CN117831926A - Bonded NdFeB-ferrite permanent magnet and preparation method and application thereof - Google Patents

Bonded NdFeB-ferrite permanent magnet and preparation method and application thereof Download PDF

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Publication number
CN117831926A
CN117831926A CN202211199801.6A CN202211199801A CN117831926A CN 117831926 A CN117831926 A CN 117831926A CN 202211199801 A CN202211199801 A CN 202211199801A CN 117831926 A CN117831926 A CN 117831926A
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magnetic powder
ferrite
permanent magnet
bonded
mixed
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杨武国
应晓东
申屠金昂
何震宇
厉华平
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Hengdian Group DMEGC Magnetics Co Ltd
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Hengdian Group DMEGC Magnetics Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—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
    • H01F1/0578—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 bonded together
    • 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
    • H01F41/026—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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0266—Moulding; Pressing

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Environmental & Geological Engineering (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 relates to a bonded NdFeB-ferrite permanent magnet, a preparation method and application thereof. The preparation method comprises the following steps: mixing ferrite magnetic powder, a silane coupling agent and a first binder, and granulating to obtain surface modified ferrite magnetic powder; mixing the surface modified ferrite magnetic powder with neodymium iron boron magnetic powder and a second binder, and granulating to obtain mixed magnetic powder, wherein the mass ratio of the surface modified ferrite magnetic powder to the neodymium iron boron magnetic powder is 1:99-1:9; and (3) pressing and forming the mixed magnetic powder to obtain a formed blank, and performing heat curing treatment on the formed blank to obtain the bonded NdFeB-ferrite permanent magnet. The preparation method provided by the invention can ensure that the bonded NdFeB-ferrite permanent magnet obviously improves the high-temperature irreversible demagnetization characteristic and reduces the raw material cost on the basis of ensuring the magnetic property, the mechanical property and the corrosion resistance of the bonded NdFeB magnet.

Description

Bonded NdFeB-ferrite permanent magnet and preparation method and application thereof
Technical Field
The invention relates to a preparation technology of a bonded rare earth permanent magnet material, in particular to a bonded NdFeB-ferrite permanent magnet, and a preparation method and application thereof.
Background
The rare earth permanent magnetic material is a material which takes an intermetallic compound formed by rare earth metal elements and transition group metals as a matrix and has the most application value in rare earth magnetic materials, wherein the bonded rare earth permanent magnetic material is prepared by uniformly mixing rare earth permanent magnetic powder and a binder, forming at high pressure and then solidifying at low temperature, has the advantages of simple preparation process, high dimensional accuracy, magnetic property between sintered ferrite and sintered rare earth permanent magnet and wide application in certain specific occasions. However, because the price of the rare earth raw materials is higher, the application cost pressure of the bonded rare earth permanent magnet material is higher, so that the material cost can be reduced and the advantages of the bonded rare earth permanent magnet material can be fully exerted under the condition of ensuring the application.
In order to adjust the performance of the bonded rare earth permanent magnet material and reduce the material cost, a part of permanent magnet ferrite is generally adopted to replace the rare earth permanent magnet material in the traditional technology to prepare the bonded NdFeB-ferrite permanent magnet. Meanwhile, in order to ensure the performances of the bonded NdFeB-ferrite permanent magnet in terms of remanence, coercive force and magnetic energy product, the granularity and the size of the permanent magnetic ferrite are usually required to be accurately regulated. However, since the permanent magnetic ferrite is a brittle ceramic material, in practical application, it is very difficult to precisely control the particle size of the permanent magnetic ferrite raw material within a certain range and difficult to realize. In addition, the bonded NdFeB-ferrite permanent magnet prepared by the traditional process only pays attention to remanence, coercive force and magnetic energy product, but has little attention on the irreversible demagnetization characteristic at high temperature.
Disclosure of Invention
Based on the above, it is necessary to provide a bonded neodymium iron boron-ferrite permanent magnet, and a preparation method and application thereof; the preparation method can ensure the magnetic property, mechanical property and corrosion resistance of the bonded NdFeB-ferrite permanent magnet, obviously improve the irreversible demagnetization characteristic at high temperature and reduce the cost of raw materials.
