Neodymium iron boron magnetic core, new motor and application

Abstract

The application relates to a neodymium-iron-boron magnetic core, a novel motor and application, and belongs to the technical field of the neodymium-iron-boron magnetic core. The neodymium-iron-boron magnetic core comprises the following components: neodymium-iron-boron magnetic powder, epoxy resin, functional additive, modified boron nitride, curing agent and lubricant; the prepared neodymium-iron-boron magnetic core takes the neodymium-iron-boron magnetic powder as a matrix, and is compounded with specific proportion of the epoxy resin, modified nano boron nitride and composite lubricant; the modified boron nitride improves the filler dispersibility and the matrix compatibility; the specific functional additive containing multiple active groups is added to optimize the interface bonding force of the magnetic core, and the mechanical strength, high-temperature resistance and salt mist resistance of the neodymium-iron-boron magnetic core material are obviously improved.

Description

Technical Field

[0001] This invention belongs to the technical field of neodymium iron boron magnetic cores, and relates to a neodymium iron boron magnetic core, a novel motor, and its applications. Background Technology

[0002] Since its invention, neodymium iron boron (NdFeB) rare-earth permanent magnet material has attracted widespread attention and is hailed as the "King of Magnets" due to its numerous advantages, including small size, light weight, excellent magnetic properties, low cost, and abundant resources. It has found wide applications in automobiles, computers, machinery, energy, and medicine. However, because NdFeB magnets exhibit a multiphase structure with large potential differences between phases, they possess extremely active electrochemical properties. Therefore, they are highly susceptible to corrosion in high-temperature, high-humidity environments and corrosive electrolytes, ultimately damaging the internal structure of the magnet and consequently impairing its magnetic properties.

[0003] Bonded NdFeB magnets are experiencing continuous market demand growth due to their flexible shape design and diverse magnetization methods. However, NdFeB materials are chemically reactive and prone to oxidation and corrosion in high-temperature, humid, electrochemical, and hydrogen-containing environments, which significantly limits their industrial applications. Most existing technologies employ a two-step process of preparing the NdFeB substrate followed by surface protection, using electroplating, electrophoresis, or other methods to coat the NdFeB substrate with a protective layer. This process is not only complex and costly, but also results in weak adhesion between the protective layer and the substrate, leading to easy detachment of the protective layer over long-term use, failing to fundamentally solve the corrosion problem within the magnetic powder and at the interface. Summary of the Invention

[0004] The purpose of this invention is to provide a neodymium iron boron (NdFeB) magnetic core, a novel motor, and its applications. The NdFeB magnetic core prepared by this invention uses NdFeB magnetic powder as a matrix, and is compounded with a specific ratio of epoxy resin, modified nano boron nitride, and composite lubricant. By modifying boron nitride, the dispersibility of the filler and its compatibility with the matrix are improved. By adding specific functional additives containing multiple active groups, the interfacial bonding force of the magnetic core is optimized, which significantly improves the mechanical strength, high temperature resistance, and salt spray resistance of the NdFeB magnetic core material.

[0005] The objective of this invention can be achieved through the following technical solutions: A neodymium iron boron magnetic core comprises the following components in parts by weight: The composition includes 82-90 parts of neodymium iron boron magnetic powder, 2.2-2.8 parts of epoxy resin, 0.8-1.2 parts of functional additives, 6-8 parts of modified boron nitride, 0.4-0.6 parts of curing agent, and 0.8-1.2 parts of lubricant.

[0006] As a preferred embodiment of the present invention, the composition of the neodymium iron boron magnetic powder is shown in the table below:

[0007] As a preferred embodiment of the present invention, the lubricant is one or more of zinc stearate, oleamide and BYK dispersant, preferably the lubricant is a mixture of zinc stearate, oleamide and dispersant BYK-163 in a mass ratio of 5-8:3-5:1-3.

[0008] As a preferred embodiment of the present invention, the curing accelerator is curing accelerator DBU, i.e., 1,8-diazabicyclohexane, and the epoxy resin is Nanya NPCN-704.

[0009] As a preferred embodiment of the present invention, the preparation of the modified boron nitride includes: adding nano-boron nitride to anhydrous ethanol and dispersing it ultrasonically, adding a silane coupling agent, heating and stirring, filtering, washing, and drying to obtain the product.

