CN114141522B - Method for improving coercivity of sintered NdFeB magnet and application - Google Patents
Method for improving coercivity of sintered NdFeB magnet and application Download PDFInfo
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- 229910001172 neodymium magnet Inorganic materials 0.000 title claims abstract description 67
- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000009792 diffusion process Methods 0.000 claims abstract description 55
- 238000001755 magnetron sputter deposition Methods 0.000 claims abstract description 16
- 238000005554 pickling Methods 0.000 claims abstract description 16
- 239000011261 inert gas Substances 0.000 claims abstract description 13
- 239000011265 semifinished product Substances 0.000 claims abstract description 13
- 238000007747 plating Methods 0.000 claims abstract description 7
- 239000012298 atmosphere Substances 0.000 claims abstract description 6
- 238000001816 cooling Methods 0.000 claims abstract description 6
- 230000006872 improvement Effects 0.000 claims abstract description 3
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 40
- 150000002910 rare earth metals Chemical class 0.000 claims description 40
- 229910052751 metal Inorganic materials 0.000 claims description 39
- 239000002184 metal Substances 0.000 claims description 39
- 229910052782 aluminium Inorganic materials 0.000 claims description 19
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 19
- 239000002253 acid Substances 0.000 claims description 17
- 238000010438 heat treatment Methods 0.000 claims description 16
- 238000004321 preservation Methods 0.000 claims description 12
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 10
- KBQHZAAAGSGFKK-UHFFFAOYSA-N dysprosium atom Chemical compound [Dy] KBQHZAAAGSGFKK-UHFFFAOYSA-N 0.000 claims description 8
- 229910052692 Dysprosium Inorganic materials 0.000 claims description 7
- 239000007789 gas Substances 0.000 claims description 7
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 6
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 5
- 229910052771 Terbium Inorganic materials 0.000 claims description 5
- 238000007599 discharging Methods 0.000 claims description 5
- 229910017604 nitric acid Inorganic materials 0.000 claims description 5
- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 claims description 5
- 239000001307 helium Substances 0.000 claims description 4
- 229910052734 helium Inorganic materials 0.000 claims description 4
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 4
- 229910052786 argon Inorganic materials 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 238000005265 energy consumption Methods 0.000 abstract description 4
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 239000010410 layer Substances 0.000 description 51
- 230000000052 comparative effect Effects 0.000 description 33
- 238000005324 grain boundary diffusion Methods 0.000 description 7
- 238000005406 washing Methods 0.000 description 7
- 238000002844 melting Methods 0.000 description 6
- 230000008018 melting Effects 0.000 description 6
- 229910045601 alloy Inorganic materials 0.000 description 5
- 239000000956 alloy Substances 0.000 description 5
- 239000012300 argon atmosphere Substances 0.000 description 4
- 238000000151 deposition Methods 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 229910000838 Al alloy Inorganic materials 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 239000000696 magnetic material Substances 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 230000003321 amplification Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000010998 test method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052729 chemical element Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000005389 magnetism Effects 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
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002344 surface layer Substances 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
-
- 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
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Hard Magnetic Materials (AREA)
- Manufacturing Cores, Coils, And Magnets (AREA)
Abstract
The invention discloses a method for improving coercive force of a sintered NdFeB magnet and application thereof, wherein the method mainly comprises the following steps: and (3) sequentially performing magnetron sputtering plating on the surface of the sintered neodymium-iron-boron magnet subjected to ultrasonic pickling from inside to outside to obtain a semi-finished product, and then placing the semi-finished product in an inert gas atmosphere for high-temperature diffusion treatment and cooling to obtain the high-coercivity sintered neodymium-iron-boron magnet. Compared with the traditional magnetron sputtering diffusion method, the method can reduce the diffusion temperature or shorten the diffusion time on the premise of ensuring the improvement of the coercive force of the sintered NdFeB magnet, thereby reducing the energy consumption and improving the production efficiency.
Description
Technical Field
The invention belongs to the field of rare earth permanent magnet materials, in particular relates to a method for improving the coercivity of a sintered NdFeB magnet, and also relates to application of the method, in particular to a high coercivity sintered NdFeB magnet prepared by the method.
