Manufacturing method for rare earth permanent magnet material

Abstract

The present invention provides a method for producing a rare earth permanent magnet material, which includes one or more deep-cooling and tempering treatments. When the method includes one deep-cooling and tempering treatment, the deep-cooling is performed between the sintering and tempering treatments or after the tempering treatment. When the method includes two or more deep-cooling and tempering treatments, at least one deep-cooling is performed between the sintering and tempering treatments, and at the same time, at least one deep-cooling is performed after the tempering treatment. The method for producing a rare earth permanent magnet material has the advantages of fine structure, homogenized structure, and rapid and easy processing, and can effectively improve the mechanical properties of the rare earth permanent magnet material and maintain excellent magnetic properties.

Description

[Technical Field]

[0001] The present invention relates to the field of magnetic material manufacturing technology, and to a method for manufacturing rare earth permanent magnet materials. [Background technology]

[0002] Rare earth permanent magnet materials are widely used in many fields due to their excellent magnetic properties. However, like many intermetallic compounds, rare earth permanent magnet materials are very brittle at room temperature, making their mechanical processing difficult. During use, magnets are prone to cracking and edge shedding, which adversely affects the stability of permanent magnet devices. This limits the application of rare earth permanent magnet materials in precision instruments and those with strict requirements for shock resistance and vibration resistance.

[0003] Currently, there are studies to improve mechanical properties using methods such as surface modification, element doping, and oxide addition. However, although the mechanical properties have improved, the magnetic properties are clearly degraded. Existing methods for improving the mechanical properties of rare earth permanent magnet materials sacrifice magnetic properties and are difficult to apply to actual manufacturing processes due to the complex and costly process.

[0004] Cryogenic treatment refers to the treatment of workpieces at temperatures below -130°C using liquid nitrogen as a refrigerant, and can significantly improve the mechanical properties of black metals and non-ferrous metals. However, the application of cryogenic treatment to optimize the mechanical properties of rare earth permanent magnet materials has not been reported. Summary of the Invention

[0005] In response to the problem that rare earth permanent magnetic materials have high room temperature brittleness and that existing methods for improving the mechanical properties of rare earth permanent magnetic materials sacrifice their magnetic properties, the present invention provides a method for improving the mechanical properties of rare earth permanent magnetic materials, which can effectively improve the mechanical properties of rare earth permanent magnetic materials while maintaining excellent magnetic properties.

[0006] The object of the present invention is achieved by the following technical solutions: A method for producing a rare earth permanent magnet material, the method comprising one or more deep cooling and tempering treatments.

[0007] Preferably, the manufacturing method includes one deep-cooling and tempering treatment, the deep-cooling treatment being performed between the sintering treatment and the tempering treatment, or the deep-cooling treatment being performed after the tempering treatment.

[0008] Preferably, the manufacturing method includes two or more deep-freezing and tempering treatments, at least one deep-freezing treatment being performed between the sintering treatment and the tempering treatment, and at least one deep-freezing treatment being performed after the tempering treatment.

[0009] Preferably, the manufacturing method includes two deep-freezing and tempering processes: a first deep-freezing process is performed after sintering, then a tempering process is performed, and then a second deep-freezing process is performed.

[0010] Preferably, the manufacturing method includes three deep cooling and tempering steps.

[0011] Preferably, the sintering process is followed by a first deep-freezing process, then a tempering process, then a second deep-freezing process, and then a third deep-freezing process. Alternatively, after the sintering treatment, a first deep-freezing treatment is performed, then a second deep-freezing treatment is performed, then a tempering treatment is performed, and then a third deep-freezing treatment is performed.

[0012] Preferably, the rare earth permanent magnet material is RFe 14 B series, SmCo5 series, Sm2Co 17 system, SmFe 17 N x The present invention includes one of the following rare earth permanent magnet material alloys:

[0013] Preferably, the manufacturing method includes raw material blending, melting and refining, powder preparation, oriented powder compaction, sintering, deep-freezing, and tempering. Alternatively, the manufacturing method includes blending raw materials, melting and smelting, powder preparation, oriented powder compaction, sintering, tempering, and deep-cooling.

