CN113539597A - Anisotropic nanocrystalline cobalt-based rare earth permanent magnet and preparation method thereof - Google Patents
Anisotropic nanocrystalline cobalt-based rare earth permanent magnet and preparation method thereof Download PDFInfo
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- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 53
- 150000002910 rare earth metals Chemical class 0.000 title claims abstract description 51
- 229910017052 cobalt Inorganic materials 0.000 title claims abstract description 41
- 239000010941 cobalt Substances 0.000 title claims abstract description 41
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 title claims abstract description 41
- 238000002360 preparation method Methods 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 32
- 239000006247 magnetic powder Substances 0.000 claims abstract description 23
- 238000007731 hot pressing Methods 0.000 claims abstract description 16
- 239000000463 material Substances 0.000 claims abstract description 16
- 238000001192 hot extrusion Methods 0.000 claims abstract description 12
- 238000003825 pressing Methods 0.000 claims description 13
- 238000010791 quenching Methods 0.000 claims description 13
- 230000000171 quenching effect Effects 0.000 claims description 13
- 238000003723 Smelting Methods 0.000 claims description 8
- 238000001125 extrusion Methods 0.000 claims description 8
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 238000000713 high-energy ball milling Methods 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 229910052772 Samarium Inorganic materials 0.000 claims description 3
- 229910052684 Cerium Inorganic materials 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- 229910052804 chromium Inorganic materials 0.000 claims description 2
- 229910052748 manganese Inorganic materials 0.000 claims description 2
- 229910052750 molybdenum Inorganic materials 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 229910052709 silver Inorganic materials 0.000 claims description 2
- 229910052718 tin Inorganic materials 0.000 claims description 2
- 230000007704 transition Effects 0.000 claims description 2
- 229910052727 yttrium Inorganic materials 0.000 claims description 2
- 229910052725 zinc Inorganic materials 0.000 claims description 2
- 229910052726 zirconium Inorganic materials 0.000 claims description 2
- 239000002243 precursor Substances 0.000 description 11
- 229910045601 alloy Inorganic materials 0.000 description 10
- 239000000956 alloy Substances 0.000 description 10
- 238000010438 heat treatment Methods 0.000 description 9
- 239000010935 stainless steel Substances 0.000 description 9
- 229910001220 stainless steel Inorganic materials 0.000 description 9
- 239000012300 argon atmosphere Substances 0.000 description 8
- 229910000938 samarium–cobalt magnet Inorganic materials 0.000 description 8
- 238000000498 ball milling Methods 0.000 description 6
- 238000005266 casting Methods 0.000 description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 239000000696 magnetic material Substances 0.000 description 5
- 239000010949 copper Substances 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 230000006698 induction Effects 0.000 description 3
- 238000004321 preservation Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 238000013329 compounding Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002159 nanocrystal Substances 0.000 description 2
- 238000004663 powder metallurgy Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000005481 NMR spectroscopy Methods 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000007885 magnetic separation Methods 0.000 description 1
- 239000006148 magnetic separator Substances 0.000 description 1
- 238000002653 magnetic therapy Methods 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000005551 mechanical alloying Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910001172 neodymium magnet Inorganic materials 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- 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
- H01F1/0555—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together
- H01F1/0556—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together pressed
-
- 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
- H01F1/0555—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together
- H01F1/0557—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 pressed, sintered or bonded together sintered
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- 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
- H01F41/0266—Moulding; Pressing
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- 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
- H01F41/0273—Imparting anisotropy
Abstract
The invention provides an anisotropic nanocrystalline cobalt-based rare earth permanent magnet and a preparation method thereof. The preparation method comprises the following steps: obtaining cobalt-based rare earth magnetic powder; hot-pressing the cobalt-based rare earth magnetic powder to obtain an isotropic magnet; and carrying out hot extrusion on the isotropic magnet to obtain the anisotropic nanocrystalline cobalt-based rare earth permanent magnet, wherein the hot extrusion temperature is 600-900 ℃. Compared with the traditional upsetting thermal deformation method, the anisotropic nanocrystalline cobalt-based rare earth permanent magnet prepared by the invention can obtain a more uniform deformation texture, has net forming characteristics, and can improve the maximum magnetic energy product of the rare earth permanent magnet material without reducing remanence and coercive force.
Description
Technical Field
The invention belongs to the technical field of rare earth magnetic material preparation, and particularly relates to an anisotropic nanocrystalline cobalt-based rare earth permanent magnet and a preparation method thereof.
