Neodymium-iron-boron magnet and method for producing the same

Abstract

The application relates to a neodymium-iron-boron magnet and a preparation method thereof, and belongs to the technical field of the neodymium-iron-boron magnet. The neodymium-iron-boron magnet comprises the following components: an acrylic resin, a vinyl epoxy resin, modified neodymium-iron-boron magnetic powder, a graphene composite, a curing agent and a lubricant; the prepared neodymium-iron-boron magnet exhibits excellent stability, mechanical strength and high-temperature resistance, thereby improving the overall magnetic performance of the magnet. In addition, the magnet has low manufacturing cost, excellent performance, high cost performance and can meet the requirements of more scenes.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of neodymium-iron-boron magnets, and relates to a neodymium-iron-boron magnet and a preparation method thereof. BACKGROUND

[0002] Thermosetting or thermoplastic polymers combined with magnetic materials form composite materials with magnetic functions, which are crucial to the development of the national economy. Neodymium-iron-boron magnetic composites composed of magnetic neodymium-iron-boron powder and non-magnetic thermosetting or thermoplastic polymer materials have the advantages of low density, easy processing into high-precision sizes and complex shapes, and excellent mechanical properties, supporting large-scale automated production. Such materials have been increasingly widely used in new energy vehicle motors, home appliances, electronic technology, automation control, computers, satellites and other high-tech fields.

[0003] Bonded neodymium-iron-boron magnets are increasingly in demand due to their diverse shapes and flexible magnetization methods. Given the active nature of neodymium-iron-boron materials, they are highly susceptible to corrosion, so bonded neodymium-iron-boron magnets are usually composed of a neodymium-iron-boron base and a protective layer covering the surface. The usual preparation process includes first preparing a neodymium-iron-boron base, and then coating a protective layer on the surface of the base by methods such as electroplating or electrophoresis. When preparing the neodymium-iron-boron base, acetone is often used as a solvent to prepare a binder solution, and zinc stearate is used as a lubricant to enhance the flowability of the powder. However, zinc stearate is prone to volatilization during the magnet solidification process, leading to surface defects, and as a single lubricant, its effectiveness is limited. In addition, neodymium-iron-boron magnetic powder is prone to adsorbing oxygen and moisture on the surface under high temperature, humidity, electrochemical environment and hydrogen-containing conditions, leading to oxidation and corrosion, which limits its widespread application in industry. SUMMARY

[0004] The present application aims to provide a neodymium-iron-boron magnet and a preparation method thereof. The neodymium-iron-boron magnet prepared by the present application exhibits excellent stability, mechanical strength and high-temperature resistance, thereby improving the overall magnetic performance of the magnet. In addition, the magnet has a reduced production cost, excellent performance, high cost performance, and can meet the needs of more scenarios.

[0005] The object of the present application can be achieved by the following technical solutions:

[0006] A neodymium-iron-boron magnet comprises the following components in parts by weight: 6.2-7.6 parts of acrylic resin, 1.8-2.2 parts of vinyl epoxy resin, 80-90 parts of modified neodymium-iron-boron magnetic powder, 6-8 parts of graphene composite, 0.4-0.6 parts of curing agent and 0.8-1.2 parts of lubricant.

[0007] As a preferred technical scheme of the present application, the lubricant is mixed by zinc stearate and zinc sorbate in a mass ratio of 2:1.2-1.4; the curing agent is one or more of benzoyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, 2,4-dichlorobenzoyl peroxide and dodecanoyl peroxide;

[0008] As a preferred technical scheme of the present application, the preparation method of the modified neodymium-iron-boron magnetic powder comprises the following steps:

[0009] In step S1, the neodymium-iron-boron magnetic powder and anhydrous ethanol are mixed under nitrogen protection, then the temperature is raised and the silane coupling agent is slowly added and stirred, the solvent is removed by rotary evaporation, and vacuum drying is performed until the weight is constant, thereby obtaining the pretreated neodymium-iron-boron magnetic powder.

[0010] In step S2, the pretreated neodymium-iron-boron magnetic powder and anhydrous ethanol are mixed under nitrogen protection and subjected to ultrasonic treatment, the composite monomer and initiator are added and stirred and heated, the solid is filtered, washed with anhydrous ethanol for three times, and vacuum dried until the weight is constant, thereby obtaining the modified neodymium-iron-boron magnetic powder.