A preparation method of a bonded NdFeB-ferrite permanent magnet comprises the following steps:
mixing ferrite magnetic powder, a silane coupling agent and a first binder, and granulating to obtain surface modified ferrite magnetic powder;
mixing the surface modified ferrite magnetic powder with neodymium iron boron magnetic powder and a second binder, and granulating to obtain mixed magnetic powder, wherein the mass ratio of the surface modified ferrite magnetic powder to the neodymium iron boron magnetic powder is 1:99-1:9; and
and (3) pressing and forming the mixed magnetic powder to obtain a formed blank, and performing heat curing treatment on the formed blank to obtain the bonded NdFeB-ferrite permanent magnet.
In one embodiment, D of the surface-modified ferrite magnetic powder 50 50-120 μm;
and/or D of the neodymium iron boron magnetic powder 50 80-120 μm;
and/or D of the mixed magnetic powder 50 80 μm to 150 μm.
In one embodiment, the silane coupling agent is used in an amount of 0.3 to 0.8% by mass of the ferrite magnetic powder, and the first binder is used in an amount of 2 to 5% by mass of the ferrite magnetic powder.
In one embodiment, the second binder is used in an amount of 2% -2.8% of the sum of the mass of the surface modified ferrite magnetic powder and the mass of the neodymium iron boron magnetic powder.
In one embodiment, the ferrite magnetic powder is at least one selected from permanent ferrite pre-sintered magnetic powder, bonded permanent ferrite magnetic powder, sintered permanent ferrite waste magnetic powder and grinding waste magnetic powder of a permanent ferrite product.
In one embodiment, the first binder comprises 95% -100% epoxy resin and 0% -5% curing agent;
and/or, the second adhesive comprises 80% -90% of epoxy resin and 10% -20% of curing agent.
In one embodiment, the process of compacting the mixed magnetic powder further comprises mixing the mixed magnetic powder with a lubricant, wherein the amount of the lubricant is 0.2% -0.5% of the mass of the mixed magnetic powder.
In one embodiment, the pressure of the compression molding is 600MPa to 1000MPa;
and/or the temperature of the heat curing treatment is 150-180 ℃ and the time is 0.5-1 h.
A bonded NdFeB-ferrite permanent magnet prepared by the preparation method of the bonded NdFeB-ferrite permanent magnet.
A bonded neodymium iron boron-ferrite permanent magnet as described above is used to fabricate a magnetic device.
According to the preparation method, the surface of the ferrite magnetic powder is modified and then is subjected to compound granulation with the neodymium-iron-boron magnetic powder, so that the first adhesive is uniformly coated on the surface of the ferrite magnetic powder to obtain the surface modified ferrite magnetic powder with a certain particle size, the requirement on the particle size of the ferrite magnetic powder raw material in the preparation process is reduced, the range of the ferrite magnetic powder raw material is widened, the surface coating of the neodymium-iron-boron magnetic powder by the second adhesive is improved, and the mutual coordination between the surface modified ferrite magnetic powder and the neodymium-iron-boron magnetic powder is enhanced, so that the bonded neodymium-iron-boron-ferrite permanent magnet is obviously improved in high-temperature irreversible demagnetization characteristic on the basis of ensuring the magnetic property, mechanical property and corrosion resistance of the bonded neodymium-iron-boron-magnet, the working temperature of the bonded neodymium-iron-boron-ferrite permanent magnet is improved, the raw material cost is reduced, and the application field of a magnetic device manufactured by the bonded neodymium-iron-boron-ferrite permanent magnet is further widened.
Detailed Description
The present invention will be described in more detail below in order to facilitate understanding of the present invention. It should be understood, however, that the invention may be embodied in many different forms and is not limited to the implementations or embodiments described herein. Rather, these embodiments or examples 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 in the description of the invention herein is for the purpose of describing particular embodiments or examples only and is not intended to be limiting of the invention.
