CN112216499A - Preparation method of antioxidant sintered neodymium-iron-boron magnet - Google Patents
Preparation method of antioxidant sintered neodymium-iron-boron magnet Download PDFInfo
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- 238000002360 preparation method Methods 0.000 title claims abstract description 35
- 229910001172 neodymium magnet Inorganic materials 0.000 title claims abstract description 30
- 230000003078 antioxidant effect Effects 0.000 title claims abstract description 14
- 239000003963 antioxidant agent Substances 0.000 title claims abstract description 13
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 57
- 239000001257 hydrogen Substances 0.000 claims abstract description 57
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 57
- 239000000843 powder Substances 0.000 claims abstract description 42
- 239000001301 oxygen Substances 0.000 claims abstract description 34
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 34
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 33
- 238000005496 tempering Methods 0.000 claims abstract description 30
- 238000005245 sintering Methods 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 22
- 238000006356 dehydrogenation reaction Methods 0.000 claims abstract description 20
- 239000002994 raw material Substances 0.000 claims abstract description 16
- 238000000462 isostatic pressing Methods 0.000 claims abstract description 15
- 238000010438 heat treatment Methods 0.000 claims abstract description 14
- 238000003723 Smelting Methods 0.000 claims abstract description 11
- 239000007789 gas Substances 0.000 claims abstract description 10
- 238000003801 milling Methods 0.000 claims abstract description 9
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 9
- 238000000748 compression moulding Methods 0.000 claims abstract description 4
- 150000002910 rare earth metals Chemical class 0.000 claims abstract description 3
- 239000006247 magnetic powder Substances 0.000 claims description 13
- 239000002245 particle Substances 0.000 claims description 13
- 229910052802 copper Inorganic materials 0.000 claims description 9
- 239000010949 copper Substances 0.000 claims description 9
- 239000000126 substance Substances 0.000 claims description 9
- 229910052720 vanadium Inorganic materials 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 229910052779 Neodymium Inorganic materials 0.000 claims description 7
- 229910052777 Praseodymium Inorganic materials 0.000 claims description 7
- 238000011049 filling Methods 0.000 claims description 7
- 229910052684 Cerium Inorganic materials 0.000 claims description 6
- 229910052692 Dysprosium Inorganic materials 0.000 claims description 6
- 229910052688 Gadolinium Inorganic materials 0.000 claims description 6
- 229910052771 Terbium Inorganic materials 0.000 claims description 6
- 150000001875 compounds Chemical class 0.000 claims description 6
- 229910052727 yttrium Inorganic materials 0.000 claims description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 5
- 229910052775 Thulium Inorganic materials 0.000 claims description 5
- 238000010902 jet-milling Methods 0.000 claims description 5
- 229910052733 gallium Inorganic materials 0.000 claims description 4
- 238000002844 melting Methods 0.000 claims description 4
- 230000008018 melting Effects 0.000 claims description 4
- 229910052758 niobium Inorganic materials 0.000 claims description 4
- 229910052726 zirconium Inorganic materials 0.000 claims description 4
- 238000005266 casting Methods 0.000 claims description 2
- 238000010298 pulverizing process Methods 0.000 claims description 2
- 238000007712 rapid solidification Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 abstract description 3
- 230000003647 oxidation Effects 0.000 description 16
- 238000007254 oxidation reaction Methods 0.000 description 16
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 11
- 230000008569 process Effects 0.000 description 11
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- 235000006708 antioxidants Nutrition 0.000 description 10
- 229910052786 argon Inorganic materials 0.000 description 6
- 239000000203 mixture Substances 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 238000005498 polishing Methods 0.000 description 3
- 238000007780 powder milling Methods 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 238000009461 vacuum packaging Methods 0.000 description 3
- 238000005303 weighing Methods 0.000 description 3
- 238000007792 addition Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 241001062472 Stokellia anisodon Species 0.000 description 1
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000005273 aeration Methods 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- -1 alkenyl ether Chemical compound 0.000 description 1