[0011] As a preferred technical scheme of the present application, in step S1, the temperature is raised to 60℃; the stirring and mixing is performed at a stirring speed of 500-800 rpm for 6-8 h; the temperature of vacuum drying is 80℃; the mass ratio of the neodymium-iron-boron magnetic powder, anhydrous ethanol and silane coupling agent is 16-18:45-50:1.8-2.1; the silane coupling agent is vinyltriethoxysilane; and the silane coupling agent impregnated neodymium-iron-boron magnetic powder can preliminarily prevent oxidation.

[0012] As a preferred technical scheme of the present application, in step S2, the ultrasonic treatment is performed at a power of 300-400 W for 15-20 min; the stirring and heating is performed at a temperature of 65-72℃ for 5-6 h; the temperature of vacuum drying is 85℃; the mass ratio of the pretreated neodymium-iron-boron magnetic powder, anhydrous ethanol, composite monomer and initiator is 20-22:50-55:3.2-3.5:0.10-0.12; the composite monomer is composed of cardanol, trans-2-hexenal and glycidyl methacrylate in a mass ratio of 3.0-3.4:1.4-1.6:0.8-1.1.

[0013] As a preferred technical scheme of the present application, the preparation method of the graphene composite comprises the following steps: graphene, ethanol solution and cysteine are ultrasonically mixed, the solid is filtered, and vacuum drying is performed until the weight is constant, thereby obtaining the graphene composite.

[0014] As a preferred technical solution of the present application, the ultrasonic mixing is ultrasonic mixing for 20-30 min at a power of 600-800 W; the temperature of the vacuum drying is 80 DEG C; and the mass ratio of the graphene, ethanol solution and cysteine is 10-12:30-40:5.2-5.4.

[0015] A preparation method of the Nd-Fe-B magnet comprises the following steps: mixing an acrylic resin, a vinyl epoxy resin, modified Nd-Fe-B magnetic powder, a graphene composite, a curing agent and a lubricant, and then performing melt extrusion at 110-120 DEG C, and curing at 150-160 DEG C, to obtain the Nd-Fe-B magnet.

[0016] The present application has the following advantages:

[0017] The Nd-Fe-B magnet prepared by the present application has excellent stability, mechanical strength and high-temperature resistance, thereby improving the overall magnetic performance of the magnet. DETAILED DESCRIPTION

[0018] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined invention purposes, the specific embodiments, structures, features and effects according to the present application are described in detail below.

[0019] Embodiment 1

[0020] A Nd-Fe-B magnet comprises the following components in parts by weight: 6.2 parts of an acrylic resin, 1.8 parts of a vinyl epoxy resin, 80 parts of modified Nd-Fe-B magnetic powder, 6 parts of a graphene composite, 0.4 parts of a curing agent and 0.8 parts of a lubricant; the lubricant is obtained by mixing zinc stearate and zinc sorbate at a mass ratio of 2:1.2; and the curing agent is benzoyl peroxide.

[0021] The preparation method of the modified Nd-Fe-B magnetic powder comprises the following steps:

[0022] In step S1, the Nd-Fe-B magnetic powder and anhydrous ethanol are mixed under nitrogen protection, and then a silane coupling agent is slowly added after heating to 60 DEG C, and stirred and mixed at a speed of 500 rpm for 6 h; the solvent is removed by rotary evaporation, and vacuum drying is performed until the weight is constant, to obtain pretreated Nd-Fe-B magnetic powder; the temperature of the vacuum drying is 80 DEG C; the mass ratio of the Nd-Fe-B magnetic powder, anhydrous ethanol and silane coupling agent is 16:45:1.8; and the silane coupling agent is vinyl triethoxysilane.

[0023] Step S2, under the condition of nitrogen protection, the pretreated neodymium iron boron magnetic powder and anhydrous ethanol were mixed and then ultrasonically treated, and then a composite monomer and an initiator were added and stirred and heated, and then the solid was filtered, washed with anhydrous ethanol for three times, and then vacuum dried to constant weight to obtain the modified neodymium iron boron magnetic powder; wherein the ultrasonic treatment was ultrasonic treatment for 15 min under a power of 300 W; the stirring and heating was stirring for 5 h at a temperature of 65 ℃; the temperature of the vacuum drying was 85 ℃; the mass ratio of the pretreated neodymium iron boron magnetic powder, the anhydrous ethanol, the composite monomer and the initiator was 20:50:3.2:0.10; the composite monomer was cashew phenol, trans-2-hexenal and glycidyl methacrylate in a mass ratio of 3.0:1.4:0.8.