[0014] Preferably, the manufacturing method includes blending raw materials, melting and refining, powder preparation, oriented powder compaction, sintering, a first deep-cooling treatment, tempering, and a second deep-cooling treatment.

[0015] Preferably, the manufacturing method includes raw material blending, melting and refining, powder preparation, oriented powder compaction, sintering, a first deep-freezing treatment, tempering, a second deep-freezing treatment, and a third deep-freezing treatment. Alternatively, the manufacturing method includes blending raw materials, melting and smelting, powder preparation, oriented powder compaction, sintering, a first deep-freezing treatment, a second deep-freezing treatment, tempering, and a third deep-freezing treatment.

[0016] Preferably, the cryogenic treatment step includes placing the compact in a cryogenic treatment system, cooling it down to a cryogenic treatment temperature, cryogenically treating it, and then removing it. Alternatively, the deep-freezing step may involve placing the compact directly into liquid nitrogen, deep-freezing the compact, and then removing the compact.

[0017] Preferably, the deep-cooling temperature is ≦−130° C. and / or the deep-cooling time is 1 to 500 minutes.

[0018] Preferably, the deep-cooling temperature is ≦−160° C. and / or the deep-cooling time is 10 to 400 minutes.

[0019] Preferably, the deep-cooling temperature is ≦−190° C. and / or the deep-cooling time is 20 to 300 minutes.

[0020] Preferably, the tempering treatment is one of a tempering diffusion treatment, an aging treatment, and a nitriding treatment.

[0021] Preferably, the tempering and diffusion treatment includes primary tempering at 800 to 950°C for 2 to 6 hours, followed by cooling to 400 to 650°C at a cooling rate of 0.3 to 1.3°C / min and secondary tempering for 2 to 6 hours. The aging treatment involves maintaining the temperature at 800 to 950°C for 10 to 25 hours, then lowering the temperature to 400 to 550°C at a cooling rate of 0.3 to 1.3°C / min, and maintaining the temperature for 2 to 12 hours. The nitriding treatment involves maintaining the temperature at 400 to 650° C. for 1 to 20 hours in nitrogen gas and / or ammonia gas.

[0022] Another object of the present invention is to provide a rare earth permanent magnet material produced by the above-mentioned production method.

[0023] Compared with the prior art, the present invention has the following advantages: 1. In the present invention, the first deep-cooling treatment is performed after sintering. The temperature reduction causes the compact to shrink in volume, resulting in internal structural defects such as stress and dislocations. This is beneficial to the precipitation and growth of precipitation phases during the tempering process, resulting in a uniform and complete structure and excellent magnetic properties. 2. The present invention is advantageous in improving the bending properties of rare earth permanent magnet materials by performing a second deep cooling treatment after the tempering treatment. Compared with methods for improving mechanical properties such as surface modification, the method of the present invention is simpler and more effective, less costly, easier to operate, and more suitable for mass production. 3. The method for producing rare earth permanent magnet material of the present invention includes two or more deep-cooling and tempering processes, at least one deep-cooling process between sintering and tempering, and at least one deep-cooling process after tempering, which is beneficial for improving the bending and magnetic properties of the material. 4. The method of the present invention for improving the mechanical properties of rare earth permanent magnet materials does not require the introduction of non-magnetic phases and does not degrade the magnetic properties, as opposed to methods such as element doping or oxide addition. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic diagram showing the dimensions, orientation, and direction of force applied to a three-point bending test sample. [Figure 2]FIG. 2 is a three-point bending curve diagram of the samarium-cobalt permanent magnet produced in Example 1 and the samarium-cobalt permanent magnet produced in Comparative Example 1. [Figure 3] FIG. 2 is a demagnetization curve diagram of the samarium-cobalt permanent magnet produced in Example 1 and the samarium-cobalt permanent magnet produced in Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the method for producing a rare earth permanent magnet material of the present invention will be described in detail, but these embodiments are merely illustrative and the disclosure of the present invention is not limited thereto.