The invention provides a preparation method of a bonded NdFeB-ferrite permanent magnet, which comprises the following steps:
s1, mixing ferrite magnetic powder, a silane coupling agent and a first binder, and granulating to obtain surface modified ferrite magnetic powder;
s2, mixing the surface modified ferrite magnetic powder with neodymium iron boron magnetic powder and a second binder, and granulating to obtain mixed magnetic powder, wherein the mass ratio of the surface modified ferrite magnetic powder to the neodymium iron boron magnetic powder is 1:99-1:9; and
and S3, pressing and forming the mixed magnetic powder to obtain a formed blank, and performing heat curing treatment on the formed blank to obtain the bonded NdFeB-ferrite permanent magnet.
In the step S1, the first binder can be uniformly coated on the surface of the ferrite magnetic powder through granulation, so that the surface modified ferrite magnetic powder with the particle size equivalent to that of typical rare earth magnetic powder is obtained, the proportion of fine powder is reduced, and the fluidity of the final mixed formed magnetic powder is improved, so that the formability of the mixed magnetic powder is improved, and the crushing strength performance of a final magnet product is improved. Preferably, the surface-modified ferrite magnetic powder D 50 50 μm to 120 μm, more preferably 65 μm to 120 μm; d of the ferrite magnetic powder 50 1 μm to 50 μm.
Specifically, the ferrite magnetic powder is a permanent magnetic ferrite magnetic powder obtained by mixing and sintering iron red, strontium carbonate or barium carbonate and other trace additives, and comprises at least one of permanent magnetic ferrite pre-sintered magnetic powder, bonded permanent magnetic ferrite magnetic powder, sintered permanent magnetic ferrite waste magnetic powder and permanent magnetic ferrite product processing waste magnetic powder.
In order to enable the first binder to be coated on the surface of the ferrite magnetic powder more uniformly, the silane coupling agent is used in an amount of 0.3-0.8% of the mass of the ferrite magnetic powder, and the first binder is used in an amount of 2-5% of the mass of the ferrite magnetic powder.
The first binder comprises 95% -100% of epoxy resin and 0% -5% of curing agent, wherein the epoxy resin is preferably W-6C epoxy resin, and the curing agent is at least one selected from dicyandiamide curing agent, boron nitride ethylamine and maleic anhydride, and is preferably dicyandiamide curing agent.
Further, it is preferred that the first binder is a W-6C epoxy glue solution comprising 98% W-6C epoxy resin and 2% dicyandiamide curing agent.
The coupling agent is at least one selected from KH-550 and KH990 silane coupling agents.
In order to better bond the silane coupling agent and the first binder to the ferrite magnetic powder, it is preferable to mix the silane coupling agent with a proper amount of a solvent such as alcohol to obtain a silane coupling agent solution, mix the first binder with a proper amount of a solvent such as acetone to obtain a first binder solution, and mix the silane coupling agent solution, the first binder solution and the ferrite magnetic powder.
Further, in order to more sufficiently exert the function of the silane coupling agent, the silane coupling agent solution is first mixed with the ferrite magnetic powder and then mixed with the first binder solution.
In the step S2, a certain proportion of surface modified ferrite magnetic powder, neodymium iron boron magnetic powder and a second binder are mixed, and through compound granulation, the surface coating of the second binder on the neodymium iron boron magnetic powder can be effectively promoted, the mutual coordination between the surface modified ferrite magnetic powder and the neodymium iron boron magnetic powder is facilitated to be enhanced, the bonded neodymium iron boron-ferrite permanent magnet can be obviously improved on the basis of ensuring the magnetic property, mechanical property and corrosion resistance of the bonded neodymium iron boron magnet, the high-temperature irreversible demagnetization characteristic is obviously improved, the raw material cost is reduced, and the forming strength of the bonded neodymium iron boron-ferrite permanent magnet can be promoted.
Preferably, D of the mixed magnetic powder 50 80-150 μm; d of the neodymium iron boron magnetic powder 50 80 μm to 120 μm.
It should be noted that, based on different molding processes, corresponding neodymium iron boron magnetic powder needs to be adopted.