[0010] As a preferred embodiment of the present invention, the ultrasonic dispersion time is 10-15 min, the heating and stirring temperature is 50-60℃ and the time is 5-6 h, the washing is washing with anhydrous ethanol 3 times, and the drying temperature is 70℃ and the drying time is 8-10 h.

[0011] As a preferred embodiment of the present invention, the mass ratio of the nano-boron nitride, anhydrous ethanol and silane coupling agent is 15-18:60-80:2.0-2.5, and the silane coupling agent is silane coupling agent KH580.

[0012] As a preferred embodiment of the present invention, the method for preparing the functional additive includes the following steps: 1) Add aminothiazole and DMF to a reaction vessel, mix and heat and stir. Under an inert gas atmosphere and continuous stirring, add polyphenol compound and glacial acetic acid and continue stirring. Remove solvent by rotary evaporation, wash and vacuum dry to obtain multi-component compound. 2) After mixing the multi-component compound and the mixed solvent, slowly add polyethyleneimine, sonicate, heat and stir to obtain the functional additive.

[0013] As a preferred technical solution of the present invention, the temperature of the heating and stirring in step 1) is 45-50℃ and the stirring time is 20-30min, the inert gas atmosphere is a nitrogen gas atmosphere, the speed of the continuous stirring is 300-400rpm, the temperature of the continued stirring is 50-60℃ and the stirring time is 4-5h, the washing is washing with deionized water 3 times, and the vacuum drying is vacuum drying at 80℃ to constant weight.

[0014] As a preferred embodiment of the present invention, in step 1), the aminothiol thiadiazole is 2-amino-5-mercapto-1,3,4-thiadiazole, the polyphenol compound is 3,4-dihydroxy-5-methoxybenzaldehyde, the ratio of aminothiol thiadiazole, polyphenol compound, glacial acetic acid and DMF is 7.5-8.0:10-11:0.2-0.3:90-100, and the DMF is N,N-dimethylformamide.

[0015] As a preferred embodiment of the present invention, in step 2), the stirring temperature is 40-45℃ and the stirring time is 20-30 min; the ultrasonic treatment power is 200-300W and the ultrasonic time is 10-15 min; and the heating and stirring temperature is 45-50℃ and the stirring time is 30-45 min.

[0016] As a preferred embodiment of the present invention, the mixed solvent in step 2) is composed of anhydrous ethanol and DMF mixed in a volume ratio of 3:1, and the mass ratio of the multi-component compound, polyethyleneimine and the mixed solvent is 1.0-1.2:5-6:12-15.

[0017] As a preferred technical solution of the present invention, a process for preparing a neodymium iron boron magnetic core includes: mixing neodymium iron boron magnetic powder, modified boron nitride and lubricant at 300-500 rpm for 15-20 min, adding epoxy resin and stirring for 10-15 min, then adding functional additives and curing agent and continuing to stir for 20-30 min, placing it in a magnetic field with a magnetic field strength of 2.0-3.0T under nitrogen protection for orientation and shaping, then pressing it under a pressure of 800-900 MPa for 30-40 s for molding, holding it at 50℃ for 2-3 h, then holding it at 80-90℃ for 2-3 h, and finally heating it to 160-180℃ for 50-60 min for curing, and then cooling it to room temperature in the furnace to complete the preparation.

[0018] As a preferred technical solution of the present invention, a novel motor is made of neodymium iron boron magnetic core as described above. The novel motor includes a housing and a rotor assembly, a stator assembly and a rotating shaft disposed within the housing. The rotor assembly includes a rotor core and the neodymium iron boron magnetic core. The rotor assembly, the housing and the rotating shaft are connected to each other.

[0019] As a preferred technical solution of the present invention, an application of a novel electric motor in the automotive industry is described.

[0020] The beneficial effects of this invention are: 1. The neodymium iron boron magnetic core prepared by this invention uses neodymium iron boron magnetic powder as the matrix, and is compounded with a specific ratio of epoxy resin, modified nano boron nitride and composite lubricant. The modified boron nitride improves the dispersibility of the filler and the compatibility with the matrix. The addition of specific functional additives containing multiple active groups optimizes the interfacial bonding force of the magnetic core, which significantly improves the mechanical strength, high temperature resistance and salt spray resistance of the neodymium iron boron magnetic core material.