[0026] A method for producing a rare earth permanent magnet material, the method comprising one or more deep cooling and tempering treatments.

[0027] In some embodiments of the present invention, the manufacturing method includes one deep-chilling and tempering treatment. The deep-chilling is performed between the sintering and tempering treatments, or after the tempering treatment. The manufacturing method includes the sintering followed by the deep-chilling and then the tempering treatment. Alternatively, the sintering followed by the tempering and then the deep-chilling treatment. Preferably, the manufacturing method includes the sintering followed by the tempering and then the deep-chilling treatment. When the manufacturing method includes one deep-chilling treatment, the deep-chilling treatment is performed after the tempering treatment, imparting superior bending strength and magnetic properties to the rare earth permanent magnet material.

[0028] In some embodiments of the present invention, the manufacturing method includes two or more deep-cooling and tempering processes, at least one deep-cooling process being performed between the sintering and tempering processes, while at least one deep-cooling process being performed after the tempering process.

[0029] In some embodiments of the present invention, the manufacturing method preferably includes two deep-freezing treatments and a tempering treatment. Specifically, after the sintering treatment, a first deep-freezing treatment is performed, followed by a tempering treatment, and then a second deep-freezing treatment. After the two deep-freezing treatments, the rare earth permanent magnet material has better bending strength and magnetic performance.

[0030] In some embodiments of the present invention, the manufacturing method includes three deep-freezing treatments and tempering treatments. Preferably, the manufacturing method includes a sintering process followed by a first deep-freezing treatment, then a tempering treatment, then a second deep-freezing treatment, and then a third deep-freezing treatment. Alternatively, the manufacturing method includes a sintering process followed by a first deep-freezing treatment, then a second deep-freezing treatment, then a tempering treatment, and then a third deep-freezing treatment.

[0031] In some embodiments of the present invention, the deep-chilling temperature is ≦−130°C, preferably ≦−160°C, and more preferably ≦−190°C.

[0032] In some embodiments of the present invention, the deep-cooling treatment time is 1 to 500 minutes, preferably 10 to 400 minutes, and more preferably 20 to 300 minutes.

[0033] In some embodiments of the present invention, the cryogenic treatment step includes placing the compact in a cryogenic treatment system, performing cryogenic treatment when the temperature is reduced to a cryogenic treatment temperature, and then removing the compact. After being removed from the cryogenic treatment system, the compact is allowed to warm to room temperature before proceeding to the next step.

[0034] In some embodiments of the present invention, the deep-freezing step includes placing the compact directly in liquid nitrogen, performing the deep-freezing treatment, and then removing the compact. After being removed from the liquid nitrogen, the compact is warmed to room temperature before proceeding to the next step.

[0035] In some embodiments of the present invention, the tempering temperature T2≧200°C, more preferably the tempering temperature T2≧400°C.

[0036] In some embodiments of the present invention, the tempering treatment includes treating at 800 to 950° C. for 2 to 25 hours, then decreasing the temperature to 400 to 650° C. and treating for 2 to 15 hours.

[0037] In some embodiments of the present invention, the rare earth permanent magnet material is RFe 14 B-based (R is one or more of La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, and Y), SmCo5-based, Sm2Co 17 system, SmFe 17 N x The rare earth permanent magnet material may be in the form of a powder or a lump, and may be one of, but not limited to, a 1:12 type rare earth permanent magnet alloy.

[0038] Rare earth permanent magnet material is R2Fe 14 For B-based rare earth permanent magnet alloys, tempering is a diffusion tempering process. 17 For rare earth permanent magnet alloys of the SmFe and 1:12 type, tempering is an aging treatment. 17 N x In the case of a rare earth-based permanent magnet material alloy, the tempering treatment is a nitriding treatment.