Specifically, when the press molding process is an isotropic press molding process, the neodymium iron boron magnetic powder is preferably an isotropic neodymium iron boron magnetic powder.
In order to enable the second binder to be coated on the surfaces of the surface modified ferrite magnetic powder and the neodymium iron boron magnetic powder more uniformly, the usage amount of the second binder is 2% -2.8% of the sum of the surface modified ferrite magnetic powder and the neodymium iron boron magnetic powder.
The second binder comprises 80% -90% of epoxy resin and 10% -20% of curing agent, wherein the epoxy resin is preferably W-6C epoxy resin, and the curing agent is at least one selected from dicyandiamide curing agent, boron nitride ethylamine and maleic anhydride, and is preferably dicyandiamide curing agent.
Further, it is preferred that the second binder is a W-6C epoxy glue solution comprising 85% W-6C epoxy resin and 15% dicyandiamide curing agent.
In order to better combine the second binder with the surface modified ferrite magnetic powder and the neodymium iron boron magnetic powder, the second binder is preferably mixed with a proper amount of solvent such as acetone to obtain a second binder solution, and then the second binder solution is mixed with the surface modified ferrite magnetic powder and the neodymium iron boron magnetic powder.
Further preferably, the surface-modified ferrite magnetic powder is mixed with the neodymium-iron-boron magnetic powder first and then with the second binder solution.
In the step S3, the mixed magnetic powder is mixed with a lubricant in the process of pressing and forming the mixed magnetic powder, wherein the using amount of the lubricant is 0.2-0.5% of the mass of the mixed magnetic powder.
Preferably, the mixed magnetic powder and the lubricant are uniformly mixed, the mixture is sieved to obtain the formable magnetic powder, and the formable magnetic powder is subjected to compression molding.
Specifically, the lubricant is at least one selected from zinc stearate and calcium stearate, and preferably zinc stearate.
The pressure of the press forming is 600MPa-1000MPa, preferably 800MPa-1000MPa, and the process of the press forming is preferably an isotropic compression molding process.
The heat curing treatment is carried out at the temperature of 150-180 ℃ for 0.5-1 h.
According to the practical application requirements, the surface treatment can be carried out on the magnet after the heat curing treatment, and the magnet is applied to the specific field.
Specifically, the surface treatment is carried out on the magnet after the heat curing treatment by adopting epoxy resin EP-703, so that an epoxy resin film with the thickness of 50-80 mu m is formed on the surface of the magnet, and the magnet is placed at 160-180 ℃ for heat preservation for 0.5-1 h, thus obtaining the bonded NdFeB-ferrite permanent magnet with the surface coated film.
The invention also provides a bonded NdFeB-ferrite permanent magnet prepared by the preparation method of the bonded NdFeB-ferrite permanent magnet.
The invention also provides a bonded NdFeB-ferrite permanent magnet used for manufacturing a magnetic device.
The bonded NdFeB-ferrite permanent magnet has low loss of high Wen Citong, good magnetic property, crushing strength, corrosion resistance and excellent high-temperature irreversible demagnetization characteristic, and can be applied to manufacturing magnetic devices, so that the working temperature range of the magnetic devices can be increased, and the application field of the magnetic devices is further expanded.
Hereinafter, the bonded NdFeB-ferrite permanent magnet, and the preparation method and application thereof will be further described by the following specific examples.
Example 1
30g of silane coupling agent (KH-550) was dissolved in 40g of alcohol and then added to 5kg of permanent magnet ferrite pre-sintered powder (D) 50 ＝8.0μm，Br＝4200Gs，Hcj＝4300Oe，(BH) m =4.3 MGOe), mixing was performed in a high-speed mixer at 300 rpm for 10min. 200g of a W-6C epoxy resin glue solution (containing 2% of dicyandiamide curing agent) was dissolved in 400g of acetone, and then added to a high-speed powder mixer and mixed at 200 rpm for 20min. Then pouring out magnetic powder, naturally airing, further crushing the bulk magnetic powder particles by using a crusher after the acetone is completely volatilized, and sieving the crushed bulk magnetic powder particles with a 50-mesh sieve to obtain D 50 Is 65 mu m of surface modified ferrite magnetic powder.