Background
The sintered NdFeB magnet is the magnetic material with the strongest magnetism so far, is widely applied to the fields of aerospace, automobile industry, electronic and electric appliances, medical appliances, energy-saving motors, new energy, wind power generation and the like, and is the permanent magnet material with the fastest development and the best market prospect in the world. The sintered NdFeB magnet has the outstanding advantages of high magnetic energy product, high coercivity, high energy density, high cost performance, good mechanical properties and the like, and plays an important role in the high and new technical field. Through research and development for more than 30 years, reasonable alloy components and a mature preparation process are designed, so that the remanence and the maximum magnetic energy product of the sintered NdFeB magnet reach more than 90% of theoretical values, however, the coercive force of the sintered NdFeB magnet is less than 30% of the theoretical values, and how to improve the coercive force of the sintered NdFeB magnet becomes an important problem in the magnetic material industry.
The current common method for preparing the high coercivity sintered NdFeB magnet is to add heavy rare earth elements Dy and/or Tb, and mainly comprises three modes: (1) directly adding Dy and/or Tb metal during alloy smelting; (2) Adding Dy and/or Tb-containing powder into the powder by means of double alloy; (3) Dy and/or Tb are diffused into the sintered NdFeB magnet through the inter-crystal rare earth-rich phase. Among the three modes, the sintered NdFeB magnet containing Dy and/or Tb is prepared by a grain boundary diffusion mode, has higher comprehensive magnetic performance, only consumes a small amount of Dy and/or Tb, and is one mode which is widely popularized currently.
At present, a heavy rare earth metal film layer is deposited on the surface of a magnet by utilizing a magnetron sputtering mode, and then diffusion heat treatment is one of the currently widely applied magnet grain boundary diffusion modes. However, the current method for directly magnetron sputtering to deposit a heavy rare earth metal film layer for grain boundary diffusion also has certain defects, mainly expressed in that:
(1) In order to prevent heavy rare earth metal film deposited on the surface of the magnet from falling off or oxidizing or being polluted, the magnet needs to be cleaned before magnetron sputtering coating, oil stains and oxide layers on the surface of the magnet are washed off, the common cleaning mode is ultrasonic pickling, and due to the special microstructure of the sintered neodymium-iron-boron magnet, the grain boundary rare earth-rich phase exposed on the surface of the magnet in the ultrasonic pickling process also reacts with acid liquor to fall off, so that 'ravines' with a certain depth are formed, and the 'ravines' have the characteristics of narrow width (usually in nano-scale, below 20 nm) and deep depth (usually in micron-scale, above 2 mu m). In the subsequent process of depositing the heavy rare earth metal film layer by magnetron sputtering, the heavy rare earth metal atoms are difficult to completely fill the 'ravines', and the 'ravines' directly separate the grain boundary phases of the heavy rare earth metal film layer and the inside of the magnet, so that the direct grain boundary diffusion of the heavy rare earth metal atoms becomes difficult, and the time required for diffusion is long.
(2) In addition, more than 95% of the area on the surface of the sintered NdFeB magnet is taken as main phase grains, so that more than 95% of heavy rare earth metal film layers are deposited on the main phase grains, and the heavy rare earth metals deposited on the surface layer of the main phase grains can react with the main phase grains to generate heavy rare earth metal-iron alloy to fill 'gully', then diffuse into the magnet along the grain boundary phase, and the temperature required by diffusion is higher because the melting point of the heavy rare earth metals is higher and the reaction temperature of the heavy rare earth metals and the main phase grains is higher.
Disclosure of Invention
In view of this, the present invention is needed to provide a method for improving the coercivity of sintered neodymium-iron-boron magnet, which comprises the steps of depositing a layer of metal aluminum film on the surface of the magnet in advance, then depositing a heavy rare earth metal film by magnetron sputtering, performing high-temperature diffusion treatment, and using the characteristics of low melting point of metal aluminum and low melting point alloy formed by the heavy rare earth metal, filling the molten metal aluminum and heavy rare earth metal-aluminum alloy with 'ravines' generated during acid washing, promoting the diffusion movement of heavy rare earth metal atoms from the surface of the magnet to the grain boundary phase, improving the coercivity of the magnet, reducing the diffusion treatment temperature, shortening the diffusion treatment time, and overcoming the defect that the current magnetron sputtering is used for the grain boundary diffusion of sintered neodymium-iron-boron magnet.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the invention provides a method for improving coercive force of a sintered NdFeB magnet, which comprises the following steps:
ultrasonic pickling of the untreated sintered NdFeB magnet to obtain a magnet to be treated;
Plating a metal film layer on the surface of the magnet to be treated by magnetron sputtering, and discharging when the temperature of the metal film layer is reduced to below 70 ℃ to obtain a semi-finished product, wherein the metal film layer is sequentially a metal aluminum film layer and a heavy rare earth metal film layer from inside to outside;
and (3) placing the semi-finished product in an inert gas atmosphere for high-temperature diffusion treatment, and cooling to obtain the high-coercivity sintered NdFeB magnet.