- 150000005215 alkyl ethers Chemical class 0.000 description 1
- 230000003064 anti-oxidating effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- RTZKZFJDLAIYFH-UHFFFAOYSA-N ether Substances CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000002356 laser light scattering Methods 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 1
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 230000002269 spontaneous effect Effects 0.000 description 1
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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
-
- 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
-
- 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
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- Hard Magnetic Materials (AREA)
Abstract
The invention belongs to the field of rare earth permanent magnet material preparation, and relates to a preparation method of an antioxidant sintered neodymium iron boron magnet. The method comprises the following steps: (1) raw material proportioning, (2) rapid hardening smelting, (3) hydrogen crushing, dehydrogenation treatment and airflow milling, (4) compression molding and isostatic pressing treatment, and (5) sintering and tempering heat treatment; in the step (3), the dehydrogenation treatment ensures that the hydrogen content of the coarse crushing powder is 1400-1800ppm, and the oxygen content introduced in the powder preparation process of the gas flow mill is 60-80 ppm. The invention leads the magnet to have excellent magnetic performance by controlling the hydrogen content and the oxygen content.
Description
Technical Field
The invention belongs to the field of rare earth permanent magnet material preparation, and relates to a preparation method of an antioxidant sintered neodymium iron boron magnet
Background
Since the 20 th century and the 80 th era, the sintered neodymium-iron-boron magnet is named as 'magawa' due to the characteristics of high coercivity and high magnetic energy product, is a commercial magnetic material with the highest cost performance so far, and is widely applied to various fields of household appliances, traffic, medical treatment and other customs. In recent years, with the pursuit of quality of life, the demand for various small household electrical appliances has been increasing, and thus the market for cylindrical magnets commonly used for small household electrical appliances has been increasing. However, due to the multi-electron-layer structure of the rare earth elements neodymium, praseodymium and the like, the chemical activity is more active, spontaneous combustion is easy to occur if the operation is improper in the powder preparation stage, serious safety accidents are caused, and meanwhile, the cylindrical magnet has a large specific surface area and is easy to oxidize, so that higher requirements are provided for controlling the oxygen content in the mass production and circulation links of enterprises. The common practice in the industry is to add a certain proportion of antioxidant, such as one or more of polyethylene oxide alkyl ether, polyethylene oxide mono-fatty ester, and polyethylene oxide alkenyl ether, but the addition of antioxidant will wear the liner of the jet milling equipment on one hand, and will also cause agglomeration of jet milled powder particles in the forming stage, which is not favorable for orientation forming of magnetic powder particles, and will also have a certain influence on the magnetic performance of the terminal magnet due to the higher proportion of carbon element and oxygen element in the antioxidant. How to reduce or avoid the use of antioxidant can make the magnet reach anti-oxidant effect again to prolong the use of the consumptive material of equipment, promote product property ability, this has very important meaning to manufacturing enterprise.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a novel preparation method of the neodymium iron boron magnet, and the obtained neodymium iron boron magnet has excellent oxidation resistance and magnet performance.
The above object of the present invention is achieved by the following technical solutions:
a preparation method of an antioxidant sintered neodymium iron boron magnet comprises the following steps: (1) raw material proportioning, (2) rapid hardening smelting, (3) hydrogen crushing, dehydrogenation treatment and airflow milling, (4) compression molding and isostatic pressing treatment, and (5) sintering and tempering heat treatment;
in the step (3), the dehydrogenation treatment ensures that the hydrogen content of the coarse crushing powder is 1400-1800ppm, and the oxygen content introduced in the powder preparation process of the gas flow mill is 60-80 ppm.
