CN111403164A - Method for improving sintered neodymium iron boron magnet coercive force through metal infiltration by powder packaging method - Google Patents
Method for improving sintered neodymium iron boron magnet coercive force through metal infiltration by powder packaging method Download PDFInfo
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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
- H01F41/026—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 protecting methods against environmental influences, e.g. oxygen, by surface treatment
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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
Abstract
The invention belongs to the technical field of rare earth permanent magnet materials, and particularly relates to a method for improving the coercive force of a sintered neodymium-iron-boron magnet through metal infiltration by a powder packaging method. By adopting a powder packaging diffusion infiltration technology, Dy, Te and other metals are infiltrated on the surface (including matrix grains and intercrystalline phases) of the sintered NdFeB magnet, and the method is used for processing, so that the coercive force of the magnet can be obviously improved, and the magnetic properties (such as residual magnetism and maximum magnetic energy product) of the magnet in other aspects are not obviously reduced. The treatment method is particularly suitable for magnets (such as sheets, plates or small-diameter round bars) with small one-dimensional linearity, has simple equipment, stable process and high efficiency, and can be used for batch treatment; the treatment method mainly adopts metal oxide powder and dysprosium iron (or terbium iron and the like) powder as the penetrant, can be repeatedly utilized, has low overall cost and has obvious advantages in industrial application.
Description
Technical Field
The invention belongs to the technical field of rare earth permanent magnet materials, and particularly relates to a method for improving the coercive force of a sintered neodymium-iron-boron magnet through metal infiltration by a powder packaging method.
Background
The NdFeB permanent magnet is a third-generation rare earth permanent magnet following the Sm-Co permanent magnet, and due to the excellent magnetic property and abundant neodymium resources in China, the NdFeB permanent magnet is rapidly developed in research, development and production. In particular, sintered nd-fe-b magnets are widely used due to their excellent overall magnetic properties. With the accelerated development of science and technology and low-carbon economy, the popularization speed and the application range of the sintered neodymium-iron-boron material in high-end fields such as wind power, variable frequency compressors, hybrid power and the like are rapidly expanded. These fields require sintered ndfeb magnets to have both a high remanence to provide sufficient magnetic energy storage and a high enough coercivity to ensure their proper operation at high temperatures.
At present, the coercivity of sintered neodymium iron boron is relatively low, which limits further expansion of the application field, and thus, the preparation of high coercivity neodymium iron boron materials is one of the main research directions in the field. It has been found that in sintered Nd-Fe-B magnet, heavy rare earth elements Dy, Te, Gd, Er, Ho, etc. are added to replace the primary phase Nd2Fe14The Nd in the B crystal grain can obviously improve the anisotropy field of the main phase magnetic crystal, so that the coercive force of the magnet is greatly increased. However, heavy rare earth resources are scarce and expensive, and the production cost can be greatly increased by adopting the traditional alloying method to improve the coercivity. On the other hand, due to the antiferromagnetic coupling between the heavy rare earth ions and the iron ions, the remanence and the magnetic energy product after the element is added are greatly reduced. Therefore, the technology of diffusing and permeating Dy, Te, Gd, Er, Ho and the like on the surface is developed at home and abroad, namely the coercive force of the magnet is improved, and the residual magnetism and the magnetic energy product of the magnet are not obviously reduced. Especially important, Dy, Te, Gd, Er, Ho and the like are only added on the surface, compared with the integral alloying, the dosage of the Dy, Te, Gd, Er, Ho and the like is greatly reduced, and the advantages of low cost and obvious effect are achieved.
To date, various methods for surface diffusion of Dy, Te, Gd, Er and Ho have been developed, and some methods have been put into practical industrial use. Among these methods, a layer of pure metal or compound containing Dy, Te, Gd, Er, Ho, etc. is effectively plated on the surface of the magnet mainly by evaporation, sputtering, coating, etc., and then grain boundary diffusion is performed by subsequent heat treatment. However, the methods still have the defects of low production efficiency, high cost, large difficulty in batch production, large equipment investment or unobvious improvement of coercive force and the like. For example, a simple method is to coat a layer of pure metal or metal oxide, chloride, fluoride on the surface of the magnet, and then directly heat treat the magnet for diffusion. The method has the advantages of low cost of raw materials, simple process and low diffusion and permeation efficiency. In another widely used method, a layer of pure metals Dy, Te, Gd, Er, Ho, etc. is first coated on the surface of the magnet by magnetron sputtering, and then heat treatment is performed to diffuse these heavy rare earth elements into the magnet. The method has high metal infiltration quality, but the method has high cost due to low utilization rate of the target material because a pure metal target material is required when magnetron sputtering is adopted.