0.5kg of surface-modified ferrite magnetic powder was mixed with 9.5kg of isotropic neodymium iron boron magnetic powder (D 50 ＝120μm，Br＝6200Gs，Hcj＝12000Oe，(BH) m =8.0 MGOe) was added to a high speed mixer to mix at 200 rpmMixing for 10min. 250g of W-6C epoxy resin glue solution (containing 15% dicyandiamide curing agent) is dissolved by 400g of acetone, and then added into a high-speed powder mixer to be mixed for 20min at 150 rpm. Then pouring out the magnetic powder, naturally airing, further crushing the agglomerated magnetic powder by using a crusher after the acetone is completely volatilized, and sieving the crushed magnetic powder with a 50-mesh sieve to obtain D 50 Is 115 μm mixed magnetic powder.
Zinc stearate is added into the mixed magnetic powder, wherein the addition amount of the zinc stearate is 0.25% of the mass of the mixed magnetic powder, and the mixed magnetic powder is fully and uniformly stirred and then is sieved by a 50-mesh sieve, so that the formable magnetic powder is obtained. And (3) carrying out compression molding on the moldable magnetic powder under the pressure of 800MPa to obtain a molded blank. And then, carrying out heat curing treatment on the molded blank in an oven at 160 ℃ for 1h to obtain the bonded NdFeB-ferrite permanent magnet. Further, the bonded NdFeB-ferrite permanent magnet is subjected to surface spraying, the spraying material is epoxy resin (EP-703), the spraying thickness is 60 mu m, and the sprayed product is subjected to heat preservation in a baking oven at 170 ℃ for 0.5h and is dried, so that the finished product magnet is obtained.
Example 2
30g of silane coupling agent (KH-550) was dissolved in 40g of alcohol and then added to 5kg of bonded permanent magnet ferrite magnetic powder (D 50 2.8 μm, br=3500gs, hcj=3800 Oe, (BH) m =3.8 MGOe), mixed in a high-speed mixer at 300 rpm for 10min. 250g of W-6C epoxy resin glue solution (containing 2% dicyandiamide curing agent) is dissolved by 400g of acetone, and then added into a high-speed powder mixer to be mixed for 20min at 200 rpm. Then pouring out magnetic powder, naturally airing, further crushing the bulk magnetic powder particles by using a crusher after the acetone is completely volatilized, and sieving the crushed bulk magnetic powder particles with a 50-mesh sieve to obtain D 50 55 μm of surface-modified ferrite magnetic powder.
0.3kg of surface-modified ferrite magnetic powder was mixed with 9.7kg of isotropic neodymium iron boron magnetic powder (D 50 ＝120μm，Br＝6200Gs，Hcj＝12000Oe，(BH) m =8.0 MGOe) was added to a high-speed mixer and mixed at 200 rpm for 10min. 280g of W-6C epoxy resin glue solution (containing 15% of dicyandiamide curing agent) is dissolved by 400g of acetone and then added into a high-speed powder mixer to be mixed for 20min at 150 rpm. Then pouring out the magnetic powder, naturally airing, and waiting for the preparation of the polypropyleneCrushing the agglomerated magnetic powder by a crusher after the ketone is completely volatilized, and sieving the crushed magnetic powder with a 50-mesh sieve to obtain D 50 Is a mixed magnetic powder of 135 μm.
Zinc stearate is added into the mixed magnetic powder, wherein the addition amount of the zinc stearate is 0.22% of the mass of the mixed magnetic powder, and the mixed magnetic powder is fully and uniformly stirred and then is sieved by a 50-mesh sieve, so that the formable magnetic powder is obtained. And (3) carrying out compression molding on the moldable magnetic powder under the pressure of 800MPa to obtain a molded blank. And then, carrying out heat curing treatment on the molded blank in an oven at 160 ℃ for 1h to obtain the bonded NdFeB-ferrite permanent magnet. Further, the bonded NdFeB-ferrite permanent magnet is subjected to surface spraying, the spraying material is epoxy resin (EP-703), the spraying thickness is 60 mu m, and the sprayed product is subjected to heat preservation in a 160 ℃ oven for 0.5h and is dried, so that the finished product magnet is obtained.