Background
The rare earth permanent magnetic material can play a role in energy storage and conversion, so that the rare earth permanent magnetic material is widely applied to various micro and special motors and plays an important role in the industries such as computers, automobiles, instruments, household appliances, petrochemical industry, medical care, aerospace and the like; meanwhile, the magnetic separator is also applied to components generating strong gap magnetic fields, and plays an important role in the industries of nuclear magnetic resonance equipment, electric devices, magnetic separation equipment, magnetic machines, magnetic therapy apparatuses and the like.
With the rapid development of new green energy fields such as wind power generation, new energy automobiles, variable frequency household appliances, energy-saving elevators, energy-saving petroleum pumping units and the like, the demand for high-end rare earth permanent magnet materials is increasing day by day, and higher requirements are provided for the magnetic properties, particularly the temperature stability, of the permanent magnet materials. Commonly used rare earth permanent magnets include iron-based and cobalt-based rare earth permanent magnets. The neodymium iron boron magnet, which is the main representative of the iron-based rare earth permanent magnet, has an ultra-high room temperature magnetic energy product and is called as "maga", but the low curie temperature is not favorable for the application in a high-temperature environment. And the samarium-cobalt magnet as a typical cobalt-based rare earth permanent magnet has high coercive force and temperature stability, and is suitable for being applied to the field of high-temperature application.
At present, the preparation method of the cobalt-based rare earth permanent magnet mainly comprises a sintering method and a thermal deformation method, wherein the sintering method adopts the traditional powder metallurgy technology in the preparation process, magnetic powder is oriented in a special magnetic field, and sintering, heat treatment and processing are carried out after the grain orientation tends to be consistent. Although the sintered magnet has high magnetic performance, the process is complex, the production time is long, and near-net-shape forming cannot be realized. The anisotropic nanocrystalline permanent magnet prepared by the thermal deformation method has short process flow and only needs two steps of hot pressing and thermal deformation. The hot pressing process is to obtain a high-density nanocrystalline magnet, and the hot deformation process is to obtain a high deformation texture to realize magnetic anisotropy. Compared with the traditional micron crystal magnet sintered by powder metallurgy, the thermal deformation nano crystal magnet can obtain anisotropy without magnetic field orientation, and the mechanical property and the corrosion resistance of the thermal deformation nano crystal magnet are better. The conventional thermal deformation method generally adopts upsetting deformation, and due to the uneven deformation, the magnetic performance of the prepared thermal deformation magnet is uneven, areas with small upper and lower surface variables need to be cut off in later processing, so that near-net forming cannot be achieved, and a large amount of waste is caused.
Disclosure of Invention
The invention provides an anisotropic nanocrystalline cobalt-based rare earth permanent magnet and a preparation method thereof.
Specifically, the invention provides the following technical scheme:
a preparation method of anisotropic nanocrystalline cobalt-based rare earth permanent magnet comprises the following steps:
obtaining cobalt-based rare earth magnetic powder;
hot-pressing the cobalt-based rare earth magnetic powder to obtain an isotropic magnet;
and carrying out hot extrusion on the isotropic magnet to obtain the anisotropic nanocrystalline cobalt-based rare earth permanent magnet, wherein the hot extrusion temperature is 600-900 ℃.
The inventor finds that in the research and development process of the cobalt-based rare earth magnetic material preparation technology, amorphous/nanocrystalline magnetic powder is firstly subjected to hot pressing to prepare an isotropic precursor, and then the precursor is extruded and molded in a through hole designed in a mold pressure head at the temperature of 600-900 ℃, so that a uniform deformation texture can be obtained, the net molding characteristic is achieved, the maximum magnetic energy product of the rare earth permanent magnetic material can be improved, and the residual magnetism and the coercive force are not reduced.
Preferably, in the above preparation method, the cobalt-based rare earth magnetic powder comprises RCoa-xTMx(atomic ratio) wherein R is at least one rare earth element and TM is at least one transition group element; a is 3, 5 or 7, and x is more than or equal to 0 and less than or equal to 0.3.
More preferably, R is selected from one or more of Sm, Pr, La, Ce and Y, and TM is selected from one or more of Ni, Fe, Mn, Cr, Al, Sn, Ga, Ti, Zn, Zr, Mo, Ag and Cu.