Preferably, the chemical formula of the neodymium iron boron magnet is ReaTmbBcFe1-a-b-c, and a, b and c satisfy the following relations in mass fraction: a is more than or equal to 28 and less than or equal to 33, b is more than or equal to 0 and less than or equal to 5, c is more than or equal to 0.85 and less than or equal to 1.5, wherein Re is a rare earth element Nd or a compound formed by Nd and one or more of Pr, Nd, Dy, Tb, Gd, Ho, La, Ce and Y, and Tm is one or more of Cu, Al, Co, Ga, Nb, Zr and V.
Preferably, the chemical formula of the neodymium iron boron magnet is ReaTmbBcFe1-a-b-c, and a, b and c satisfy the following relations in mass fraction: a is more than or equal to 30 and less than or equal to 32, b is more than or equal to 1.0 and less than or equal to 3.0, c is more than or equal to 0.9 and less than or equal to 1.2, wherein Re is a rare earth element Nd or a compound formed by Nd and one or more of Pr, Nd, Dy, Tb, Gd, Ho, La, Ce and Y, and Tm is the mass ratio of Al to V (1-2): 1, and (b) a complex formed.
Preferably, the rapid solidification smelting step comprises: feeding the proportioned raw materials into a rapid hardening furnace, carrying out vacuum melting under the protection of inert atmosphere, wherein the melting temperature is 1300-1500 ℃, the rotating speed of a copper roller is 1.0-1.5m/s, and casting to obtain a rapid hardening sheet with the thickness of 0.2-0.4 mm.
Preferably, the hydrogen crushing, dehydrogenation treatment and gas milling step comprises: and placing the obtained quick-setting sheet in a hydrogen breaking furnace, filling hydrogen for crushing to obtain coarse crushed powder, performing dehydrogenation heat treatment to ensure that the hydrogen content of the coarse crushed powder is 1400-1800ppm, and then continuously crushing the coarse crushed powder in an airflow mill protected by inert atmosphere, wherein the oxygen content introduced in the airflow mill powder preparation process is 60-80ppm to obtain airflow mill magnetic powder.
Preferably, the coarsely crushed powder has an average particle diameter of 15 μm to 30 μm, and the jet mill magnetic powder has an average particle diameter of 2.0 to 3.5 μm.
Preferably, the dehydrogenation treatment is carried out so that the hydrogen content of the coarse crushed powder is 1600ppm and the oxygen content introduced during the milling of the gas stream is 70 ppm.
Preferably, the isostatic pressing treatment in the step (4) is a pressure maintaining treatment at a pressure of 180-200MPa for 10-40 s.
Preferably, the sintering temperature in the step (5) is 900-1150 ℃, and the sintering time is 1-6 hours.
Preferably, the tempering heat treatment in the step (5) includes: the primary tempering temperature is 750-; the secondary tempering temperature is 350-550 ℃, and the tempering time is 1-4 hours.
Compared with the prior art, the invention has the following beneficial effects:
(1) in the preparation method, in the processes of hydrogen crushing, dehydrogenation treatment and airflow milling powder preparation, the hydrogen content of the coarse crushed powder is 1400-1800ppm through the dehydrogenation treatment, the oxygen content is 60-80ppm through the airflow milling powder preparation process, and the oxidation resistance of the magnet is improved and excellent magnetic performance is presented through the control of the hydrogen content and the oxygen content;
(2) the preparation method further controls the hydrogen content and the oxygen content to be 1600ppm and 70ppm respectively, and the prepared magnet has the best magnetic performance;
(3) the neodymium iron boron magnet is added with Al and V according to the mass ratio (1-2): 1, the performance of the magnet can be obviously improved;
(4) the preparation method of the neodymium iron boron magnet is simple and easy to operate, and the magnet can achieve the anti-oxidation effect without using an antioxidant, so that the magnetic property of the magnet is improved.