[0039] The tempering diffusion treatment involves primary tempering at 800 to 950°C for 2 to 6 hours, followed by cooling down to 400 to 650°C at a cooling rate of 0.3 to 1.3°C / min and secondary tempering for 2 to 6 hours.

[0040] The aging treatment involves maintaining the temperature at 800 to 950°C for 10 to 25 hours, then lowering the temperature to 400 to 550°C at a cooling rate of 0.3 to 1.3°C / min, and maintaining the temperature for 2 to 12 hours.

[0041] The nitriding treatment involves maintaining the temperature at 400 to 650° C. for 1 to 20 hours in an atmosphere of nitrogen gas, ammonia gas, or a mixture of nitrogen gas and ammonia gas.

[0042] In some embodiments of the present invention, the sintering process may further include blending raw materials, melting and refining, powder preparation, and oriented powder compaction.

[0043] In some embodiments of the present invention, the manufacturing method includes raw material blending, melting and refining, powder preparation, oriented powder compaction, sintering, deep-cooling, and tempering.

[0044] In some embodiments of the present invention, the manufacturing method includes raw material blending, melting and refining, powder preparation, oriented powder compaction, sintering, tempering, and deep-cooling.

[0045] In some embodiments of the present invention, the manufacturing method includes raw material blending, melting and refining, powder preparation, oriented powder compaction, sintering, a first deep-cooling treatment, tempering, and a second deep-cooling treatment.

[0046] In some embodiments of the present invention, the manufacturing method includes raw material blending, melting and refining, powder preparation, oriented powder compaction, sintering, a first deep-freezing treatment, a tempering treatment, a second deep-freezing treatment, and a third deep-freezing treatment.

[0047] In some embodiments of the present invention, the manufacturing method includes raw material blending, melting and refining, powder preparation, oriented powder compaction, sintering, a first deep-freezing treatment, a second deep-freezing treatment, a tempering treatment, and a third deep-freezing treatment.

[0048] The steps of raw material blending, melting and refining, powder preparation, oriented powder compaction, and sintering are not limited, and it is sufficient to use process steps that are commonly used in this field.

[0049] The specific steps of raw material blending, melting and refining, powder preparation, oriented powder compaction, and sintering are listed as follows.

[0050] Raw material blending: Each raw material is weighed and blended according to the stoichiometric ratio of the molecular formula of the rare earth permanent magnet material.

[0051] Melting and smelting: The blended raw materials are placed in a vacuum melting and smelting furnace and melted and smelted at a temperature of 1200-1800°C. The melted raw materials form a homogeneous alloy solution, which is then poured into a cooled copper mold to obtain an alloy ingot.

[0052] Powder production: The alloy ingot is mechanically crushed into powder of 100 to 500 m, and the powder is further pulverized into powder with an average particle size of 2 to 6 m using a jet mill process.

[0053] Oriented powder compaction: Oriented compaction is performed in a magnetic field of 1 to 5 T, and after sealing, a cold isostatic press is used to maintain pressure at 150 to 200 MPa for 10 to 40 seconds to compact the powder to obtain a compact.

[0054] Sintering treatment: The compact is sintered at 1150-1250°C for 1-5 hours under inert gas protection, and then solution treated at 1130-1210°C for 1-5 hours under inert gas protection, followed by cooling to room temperature. Alternatively, the compact is vacuum sintered at 1020-1100°C for 2-8 hours.