[0021] 2. The present invention is prepared by using magnetic field orientation, high pressure molding and multi-level gradient thermosetting process. The resulting magnetic core has both excellent magnetic orientation and structural stability, which is suitable for the application requirements of new motors in the automotive industry. Attached Figure Description

[0022] Figure 1 This is an overall structural diagram of the novel motor in the embodiments of this application; Figure 2 This is a radial sectional view of the novel motor in the embodiments of this application; Figure 3 This is a circumferential sectional view of the novel motor in the embodiments of this application; Explanation of reference numerals in the attached drawings: 1. Housing; 2. Rotor assembly; 3. Stator assembly; 4. Shaft. Detailed Implementation

[0023] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0024] Example 1 A neodymium iron boron magnetic core comprises the following components in parts by weight: The composition includes 82 parts of neodymium iron boron magnetic powder, 2.2 parts of epoxy resin, 0.8 parts of functional additives, 6 parts of modified boron nitride, 0.4 parts of curing agent, and 0.8 parts of lubricant. The epoxy resin is of the type Nanya NPCN-704; The curing accelerator is 1,8-diazabicyclohexane; The lubricant is composed of zinc stearate, oleamide, and dispersant BYK-163 in a mass ratio of 5:3:1.

[0025] The preparation of the modified boron nitride includes: adding nano-boron nitride to anhydrous ethanol and ultrasonically dispersing for 10 min, adding silane coupling agent KH580, heating and stirring, filtering, washing three times with anhydrous ethanol, and drying at 70°C for 8 h to obtain the modified boron nitride; the mass ratio of the nano-boron nitride, anhydrous ethanol and silane coupling agent KH580 is 15:60:2.0.

[0026] The preparation method of the functional additive includes the following steps: 1) Add aminothiazole and DMF to a reaction vessel and mix. Stir at 45°C for 30 min. Under a nitrogen atmosphere and continuous stirring at 300 rpm, add polyphenol compound and glacial acetic acid. Stir at 50°C for 5 h. Remove solvent by rotary evaporation. Wash three times with deionized water. Dry under vacuum at 80°C to constant weight to obtain multi-component compound. The aminothiazole is 2-amino-5-mercapto-1,3,4-thiadiazole, the polyphenol compound is 3,4-dihydroxy-5-methoxybenzaldehyde, and the ratio of aminothiazole, polyphenol compound, glacial acetic acid and DMF is 7.5:10:0.2:90. 2) After stirring and mixing the multi-component compound and the mixed solvent at 40°C for 30 min, slowly add polyethyleneimine and sonicate at 200W power for 15 min, then heat and stir at 45°C for 45 min to obtain the functional additive. The mixed solvent is composed of anhydrous ethanol and DMF in a volume ratio of 3:1, and the mass ratio of the multi-component compound, polyethyleneimine and the mixed solvent is 1.0:5:12.

[0027] A process for preparing a neodymium iron boron magnetic core includes: mixing neodymium iron boron magnetic powder, modified boron nitride, and lubricant at 300 rpm for 20 min, adding epoxy resin and stirring for 15 min, then adding functional additives and curing agent and stirring for another 30 min, placing it in a magnetic field with a magnetic field strength of 2.0 T under nitrogen protection for orientation and shaping, then pressing it under a pressure of 800 MPa for 40 s to form it, holding it at 50℃ for 2 h, then holding it at 80℃ for 3 h, and finally heating it to 160℃ for 60 min to cure it, and then cooling it to room temperature in the furnace to complete the preparation.

[0028] A novel motor includes a housing 1 and a rotor assembly 2, a stator assembly 3, and a shaft 4 disposed within the housing 1. The rotor assembly 2 includes a rotor core and the aforementioned neodymium iron boron magnetic core. The rotor assembly 2, the housing 1, and the shaft 4 are connected. The novel motor is also equipped with an electronic commutation system and other necessary auxiliary structures, and is applied in the automotive industry.

[0029] Example 2 A neodymium iron boron magnetic core comprises the following components in parts by weight: The composition includes 86 parts of neodymium iron boron magnetic powder, 2.5 parts of epoxy resin, 1 part of functional additive, 7 parts of modified boron nitride, 0.5 parts of curing agent, and 1 part of lubricant. The epoxy resin is of the type Nanya NPCN-704; The curing accelerator is 1,8-diazabicyclohexane; The lubricant is composed of zinc stearate, oleamide, and dispersant BYK-163 in a mass ratio of 6:4:2.