Drawings
FIG. 1 is a variation curve of magnet remanence Br under the conditions that the gas flow mill oxygen introduction amount is 50, 60, 70, 80 and 100ppm and the hydrogen content is 800-;
FIG. 2 is a graph showing the change of intrinsic coercivity iHc of a magnet with a hydrogen content of 800-2000ppm at an air flow mill oxygen introduction amount of 50, 60, 70, 80, 100 ppm;
FIG. 3 is a variation curve of maximum magnetic energy (BH) m of a magnet under the conditions that the oxygen introduction amount of the jet mill is 50, 60, 70, 80 and 100ppm and the hydrogen content is 800-2000 ppm;
FIG. 4 is a graph showing changes in magnet squareness SQ at a hydrogen content of 800-.
Detailed Description
The method for preparing the oxidation-resistant sintered ndfeb magnet according to the present invention will be described in detail below, and technical or scientific terms used herein have meanings that are commonly understood by those skilled in the art of the present invention, if not defined otherwise.
The preparation method of the antioxidant sintered neodymium-iron-boron magnet is characterized by comprising the following steps: (1) raw material proportioning, (2) rapid hardening smelting, (3) hydrogen crushing, dehydrogenation treatment and airflow milling, (4) compression molding and isostatic pressing treatment, and (5) sintering and tempering heat treatment;
in the step (3), the dehydrogenation treatment ensures that the hydrogen content of the coarse crushing powder is 1400-1800ppm, and the oxygen content introduced in the powder preparation process of the gas flow mill is 60-80 ppm.
The hydrogen content of the crude crushed powder after dehydrogenation treatment is controlled to be in the range of 1400-1800ppm, and the residual hydrogen in the range plays a role of a reducing agent to reduce the absorption of oxygen in the subsequent preparation process of the magnet; meanwhile, in the powder milling stage of the air flow mill, the oxygen content of the air is controlled to be 60-80ppm so as to ensure the consistency of the oxygen content inside and outside the magnet and keep the improvement and stability of the magnetic performance of the subsequent product. According to the invention, the hydrogen content in the hydrogen pulverizing step and the oxygen content in the powder milling step are simultaneously adjusted, so that the magnet is good in oxidation resistance, and the prepared magnet is excellent in magnetic property.
Weighing each raw material according to the chemical molecular formula of the neodymium iron boron magnet to be prepared, polishing the proportioned raw materials, putting the grinded raw materials into a rapid hardening furnace, vacuumizing the furnace to 0.1-1.0Pa, preheating, and then filling inert atmosphere for protection to smelt, wherein the inert atmosphere is preferably argon and nitrogen, the smelting temperature is preferably 1300-1450 ℃, the rotating speed of a copper roller is kept within the range of 1.0-1.5m/s during smelting, and the average thickness of the rapid hardening piece obtained by the rapid hardening process is within the range of 0.2-0.4 mm.
Cooling the quick-setting tablets for 5-10min, placing the quick-setting tablets in a hydrogen breaking furnace, introducing hydrogen into the hydrogen breaking furnace, filling hydrogen for breaking to obtain coarse broken powder, and then dehydrogenating at 650 ℃ for 3-6h at 500-1800 ℃ to ensure that the hydrogen content of the coarse broken powder is 1400-1800 ppm; and then continuously crushing the coarse crushed powder in a jet mill protected by micro-oxygen inert atmosphere, wherein the oxygen content introduced in the powder preparation process of the jet mill is 60-80ppm, the inert atmosphere is preferably argon and nitrogen, the rotating speed of a sorting wheel is adjusted to 3000-3300r/min, and the jet mill magnetic powder is prepared by mutual collision.
The average particle diameter of the coarsely crushed powder is preferably 15 μm to 30 μm, and the average particle diameter of the jet-milled magnetic powder is 2.0 to 3.5 μm. "average particle size" is defined as the value of the particle size distribution d50 obtained by, for example, dynamic laser light scattering measurements, the methods for determining the particle size distribution described above being well known to those skilled in the art. The smaller the average grain diameter of the jet milling magnetic powder is, the magnetic performance of the prepared magnet is firstly increased and then reduced, the average grain diameter is in the range of 2.0-3.5 mu m, and the prepared magnet has higher magnetic performance.