Disclosure of Invention
The invention aims to provide a method for improving the coercive force of a sintered neodymium-iron-boron magnet by metal infiltration through a powder packaging method, which utilizes a powder packaging diffusion infiltration technology to infiltrate metals such as Dy, Te, Gd, Er, Ho, Hf and the like into the surface of the sintered neodymium-iron-boron magnet, so that the coercive force of the magnet is obviously improved, and meanwhile, the magnetic performance of the magnet in other aspects cannot be obviously reduced.
The technical scheme of the invention is as follows:
a method for improving the coercive force of a sintered neodymium iron boron magnet through metal infiltration by a powder packaging method comprises the following steps:
(1) the powder penetrating agent consisting of M-containing powder, an active agent and an anti-sintering agent is adopted, wherein M is one or the combination of more than two of Dy, Te, Gd, Er, Ho and Hf;
(2) selecting a material tank with a cover, embedding the sintered neodymium iron boron magnet to be processed in the material tank layer by layer at intervals by using a powder impregnation agent, and tightly covering the sintered neodymium iron boron magnet by using an upper cover with a hole;
(3) placing the charging bucket in a heat treatment furnace, vacuumizing, filling Ar gas, and repeating the operation of vacuumizing and filling Ar gas for 1-3 times to reduce the oxygen content in Ar atmosphere in the heat treatment furnace;
(4) heating the heat treatment furnace, keeping the temperature for 1-10 h when the temperature reaches 800-1100 ℃ in Ar atmosphere, and cooling to room temperature along with the furnace;
(5) and cleaning the magnet after heat treatment by using a brush, cleaning the magnet by using alcohol, and then carrying out aging treatment at the temperature of 450-650 ℃ for 1-10 h under the Ar atmosphere or vacuum condition.
The method for improving the coercive force of the sintered neodymium-iron-boron magnet through metal infiltration by a powder packaging method comprises the step (1), wherein the M-containing powder adopts Fe-M alloy powder or M oxide powder, and the Fe-M alloy powder is DyFe or DyFe2、TeFe、TeFe2Fe, (Dy, Te) or (Dy, Te) Fe2Intermetallic compound alloy, M oxide powder is Dy2O3、Tb2O3、HfO2、Dy2O3+Tb2O3Or Dy2O3+Tb2O3+HfO2(ii) a The active agent is ammonia chloride NH4Cl or ammonium fluoride NH4F, the anti-sintering agent is oxide powder of M; the mass ratio of the M-containing powder, the activator and the anti-sintering agent is as follows: (30-60), (0.1-4), (36-70), the particle size of the M-containing powder and the anti-sintering agent is 20-120 μ M.
In the step (2), the charging bucket is made of heat-resistant stainless steel or graphite with good thermal stability, the sintered neodymium iron boron magnets to be processed are embedded in the charging bucket layer by layer at intervals by using a powder penetrant, and the distances among the sintered neodymium iron boron magnets and between the sintered neodymium iron boron magnets and the inner wall of the charging bucket are larger than 15 mm.
Preferably, in the step (3), the vacuum degree is less than 10 Pa.
The method for improving the coercive force of the sintered neodymium iron boron magnet through metal infiltration by the powder packaging method is preferable, and in the step (4), the heat treatment conditions are as follows: maintaining Ar gas pressure in furnace 102～105And (3) keeping the temperature of the mixture Pa at 800-1000 ℃ for 3-6 h.