[0030] The preparation of the modified boron nitride includes: adding nano boron nitride to anhydrous ethanol and ultrasonically dispersing for 12 min, adding silane coupling agent KH580, heating and stirring, filtering, washing three times with anhydrous ethanol, and drying at 70°C for 9 h to obtain the modified boron nitride; the mass ratio of the nano boron nitride, anhydrous ethanol and silane coupling agent KH580 is 16:70:2.2.

[0031] The preparation method of the functional additive includes the following steps: 1) Add aminothiazole and DMF to a reaction vessel and mix. Stir at 48°C for 25 min. Under a nitrogen atmosphere and continuous stirring at 350 rpm, add polyphenol compound and glacial acetic acid. Continue stirring at 55°C for 4.5 h. Remove solvent by rotary evaporation. Wash three times with deionized water. Dry under vacuum at 80°C to constant weight to obtain a multi-component compound. The aminothiazole is 2-amino-5-mercapto-1,3,4-thiadiazole, the polyphenol compound is 3,4-dihydroxy-5-methoxybenzaldehyde, and the ratio of aminothiazole, polyphenol compound, glacial acetic acid and DMF is 7.8:10.5:0.25:95. 2) After stirring and mixing the multi-component compound and the mixed solvent at 42°C for 25 min, polyethyleneimine is slowly added and ultrasonically treated at 250W power for 12 min. Then, the mixture is heated and stirred at 48°C for 38 min to obtain the functional additive. The mixed solvent is composed of anhydrous ethanol and DMF in a volume ratio of 3:1, and the mass ratio of the multi-component compound, polyethyleneimine and the mixed solvent is 1.1:5.5:14.

[0032] A process for preparing a neodymium iron boron magnetic core includes: mixing neodymium iron boron magnetic powder, modified boron nitride, and lubricant at 400 rpm for 18 min, adding epoxy resin and stirring for 12 min, then adding functional additives and curing agent and continuing to stir for 25 min, placing it in a magnetic field with a magnetic field strength of 2.5T under nitrogen protection for orientation and shaping, then pressing it under a pressure of 850 MPa for 35 s to form it, holding it at 50℃ for 2.5 h, then holding it at 85℃ for 2.5 h, and finally heating it to 170℃ for 55 min to cure it, and then cooling it to room temperature in the furnace to complete the preparation.

[0033] Example 3 A neodymium iron boron magnetic core comprises the following components in parts by weight: The composition includes 90 parts neodymium iron boron magnetic powder, 2.8 parts epoxy resin, 1.2 parts functional additives, 8 parts modified boron nitride, 0.6 parts curing agent, and 1.2 parts lubricant. The epoxy resin is of the type Nanya NPCN-704; The curing accelerator is 1,8-diazabicyclohexane; The lubricant is composed of zinc stearate, oleamide, and dispersant BYK-163 in a mass ratio of 8:5:3.

[0034] The preparation of the modified boron nitride includes: adding nano-boron nitride to anhydrous ethanol and ultrasonically dispersing for 15 min, adding silane coupling agent KH580, heating and stirring, filtering, washing three times with anhydrous ethanol, and drying at 70°C for 10 h to obtain the modified boron nitride; the mass ratio of the nano-boron nitride, anhydrous ethanol and silane coupling agent KH580 is 18:80:2.5.

[0035] The preparation method of the functional additive includes the following steps: 1) Add aminothiazole and DMF to a reaction vessel and mix. Stir at 50°C for 20 min. Under a nitrogen atmosphere and continuous stirring at 400 rpm, add polyphenol compound and glacial acetic acid. Stir at 60°C for 4 h. Remove solvent by rotary evaporation. Wash three times with deionized water. Dry under vacuum at 80°C to constant weight to obtain multi-component compound. The aminothiazole is 2-amino-5-mercapto-1,3,4-thiadiazole, the polyphenol compound is 3,4-dihydroxy-5-methoxybenzaldehyde, and the ratio of aminothiazole, polyphenol compound, glacial acetic acid and DMF is 8.0:11:0.3:100. 2) After stirring and mixing the multi-component compound and the mixed solvent at 45°C for 20 min, slowly add polyethyleneimine and sonicate at 300W power for 10 min, then heat and stir at 50°C for 30 min to obtain the functional additive. The mixed solvent is composed of anhydrous ethanol and DMF in a volume ratio of 3:1, and the mass ratio of the multi-component compound, polyethyleneimine and the mixed solvent is 1.2:6:15.

