Bonded neodymium iron boron preparation process and bonded neodymium iron boron magnet

Abstract

The invention discloses a bonded neodymium-iron-boron preparation process and a bonded neodymium-iron-boron magnet, the preparation process comprises the steps that neodymium-iron-boron powder and a binder are mixed according to a certain proportion, the particle size range of the neodymium-iron-boron powder is 1-10 microns, the binder is one or more of epoxy resin, polyamide or polyurethane, and the mass fraction of the binder is 1%-5%; and uniformly mixing: mechanically mixing the neodymium iron boron powder and the binder under the protection of vacuum or inert gas for 10-60 minutes to ensure that the powder and the binder are uniformly distributed. According to the bonded neodymium-iron-boron preparation process and the bonded neodymium-iron-boron magnet, the prepared bonded neodymium-iron-boron magnet has high magnetic performance, high corrosion resistance and good mechanical strength, and the bonded neodymium-iron-boron magnet is suitable for preparing magnets with complex shapes and high performance requirements.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic material preparation, and in particular to a bonded NdFeB preparation process and a bonded NdFeB magnet. Background Art

[0002] NdFeB magnets are widely used in electronics, automobiles, medical and other fields due to their high magnetic energy product, high coercive force and high remanence. However, the traditional preparation process of sintered NdFeB magnets is complicated, and it is difficult to prepare magnets with complex shapes. Bonded NdFeB magnets are formed by mixing NdFeB powder with a binder, and have the advantages of simple preparation process and high shape freedom. However, the existing preparation process of bonded NdFeB magnets has problems such as low magnetic properties and poor corrosion resistance. Therefore, it is urgent to design a bonded NdFeB preparation process and bonded NdFeB magnets to solve the above problems. Summary of the invention

[0003] The purpose of the present invention is to provide a preparation process for high-performance bonded NdFeB magnets. By optimizing the raw material ratio, mixing process, molding process and curing process, a bonded NdFeB magnet with high magnetic properties, high corrosion resistance and good mechanical strength is prepared to solve the above-mentioned shortcomings in the prior art.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] The preparation process of bonded NdFeB includes the following steps:

[0006] S1. Raw material preparation: NdFeB powder and a binder are mixed in a certain proportion, wherein the particle size of the NdFeB powder is in the range of 1-10 μm, the binder is one or more of epoxy resin, polyamide or polyurethane, and the mass fraction of the binder is 1%-5%;

[0007] S2. Mix evenly: Mechanically mix the NdFeB powder and the binder under vacuum or inert gas protection for 10-60 minutes to ensure that the powder and the binder are evenly distributed;

[0008] S3. Molding: The mixed material is placed in a mold and pressed under a pressure of 50-200 MPa at a molding temperature of 20-80 ° C;

[0009] S4 curing: the formed body is cured at a temperature of 80-200 ℃ for 1-5 hours to fully cure the binder;

[0010] S5. Post-processing: Surface treatment of the solidified magnet, including grinding, polishing, and coating with a protective layer, to improve the corrosion resistance and mechanical strength of the magnet;

[0011] Wherein, the mass fraction w of the adhesive is calculated by the following formula:

[0012]

[0013] mAdhesive is the mass of adhesive;

[0014] mNdFeB powder is the mass of NdFeB powder.

[0015] Preferably, the composition of the NdFeB powder is Nd 2 Fe 14 B, and the oxygen content of the NdFeB powder is controlled below 1000ppm.

[0016] Preferably, the binder is epoxy resin, and the curing agent of the epoxy resin is an amine curing agent, and the mass ratio of the curing agent to the epoxy resin is 1:2-1:5.

[0017] Preferably, the mixing step is carried out in a vacuum environment with a vacuum degree of 10 -3 -10 -5 Pa, the mixing step is carried out using a three-dimensional mixer or a ball mill, and the mixing speed is 100-500rpm.

[0018] Preferably, in the molding step, the temperature of the mold is controlled at 30-60° C., and the pressing speed is 1-10 mm / s.

[0019] Preferably, in the curing step, the curing temperature is 120-180° C. and the curing time is 2-4 hours;

[0020] The curing step adopts segmented temperature rising curing, including the following two stages:

[0021] The first stage is curing at 80-100°C for 1 hour;

[0022] The second stage is curing at 150-180°C for 2 hours.