Example 3
30g of silane coupling agent (KH-550) was dissolved in 40g of alcohol and then added to 5kg of sintered permanent magnet ferrite waste magnetic powder (D 50 6.9 μm, br=4400 gs, hcj=4800 Oe, (BH) m =4.8 MGOe), mixed in a high-speed mixer at 300 rpm for 10min. 175g of W-6C epoxy resin glue solution (containing 2% dicyandiamide curing agent) is dissolved by 400g of acetone, and then added into a high-speed powder mixer to be mixed for 20min at 200 rpm. Then pouring out magnetic powder, naturally airing, further crushing the bulk magnetic powder particles by using a crusher after the acetone is completely volatilized, and sieving the crushed bulk magnetic powder particles with a 50-mesh sieve to obtain D 50 Is 80 mu m surface modified ferrite magnetic powder.
1.0kg of surface-modified ferrite magnetic powder and 9.0kg of isotropic neodymium iron boron magnetic powder (D 50 ＝120μm，Br＝6200Gs，Hcj＝12000Oe，(BH) m =8.0 MGOe) was added to a high-speed mixer and mixed at 200 rpm for 10min. 230g of a W-6C epoxy resin glue solution (containing 15% of dicyandiamide curing agent) was dissolved in 400g of acetone, and then added to a high-speed powder mixer and mixed at 150 rpm for 20min. Then pouring out the magnetic powder, naturally airing, further crushing the agglomerated magnetic powder by using a crusher after the acetone is completely volatilized, and sieving the crushed magnetic powder with a 50-mesh sieve to obtain D 50 Is 115 μm mixed magnetic powder.
Zinc stearate is added into the mixed magnetic powder, wherein the addition amount of the zinc stearate is 0.35 percent of the mass of the mixed magnetic powder, and the mixed magnetic powder is fully and uniformly stirred and then is sieved by a 50-mesh sieve, so that the formable magnetic powder is obtained. And (3) carrying out compression molding on the moldable magnetic powder under the pressure of 800MPa to obtain a molded blank. And then, carrying out heat curing treatment on the molded blank in an oven at 160 ℃ for 1h to obtain the bonded NdFeB-ferrite permanent magnet. Further, the bonded NdFeB-ferrite permanent magnet is subjected to surface spraying, the spraying material is epoxy resin (EP-703), the spraying thickness is 60 mu m, and the sprayed product is subjected to heat preservation in a baking oven at 170 ℃ for 0.5h and is dried, so that the finished product magnet is obtained.
Example 4
30g of silane coupling agent (KH-550) was dissolved in 40g of alcohol, and then added to 5kg of permanent magnet ferrite mill processed waste magnetic powder (D 50 3.5 μm, br=4000 gs, hcj=4400 Oe, (BH) m =4.1 MGOe), mixing was performed in a high-speed mixer at 300 rpm for 10min. 225g of a W-6C epoxy resin glue solution (containing 2% dicyandiamide curing agent) was dissolved in 400g of acetone, and then added to a high-speed powder mixer and mixed at 200 rpm for 20 minutes. Then pouring out magnetic powder, naturally airing, further crushing the bulk magnetic powder particles by using a crusher after the acetone is completely volatilized, and sieving the crushed bulk magnetic powder particles with a 50-mesh sieve to obtain D 50 The surface-modified ferrite magnetic powder was 68. Mu.m.
0.2kg of surface-modified ferrite magnetic powder was mixed with 9.8kg of isotropic neodymium iron boron magnetic powder (D 50 ＝120μm，Br＝6200Gs，Hcj＝12000Oe，(BH) m =8.0 MGOe) was added to a high-speed mixer and mixed at 200 rpm for 10min. 260g of W-6C epoxy resin glue solution (containing 15% dicyandiamide curing agent) was dissolved with 400g of acetone, and then added to a high-speed powder mixer and mixed at 150 rpm for 20min. Then pouring out the magnetic powder, naturally airing, further crushing the agglomerated magnetic powder by using a crusher after the acetone is completely volatilized, and sieving the crushed magnetic powder with a 50-mesh sieve to obtain D 50 Is 148 μm mixed magnetic powder.