[0036] A process for preparing a neodymium iron boron magnetic core includes: mixing neodymium iron boron magnetic powder, modified boron nitride, and lubricant at 500 rpm for 15 min, adding epoxy resin and stirring for 10 min, then adding functional additives and curing agent and continuing to stir for 20 min, placing it in a magnetic field with a magnetic field strength of 3.0 T under nitrogen protection for orientation and shaping, then pressing it under a pressure of 900 MPa for 30 s to form it, holding it at 50℃ for 3 h, then holding it at 90℃ for 2 h, and finally heating it to 180℃ for 50 min to cure it, and then cooling it to room temperature in the furnace to complete the preparation.

[0037] Comparative Example 1 Compared with Example 3, the difference is that Comparative Example 1 does not perform step 1), and uses aminothiolthiadiazole instead of the multi-component compound, while the rest are the same.

[0038] Comparative Example 2 Compared with Example 3, the difference is that Comparative Example 2 does not perform step 1), and uses a polyphenol compound instead of a multi-component compound; otherwise, they are the same.

[0039] Comparative Example 3 Compared with Example 3, the difference is that Comparative Example 3 uses benzaldehyde instead of polyphenol compounds, otherwise they are the same.

[0040] Comparative Example 4 Compared with Example 3, the difference in Comparative Example 4 is that polyethyleneimine was not used, while the other components, preparation steps and parameters were the same.

[0041] Comparative Example 5 The difference from Example 3 is that in Comparative Example 5, step 2) does not involve the addition of polyethyleneimine; A process for preparing a neodymium iron boron magnetic core includes: mixing neodymium iron boron magnetic powder, modified boron nitride, and lubricant at 500 rpm for 15 min, adding epoxy resin and stirring for 10 min, then adding functional additives, polyethyleneimine, and curing agent and continuing to stir for 20 min, placing it in a magnetic field with a magnetic field strength of 3.0 T under nitrogen protection for orientation and shaping, then pressing it under a pressure of 900 MPa for 30 s to form it, holding it at 50℃ for 3 h, then holding it at 90℃ for 2 h, and finally heating it to 180℃ for 50 min to cure it, and then cooling it to room temperature in the furnace to complete the preparation.

[0042] Everything else is the same.

[0043] The samples prepared in Examples 1-3 and Comparative Examples 1-5 were tested as follows; Impact resistance: According to GB / T1732-1993, in 5cm increments; Salt spray test performance: Salt spray test conditions: 5% NaCl, 35℃; High temperature resistance: After being treated at 300℃ for 2 hours, the tensile strength before and after treatment was recorded, and the rate of change of tensile strength was calculated. The test results are shown in Table 1.

[0044] Table 1

[0045] As can be seen from the test results in Table 1, compared with Comparative Examples 1-5, the neodymium iron boron magnetic core material prepared by the present invention has excellent mechanical strength, corrosion resistance and high temperature resistance.

[0046] This invention relates to a multi-component compound formed by the chemical bonding of 2-amino-5-mercapto-1,3,4-thiadiazole and 4-dihydroxy-5-methoxybenzaldehyde. This compound contains imine bonds, mercapto groups, phenolic hydroxyl groups, and thiadiazole heterocyclic functional groups. Specifically, the imine bonds and phenolic hydroxyl groups can form hydrogen bonds and covalent bonds with the epoxy resin matrix. The mercaptopropyl functional group introduced by the modified boron nitride after treatment with the silane coupling agent KH580 can enhance the interfacial bonding force with the resin. Simultaneously, the flexible polyamino segments of polyethyleneimine can effectively disperse impact stress, collectively contributing to the excellent impact resistance of the embodiment. The mercapto group, the N atom on the thiadiazole ring, and the phenolic hydroxyl group can react with neodymium. The Fe and Nd metal atoms on the surface of NdFeB magnetic powder form stable coordination bonds, constructing a dense chemical adsorption layer. The polyamino groups of polyethyleneimine further crosslink to form a shielding network, hindering chloride ion penetration and the diffusion of corrosive media, significantly improving the salt spray resistance of NdFeB magnetic core materials, with a testing time of over 800 hours. In addition, the layered structure and silane functional groups of modified boron nitride can enhance the heat resistance of the system, the carbon-nitrogen double bonds and phenolic hydroxyl groups of imine can improve the thermal stability of the resin crosslinking network, and the crosslinking reaction of amino and epoxy groups of polyethyleneimine can reduce molecular chain segment movement at high temperatures, significantly improving the high-temperature resistance of NdFeB magnetic core materials.