Preferably, in the preparation method, the cobalt-based rare earth magnetic powder is prepared by material preparation, smelting, rapid quenching and/or high-energy ball milling. The magnetic powder used in the invention needs to ensure that the grain size is nano-grade or amorphous. The smelting is used for preparing alloy ingots; the rapid quenching and/or high-energy ball milling is used for preparing amorphous/nanocrystalline magnetic powder, and the magnetic powder prepared by grinding a rapid quenching belt is generally used; or magnetic powder prepared by a mechanical alloying method, namely high-energy ball milling.
Preferably, in the above preparation method, the cobalt-based rare earth magnetic powder is according to the formula RCoa-xTMxAnd (3) preparing materials, wherein the actual R preparation amount is 1.03-1.10 times of the theoretical R consumption.
Preferably, in the preparation method, the hot pressing temperature is 500-700 ℃; and/or the pressure of hot pressing is 400-1000 MPa.
Preferably, in the preparation method, the pressure of the hot extrusion is 50-500 MPa. Further preferably, the thermal extrusion process is performed under vacuum or an Ar gas atmosphere; the heating rate has no specific requirement, such as 50-200 ℃/min.
Preferably, in the above preparation method, in the hot extrusion step, the upper and lower pressing heads have the same diameter, and the lower pressing head is provided with a through hole for extruding the material. And heating to the deformation temperature, pressurizing to perform extrusion deformation, and extruding the magnet into the through hole of the lower pressure head by the downward movement of the upper pressure head.
Preferably, in the above manufacturing method, the aspect ratio of the through hole is at least 4. In the invention, the large length-width ratio is the key for obtaining the magnetic anisotropy by extrusion, and meanwhile, the thermal deformation magnets with different cross-sectional shapes, such as various cross-sectional shapes of a flake shape, a tile shape, a thin ring shape and the like, can be continuously produced by designing the shape of the through hole of the lower pressure head.
The invention also provides the anisotropic nanocrystalline cobalt-based rare earth permanent magnet prepared by the preparation method.
The invention has the following beneficial effects:
compared with the traditional upsetting thermal deformation method, the anisotropic nanocrystalline cobalt-based rare earth permanent magnet prepared by the invention can obtain a more uniform deformation texture, has net forming characteristics, and can improve the maximum magnetic energy product of the rare earth permanent magnet material without reducing remanence and coercive force.
Detailed Description
The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention. The examples do not show the specific techniques or conditions, according to the technical or conditions described in the literature in the field, or according to the product specifications.
In the following examples, the equipment and the like used are not shown to manufacturers, and are all conventional products available from regular vendors. The process is conventional unless otherwise specified, and the starting materials are commercially available from the open literature.
Example 1
Embodiment 1 provides a method for preparing an anisotropic nanocrystalline cobalt-based rare earth permanent magnet, which comprises the following steps:
1) SmCo according to the chemical formula5Preparing materials, wherein the actual Sm amount prepared in the material preparing process is 1.05 times of the theoretical Sm consumption;
2) smelting the alloy raw material obtained in the step 1) in an argon atmosphere through a PZGF-40 type intermediate frequency vacuum induction smelting furnace, sequentially increasing the heating power from 5kW to 8kW, 10kW and 13kW, respectively keeping the corresponding residence time for 5min, 3min and 2min, and obtaining SmCo with the thickness of 10mm by adopting a water-cooled copper mold during casting5Alloy ingot casting;
3) SmCo is mixed5Performing melt rapid quenching on the alloy cast ingot at the roller speed of 25m/s in the argon atmosphere to obtain SmCo5A rapid quenching zone; placing the rapid quenching belt into a stainless steel tank, taking a stainless steel ball as a ball milling medium, wherein the diameter of the stainless steel ball is 4-12mm, the ball-material ratio is 15:1, the rotating speed is 600r/min, and ball milling is carried out for 4 hours in a GN-2 type high-energy ball mill under the argon atmosphere to obtain magnetic powder;
4) the magnetic powder in the step 3) is loaded into a die for hot pressing, and the hot pressing process comprises the following steps: the temperature is 600 ℃, the pressure is 500MPa, and the heat preservation time is 5min, so as to prepare a deformation precursor;
5) and (3) putting the precursor in the step 4) into a die with the diameter of 20mm and the cross section size of a through hole extruded by a lower pressing head of 10 multiplied by 2mm, heating to 800 ℃ in a vacuum state (less than 10Pa), gradually applying pressure to 100MPa, extruding the precursor into the through hole of the lower pressing head, and performing extrusion molding to obtain the anisotropic nanocrystalline cobalt-based rare earth permanent magnet.