The method for improving the coercive force of the sintered neodymium iron boron magnet through metal infiltration by the powder packaging method is preferable, and in the step (5), the aging treatment conditions are as follows: in 1atm Ar atmosphere or 10-1～10-3And (3) keeping the temperature for 3-6 h at 500-600 ℃ in a Pa vacuum.
The method for improving the coercive force of the sintered neodymium-iron-boron magnet through metal infiltration by a powder packaging method is characterized in that a powder infiltration agent is recycled, namely, a new M-containing powder and an anti-sintering agent which account for 20-40 wt% of the total amount of the powder infiltration agent are added into the powder infiltration agent used at the previous time, and all active agents are newly added; in the powder penetrant, the mass ratio of M-containing powder, an active agent and an anti-sintering agent is as follows: (30-60), (0.1-4), (36-70).
The principle of the invention is as follows:
dy, Tb and the like belong to heavy rare earth elements, the atomic radius is large, the speed of permeating into the surface of neodymium iron boron through thermal diffusion is low, the permeation amount is small, and the permeation depth is shallow. Therefore, the practical technique of thermal diffusion infiltration of Dy and Tb in sintered nd-fe-b magnets is mainly to solve the problem of low infiltration efficiency. As is known, the thermal diffusion metallizing process mainly comprises three steps: the metal atoms diffuse to reach the surface of the workpiece to be infiltrated (sintered neodymium-iron-boron magnet), generate physical/chemical adsorption on the surface, and diffuse into the workpiece under the drive of chemical potential gradient. The three steps will differ for different processes and hence the infiltration efficiency will also differ. For example, in the method of sputtering a layer of pure Dy or Tb metal on the surface and then performing heat treatment, the infiltration efficiency is limited due to the presence of the interface of the neodymium iron boron/sputtered layer and the fact that Dy or Tb atoms reach the surface through solid phase diffusion. And DyCl is coated on the surface3、TbCl3As the penetrating agent, because of their low melting points (647 ℃ and 588 ℃, respectively), the vapor pressure is high when the magnet is processed at higher temperature, the transportation speed to the surface of the sintered NdFeB magnet is also high, but the DyCl needs higher temperature and certain time when Dy and Tb are diffused into the NdFeB crystal lattice at the temperature3、TbCl3The volatilization is serious, and the duration of the thermal diffusion infiltration process is insufficient.
The invention provides a powder packaging method, wherein Dy, Te, Gd, Er, Ho, Hf and the like are infiltrated into the surface of a sintered neodymium-iron-boron rare earth permanent magnet to improve the coercive force of the sintered neodymium-iron-boron rare earth permanent magnet. The powder packaging method is a conventional method for infiltrating metal on the surface of an alloy workpiece, and is widely applied to the fields of aviation, aerospace, metallurgy, petrifaction, energy sources and the like particularly in the aspect of high-temperature corrosion resistant structural materials. For example, Al, Cr, Al + Cr, Ti, Si, RE (rare earth element) and the like are infiltrated on the surface of the nickel-based superalloy, so that the high-temperature oxidation resistance and the hot corrosion resistance of the alloy can be obviously improved. The principle of the method is as follows: for example, using one or more of Fe-M (M ═ Dy, Te, Gd, Er, Ho, Hf, etc.) alloy powder and NH as activator4Cl, at the heat treatment temperature, the following chemical reaction occurs:
NH4Cl→NH3↑+HCl↑
M+3HCl→MCl3↑+3/2H2either ≈ or M2O3+6HCl→2MCl3↑+3H2O↑
MCl3→[M]+Cl2↓ (sintered Nd-Fe-B magnet surface)
H2+Cl2→2HCl↑
Active atom [ M ]]The inward diffusion occurs on the surface of the sintered nd-fe-b magnet. Due to gaseous MCl3Formation of NH4Decomposition of Cl and H2And Cl2The recombination forms a supporting reaction process, and the method can realize the stable and efficient infiltration of the metal M and has the characteristics of simple process and low cost. The anti-sintering agent is added to prevent the powder penetrating agent from sintering in the heat treatment process to influence gaseous MCl3And (4) conveying to the surface of the sintered neodymium-iron-boron magnet.