The invention further controls the hydrogen content of the coarse crushed powder after dehydrogenation treatment to be 1600ppm, and the oxygen content introduced in the powder process of the jet mill to be 70 ppm. When the hydrogen content and the oxygen content were controlled at 1600ppm and 70ppm, respectively, the prepared magnet had the best magnetic properties.
And uniformly mixing the jet mill magnetic powder prepared by the jet mill, putting the mixture into a forming press mold under the protection of nitrogen, adding a 1.5-2.0T magnetic field for orientation, and pressing and forming the blank magnet after orientation. And (3) carrying out isostatic pressing treatment on the blank magnet in an oil press after vacuum packaging, wherein the isostatic pressing treatment is pressure-maintaining treatment for 10-40s under the pressure of 180-200 MPa.
Sintering the blank magnet after isostatic pressing treatment in a vacuum sintering furnace, wherein the sintering process parameters are as follows: the sintering temperature is 900-1150 ℃, and the sintering time is 1-6 hours. Carrying out tempering heat treatment on the obtained sintered magnet, wherein the tempering heat treatment process parameters are as follows: the primary tempering temperature is 750-850 ℃, the tempering time is 1-3 hours, the secondary tempering temperature is 350-550 ℃, and the tempering time is 1-4 hours.
The chemical molecular formula of the antioxidant sintered neodymium-iron-boron magnet prepared by the invention is ReaTmbBcFe1-a-b-cIn terms of mass fraction, a, b and c satisfy the following relations: a is more than or equal to 28 and less than or equal to 33, b is more than or equal to 0 and less than or equal to 5, c is more than or equal to 0.85 and less than or equal to 1.5, wherein Re is a rare earth element Nd or a compound formed by Nd and one or more of Pr, Nd, Dy, Tb, Gd, Ho, La, Ce and Y, and Tm is one or more of Cu, Al, Co, Ga, Nb, Zr and V.
Further, the method can be used for preparing a novel materialPreferably, the chemical formula Re of the neodymium-iron-boron magnet of the present inventionaTmbBcFe1-a-b-cIn terms of mass fraction, a, b and c satisfy the following relations: a is more than or equal to 30 and less than or equal to 32, b is more than or equal to 1.0 and less than or equal to 3.0, c is more than or equal to 0.9 and less than or equal to 1.2, wherein Re is a rare earth element Nd or a compound formed by Nd and one or more of Pr, Nd, Dy, Tb, Gd, Ho, La, Ce and Y, and Tm is one or more of Cu, Al, Co, Ga, Nb, Zr and V.
Further preferably, the chemical formula Re of the neodymium-iron-boron magnet of the present inventionaTmbBcFe1-a-b-cWherein Tm is the mass ratio of Al to V (1-2): 1, and (b) a complex formed. Al and V elements are independently added into the neodymium iron boron magnet, and can replace Fe to improve the oxidation resistance and corrosion resistance of the magnet, thereby being beneficial to the improvement of the intrinsic coercive force of the magnet. The invention combines the two components according to a certain proportion, and the obtained magnet has more excellent intrinsic coercive force.
Hereinafter, the technical solution of the present invention will be further described and illustrated by specific examples and drawings. However, these embodiments are exemplary, and the present disclosure is not limited thereto. Unless otherwise specified, the raw materials used in the following specific examples of the present invention are those commonly used in the art, and the methods used in the examples are those conventional in the art.
Example 1
The 45H oxidation resistant sintered neodymium iron boron magnet with specification D8 × 13 of the present embodiment is obtained by the following preparation method:
according to the formula Pr6Nd24Al1.6V0.8B1.0Fe66.6Weighing the raw materials, polishing the proportioned raw materials, putting the grinded raw materials into a rapid hardening furnace, vacuumizing to 0.3Pa, preheating, introducing argon for protection, and smelting at 1400 ℃, wherein the rotating speed of a copper roller is kept at 1.2m/s during smelting, so that the rapid hardening sheet with the average thickness of 0.3mm is obtained.