Example 2
Embodiment 2 provides a method for preparing an anisotropic nanocrystalline cobalt-based rare earth permanent magnet, which comprises the following steps:
1) according to the chemical formula Sm0.6Pr0.4Co5Compounding, wherein the actually compounded Sm amount is 1.05 times of the theoretical Sm consumption in the compounding process, and the actually compounded Pr amount is 1.05 times of the theoretical Pr consumption, namely, 5 wt% of Sm and Pr are additionally added to be used as burning loss;
2) smelting the alloy raw material obtained in the step 1) in an argon atmosphere through a PZGF-40 type intermediate frequency vacuum induction smelting furnace, sequentially increasing the heating power from 5kW to 8kW, 10kW and 13kW, respectively keeping the corresponding residence time for 5min, 3min and 2min, and obtaining Sm with the thickness of 10mm by adopting a water-cooled copper mold during casting0.6Pr0.4Co5Alloy ingot casting;
3) mixing Sm0.6Pr0.4Co5The alloy cast ingot is subjected to melt rapid quenching at a roll speed of 25m/s in an argon atmosphere to obtain Sm0.6Pr0.4Co5A rapid quenching zone; placing the rapid quenching belt into a stainless steel tank, taking a stainless steel ball as a ball milling medium, wherein the diameter of the stainless steel ball is 4-12mm, the ball-material ratio is 15:1, the rotating speed is 600r/min, and ball milling is carried out for 4 hours in a GN-2 type high-energy ball mill under the argon atmosphere to obtain magnetic powder;
4) the magnetic powder in the step 3) is loaded into a die for hot pressing, and the hot pressing process comprises the following steps: the temperature is 600 ℃, the pressure is 500MPa, and the heat preservation time is 5min, so as to prepare a deformation precursor;
5) and (3) putting the precursor in the step 4) into a die with the diameter of 20mm and the cross section size of a through hole extruded by a lower pressing head of 10 multiplied by 2mm, heating to 800 ℃ in a vacuum state (less than 10Pa), gradually applying pressure to 100MPa, extruding the precursor into the through hole of the lower pressing head, and performing extrusion molding to obtain the anisotropic nanocrystalline cobalt-based rare earth permanent magnet.
Example 3
Embodiment 2 provides a method for preparing an anisotropic nanocrystalline cobalt-based rare earth permanent magnet, which comprises the following steps:
1) SmCo according to the chemical formula4.8Zr0.2Preparing materials, wherein the actual Sm amount prepared in the material preparing process is 1.05 times of the theoretical Sm consumption;
2) passing the alloy raw material obtained in the step 1) through a PZGF-40 type intermediate frequency vacuum induction smelting furnace in an argon atmosphereSmelting, increasing the heating power from 5kW to 8kW, 10kW and 13kW in sequence, keeping the corresponding residence time for 5min, 3min and 2min respectively, and adopting a water-cooling copper mould during casting to obtain SmCo with the thickness of 10mm4.8Zr0.2Alloy ingot casting;
3) SmCo is mixed4.8Zr0.2Performing melt rapid quenching on the alloy cast ingot at the roller speed of 25m/s in the argon atmosphere to obtain SmCo4.8Zr0.2A rapid quenching zone; placing the rapid quenching belt into a stainless steel tank, taking a stainless steel ball as a ball milling medium, wherein the diameter of the stainless steel ball is 4-12mm, the ball-material ratio is 15:1, the rotating speed is 600r/min, and ball milling is carried out for 4 hours in a GN-2 type high-energy ball mill under the argon atmosphere to obtain magnetic powder;
4) the magnetic powder in the step 3) is loaded into a die for hot pressing, and the hot pressing process comprises the following steps: the temperature is 600 ℃, the pressure is 500MPa, and the heat preservation time is 5min, so as to prepare a deformation precursor;
5) and (3) putting the precursor in the step 4) into a die with the diameter of 20mm and the cross section size of a through hole extruded by a lower pressing head of 10 multiplied by 2mm, heating to 800 ℃ in a vacuum state (less than 10Pa), gradually applying pressure to 100MPa, extruding the precursor into the through hole of the lower pressing head, and performing extrusion molding to obtain the anisotropic nanocrystalline cobalt-based rare earth permanent magnet.
And (3) magnetic property testing:
the anisotropic nanocrystalline cobalt-based rare earth permanent magnet obtained in example 1 and having a length of 50mm was sampled and tested at the front end (5 mm), the middle portion (25 mm), and the rear end (45 mm) of the magnet along the extrusion direction of hot extrusion, and the magnetic property data are shown in table 1 below.