Further, the untreated sintered neodymium-iron-boron magnet is a magnet taking RE 2Fe14 B phase as a main magnetic phase, wherein RE is at least one of rare earth elements.
Further, the acid liquid adopted by the ultrasonic pickling is mixed acid, and the mixed acid is formed by mixing 4-10wt% of hydrochloric acid and 4-10wt% of nitric acid.
Further, the metal film layer is plated on any one or more surfaces of the untreated sintered NdFeB magnet.
Further, the thickness of the metal aluminum film layer is 0.5-2 mu m, and the thickness of the heavy rare earth metal film layer is 1-15 mu m.
Further, in the heavy rare earth metal film layer, the heavy rare earth metal element is selected from at least one of dysprosium and terbium.
Further, the inert gas is selected from argon or helium, the air pressure is 0.05-0.3MPa, and the gas purity is more than 99.999%;
the high-temperature diffusion treatment temperature is 750-850 ℃, and the heat preservation time is 5-40h.
Further, after the high-temperature diffusion treatment, the method further comprises a step of heat treatment.
Further scheme, the temperature of the heat treatment is 460-600 ℃ and the time is 3-6h.
The invention further provides a high-coercivity sintered NdFeB magnet which is obtained by adopting the improvement method according to any one of the above steps, and the coercivity of the high-coercivity sintered NdFeB magnet is improved by 4kOe-12kOe compared with that of the untreated sintered NdFeB magnet.
Compared with the prior art, the invention has the following beneficial effects:
A layer of metal aluminum film is deposited on the surface of a sintered NdFeB magnet in advance, then a heavy rare earth metal film is deposited by magnetron sputtering, then high-temperature diffusion treatment is carried out in an inert gas environment, the characteristics that the melting point of metal aluminum is low and low-melting-point alloy can be formed with the heavy rare earth metal are utilized, under the action of external inert gas pressure, the fused metal aluminum and the heavy rare earth metal-aluminum alloy are used for filling grain boundary gaps generated during acid washing, the diffusion movement of heavy rare earth metal atoms from the surface of the magnet to a grain boundary phase is promoted, the coercive force of the magnet is improved, meanwhile, the diffusion heat treatment temperature is reduced, the diffusion heat treatment time is shortened, and the defect that the current magnetron sputtering is used for the grain boundary diffusion of the sintered NdFeB magnet is overcome.
Detailed Description
In order that the invention may be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments that are illustrated below. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
The invention provides a method for improving coercive force of a sintered NdFeB magnet, which comprises the following steps:
ultrasonic pickling of the untreated sintered NdFeB magnet to obtain a magnet to be treated;
Plating a metal film layer on the surface of the magnet to be treated by magnetron sputtering, and discharging when the temperature of the metal film layer is reduced to below 70 ℃ to obtain a semi-finished product, wherein the metal film layer is sequentially a metal aluminum film layer and a heavy rare earth metal film layer from inside to outside;
and (3) placing the semi-finished product in an inert gas atmosphere for high-temperature diffusion treatment, and cooling to obtain the high-coercivity sintered NdFeB magnet.
According to the invention, the metal aluminum film layer is firstly deposited on the surface of the sintered neodymium-iron-boron magnet, then the heavy rare earth metal layer is formed by magnetron sputtering deposition, and the characteristic that the metal aluminum has a low melting point and can form a low melting point heavy rare earth-aluminum alloy with the heavy rare earth metal layer is utilized to fill the 'gully' generated during acid washing of the sintered neodymium-iron-boron magnet, so that the diffusion movement of heavy rare earth metal atoms from the surface of the magnet to a grain boundary phase is promoted, the coercive force of the sintered neodymium-iron-boron magnet is improved, the diffusion heat treatment temperature is reduced, and the diffusion heat treatment time is shortened.