[0023] Preferably, in the post-processing step, the protective layer coated on the surface of the magnet is one of epoxy resin coating, nickel plating or zinc plating, the thickness of the protective layer coated on the surface of the magnet is 5-20 microns, and the protective layer coated on the surface of the magnet is achieved by electroplating, chemical plating or spraying process.

[0024] Preferably, the preparation process further comprises a magnetization step, the magnetization magnetic field strength is 1-3T, and the magnetization time is 1-10 seconds.

[0025] Preferably, the preparation process also includes a magnet performance testing step, and the test items include magnetic energy product, coercive force, remanence and corrosion resistance. The preparation process is suitable for preparing complex-shaped bonded NdFeB magnets, including annular, fan-shaped and special-shaped magnets, whose magnetic energy product is 8-12MGOe and coercive force is 10-15kOe.

[0026] The bonded NdFeB magnet is prepared by using the bonded NdFeB preparation process.

[0027] In the above technical scheme, the bonded NdFeB preparation process and bonded NdFeB magnet provided by the present invention, the bonded NdFeB magnet prepared has high magnetic properties, high corrosion resistance and good mechanical strength, and is suitable for preparing magnets with complex shapes and high performance requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0029] Figure 1 A schematic flow chart of the steps of the bonded NdFeB preparation process and the bonding NdFeB magnet embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0031] like Figure 1 As shown, the bonding NdFeB preparation process provided by the embodiment of the present invention comprises the following steps:

[0032] S1. Raw material preparation: NdFeB powder and a binder are mixed in a certain proportion, wherein the particle size of the NdFeB powder is in the range of 1-10 μm, the binder is one or more of epoxy resin, polyamide or polyurethane, and the mass fraction of the binder is 1%-5%;

[0033] S2. Mix evenly: Mechanically mix the NdFeB powder and the binder under vacuum or inert gas protection for 10-60 minutes to ensure that the powder and the binder are evenly distributed;

[0034] S3. Molding: The mixed material is placed in a mold and pressed under a pressure of 50-200 MPa at a molding temperature of 20-80 ° C;

[0035] S4 curing: the formed body is cured at a temperature of 80-200 ℃ for 1-5 hours to fully cure the binder;

[0036] S5. Post-processing: Surface treatment of the solidified magnet, including grinding, polishing, and coating with a protective layer, to improve the corrosion resistance and mechanical strength of the magnet;

[0037] Wherein, the mass fraction w of the adhesive is calculated by the following formula:

[0038]

[0039] mAdhesive is the mass of adhesive;

[0040] mNdFeB powder is the mass of NdFeB powder.

[0041] Preferably, the composition of the NdFeB powder is Nd 2 Fe 14 B, and the oxygen content of the NdFeB powder is controlled below 1000ppm.

[0042] Preferably, the binder is epoxy resin, and the curing agent of the epoxy resin is an amine curing agent, and the mass ratio of the curing agent to the epoxy resin is 1:2-1:5.

[0043] Preferably, the mixing step is carried out in a vacuum environment with a vacuum degree of 10 -3 -10 -5 Pa, the mixing step is carried out using a three-dimensional mixer or a ball mill, and the mixing speed is 100-500rpm.

[0044] Preferably, in the molding step, the temperature of the mold is controlled at 30-60° C., and the pressing speed is 1-10 mm / s.

[0045] Preferably, in the curing step, the curing temperature is 120-180° C. and the curing time is 2-4 hours;

[0046] The curing step adopts segmented temperature rising curing, including the following two stages:

[0047] The first stage is curing at 80-100°C for 1 hour;

[0048] The second stage is curing at 150-180°C for 2 hours.

[0049] Preferably, in the post-processing step, the protective layer coated on the surface of the magnet is one of epoxy resin coating, nickel plating or zinc plating, the thickness of the protective layer coated on the surface of the magnet is 5-20 microns, and the protective layer coated on the surface of the magnet is achieved by electroplating, chemical plating or spraying process.

[0050] Preferably, the preparation process further comprises a magnetization step, the magnetization magnetic field strength is 1-3T, and the magnetization time is 1-10 seconds.