[0024] The preparation method of the graphene composite comprises the following steps:

[0025] The graphene, the ethanol solution and the cysteine were ultrasonically mixed, the solid was filtered, vacuum dried to constant weight, and then the graphene composite was obtained. The ultrasonic mixing was ultrasonic mixing for 20 min under a power of 600 W; the temperature of the vacuum drying was 80 ℃; the mass ratio of the graphene, the ethanol solution and the cysteine was 10:30:5.2.

[0026] A preparation method of a neodymium iron boron magnet comprises the following steps: after the acrylic resin, the vinyl epoxy resin, the modified neodymium iron boron magnetic powder, the graphene composite, the curing agent and the lubricant are mixed and then melt-extruded at 110 ℃, the product is obtained after being cured at 150 ℃.

[0027] Example 2

[0028] A neodymium iron boron magnet comprises the following components in parts by weight: 6.9 parts of acrylic resin, 2 parts of vinyl epoxy resin, 85 parts of modified neodymium iron boron magnetic powder, 7 parts of graphene composite, 0.5 parts of curing agent and 1.0 parts of lubricant; the lubricant is obtained by mixing zinc stearate and zinc sorbate in a mass ratio of 2:1.3; the curing agent is benzoyl peroxide;

[0029] The preparation method of the modified neodymium iron boron magnetic powder comprises the following steps:

[0030] Step S1, under the condition of nitrogen protection, the neodymium iron boron magnetic powder and anhydrous ethanol were mixed, and then slowly added and stirred and mixed with a silane coupling agent after being heated, and then the solvent was removed by rotary evaporation, and then vacuum dried to constant weight to obtain the pretreated neodymium iron boron magnetic powder; wherein the heating was heating to 60 ℃; the stirring and mixing was stirring for 7 h at a rotating speed of 650 rpm; the temperature of the vacuum drying was 80 ℃; the mass ratio of the neodymium iron boron magnetic powder, the anhydrous ethanol and the silane coupling agent was 17:48:2; the silane coupling agent was vinyl triethoxysilane;

[0031] Step S2, under the condition of nitrogen protection, the pretreated neodymium iron boron magnetic powder and anhydrous ethanol were mixed and then ultrasonically treated, a composite monomer and an initiator were added and stirred and heated, the solid was obtained by filtration, washed with anhydrous ethanol for three times, and then vacuum dried to constant weight to obtain the modified neodymium iron boron magnetic powder; wherein the ultrasonic treatment was ultrasonic treatment for 18 min at a power of 350 W; the stirring and heating was stirring and heating for 5.5 h at a temperature of 68 ℃; the temperature of the vacuum drying was 85 ℃; the mass ratio of the pretreated neodymium iron boron magnetic powder, anhydrous ethanol, composite monomer and initiator was 21:52:3.4:0.11; the composite monomer was cashew phenol, trans-2-hexenal and glycidyl methacrylate in a mass ratio of 3.2:1.5:1.

[0032] The preparation method of the graphene composite comprises the following steps:

[0033] The graphene, ethanol solution and cysteine were ultrasonically mixed, the solid was obtained by filtration, and then vacuum dried to constant weight to obtain the graphene composite. The ultrasonic mixing was ultrasonic mixing for 25 min at a power of 700 W; the temperature of the vacuum drying was 80 ℃; the mass ratio of the graphene, ethanol solution and cysteine was 11:35:5.3.

[0034] A preparation method of a neodymium iron boron magnet comprises the following steps: after the acrylic resin, vinyl epoxy resin, modified neodymium iron boron magnetic powder, graphene composite, curing agent and lubricant are mixed, melt extrusion is carried out at 115 ℃, and after curing at 155 ℃, the neodymium iron boron magnet is obtained.