Zinc stearate is added into the mixed magnetic powder, wherein the addition amount of the zinc stearate is 0.42% of the mass of the mixed magnetic powder, and the mixed magnetic powder is fully and uniformly stirred and then is sieved by a 50-mesh sieve, so that the formable magnetic powder is obtained. And (3) carrying out compression molding on the moldable magnetic powder under the pressure of 800MPa to obtain a molded blank. And then, carrying out heat curing treatment on the molded blank in an oven at 180 ℃ for 1h to obtain the bonded NdFeB-ferrite permanent magnet. Further, the bonded NdFeB-ferrite permanent magnet is subjected to surface spraying, the spraying material is epoxy resin (EP-703), the spraying thickness is 60 mu m, and the sprayed product is subjected to heat preservation in a drying oven at 180 ℃ for 0.3h and dried, so that the finished product magnet is obtained.
Comparative example 1
10kg of isotropic NdFeB magnetic powder (D 50 ＝120μm，Br＝6200Gs，Hcj＝12000Oe，(BH) m =8.0 MGOe) was added to a high-speed mixer, 250g of W-6C epoxy resin dope (15% dicyandiamide curing agent) was dissolved with 400g of acetone, and then added to the high-speed mixer to mix for 20min at 150 rpm. Then pouring out the magnetic powder, naturally airing, further crushing the agglomerated magnetic powder by using a crusher after the acetone is completely volatilized, and sieving the crushed magnetic powder with a 50-mesh sieve to obtain D 50 Is 132 mu m of bonded NdFeB magnetic powder.
Zinc stearate is added into the bonded NdFeB magnetic powder, wherein the addition amount of the zinc stearate is 0.25% of the mass of the bonded NdFeB magnetic powder, and the bonded NdFeB magnetic powder is fully and uniformly stirred and then is sieved by a 50-mesh sieve, so that the formable magnetic powder is obtained. And (3) carrying out compression molding on the moldable magnetic powder under the pressure of 800MPa to obtain a molded blank. And then, carrying out heat curing treatment on the molded blank in an oven at 160 ℃ for 1h to obtain the bonded NdFeB magnet. Further, the bonded NdFeB magnet is subjected to surface spraying, the spraying material is epoxy resin (EP-703), the spraying thickness is 60 mu m, and the sprayed product is subjected to heat preservation in a 160 ℃ oven for 0.5h and is dried, so that the finished product magnet is obtained.
Comparative example 2
Comparative example 2 differs from example 1 only in that the permanent ferrite pre-sintered magnetic powder and the isotropic neodymium iron boron magnetic powder are directly mixed, then the silane coupling agent solution and the epoxy resin solution are sequentially added to prepare mixed magnetic powder, and the mixed magnetic powder is molded, heated and cured, and the surface sprayed to prepare the finished magnet.
The finished magnets prepared in examples 1 to 4 and comparative examples 1 to 2 were subjected to performance test, respectively, and the results are shown in Table 1.
The irreversible demagnetization test method is to examine the magnetic flux of the finished magnet at normal temperature after magnetizing, then heat the finished magnet to 120 ℃ and preserving heat for 2 hours, cool the finished magnet to normal temperature, examine the magnetic flux of the finished magnet, and calculate the proportion of the difference value of the two magnetic flux tests to the magnetic flux of the finished magnet at normal temperature, namely the loss (%) of high Wen Citong.