The invention has the advantages and beneficial effects that:
1. the invention adopts the powder packaging method to infiltrate metal, Dy, Te, Gd, Er, Ho, Hf and the like on the sintered NdFeB magnets with various sizes.
2. Dy, Te, Gd, Er, Ho, Hf and the like are infiltrated into the sintered neodymium iron boron magnet through thermal diffusion, so that the coercive force of the sintered neodymium iron boron magnet can be obviously improved, the sintered neodymium iron boron magnet has the most obvious effect on smaller magnets (such as sheets, plates or small-diameter rods) with one-dimensional linearity less than 7mm, and the influence on the magnetic performance of other aspects of the magnets is small.
3. The powder penetrant of the present invention adopts dysprosium iron or dysprosium oxide (the same applies to other metals), has low cost of raw materials, and can be repeatedly used.
4. The main equipment required by the invention comprises a heat treatment furnace and a heat treatment charging bucket, the process equipment is simple, and the process is stable.
5. The powder packaging method disclosed by the invention can be used for carrying out thermal diffusion infiltration on Dy, Te, Gd, Er, Ho, Hf and the like, can be used for carrying out batch treatment, has higher efficiency, and can be used for conveniently regulating and controlling the surface infiltration dosage and infiltration depth of the sintered neodymium-iron-boron magnet by controlling the content of main materials in the powder infiltration agent, the heat treatment temperature and the heat treatment time.
In conclusion, the invention adopts the powder packaging diffusion infiltration technology to infiltrate Dy, Te, Gd, Er, Ho, L u, Hf and other metals into the surface (including matrix crystal grains and intercrystalline phases) of the sintered NdFeB magnet, and through the treatment of the method, the coercive force of the magnet can be obviously improved without obviously reducing the magnetic performance (such as remanence and maximum magnetic energy product) of other aspects of the magnet.
Drawings
Fig. 1 is a schematic diagram of the placement of sintered ndfeb magnets in a powder packaging canister. In the figure, 1 air hole, 2 upper cover, 3 powder seeping agent, 4 workpieces and 5 material tanks.
FIG. 2 is a sectional element distribution diagram of a sintered NdFeB magnet after Dy infiltration in a powder package.
Detailed Description
In the specific implementation process, the method for improving the magnetic performance of the sintered neodymium iron boron (NdFeB) magnet by infiltrating metal M (one or a combination of more than two of M ═ Dy, Te, Gd, Er, Ho, L u, Hf and the like) through the powder packaging method adopts a powder infiltration agent consisting of M-containing alloy or oxide powder, an active agent and an anti-sintering agent, and infiltrates the metal M on the surface (including matrix grains and intergranular phases) of the sintered neodymium iron boron magnet through heat treatment, so that the coercive force of the magnet can be obviously improved.
(1) The powder penetrating agent is composed of powder containing M (one or more of Dy, Te, Gd, Er, Ho, Hf, etc.), activator and sintering resisting agent. Wherein the M-containing powder comprises: Fe-M alloy powders, e.g. DyFe, DyFe2，TeFe，TeFe2，(Dy,Te)Fe，(Dy,Te)Fe2An intermetallic compound alloy; and oxides of M, e.g. Dy2O3,Tb2O3,HfO2,Dy2O3+Tb2O3,Dy2O3+Tb2O3+HfO2And the like. The active agents are: ammonium chloride (NH)4Cl) or ammonium fluoride (NH)4F) In that respect The sintering resistant agent is an oxide of M. The mass ratio of the M-containing powder, the activator and the anti-sintering agent is as follows: (30-60): (0.1-4): 36-70), the particle size of M-containing powder and anti-sintering agent: 20 to 100 μm.
(2) Selecting a material tank made of materials such as heat-resistant stainless steel or graphite with good thermal stability and proper size, and embedding the sintered NdFeB magnets to be processed in the material tank layer by layer at intervals by using a powder penetrant, wherein the distances between the sintered NdFeB magnets and the inner wall of the heat treatment tank are larger than 15 mm. And then, tightly covering the charging bucket by using an upper cover with an air hole.