[0035] Example 3

[0036] A neodymium iron boron magnet comprises the following components in parts by weight: 7.6 parts of acrylic resin, 2.2 parts of vinyl epoxy resin, 90 parts of modified neodymium iron boron magnetic powder, 8 parts of graphene composite, 0.6 parts of curing agent and 1.2 parts of lubricant; the lubricant is obtained by mixing zinc stearate and zinc sorbate in a mass ratio of 2:1.4; the curing agent is benzoyl peroxide;

[0037] The preparation method of the modified neodymium iron boron magnetic powder comprises the following steps:

[0038] Step S1, under the condition of nitrogen protection, the neodymium iron boron magnetic powder and anhydrous ethanol were mixed, then heated and slowly added with a silane coupling agent and stirred and mixed, the solvent was removed by rotary evaporation, and then vacuum dried to constant weight to obtain the pretreated neodymium iron boron magnetic powder; wherein the heating was heating to 60 ℃; the stirring and mixing was stirring and mixing at a rotating speed of 800 rpm for 8 h; the temperature of the vacuum drying was 80 ℃; the mass ratio of the neodymium iron boron magnetic powder, anhydrous ethanol and silane coupling agent was 18:50:2.1; the silane coupling agent was vinyl triethoxysilane;

[0039] Step S2, under the condition of nitrogen protection, the pretreated neodymium iron boron magnetic powder and anhydrous ethanol are mixed and then ultrasonic treated, the composite monomer and initiator are added and stirred and heated, the solid is obtained by filtration, the solid is washed with anhydrous ethanol for three times, and then vacuum dried to constant weight to obtain the modified neodymium iron boron magnetic powder; wherein the ultrasonic treatment is ultrasonic treatment for 20 min under the power of 400 W; the stirring and heating is stirring and heating for 6 h under the temperature of 72℃; the temperature of the vacuum drying is 85℃; the mass ratio of the pretreated neodymium iron boron magnetic powder, anhydrous ethanol, composite monomer and initiator is 22:55:3.5:0.12; the composite monomer is cashew phenol, trans-2-hexenal and glycidyl methacrylate in a mass ratio of 3.4:1.6:1.1.

[0040] The preparation method of the graphene composite comprises the following steps:

[0041] The graphene, ethanol solution and cysteine are ultrasonic mixed, the solid is obtained by filtration, and then vacuum dried to constant weight to obtain the graphene composite. The ultrasonic mixing is ultrasonic mixing for 30 min under the power of 800 W; the temperature of the vacuum drying is 80℃; the mass ratio of the graphene, ethanol solution and cysteine is 12:40:5.4.

[0042] A preparation method of a neodymium iron boron magnet comprises the following steps: the acrylic resin, vinyl epoxy resin, modified neodymium iron boron magnetic powder, graphene composite, curing agent and lubricant are mixed and then melt extruded at 120℃, and then cured at 160℃ to obtain the neodymium iron boron magnet.

[0043] Comparative Example 1

[0044] Comparative Example 1 is different from Example 3 in that the vinyl triethoxysilane is not used, and the other components, preparation steps and parameters are consistent.

[0045] Comparative Example 2

[0046] Comparative Example 2 is different from Example 3 in that the cashew phenol is not used, and the other components, preparation steps and parameters are consistent.

[0047] Comparative Example 3

[0048] Comparative Example 3 is different from Example 3 in that the trans-2-hexenal is not used, and the other components, preparation steps and parameters are consistent.

[0049] Comparative Example 4

[0050] Comparative Example 4 is different from Example 3 in that the glycidyl methacrylate is not used, and the other components, preparation steps and parameters are consistent.

[0051] Comparative Example 5

[0052] Comparative Example 5 differs from Example 3 in that cysteine is not used, and the remaining components, preparation steps and parameters are identical.

[0053] The Nd-Fe-B magnets prepared in Examples 1-3 and Comparative Examples 1-5 were respectively subjected to the following performance tests, and the test results are shown in Table 1.

[0054] Table 1

[0055]

[0056]

[0057] As can be seen from the test results in Table 1, compared with Comparative Examples 1-5, the Nd-Fe-B magnets prepared in Examples 1-3 have excellent stability, mechanical strength and high-temperature resistance, improve the comprehensive magnetic properties of the magnets, and at the same time, reduce the manufacturing cost, the prepared magnets have good performance, high cost performance, and can meet more occasions.