Cooling the quick-setting tablet for 8min, placing the quick-setting tablet in a hydrogen breaking furnace, introducing hydrogen into the hydrogen breaking furnace, filling hydrogen for breaking to obtain coarse broken powder with the average particle size of 20 mu m, and then dehydrogenating at 560 ℃ for 5.3h to ensure that the hydrogen content of the coarse broken powder is 800 ppm; then, the coarse crushed powder is continuously crushed in an air flow mill protected by argon gas and provided with the oxygen content of 50ppm, the rotating speed of a sorting wheel is adjusted to 3200r/min, and air flow mill magnetic powder with the average grain diameter of 2.5 mu m is prepared through mutual collision.
And uniformly mixing the jet mill magnetic powder prepared by the jet mill, putting the mixture into a forming press mold under the protection of nitrogen, adding a 1.6T magnetic field for orientation, and pressing and forming the blank magnet after orientation. And (3) carrying out isostatic pressing treatment on the blank magnet in an oil press after vacuum packaging, wherein the isostatic pressing treatment is carried out for 50s under the pressure of 180 MPa.
Sintering the blank magnet after isostatic pressing treatment in a vacuum sintering furnace, wherein the sintering process parameters are as follows: the sintering temperature is 1000 ℃, and the sintering time is 3 hours. Carrying out tempering heat treatment on the obtained sintered magnet, wherein the tempering heat treatment process parameters are as follows: the first-stage tempering temperature is 800 ℃, the tempering time is 2 hours, the second-stage tempering temperature is 450 ℃, and the tempering time is 3 hours.
Example 2-example 25 of the method for manufacturing a 45H oxidation resistant sintered ndfeb magnet, the dehydrogenation time is controlled such that the hydrogen content of the coarsely crushed powder after the dehydrogenation process is shown in table 1, the oxygen content introduced during the powder milling process by the jet mill is shown in table 1, and the other manufacturing steps are the same as those of example 1.
Example 26
The 45H oxidation resistant sintered neodymium iron boron magnet with specification D8 × 13 of the present embodiment is obtained by the following preparation method:
according to the formula Pr6Nd24Al1.6V0.8B1.0Fe66.6Weighing the raw materials, polishing the proportioned raw materials, putting the grinded raw materials into a rapid hardening furnace, vacuumizing to 0.5Pa, preheating, filling argon for protection, and smelting at 1450 ℃ while keeping the rotation speed of a copper roller at 1.5m/s to obtain the rapid hardening sheet with the average thickness of 0.25 mm.
Cooling the quick-setting tablet for 6min, placing the quick-setting tablet in a hydrogen breaking furnace, introducing hydrogen into the hydrogen breaking furnace, filling hydrogen for breaking to obtain coarse broken powder with the average particle size of 22 mu m, and then dehydrogenating at 550 ℃ for 4h to ensure that the hydrogen content of the coarse broken powder is 1600 ppm; then, the coarse crushed powder is continuously crushed in an air flow mill protected by argon gas and provided with the oxygen content of 70ppm, the rotating speed of a sorting wheel is adjusted to 3200r/min, and air flow mill magnetic powder with the average grain diameter of 3.0 mu m is prepared through mutual collision.
And uniformly mixing the jet mill magnetic powder prepared by the jet mill, putting the mixture into a forming press mold under the protection of nitrogen, adding a 1.8T magnetic field for orientation, and pressing and forming the blank magnet after orientation. And (3) carrying out isostatic pressing treatment on the blank magnet in an oil press after vacuum packaging, wherein the isostatic pressing treatment is carried out for 35s under the pressure of 200 MPa.