In the coercivity improving method, the ultrasonic pickling is not particularly limited, and can be a pickling step conventional in the art, and acid liquor conventional in the art is adopted, so that oil stains and oxide layers on the surface of an untreated sintered NdFeB magnet are washed away; the mixed acid is formed by mixing 4-10wt% of hydrochloric acid and 4-10wt% of nitric acid. It will be appreciated that ultrasonic pickling is followed by a water wash step, which is conventional in the art and will not be described in detail, in one or more embodiments of the invention, ultrasonic pickling is followed by two ultrasonic water washes.
The untreated sintered neodymium-iron-boron magnet refers to a magnet taking RE 2Fe14 B phase as a main magnetic phase, wherein RE is at least one of rare earth elements, and the rare earth elements can be neodymium (Nd), dysprosium (Dy), praseodymium (Pr) and the like, and are not particularly limited; the preparation of the untreated sintered neodymium-iron-boron magnet is not particularly limited and may be performed using a preparation process conventional in the art, and in one or more embodiments of the present invention, the untreated sintered neodymium-iron-boron magnet is prepared by a powder metallurgy process. Further, the plating surface of the metal film layer on the untreated sintered nd-fe-b magnet is not particularly limited, and may be any surface, or may be any surface such as two surfaces, three surfaces, four surfaces, or the like, and may be selected according to the shape and diffusion requirements of the untreated sintered nd-fe-b magnet. Further, the thickness of the heavy rare earth metal film layer can be adjusted according to the requirement of the diffusion amount, and in general, the thickness of the metal aluminum film layer is controlled to be more than 0.5 μm and preferably less than half of the thickness of the heavy rare earth metal film layer, preferably, in one or more embodiments of the present invention, the thickness of the metal aluminum film layer is 0.5-2 μm, and the thickness of the heavy rare earth metal film layer is 1-15 μm.
Further, in the heavy rare earth metal film layer according to the present invention, heavy rare earth metal elements commonly used in the art for grain boundary diffusion of permanent magnetic materials may be used, and specific examples include, but are not limited to, at least one of dysprosium and terbium.
Further, the discharged semi-finished product is placed in an inert gas atmosphere for high-temperature diffusion treatment, wherein the inert gas refers to a gas simple substance corresponding to all 0 groups of elements on a chemical element periodic table, and in one or more embodiments of the invention, the inert gas adopts common argon or helium, the air pressure is 0.05-0.3MPa, the gas purity is more than 99.999%, and because unfilled gaps on the surface of a magnet are in a vacuum state due to acid washing treatment, the film on the surface of the magnet is melted at high temperature, and the external gas pressure provides power for filling the gaps on the melted film, so that the melted film can fill the gaps, the connection between the film and a grain boundary phase is established, and the film is promoted to diffuse towards the inside of the magnet along the grain boundary phase, so that the advantage is obvious compared with the traditional vacuum diffusion treatment; the introduction of impurity gas can be avoided by adopting high-purity inert gas, so that the impurity gas is prevented from reacting with the film layer, and the property of the film layer is changed;
in one or more embodiments of the invention, the high temperature diffusion treatment is performed at a temperature of 750 ℃ to 850 ℃ for a holding time of 5 to 40 hours.
Further, after the high-temperature diffusion treatment, the method further comprises a heat treatment step, wherein the purpose is to further optimize the internal structure of the grain boundary phase and improve the coercive force of the magnet, the temperature can be adopted as usual in the art, the heat preservation time can be adjusted according to requirements, and in one or more embodiments of the invention, the heat treatment temperature is 460-600 ℃ and the time is 3-6h.
In a second aspect, the present invention provides a high coercivity sintered neodymium-iron-boron magnet obtained by the method according to any one of the first aspects of the present invention, the coercivity of the high coercivity sintered neodymium-iron-boron magnet being increased by 4-12 kOe compared to the untreated sintered neodymium-iron-boron magnet.
The technical scheme of the present invention will be further described with reference to specific examples and comparative examples.