[0055] The technical solutions of the present invention will be further described below through specific examples and the accompanying drawings. However, it should be understood that the specific examples described herein are only used to help understand the present invention and are not intended to particularly limit the present invention. In addition, the accompanying drawings used in this specification are only used to better explain the disclosure of the present invention and do not limit the scope of protection. Unless otherwise specified, the raw materials used in the examples of the present invention are raw materials commonly used in the technical field, and the methods used in the examples are conventional methods in the technical field. Example 1

[0056] Raw material composition: Sm2Co used in this embodiment 17The raw material composition of the samarium-cobalt permanent magnet material was, in weight percent, 24.75% samarium, 49.70% cobalt, 18.97% iron, 4.37% copper, and the remainder zirconium, with the purity of Sm, Co, and Cu being ≥ 99.9%, and the purity of Fe and Zr being ≥ 99.5%. Melting and refining: The blended raw materials were melted and refined in a vacuum high-frequency induction electric furnace, and high-purity argon gas was introduced. The melted raw materials formed a homogeneous alloy solution, which was then poured into a cooled copper mold to obtain an alloy ingot. Powder preparation: The ingots were mechanically crushed into powders of 100-300 μm, and the powders were further pulverized into powders with an average particle size of 4.6 μm using a jet mill process. Orientation compaction: Orientation compaction was performed under a magnetic field of 2 T, and after sealing, a cold isostatic press was used to maintain a pressure of 170 MPa for 20 seconds to compact the powder, thereby obtaining a green body. Sintering and solution treatment: The compact was sintered at 1206°C for 2 hours under argon gas protection, and then solution treated at 1190°C for 2 hours under argon gas protection, and then air-cooled to room temperature. First deep-freezing treatment: The molded body was placed directly in liquid nitrogen and subjected to deep-freezing treatment for 0.5 hours, then removed and placed in the air to allow the temperature to rise naturally. Aging treatment: Under argon gas protection, the material was aged at 840°C for 12 hours, then cooled to 400°C at a rate of 0.5°C / min, kept at that temperature for 3 hours, and then air-cooled to room temperature to obtain a magnet. Second deep-freezing treatment: The molded body was placed directly in liquid nitrogen and subjected to deep-freezing treatment for 1 hour, then removed and placed in the air to allow the temperature to rise naturally. <Example 2>

[0057] Raw material composition: Sm2Co used in this embodiment 17 The raw material composition of the samarium-cobalt permanent magnet material was, in weight percent, 25.76% samarium, 57.23% cobalt, 6.72% iron, 7.23% copper, and the remainder zirconium, with the purity of Sm, Co, and Cu being ≥ 99.9%, and the purity of Fe and Zr being ≥ 99.5%. Melting and refining: The blended raw materials were melted and refined in a vacuum high-frequency induction electric furnace, and high-purity argon gas was introduced. The melted raw materials formed a homogeneous alloy solution, which was then poured into a cooled copper mold to obtain an alloy ingot. Powder preparation: The ingots were mechanically crushed into powders of 100-300 μm, and the powders were further pulverized into powders with an average particle size of 4.5 μm using a jet mill process. Orientation compaction: Orientation compaction was performed under a magnetic field of 2 T, and after sealing, a cold isostatic press was used to maintain a pressure of 160 MPa for 25 seconds to compact the powder, thereby obtaining a green body. Sintering and solution treatment: The compact was sintered at 1233°C for 2 hours under argon gas protection, and then solution treated at 1180°C for 2 hours under argon gas protection, and then air-cooled to room temperature. First deep-freezing treatment: The molded body was placed directly in liquid nitrogen and subjected to deep-freezing treatment for 0.5 hours, then removed and placed in the air to allow the temperature to rise naturally. Aging treatment: Under argon gas protection, the material was aged at 840°C for 20 hours, then cooled to 400°C at a cooling rate of 0.5°C / min, kept at that temperature for 10 hours, and then air-cooled to room temperature to obtain a magnet. Second deep-freezing treatment: The molded body was placed directly in liquid nitrogen and subjected to deep-freezing treatment for 1 hour, then removed and placed in the air to allow the temperature to rise naturally. Example 3