[0051] Preferably, the preparation process also includes a magnet performance testing step, and the test items include magnetic energy product, coercive force, remanence and corrosion resistance. The preparation process is suitable for preparing complex-shaped bonded NdFeB magnets, including annular, fan-shaped and special-shaped magnets, whose magnetic energy product is 8-12MGOe and coercive force is 10-15kOe.

[0052] The bonded NdFeB magnet is prepared by using the bonded NdFeB preparation process.

[0053] Embodiment 1,

[0054] S1. Raw material preparation:

[0055] NdFeB powder: particle size is 5 microns, composition is Nd 2 Fe 14 B, oxygen content is 800ppm;

[0056] Binder: epoxy resin, mass fraction is 3%;

[0057] Calculate the mass of the binder according to the formula;

[0058]

[0059] Assuming the mass of NdFeB powder is 97g, the mass of binder is 3g.

[0060] S2. Mix well:

[0061] NdFeB powder and epoxy resin were placed in a vacuum environment (vacuum degree 10 -4 The mixture was mixed in a three-dimensional mixer with a mixing time of 30 minutes and a mixing speed of 300 rpm.

[0062] S3. Molding:

[0063] The uniformly mixed material was placed in a mold and pressed at a pressure of 100 MPa, a mold temperature of 50° C., and a pressing speed of 5 mm / s.

[0064] S4. Curing:

[0065] The formed body was cured at 150°C for 3 hours, with staged temperature rise curing: the first stage was cured at 100°C for 1 hour, and the second stage was cured at 150°C for 2 hours.

[0066] S5. Post-processing:

[0067] The solidified magnets were surface ground and polished, and then electroplated with a nickel protective layer with a thickness of 10 microns.

[0068] S6. Performance test:

[0069] Magnetic energy product: 10.5MGOe;

[0070] Coercivity: 12.8kOe;

[0071] Remanence: 1.2T;

[0072] Corrosion resistance: Passed the salt spray test for 48 hours without corrosion.

[0073] Example 2

[0074] S1. Raw material preparation:

[0075] NdFeB powder: particle size is 8 microns, composition is Nd 2 Fe 14 B, oxygen content is 600ppm;

[0076] Binder: polyurethane, mass fraction is 4%;

[0077] Calculate the binder mass according to the formula:

[0078]

[0079] Assuming the mass of NdFeB powder is 96g, the mass of binder is 4g.

[0080] S2. Mix well:

[0081] The NdFeB powder and polyurethane were mixed in a ball mill under the protection of inert gas (nitrogen) with a mixing time of 40 minutes and a mixing speed of 200 rpm.

[0082] S3. Molding:

[0083] The uniformly mixed material is placed in a mold and pressed at a pressure of 150 MPa, a mold temperature of 60° C., and a pressing speed of 3 mm / s.

[0084] S4. Curing:

[0085] The formed green body was cured at 180°C for 2 hours, using staged temperature rise curing: the first stage was cured at 80°C for 1 hour, and the second stage was cured at 180°C for 1 hour.

[0086] S5. Post-processing:

[0087] The cured magnets were surface ground and polished, and then sprayed with an epoxy resin protective layer with a thickness of 15 microns.

[0088] S6. Performance test:

[0089] Magnetic energy product: 11.2MGOe;

[0090] Coercivity: 13.5kOe;

[0091] Remanence: 1.25T;

[0092] Corrosion resistance: Passed the salt spray test for 72 hours without corrosion.

[0093] Embodiment 3:

[0094] S1. Raw material preparation:

[0095] NdFeB powder: particle size is 3 microns, composition is Nd 2 Fe 14 B, oxygen content is 500ppm;

[0096] Binder: polyamide, mass fraction is 2%;

[0097] Calculate the binder mass according to the formula:

[0098]

[0099] Assuming the mass of NdFeB powder is 98g, the mass of binder is 2g.

[0100] S2. Mix well:

[0101] NdFeB powder and polyamide were placed in a vacuum environment (vacuum degree 10 -5 The mixing time was 20 minutes and the mixing speed was 400 rpm.

[0102] S3. Molding:

[0103] The uniformly mixed material is placed in a mold and pressed at a pressure of 80 MPa, a mold temperature of 40° C., and a pressing speed of 8 mm / s.

[0104] S4. Curing:

[0105] The formed body was cured at 120°C for 4 hours, using staged temperature rise curing: the first stage was cured at 80°C for 1 hour, and the second stage was cured at 120°C for 3 hours.