Sintering the blank magnet after isostatic pressing treatment in a vacuum sintering furnace, wherein the sintering process parameters are as follows: the sintering temperature is 1100 ℃, and the sintering time is 3.5 hours. Carrying out tempering heat treatment on the obtained sintered magnet, wherein the tempering heat treatment process parameters are as follows: the primary tempering temperature is 820 ℃, the tempering time is 2 hours, the secondary tempering temperature is 480 ℃, and the tempering time is 2.5 hours.
Example 27
Example 27 Oxidation resistant sintered Neodymium iron boron magnet molecular formula Pr6Nd24Al2.4B1.0Fe66.6The other preparation method is the same as that of example 14.
Example 28
Example 28 an oxidation resistant sintered NdFeB magnet having the formula Pr6Nd24V2.4B1.0Fe66.6The other preparation method is the same as that of example 14.
Example 29
Example 29 the molecular formula of the oxidation resistant sintered neodymium iron boron magnet is Pr6Nd24Al1.0B1.0Fe68The other preparation method is the same as that of example 14.
Example 30
Example 30 an oxidation resistant sintered NdFeB magnet having the formula Pr6Nd24V1.0B1.0Fe68The other preparation method is the same as that of example 14.
Example 31
Example 31 an oxidation resistant sintered neodymium iron boron magnet having the molecular formula Pr6Nd24Al0.5V0.5B1.0Fe68The other preparation method is the same as that of example 14.
Example 32
Example 32 an oxidation resistant sintered NdFeB magnet having the formula Pr6Nd24Al3.0B1.0Fe66The other preparation method is the same as that of example 14.
Example 33
Example 33 Oxidation resistant sintered Neodymium iron boron magnet formula Pr6Nd24V3.0B1.0Fe66The other preparation method is the same as that of example 14.
Example 34
Example 34 the molecular formula of the oxidation resistant sintered neodymium iron boron magnet is Pr6Nd24Al1.8V1.2B1.0Fe66The other preparation method is the same as that of example 14.
The magnetic properties of the ndfeb magnets of examples 1-34 were measured and the results are shown in table 1.
TABLE 1 magnetic Performance data for the Neodymium iron boron magnets of examples 1-34
As can be seen from table 1, changes in the hydrogen content and the amount of aeration in the jet mill of the coarsely crushed powder during the magnet production process significantly changed the magnet properties. In order to more intuitively show that the performance of the magnet changes along with the changes of the mill oxygen flow and the hydrogen content, a magnetic performance change curve is drawn, as shown in fig. 1-4, wherein fig. 1 is a magnet remanence Br change curve under the mill oxygen flow of 50, 60, 70, 80 and 100ppm and the hydrogen content of 800-2000 ppm; FIG. 2 is a graph showing the change of intrinsic coercivity iHc of a magnet with a hydrogen content of 800-2000ppm at an air flow mill oxygen introduction amount of 50, 60, 70, 80, 100 ppm; FIG. 3 is a variation curve of maximum magnetic energy (BH) m of a magnet under the conditions that the oxygen introduction amount of the jet mill is 50, 60, 70, 80 and 100ppm and the hydrogen content is 800-2000 ppm; FIG. 4 is a graph showing changes in magnet squareness SQ at a hydrogen content of 800-. As can be seen from fig. 1 to 4, the magnet had different rules of Br, iHc, (BH) m and squareness according to the hydrogen content at different gas-flow mill oxygen passing amounts, but Br, iHc, (BH) m and squareness of the magnet showed the maximum at a crude crushed powder hydrogen content of 1600ppm and a gas-flow mill oxygen passing amount of 70 ppm.
From the experimental data of examples 27-34, it can be seen that: by changing the magnet composition, the performance of the magnet can be improved, and when the magnet composition includes both Al and V, the intrinsic coercive force of the magnet is significantly larger than that of a magnet including only Al and V alone. This is probably because the simultaneous presence of Al and V produces a mutual reinforcing effect, giving the magnet better magnetic properties.