Example 1
Carrying out ultrasonic pickling treatment and 2 times of ultrasonic washing on a processed magnet I 1 (with the name of N50 and the main component of Nd 30.5Fe68.5B1 and weight percent) with the specification of 40mm multiplied by 30mm multiplied by 3mm in sequence to wash away greasy dirt and oxide layers on the surface of the magnet, and obtaining a magnet II 1, wherein the acid liquor used for ultrasonic pickling is mixed acid of 4% hydrochloric acid and 6% nitric acid;
Sequentially plating the surfaces of two 40mm multiplied by 30mm of the magnet II 1 from inside to outside by using magnetron sputtering coating equipment to form a metal aluminum film layer with the thickness of 0.5 mu m and a metal dysprosium film layer with the thickness of 5 mu m, and discharging when the temperature of the film layer is reduced to below 70 ℃ to obtain a semi-finished product III 1;
Placing the semi-finished product III 1 in an argon atmosphere (the air pressure is 0.1MPa, the purity is more than 99.999%) for high-temperature diffusion treatment, and then cooling to below 100 ℃, wherein the heat preservation temperature of the high-temperature diffusion treatment is 800 ℃ and the time is 10 hours;
And carrying out heat treatment on the magnet subjected to high-temperature diffusion treatment at 500 ℃ for 3 hours to obtain the high-coercivity sintered NdFeB magnet IV 1.
Comparative example 1
The present comparative example uses the same embodiment as in example 1, except that: the high-temperature diffusion treatment is carried out in a vacuum environment with the vacuum degree being better than 1X 10 -2 Pa; and obtaining the high-coercivity sintered NdFeB magnet IV 2.
Comparative example 2
The present comparative example uses the same embodiment as in example 1, except that: the metal film layer is a single dysprosium metal film layer with the thickness of 5 mu m; and obtaining the high-coercivity sintered NdFeB magnet IV 3.
Comparative example 3
The present comparative example uses the same embodiment as in example 1, except that: the high-temperature diffusion treatment is carried out in a vacuum environment with the vacuum degree being better than 1X 10 -2 Pa, the heat preservation temperature is 900 ℃ and the time is 10 hours; and obtaining the high-coercivity sintered NdFeB magnet IV 4.
Comparative example 4
The present comparative example uses the same embodiment as in example 1, except that: the high-temperature diffusion treatment is carried out in a vacuum environment with the vacuum degree being better than 1 multiplied by 10 -2 Pa, the heat preservation temperature is 800 ℃ and the time is 20h; and obtaining the high-coercivity sintered NdFeB magnet IV 5.
The coercivity of example 1 and comparative examples 1-4 were compared using a magnetic property tester at room temperature (23.+ -. 1 ℃ C.) as required by GB/T3217-2013 permanent magnet (hard magnet) material-magnetic test method, and the results are shown in Table 1.
TABLE 1 coercivity contrast for example 1 and comparative examples 1-4
| Sample number | Coercivity before treatment | Coercivity after treatment | Coercivity amplification |
| Example 1 | 12.8kOe | 18.3kOe | 5.5kOe |
| Comparative example 1 | 12.8kOe | 17.2kOe | 4.4kOe |
| Comparative example 2 | 12.8kOe | 17.4kOe | 4.6kOe |
| Comparative example 3 | 12.8kOe | 18.2kOe | 5.4kOe |
| Comparative example 4 | 12.8kOe | 18.4kOe | 5.6kOe |
As can be seen from the test results in table 1, the coercivity is improved by a higher extent than in comparative examples 1 and 2 using the technical scheme of example 1 herein; in example 1, compared with comparative examples 3 to 4, although the coercive force is improved by a similar extent, the technical scheme of example 1 reduces the diffusion heat treatment temperature, shortens the diffusion heat treatment time, reduces the energy consumption and improves the production efficiency.