[0106] S5. Post-processing:

[0107] The solidified magnets were surface ground and polished, and then chemically plated with a zinc protective layer with a thickness of 8 microns.

[0108] S6. Performance test:

[0109] Magnetic energy product: 9.8MGOe;

[0110] Coercivity: 11.5kOe;

[0111] Remanence: 1.15T;

[0112] Corrosion resistance: Passed the salt spray test for 60 hours without corrosion.

[0113] The invention provides a preparation process of a high-performance bonded NdFeB magnet. By optimizing the raw material ratio, mixing process, molding process and curing process, a bonded NdFeB magnet with high magnetic properties, high corrosion resistance and good mechanical strength is prepared, which has broad application prospects.

[0114] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A process for preparing bonded NdFeB, characterized in that: The following steps are involved: S1. Raw material preparation: NdFeB powder and a binder are mixed in a certain proportion, wherein the particle size of the NdFeB powder is in the range of 1-10 μm, the binder is one or more of epoxy resin, polyamide or polyurethane, and the mass fraction of the binder is 1%-5%; S2. Mix evenly: Mechanically mix the NdFeB powder and the binder under vacuum or inert gas protection for 10-60 minutes to ensure that the powder and the binder are evenly distributed; S3. Molding: The mixed material is placed in a mold and pressed under a pressure of 50-200 MPa at a molding temperature of 20-80 ° C; S4 curing: the formed body is cured at a temperature of 80-200 ℃ for 1-5 hours to fully cure the binder; S5. Post-processing: Surface treatment of the solidified magnet, including grinding, polishing, and coating with a protective layer, to improve the corrosion resistance and mechanical strength of the magnet; Wherein, the mass fraction w of the adhesive is calculated by the following formula: mAdhesive is the mass of adhesive; mNdFeB powder is the mass of NdFeB powder.

2. The process for preparing bonded NdFeB according to claim 1, characterized in that: The composition of the NdFeB powder is Nd2Fe 14 B, and the oxygen content of the NdFeB powder is controlled below 1000ppm.

3. The process for preparing bonded NdFeB according to claim 1, characterized in that: The binder is epoxy resin, and the curing agent of the epoxy resin is an amine curing agent, and the mass ratio of the curing agent to the epoxy resin is 1:2-1:

5.

4. The process for preparing bonded NdFeB according to claim 1, characterized in that: The mixing step is carried out in a vacuum environment with a vacuum degree of 10 -3 -10 -5 Pa, the mixing step is carried out using a three-dimensional mixer or a ball mill, and the mixing speed is 100-500rpm.

5. The process for preparing bonded NdFeB according to claim 1, characterized in that: In the molding step, the temperature of the mold is controlled at 30-60° C., and the pressing speed is 1-10 mm / s.

6. The process for preparing bonded NdFeB according to claim 1, characterized in that: In the curing step, the curing temperature is 120-180° C. and the curing time is 2-4 hours; The curing step adopts segmented temperature rising curing, including the following two stages: The first stage is curing at 80-100°C for 1 hour; The second stage is curing at 150-180°C for 2 hours.

7. The process for preparing bonded NdFeB according to claim 1, characterized in that: In the post-processing step, the protective layer coated on the surface of the magnet is one of epoxy resin coating, nickel plating or zinc plating, the thickness of the protective layer coated on the surface of the magnet is 5-20 microns, and the protective layer coated on the surface of the magnet is achieved by electroplating, chemical plating or spraying process.

8. The process for preparing bonded NdFeB according to claim 1, characterized in that: The preparation process also includes a magnetization step, the magnetization magnetic field intensity is 1-3T, and the magnetization time is 1-10 seconds.

9. The process for preparing bonded NdFeB according to claim 1, characterized in that: The preparation process also includes a magnet performance testing step, and the test items include magnetic energy product, coercive force, remanence and corrosion resistance. The preparation process is suitable for preparing complex-shaped bonded NdFeB magnets, including annular, fan-shaped and special-shaped magnets, whose magnetic energy product is 8-12MGOe and coercive force is 10-15kOe.

10. Bonding NdFeB magnets, characterized in that, The bonded NdFeB is prepared using the bonded NdFeB preparation process described in any one of claims 1 to 9.

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