The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.
Claims (10)
1. The preparation method of the antioxidant sintered neodymium-iron-boron magnet is characterized by comprising the following steps: (1) raw material proportioning, (2) rapid hardening smelting, (3) hydrogen crushing, dehydrogenation treatment and airflow milling, (4) compression molding and isostatic pressing treatment, and (5) sintering and tempering heat treatment;
in the step (3), the dehydrogenation treatment ensures that the hydrogen content of the coarse crushing powder is 1400-1800ppm, and the oxygen content introduced in the powder preparation process of the gas flow mill is 60-80 ppm.
2. The method of claim 1, wherein the ndfeb magnet has a chemical formula of ReaTmbBcFe1-a-b-cIn terms of mass fraction, a, b and c satisfy the following relations: a is more than or equal to 28 and less than or equal to 33, b is more than or equal to 0 and less than or equal to 5, c is more than or equal to 0.85 and less than or equal to 1.5, wherein Re is a rare earth elementNd or a compound formed by Nd and one or more of Pr, Nd, Dy, Tb, Gd, Ho, La, Ce and Y, wherein Tm is one or more of Cu, Al, Co, Ga, Nb, Zr and V.
3. The method of claim 1 or 2, wherein the ndfeb magnet has a chemical formula of ReaTmbBcFe1-a-b-cIn terms of mass fraction, a, b and c satisfy the following relations: a is more than or equal to 30 and less than or equal to 32, b is more than or equal to 1.0 and less than or equal to 3.0, c is more than or equal to 0.9 and less than or equal to 1.2, wherein Re is a rare earth element Nd or a compound formed by Nd and one or more of Pr, Nd, Dy, Tb, Gd, Ho, La, Ce and Y, and Tm is the mass ratio of Al to V (1-2): 1, and (b) a complex formed.
4. The method of claim 1, wherein the rapid solidification smelting step comprises: feeding the proportioned raw materials into a rapid hardening furnace, carrying out vacuum melting under the protection of inert atmosphere, wherein the melting temperature is 1300-1500 ℃, the rotating speed of a copper roller is 1.0-1.5m/s, and casting to obtain a rapid hardening sheet with the thickness of 0.2-0.4 mm.
5. The method of claim 1, wherein the hydrogen crushing, dehydrogenation treatment and gas milling steps comprise: and placing the obtained quick-setting sheet in a hydrogen breaking furnace, filling hydrogen for crushing to obtain coarse crushed powder, performing dehydrogenation heat treatment to ensure that the hydrogen content of the coarse crushed powder is 1400-1800ppm, and then continuously crushing the coarse crushed powder in an airflow mill protected by inert atmosphere, wherein the oxygen content introduced in the airflow mill powder preparation process is 60-80ppm to obtain airflow mill magnetic powder.
6. The production method according to claim 5, wherein the coarsely pulverized powder has an average particle diameter of 15 μm to 30 μm, and the jet-milled magnetic powder has an average particle diameter of 2.0 to 3.5 μm.
7. The production method according to claim 1 or 5, wherein the dehydrogenation treatment is carried out so that the hydrogen content of the coarsely crushed powder is 1600ppm and the oxygen content introduced during the pulverization by the jet mill is 70 ppm.
8. The preparation method according to claim 1, wherein the isostatic pressing treatment of step (4) is a pressure-holding treatment at a pressure of 180 and 200MPa for 10-40 s.
9. The method as set forth in claim 1, wherein the sintering temperature in step (5) is 900-1150 ℃ and the sintering time is 1-6 hours.
10. The production method according to claim 1, wherein the tempering heat treatment in the step (5) includes: the primary tempering temperature is 750-; the secondary tempering temperature is 350-550 ℃, and the tempering time is 1-4 hours.
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| CN114101687A (en) * | 2021-12-07 | 2022-03-01 | 鞍山安特磁材有限公司 | Novel pressure-resistant magnetic powder |
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