[0058] As can be seen from the comparative analysis, this is because the surface of the Nd-Fe-B magnetic powder is modified by vinyl triethoxysilane in the application, and unsaturated carbon-carbon double bonds are introduced, so that the composite monomer can occur in-situ polymerization reaction on the surface, cashew phenol can form a protective film on the surface of the magnet material by its own antioxidant properties, prevent oxidation from reducing the mechanical properties and magnetic properties, the carbon long chain contained therein can act as a lubricant, can give the Nd-Fe-B magnetic powder excellent fluidity, reduce the friction between particles, prevent agglomeration, the active functional groups of trans-2-hexenal and glycidyl methacrylate can increase the compatibility between the Nd-Fe-B magnetic powder and the resin, and improve the high-temperature resistance, mechanical strength and toughness of the magnet material; cashew phenol and trans-2-hexenal are both natural materials, have degradability, meet the environmental protection requirements, and trans-2-hexenal can also be used to graft with amino and aldehyde groups, promote the combination between the graphene composite and the modified Nd-Fe-B magnetic powder, and the graphite can also play a lubricating and reinforcing role, significantly improve the mechanical strength and high-temperature resistance of the magnet material.

[0059] The above is only a preferred embodiment of the application, and does not limit the application in any form. Although the application has been disclosed as above with a preferred embodiment, it is not intended to limit the application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the application. Any indirect modification, equivalent change and modification of the above embodiments made in accordance with the technical essence of the application are still within the scope of the technical solution of the application.

Claims

1. A neodymium-iron-boron magnet, characterized in that The composition comprises the following components by weight: 6.2-7.6 parts acrylic resin, 1.8-2.2 parts vinyl epoxy resin, 80-90 parts modified NdFeB magnetic powder, 6-8 parts graphene composite, 0.4-0.6 parts curing agent, and 0.8-1.2 parts lubricant; The preparation method of the modified NdFeB magnetic powder includes the following steps: Step S1: Under nitrogen protection, NdFeB magnetic powder and anhydrous ethanol are mixed, heated, and then a silane coupling agent is slowly added and stirred. After removing the solvent by rotary evaporation, the mixture is vacuum dried to constant weight to obtain pretreated NdFeB magnetic powder. The silane coupling agent is vinyltriethoxysilane. The mass ratio of NdFeB magnetic powder, anhydrous ethanol, and silane coupling agent is 16-18:45-50:1.8-2.

1. Step S2: Under nitrogen protection, pretreated NdFeB magnetic powder and anhydrous ethanol are mixed and ultrasonically treated. A composite monomer and initiator are added, and the mixture is stirred and heated. The solid is filtered, washed three times with anhydrous ethanol, and then vacuum dried to constant weight to obtain modified NdFeB magnetic powder. The mass ratio of the pretreated NdFeB magnetic powder, anhydrous ethanol, composite monomer, and initiator is 20-22:50-55:3.2-3.5:0.10-0.

12. The composite monomer consists of cashew nut shell powder, trans-2-hexenal, and glycidyl methacrylate in a mass ratio of 3.0-3.4:1.4-1.6:0.8-1.

1. The preparation method of the graphene composite includes the following steps: ultrasonically mixing graphene, ethanol solution and cysteine, filtering to obtain solid matter, vacuum drying to constant weight, and obtaining graphene composite.

2. The neodymium-iron-boron magnet according to claim 1, characterized in that: The lubricant is a mixture of zinc stearate and zinc sorbate in a mass ratio of 2:1.2-1.4; the curing agent is one or more of benzoyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, 2,4-dichlorobenzoyl peroxide and dodecyl peroxide.

3. The neodymium-iron-boron magnet according to claim 1, characterized in that: In step S1, the heating is raised to 60°C; the stirring and mixing is carried out at a speed of 500-800 rpm for 6-8 hours; and the vacuum drying temperature is 80°C.

4. The neodymium-iron-boron magnet according to claim 1, characterized in that: In step S2, the ultrasonic treatment is performed at a power of 300-400W for 15-20 minutes; the stirring and heating is performed at a temperature of 65-72℃ for 5-6 hours; and the vacuum drying temperature is 85℃.

5. The neodymium iron boron magnet according to claim 1, characterized in that: In the preparation of the graphene composite, the ultrasonic mixing is performed by ultrasonication at a power of 600-800W for 20-30 minutes; the vacuum drying temperature is 80℃; and the mass ratio of graphene, ethanol solution and cysteine ​​is 10-12:30-40:5.2-5.

4.

6. A method for preparing a neodymium iron boron magnet as described in any one of claims 1 to 5, characterized in that, The preparation method includes the following steps: mixing acrylic resin, vinyl epoxy resin, modified NdFeB magnetic powder, graphene composite, curing agent and lubricant, then performing melt extrusion at 110-120℃ and curing at 150-160℃ to obtain the final product.

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