TABLE 1
As can be seen from Table 1, the finished bonded NdFeB-ferrite permanent magnets prepared in examples 1 to 4 maintained residual magnetism (Br), coercive force (Hcj), and magnetic energy product ((BH) relative to the finished bonded NdFeB magnet prepared in comparative example 1 m ) On the basis of basically unchanged crushing strength, corrosion resistance and magnet density, the loss of high Wen Citong is obviously reduced, the high-temperature irreversible demagnetization characteristic of the bonded NdFeB-ferrite permanent magnet is improved, the application temperature of the finished product magnet is increased, the cost of raw materials can be effectively reduced, and the application field of the bonded NdFeB-ferrite permanent magnet is expanded. In comparative example 2, the ferrite magnetic powder and the neodymium-iron-boron magnetic powder are directly mixed for granulation, so that the coating of the adhesive on the surfaces of the ferrite magnetic powder and the neodymium-iron-boron magnetic powder is uneven, and the prepared finished bonded neodymium-iron-boron-ferrite permanent magnet has poor magnetic performance, and obviously reduced crushing strength and corrosion resistance.
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 (10)

1. The preparation method of the bonded NdFeB-ferrite permanent magnet is characterized by comprising the following steps of:
mixing ferrite magnetic powder, a silane coupling agent and a first binder, and granulating to obtain surface modified ferrite magnetic powder;
mixing the surface modified ferrite magnetic powder with neodymium iron boron magnetic powder and a second binder, and granulating to obtain mixed magnetic powder, wherein the mass ratio of the surface modified ferrite magnetic powder to the neodymium iron boron magnetic powder is 1:99-1:9; and
and (3) pressing and forming the mixed magnetic powder to obtain a formed blank, and performing heat curing treatment on the formed blank to obtain the bonded NdFeB-ferrite permanent magnet.
2. The method for producing a bonded NdFeB-ferrite permanent magnet according to claim 1, wherein the surface-modified ferrite magnetic powder has D 50 50-120 μm;
and/or D of the neodymium iron boron magnetic powder 50 80-120 μm;
and/or D of the mixed magnetic powder 50 80 μm to 150 μm.
3. The method of manufacturing a bonded neodymium iron boron-ferrite permanent magnet according to claim 1, wherein the silane coupling agent is used in an amount of 0.3% -0.8% of the mass of the ferrite magnetic powder, and the first binder is used in an amount of 2% -5% of the mass of the ferrite magnetic powder.
4. The method of manufacturing a bonded neodymium-iron-boron-ferrite permanent magnet according to claim 1, wherein the amount of the second binder is 2% -2.8% of the sum of the mass of the surface-modified ferrite magnetic powder and the mass of the neodymium-iron-boron magnetic powder.
5. The method for producing a bonded neodymium iron boron-ferrite permanent magnet according to claim 1, wherein the ferrite magnetic powder is at least one selected from the group consisting of permanent ferrite pre-sintered material magnetic powder, bonded permanent ferrite magnetic powder, sintered permanent ferrite waste magnetic powder, and permanent ferrite product grinding waste magnetic powder.
6. The method of manufacturing a bonded neodymium iron boron-ferrite permanent magnet according to claim 1, wherein the first binder comprises 95% -100% of epoxy resin and 0% -5% of curing agent;
and/or, the second adhesive comprises 80% -90% of epoxy resin and 10% -20% of curing agent.
7. The method for manufacturing a bonded neodymium-iron-boron-ferrite permanent magnet according to claim 1, further comprising mixing the mixed magnetic powder with a lubricant in the process of compression molding the mixed magnetic powder, wherein the amount of the lubricant is 0.2% -0.5% of the mass of the mixed magnetic powder.
8. The method for producing a bonded NdFeB-ferrite permanent magnet according to claim 1, wherein the pressure of the press forming is 600MPa to 1000MPa;
and/or the temperature of the heat curing treatment is 150-180 ℃ and the time is 0.5-1 h.
9. A bonded neodymium-iron-boron-ferrite permanent magnet prepared by the method for preparing a bonded neodymium-iron-boron-ferrite permanent magnet according to any one of claims 1 to 8.
10. A bonded neodymium iron boron-ferrite permanent magnet according to claim 9 for use in the manufacture of magnetic devices.
CN202211199801.6A 2022-09-29 2022-09-29 Bonded NdFeB-ferrite permanent magnet and preparation method and application thereof Pending CN117831926A (en)

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