[0047] Multi-component compounds and polyethyleneimine can undergo physical and covalent cross-linking with the epoxy groups of epoxy resins. The two work synergistically to enhance the cross-linking density of the resin matrix. At the same time, the flexible segments of polyethyleneimine can disperse impact stress and complement the rigid heterocyclic structure of the multi-component compounds, thereby improving the impact resistance and mechanical strength of the system. In addition, the rigid heterocyclic structure of the multi-component compounds and the imine double bonds can improve the thermal stability of the molecular chains, while the cross-linking network of polyethyleneimine restricts the movement of molecular chains at high temperatures. The two work synergistically to reduce the rate of change of tensile strength after high-temperature treatment.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any indirect modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A neodymium iron boron magnetic core, characterized in that, The following components are included by weight: The composition includes 82-90 parts of neodymium iron boron magnetic powder, 2.2-2.8 parts of epoxy resin, 0.8-1.2 parts of functional additives, 6-8 parts of modified boron nitride, 0.4-0.6 parts of curing agent, and 0.8-1.2 parts of lubricant. The preparation method of the functional additive includes the following steps: 1) Add aminothiazole and DMF to a reaction vessel, mix and heat and stir. Under an inert gas atmosphere and continuous stirring, add polyphenol compound and glacial acetic acid and continue stirring. Remove solvent by rotary evaporation, wash and vacuum dry to obtain multi-component compound. 2) After mixing the multi-component compound and the mixed solvent, slowly add polyethyleneimine, sonicate, heat and stir to obtain the functional additive.

2. The neodymium iron boron magnetic core according to claim 1, characterized in that: The lubricant is one or more of zinc stearate, oleamide and BYK dispersant, and the curing accelerator is 1,8-diazabicyclohexane.

3. A neodymium iron boron magnetic core according to claim 1, characterized in that: The preparation of the modified boron nitride includes: adding nano-boron nitride to anhydrous ethanol and ultrasonically dispersing it, adding a silane coupling agent, heating and stirring, filtering, washing, and drying to obtain the product.

4. A neodymium iron boron magnetic core according to claim 3, characterized in that: The heating and stirring temperature is 50-60℃ and the time is 5-6h. The mass ratio of the nano boron nitride, anhydrous ethanol and silane coupling agent is 15-18:60-80:2.0-2.

5. The silane coupling agent is silane coupling agent KH580.

5. A neodymium iron boron magnetic core according to claim 1, characterized in that: Step 1) The temperature for heating and stirring is 45-50℃ and the stirring time is 20-30 minutes. The temperature for continued stirring is 50-60℃ and the stirring time is 4-5 hours.

6. A neodymium iron boron magnetic core according to claim 1, characterized in that: In step 1), the ratio of aminothiazole, polyphenol compound, glacial acetic acid and DMF is 7.5-8.0:10-11:0.2-0.3:90-100.

7. A neodymium iron boron magnetic core according to claim 1, characterized in that: Step 2) The ultrasonic treatment power is 200-300W and the ultrasonic time is 10-15min. The heating and stirring temperature is 45-50℃ and the stirring time is 30-45min.

8. A neodymium iron boron magnetic core according to claim 1, characterized in that: Step 2) The mixed solvent is composed of anhydrous ethanol and DMF in a volume ratio of 3:1, and the mass ratio of the multi-component compound, polyethyleneimine and the mixed solvent is 1.0-1.2:5-6:12-15.

9. A novel motor, made using a neodymium iron boron magnetic core as described in any one of claims 1 to 8, characterized in that, The novel motor includes a housing and a rotor assembly, a stator assembly, and a shaft disposed within the housing. The rotor assembly includes a rotor core and a neodymium iron boron magnetic core. The rotor assembly, the housing, and the shaft are connected together.

10. The application of the novel electric motor as described in claim 9 in the automotive industry.

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