(3) And (3) placing the treated charging bucket in a heat treatment furnace, vacuumizing (the vacuum degree is better than 1Pa), filling 1atmAr gas, and performing 2-3 times of operation to ensure that the oxygen content in the heat treatment furnace is very low.
(4) Heating the heat treatment furnace, and maintaining the Ar gas pressure in the furnace at 102～105And (3) when the temperature of Pa reaches 800-1100 ℃, preserving the heat for 1-10 h, and then cooling to room temperature along with the furnace.
(5) The heat-treated magnet was cleaned with a brush and alcohol, and then treated in an atmosphere of 1atmAr or 10 atm-1～10-3And (4) in Pa vacuum, carrying out aging treatment at the temperature of 450-650 ℃ for 1-10 h.
The present invention will be described in more detail below with reference to examples.
Example 1
In the embodiment, Dy. magnet size of a sintered NdFeB magnet (N38TH) is 50mm × 20mm × 2mm, as shown in FIG. 1, a material tank 5 is filled with a powder penetrating agent 3, a workpiece 4 (sintered NdFeB magnet) is placed in the powder penetrating agent 3 at an interval of an upper layer and a lower layer, the top of the material tank 5 is covered and fastened with an upper cover 2, an air hole 1 is formed in the center of the upper cover 2, and distances between the sintered NdFeB magnet and the inner wall of the material tank are larger than 15 mm.
(1) Taking dysprosium iron powder (DyFe)2Average particle size 120 μm, technical grade), ammonium chloride (NH)4Cl, used after grinding, chemically pure) and dysprosium oxide (Dy)2O3Average particle size of 80 μm, industrial purity), and mixing uniformly according to the weight ratio of 60.0:1.5:36.5 to prepare the powder penetrating agent.
(2) The powder impregnation agent is paved into a material tank with a cover, wherein the material tank is made of HK40 heat-resistant steel, the diameter of the material tank is 50mm, the height of the material tank is 60mm, an upper layer and a lower layer of sintered NdFeB magnet samples are buried in the material tank, 6 sintered NdFeB magnet samples are arranged in each row, and the top of the material tank is covered and buckled with the cover.
(3) And (3) placing the treated charging bucket in a heat treatment furnace, vacuumizing (the vacuum degree is better than 10Pa), then filling Ar gas, repeating the operations of vacuumizing and filling Ar gas twice, and finally keeping Ar gas flowing in the furnace at 1 atm.
(4) And (4) heating the heat treatment furnace to 900 ℃, keeping the temperature for 4 hours, and cooling the furnace to room temperature.
(5) After the magnet after heat treatment is cleaned by a brush and alcohol, the magnet is subjected to aging treatment at 500 ℃ for 5 hours under the Ar gas atmosphere flowing at 1 atm.
Table 1 lists the main process conditions. The distribution analysis of main elements Fe, Nd, B and Dy on the section of the sintered Nd-Fe-B magnet processed by the process is carried out by using Electron Probe Microanalysis (EPMA), and the result is shown in figure 2. Showing that Dy permeates into the magnet, the depth of a permeated layer is about 280 mu m, and Dy is mainly distributed along the intergranular phase of the magnet. The magnetic properties of the treated magnets were measured using a Vibrating Sample Magnetometer (VSM), and the results are shown in table 2. As can be seen from Table 2, after Dy doping, the intrinsic coercive force (Hcj) of the magnet was increased by 48%, while the remanence (Br) and the maximum energy product ((BH)max) Only slightly decreased.
Example 2
The difference from the embodiment 1 is that:
the powder penetrant is prepared from dysprosium oxide (Dy)2O3Average particle size 80 μm, technical grade) and ammonium chloride (NH)4Cl, used after grinding, chemically pure) were prepared in a weight ratio of 99: 1. The thermal diffusion infiltration conditions are as follows: keeping the temperature at 820 ℃ for 5h in Ar gas flowing at 1 atm; the aging conditions are as follows: keeping the temperature at 500 ℃ for 3h in Ar gas flowing at 1 atm. The main process conditions are listed in table 1.
The magnetic properties of the treated magnets were measured using a Vibrating Sample Magnetometer (VSM), and the results are shown in table 2. As can be seen from Table 2, after Dy impregnation, the Hcj of the magnet increased by 29%, while Br and (BH)maxOnly slightly decreased.
