnet to achieve the rapid diffusion of the heavy rare earth element along the grain.
As shown in Example 1, the magnet test sample was prepared by deposition and diffusion. The difference lies in that the step (6) was not taken; and the heat treatment process was as follows: the magnet was heat preserved for 8 h at 860°C under a condition of a vacuum degree lower than 1x10% Pa; and then heat preserved for 5 h at 900°C, and finally tempered at 500°C; the tempering time was 2 h. The magnetic properties of the prepared magnet test sample having a high diffusion-repair temperature are shown in Table S.
[47]
Test sample Br Hej (BH)max Hi/Hej (kGs) (kOe) (MGOe) (%)
High 12.60 17.11 40.35 85.80 diffusion-repair temperature
[48] Table 5 The magnetic properties of the prepared magnet test sample having a high diffusion-repair temperature
[49] It can be seen from the magnetic properties in Example 1 and Comparative
Example 4 that the use of high temperature in the initial stage of the heat treatment will cause the diffusion of the heavy rare earth element in case of not repairing the grain boundary path completely; the diffusion efficiency and depth are reduced significantly, and the promotion effect on the magnetic properties is decreased accordingly.
[50] Compared with the prior art, the present invention has the following beneficial effects:
[51] (1) Low-melting properties of a metal or alloy are utilized to preferably diffuse and repair the discontinuous grain boundary rare earth phase on the surface layer of the magnet, thus obtaining a continuous low-melting rare earth phase; the continuous low-melting rare earth phase serves as a rapid diffusion path for the heavy rare earth element to effectively promote the diffusion depth of the heavy rare earth element in the magnet and facilitate the promotion of magnetic properties.
[52] (2) The low-melting flow is utilized to repair the grain boundary to promote the diffusion depth of rare earth in magnet and effectively reduce the use amount of the heavy rare earth element, thus reducing the manufacturing cost of the magnet.
[53] (3) The present invention has simple process and relatively low equipment requirements, and can complete the operation based on the original grain boundary diffusion device and thus, has prospects of large-scale promotion and application.
Claims (6)
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL2031758A NL2031758B1 (en) | 2022-05-02 | 2022-05-02 | METHOD FOR PROMOTING MAGNETIC PROPERTIES OF SINTERED NEODYMIUM-IRON-BORON (Nd-Fe-B) MAGNET |
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| NL2031758A NL2031758B1 (en) | 2022-05-02 | 2022-05-02 | METHOD FOR PROMOTING MAGNETIC PROPERTIES OF SINTERED NEODYMIUM-IRON-BORON (Nd-Fe-B) MAGNET |
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