TABLE 1
| Remanence (kG) | Coercive force (kOe) | Maximum magnetic energy product (MGOe) | |
| Position 1-front end | 7.8 | 19.6 | 12.9 |
| Position 2-middle part | 8.1 | 18.7 | 14.6 |
| Position 3-rear end | 8.0 | 20.2 | 13.8 |
As can be seen from Table 1, the front, middle and rear ends of the magnet had uniform magnetic properties (remanence difference < 4%; coercivity difference < 8%; product difference < 14%), indicating that SmCo prepared in example 1 was present5The deformation texture of the rare earth magnet has good uniformity.
The magnetic properties of the anisotropic nanocrystalline cobalt-based rare earth permanent magnet prepared in examples 1 to 3 were measured, and the measurement data are shown in Table 2.
TABLE 2
| Remanence (kG)) | Coercive force (kOe) | Maximum magnetic energy product (MGOe) | |
| Example 1 | 8.1 | 18.7 | 14.6 |
| Example 2 | 8.5 | 12.5 | 15.9 |
| Example 3 | 8.3 | 21.7 | 15.2 |
Although the invention has been described in detail hereinabove by way of general description, specific embodiments and experiments, it will be apparent to those skilled in the art that many modifications and improvements can be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.
Claims (10)
1. A preparation method of anisotropic nanocrystalline cobalt-based rare earth permanent magnet is characterized by comprising the following steps:
obtaining cobalt-based rare earth magnetic powder;
hot-pressing the cobalt-based rare earth magnetic powder to obtain an isotropic magnet;
and carrying out hot extrusion on the isotropic magnet to obtain the anisotropic nanocrystalline cobalt-based rare earth permanent magnet, wherein the hot extrusion temperature is 600-900 ℃.
2. The method of claim 1, wherein the cobalt-based rare earth magnetic powder comprises formula RCoa-xTMxWherein R is at least one rare earth element and TM is at least one transition group element; a is 3, 5 or 7, and x is more than or equal to 0 and less than or equal to 0.3.
3. The method of claim 2, wherein R is one or more selected from Sm, Pr, La, Ce, Y, and TM is one or more selected from Ni, Fe, Mn, Cr, Al, Sn, Ga, Ti, Zn, Zr, Mo, Ag, Cu.
4. The method for preparing the anisotropic nanocrystalline cobalt-based rare earth permanent magnet according to any one of claims 1 to 3, wherein the cobalt-based rare earth magnetic powder is prepared by batching, smelting, rapid quenching and/or high-energy ball milling.
5. The method of claim 4, wherein the RCo is a formula ofa-xTMxAnd (3) preparing materials, wherein the actual R preparation amount is 1.03-1.10 times of the theoretical R consumption.
6. The method for preparing the anisotropic nanocrystalline cobalt-based rare earth permanent magnet according to any one of claims 1 to 5, wherein the hot pressing temperature is 500-700 ℃; and/or the pressure of hot pressing is 400-1000 MPa.
7. The method for preparing the anisotropic nanocrystalline cobalt-based rare earth permanent magnet according to any one of claims 1 to 6, wherein the pressure of the hot extrusion is 50 to 500 MPa; and/or, the hot extrusion is performed under vacuum conditions.
8. The method for preparing the anisotropic nanocrystalline cobalt-based rare earth permanent magnet according to any one of claims 1 to 7, wherein in the hot extrusion step, the upper and lower pressing heads have the same diameter, and a through hole for material extrusion is formed in the lower pressing head.
9. The method of claim 8, wherein the aspect ratio of the through-hole is at least 4.
10. An anisotropic nanocrystalline cobalt-based rare earth permanent magnet prepared by the preparation method of any one of claims 1 to 9.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104576028A (en) * | 2014-12-30 | 2015-04-29 | 四川大学 | Methods for manufacturing cerium-rich anisotropy nano-crystalline rare-earth permanent magnets |
| CN106448986A (en) * | 2016-09-23 | 2017-02-22 | 四川大学 | Anisotropic nanocrystalline rare earth permanent magnet and preparation method therefor |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104576028A (en) * | 2014-12-30 | 2015-04-29 | 四川大学 | Methods for manufacturing cerium-rich anisotropy nano-crystalline rare-earth permanent magnets |
| CN106448986A (en) * | 2016-09-23 | 2017-02-22 | 四川大学 | Anisotropic nanocrystalline rare earth permanent magnet and preparation method therefor |
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