Example 2
Sequentially carrying out ultrasonic pickling treatment on a processed magnet I 6 (with the mark of 50M and the main component of Nd 30Dy1Fe68B1 and weight percent) with the specification of 35mm multiplied by 30mm multiplied by 3mm, and then carrying out ultrasonic washing for 2 times to wash away greasy dirt and an oxidation layer on the surface of the magnet to obtain a magnet II 6, wherein the acid liquor adopted by the ultrasonic pickling is mixed acid of 6% hydrochloric acid and 8% nitric acid;
Sequentially plating a metal aluminum film layer with the thickness of 1 mu m and a metal terbium film layer with the thickness of 10 mu m on the surface of 35mm multiplied by 30mm of a magnet II 6 from inside to outside by using magnetron sputtering coating equipment, and discharging when the temperature of the film layer is reduced to below 70 ℃ to prepare a semi-finished product III 6;
And placing the semi-finished product III 6 in helium atmosphere (the air pressure is 0.2MPa, the purity is more than 99.999%) for high-temperature diffusion treatment, and then cooling to below 100 ℃ to obtain the sintered neodymium-iron-boron magnet IV 6 with improved coercivity, wherein the heat preservation temperature of the high-temperature diffusion treatment is 850 ℃ and the time is 15h.
Comparative example 5
The present comparative example uses the same embodiment as in example 4, except that: the high-temperature diffusion treatment is carried out in a vacuum environment with the vacuum degree being better than 1X 10 -2 Pa; and obtaining the sintered NdFeB magnet IV 7 with high coercivity.
Comparative example 6
The present comparative example uses the same embodiment as in example 4, except that: the metal film layer is a single terbium metal film layer with the thickness of 10 mu m; and obtaining the high-coercivity sintered NdFeB magnet IV 8.
Comparative example 7
The present comparative example uses the same embodiment as in example 4, except that: the high-temperature diffusion treatment is carried out in a vacuum environment with the vacuum degree being better than 1 multiplied by 10 -2 Pa, the heat preservation temperature is 900 ℃ and the time is 15h; and obtaining the high-coercivity sintered NdFeB magnet IV 9.
Comparative example 8
The present comparative example uses the same embodiment as in example 4, except that: the high-temperature diffusion treatment is carried out in a vacuum environment with the vacuum degree being better than 1 multiplied by 10 -2 Pa, the heat preservation temperature is 850 ℃ and the time is 25 hours; and obtaining the high-coercivity sintered NdFeB magnet IV 10.
The coercivity of example 2 and comparative examples 5-8 were compared using a magnetic property tester at room temperature (23.+ -. 1 ℃ C.) as required by GB/T3217-2013 permanent magnet (hard magnet) material-magnetic test method, and the results are shown in Table 2.
TABLE 2 coercivity contrast for example 2 and comparative examples 5-8
| Sample number | Coercivity before treatment | Coercivity after treatment | Coercivity amplification |
| Example 2 | 15.4kOe | 23.7kOe | 8.3kOe |
| Comparative example 5 | 15.4kOe | 22.2kOe | 6.8kOe |
| Comparative example 6 | 15.4kOe | 22.4kOe | 7.0kOe |
| Comparative example 7 | 15.4kOe | 23.9kOe | 8.5kOe |
| Comparative example 8 | 15.4kOe | 23.7kOe | 8.3kOe |
As can be seen from the test results in table 2, the coercivity is improved by a higher extent than in comparative examples 5 and 6 using the technical scheme of example 2 herein; in example 2, compared with comparative examples 7 to 8, although the coercive force is improved by a similar extent, the technical scheme of example 2 reduces the diffusion heat treatment temperature, shortens the diffusion heat treatment time, reduces the energy consumption and improves the production efficiency.
Other parallel embodiments
Example 3
This example uses the same implementation as example 1, except that: the thickness of the metal aluminum film layer is 2 mu m, and the thickness of the metal dysprosium film layer is 15 mu m.
Example 4
This example uses the same implementation as example 3, except that: in the high-temperature diffusion treatment, an argon atmosphere (the air pressure is 0.3MPa, the purity is more than 99.999%) is adopted, and the heat preservation temperature of the high-temperature diffusion treatment is 850 ℃ and the time is 7 hours.
Example 5
This example uses the same implementation as example 1, except that: in the high-temperature diffusion treatment, an argon atmosphere (the air pressure is 0.05MPa, the purity is more than 99.999 percent), and the heat preservation temperature of the high-temperature diffusion treatment is 750 ℃ and the time is 40 hours.
Example 6
This example uses the same implementation as example 1, except that: the thickness of the metal aluminum film layer is 0.5 mu m, and the thickness of the metal dysprosium film layer is 1 mu m; in the high-temperature diffusion treatment, an argon atmosphere (the air pressure is 0.05MPa, the purity is more than 99.999%) is adopted, and the heat preservation temperature of the high-temperature diffusion treatment is 750 ℃ and the time is 5 hours.