Example 3
The difference from the embodiment 1 and the embodiment 2 is that:
a sintered NdFeB magnet (N38TH) was subjected to Dy + Tb composite co-infiltration. The powder penetrant is prepared from dysprosium oxide (Dy)2O3Average particle size 80 μm, industrialPure), terbium oxide (Tb)2O3Average particle size 83 μm, technical purity) and ammonium chloride (NH)4Cl, used after grinding, chemically pure) and prepared in a weight ratio of 50:49: 1. The heat treatment conditions were the same as in example 1, i.e. the thermal diffusion conditions were: keeping the temperature at 820 ℃ for 5h in Ar gas flowing at 1 atm; the aging conditions are as follows: keeping the temperature at 500 ℃ for 3h in Ar gas flowing at 1 atm. The main process conditions are listed in table 1.
The magnetic properties of the treated magnets were measured using a Vibrating Sample Magnetometer (VSM), and the results are shown in table 2. As can be seen from Table 2, after Dy impregnation, the Hcj of the magnet was increased by 42%, while Br and (BH)maxOnly slightly decreased.
TABLE 1 comparison of magnetic Properties of magnetic powder bonded bodies prepared under the Process conditions used in the examples
TABLE 2 magnetic comparison of NdFeB magnets treated in the examples
| Br(T) | Hcj(MA/m) | (BH)max(kJ/m3) | |
| Raw sample | 1.38 | 0.96 | 298 |
| Example 1 | 1.32 | 1.42 | 291 |
| Example 2 | 1.29 | 1.24 | 287 |
| Example 3 | 1.30 | 1.36 | 290 |
As seen from the results of 3 examples in Table 2, the coercive force of the magnet is improved in all the 3 examples, and the improvement is most obvious in example 1; the maximum magnetic energy and remanence for the magnet were slightly reduced, and the reduction was the smallest in example 1.
The results of the examples show that the invention adopts the powder packaging diffusion infiltration technology to infiltrate M (M ═ Dy, Te, Gd, Er, Ho, Hf, etc.) into the surface (including matrix grains and intercrystalline phases) of the sintered nd-fe-b magnet to improve the coercive force of the magnet, and mainly adopts metal oxide powder and dysprosium iron (or terbium iron, etc.) powder as infiltrants, which can be recycled. Because Fe-M alloy powder or M oxide is used as powder for packaging diffusion infiltration, and an active agent is added in the powder infiltration agent, compared with other methods, the metal infiltration efficiency is higher, and the treatment method has the advantages of simple equipment, stable process, batch treatment, low overall cost and obvious advantages in industrial application.
Claims (7)
1. A method for improving the coercive force of a sintered neodymium iron boron magnet through metal infiltration by a powder packaging method is characterized by comprising the following steps:
(1) the powder penetrating agent consisting of M-containing powder, an active agent and an anti-sintering agent is adopted, wherein M is one or the combination of more than two of Dy, Te, Gd, Er, Ho and Hf;
(2) selecting a material tank with a cover, embedding the sintered neodymium iron boron magnet to be processed in the material tank layer by layer at intervals by using a powder impregnation agent, and tightly covering the sintered neodymium iron boron magnet by using an upper cover with a hole;
(3) placing the charging bucket in a heat treatment furnace, vacuumizing, filling Ar gas, and repeating the operation of vacuumizing and filling Ar gas for 1-3 times to reduce the oxygen content in Ar atmosphere in the heat treatment furnace;
(4) heating the heat treatment furnace, keeping the temperature for 1-10 h when the temperature reaches 800-1100 ℃ in Ar atmosphere, and cooling to room temperature along with the furnace;
(5) and cleaning the magnet after heat treatment by using a brush, cleaning the magnet by using alcohol, and then carrying out aging treatment at the temperature of 450-650 ℃ for 1-10 h under the Ar atmosphere or vacuum condition.
2. The method for improving the coercive force of a sintered neodymium-iron-boron magnet through metal infiltration by a powder packaging method according to claim 1, wherein in the step (1), the M-containing powder adopts Fe-M alloy powder or M oxide powder, and the Fe-M alloy powder is DyFe or DyFe2、TeFe、TeFe2Fe, (Dy, Te) or (Dy, Te) Fe2Intermetallic compound alloy, M oxide powder is Dy2O3、Tb2O3、HfO2、Dy2O3+Tb2O3Or Dy2O3+Tb2O3+HfO2(ii) a The active agent is ammonia chloride NH4Cl or ammonium fluoride NH4F, the anti-sintering agent is oxide powder of M; the mass ratio of the M-containing powder, the activator and the anti-sintering agent is as follows: (30-60), (0.1-4), (36-70), the particle size of the M-containing powder and the anti-sintering agent is 20-120 μ M.
3. The method for improving the coercivity of the sintered NdFeB magnet through metal infiltration by a powder packaging method according to claim 1, wherein in the step (2), the charging bucket is made of heat-resistant stainless steel or graphite with good thermal stability, the sintered NdFeB magnet to be processed is embedded in the charging bucket layer by layer at intervals by using a powder infiltration agent, and the distances between the sintered NdFeB magnets and the inner wall of the charging bucket are more than 15 mm.
4. The method for improving the coercive force of a sintered neodymium-iron-boron magnet through metal infiltration by a powder packaging method according to claim 1, wherein, preferably, in the step (3), the vacuum degree is below 10 Pa.
5. The method for improving the coercive force of the sintered neodymium-iron-boron magnet through metal infiltration by a powder packaging method according to claim 1, wherein preferably, in the step (4), the heat treatment conditions are as follows: maintaining Ar gas pressure in furnace 102～105And (3) keeping the temperature of the mixture Pa at 800-1000 ℃ for 3-6 h.
6. The method for improving the coercive force of the sintered neodymium-iron-boron magnet through metal infiltration by a powder packaging method according to claim 1, wherein preferably, in the step (5), the aging treatment conditions are as follows: in 1atm Ar atmosphere or 10-1～10-3And (3) keeping the temperature for 3-6 h at 500-600 ℃ in a Pa vacuum.
7. The method for improving the coercive force of the sintered neodymium-iron-boron magnet through metal infiltration by the powder packaging method according to claim 1 or 2, characterized in that a powder infiltration agent is recycled, namely 20-40 wt% of the total amount of the powder infiltration agent used at the previous time is added into a new M-containing powder and an anti-sintering agent, and all active agents are newly added; in the powder penetrant, the mass ratio of M-containing powder, an active agent and an anti-sintering agent is as follows: (30-60), (0.1-4), (36-70).
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| CN101942635A (en) * | 2010-09-09 | 2011-01-12 | 西北工业大学 | Aluminum yttrium magnesium co-diffusion powder coating diffusion agent, preparation method and coating method thereof |
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| CN110299236A (en) * | 2018-03-22 | 2019-10-01 | 日立金属株式会社 | The manufacturing method of R-T-B based sintered magnet |
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| CN101942635A (en) * | 2010-09-09 | 2011-01-12 | 西北工业大学 | Aluminum yttrium magnesium co-diffusion powder coating diffusion agent, preparation method and coating method thereof |
| CN102592818A (en) * | 2011-01-14 | 2012-07-18 | 通用汽车环球科技运作有限责任公司 | Method of making ND-FE-b sintered magnets with DY or TB |
| EP2521147B1 (en) * | 2011-05-02 | 2018-04-25 | Shin-Etsu Chemical Co., Ltd. | Preparation of rare earth permanent magnets |
| CN105632748A (en) * | 2015-12-25 | 2016-06-01 | 宁波韵升股份有限公司 | Method for improving magnetic properties of sintered neodymium-iron-boron thin-sheet magnet |
| CN108417374A (en) * | 2018-02-05 | 2018-08-17 | 宁波松科磁材有限公司 | A kind of preparation method of neodymium iron boron magnetic body |
| CN110299236A (en) * | 2018-03-22 | 2019-10-01 | 日立金属株式会社 | The manufacturing method of R-T-B based sintered magnet |
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