The schemes in examples 3 to 6 are tested in the same test mode as in examples 1 to 2, and the coercivity is improved by 4kOe to 12kOe, and compared with the diffusion process, the method shortens the high-temperature diffusion time, reduces the diffusion temperature and can obviously reduce the energy consumption under the condition that the coercivity is improved by close.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (9)
1. The method for improving the coercive force of the sintered NdFeB magnet is characterized by comprising the following steps of:
ultrasonic pickling of the untreated sintered NdFeB magnet to obtain a magnet to be treated;
Plating a metal film layer on the surface of the magnet to be treated by magnetron sputtering, and discharging when the temperature of the metal film layer is reduced to below 70 ℃ to obtain a semi-finished product, wherein the metal film layer is sequentially provided with a metal aluminum film layer and a heavy rare earth metal film layer from inside to outside, the thickness of the metal aluminum film layer is 0.5-2 mu m, and the thickness of the heavy rare earth metal film layer is 1-15 mu m;
Placing the semi-finished product in an inert gas atmosphere for high-temperature diffusion treatment, and cooling to obtain a high-coercivity sintered NdFeB magnet;
Wherein the air pressure of the inert gas is 0.05-0.3MPa; the high-temperature diffusion treatment temperature is 750-850 ℃, and the heat preservation time is 5-40h.
2. The method of claim 1, wherein the untreated sintered neodymium-iron-boron magnet is a magnet having an RE 2Fe14 B phase as a main magnetic phase, wherein RE is at least one of rare earth elements.
3. The method for improving the coercivity of a sintered NdFeB magnet according to claim 1, wherein the acid solution used for ultrasonic pickling is a mixed acid, and the mixed acid is formed by mixing 4-10wt% of hydrochloric acid and 4-10wt% of nitric acid.
4. A method of increasing the coercivity of a sintered neodymium-iron-boron magnet according to claim 1, in which the metal film layer is plated on any one or more surfaces of the untreated sintered neodymium-iron-boron magnet.
5. The method for improving coercivity of a sintered neodymium-iron-boron magnet according to claim 1, wherein the heavy rare earth metal element is at least one selected from dysprosium and terbium in the heavy rare earth metal film layer.
6. A method of increasing the coercivity of a sintered neodymium-iron-boron magnet according to claim 1 in which the inert gas is selected from argon or helium with a gas purity of > 99.999%.
7. The method for improving the coercivity of a sintered NdFeB magnet according to claim 1, further comprising a step of heat treatment after the high-temperature diffusion treatment.
8. The method for improving coercivity of a sintered NdFeB magnet according to claim 7, in which the heat treatment is carried out at a temperature of 460 to 600 ℃ for 3 to 6 hours.
9. A high coercivity sintered neodymium-iron-boron magnet obtained by the improvement method according to any one of claims 1 to 8, wherein the coercivity of the high coercivity sintered neodymium-iron-boron magnet is improved by 4kOe to 12kOe compared to the untreated sintered neodymium-iron-boron magnet.
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| KR101624245B1 (en) * | 2015-01-09 | 2016-05-26 | 현대자동차주식회사 | Rare Earth Permanent Magnet and Method Thereof |
| CN111292951A (en) * | 2020-02-28 | 2020-06-16 | 安徽大地熊新材料股份有限公司 | Method for improving coercive force of sintered neodymium-iron-boron magnet |
| CN111383833A (en) * | 2019-11-11 | 2020-07-07 | 浙江东阳东磁稀土有限公司 | Grain boundary diffusion method for rare earth neodymium iron boron magnet |
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| KR101624245B1 (en) * | 2015-01-09 | 2016-05-26 | 현대자동차주식회사 | Rare Earth Permanent Magnet and Method Thereof |
| CN111383833A (en) * | 2019-11-11 | 2020-07-07 | 浙江东阳东磁稀土有限公司 | Grain boundary diffusion method for rare earth neodymium iron boron magnet |
| CN111292951A (en) * | 2020-02-28 | 2020-06-16 | 安徽大地熊新材料股份有限公司 | Method for improving coercive force of sintered neodymium-iron-boron magnet |
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