[0058] Raw material composition: Sm2Co used in this embodiment 17 The raw material composition of the samarium-cobalt permanent magnet material was, in weight percent, 24.75% samarium, 49.70% cobalt, 18.97% iron, 4.37% copper, and the remainder zirconium, with the purity of Sm, Co, and Cu being ≥ 99.9%, and the purity of Fe and Zr being ≥ 99.5%. Melting and refining: The blended raw materials were melted and refined in a vacuum high-frequency induction electric furnace, and high-purity argon gas was introduced. The melted raw materials formed a homogeneous alloy solution, which was then poured into a cooled copper mold to obtain an alloy ingot. Powder preparation: The ingots were mechanically crushed into powders of 100-300 μm, and the powders were further pulverized into powders with an average particle size of 4.6 μm using a ball mill process. Orientation compaction: Orientation compaction was performed under a magnetic field of 2 T, and after sealing, a cold isostatic press was used to maintain a pressure of 170 MPa for 20 seconds to compact the powder, thereby obtaining a green body. Sintering and solution treatment: The compact was sintered at 1206°C for 2 hours under argon gas protection, and then solution treated at 1190°C for 2 hours under argon gas protection, and then air-cooled to room temperature. Aging treatment: Under argon gas protection, the material was aged at 840°C for 12 hours, then cooled to 400°C at a rate of 0.5°C / min, kept at that temperature for 3 hours, and then air-cooled to room temperature to obtain a magnet. Deep-freezing treatment: The molded body was placed directly in liquid nitrogen and subjected to deep-freezing treatment for 1 hour, then removed and placed in the air to allow the temperature to rise naturally. Example 4

[0059] Raw material composition: Sm2Co used in this embodiment 17 The raw material composition of the samarium-cobalt permanent magnet material was, in weight percent, 24.75% samarium, 49.70% cobalt, 18.97% iron, 4.37% copper, and the remainder zirconium, with the purity of Sm, Co, and Cu being ≥ 99.9%, and the purity of Fe and Zr being ≥ 99.5%. Melting and refining: The blended raw materials were melted and refined in a vacuum high-frequency induction electric furnace, and high-purity argon gas was introduced. The melted raw materials formed a homogeneous alloy solution, which was then poured into a cooled copper mold to obtain an alloy ingot. Powder preparation: The ingots were mechanically crushed into powders of 100-300 μm, and the powders were further pulverized into powders with an average particle size of 4.7 μm using a jet mill process. Orientation compaction: Orientation compaction was performed under a magnetic field of 2 T, and after sealing, a cold isostatic press was used to maintain a pressure of 170 MPa for 20 seconds to compact the powder, thereby obtaining a green body. Sintering and solution treatment: The compact was sintered at 1206°C for 2 hours under argon gas protection, and then solution treated at 1190°C for 2 hours under argon gas protection, and then air-cooled to room temperature. First deep-freezing treatment: The molded body was placed directly in liquid nitrogen and subjected to deep-freezing treatment for 0.5 hours, then removed and placed in the air to allow the temperature to rise naturally. Aging treatment: Under argon gas protection, the material was aged at 840°C for 12 hours, then cooled to 400°C at a rate of 0.5°C / min, kept at that temperature for 3 hours, and then air-cooled to room temperature to obtain a magnet. Second deep-freezing treatment: The molded body was placed directly in liquid nitrogen and subjected to deep-freezing treatment for 0.5 hours, then removed and placed in the air to allow the temperature to rise naturally. Third deep-freezing treatment: The molded body was again directly placed in liquid nitrogen and subjected to deep-freezing treatment for 1 hour, after which it was taken out and placed in the air to be allowed to warm naturally. <Example 5>

[0060] Raw material composition: Sm2Co used in this embodiment 17 The raw material composition of the samarium-cobalt permanent magnet material was, in weight percent, 24.75% samarium, 49.70% cobalt, 18.97% iron, 4.37% copper, and the remainder zirconium, with the purity of Sm, Co, and Cu being ≥ 99.9%, and the purity of Fe and Zr being ≥ 99.5%. Melting and refining: The blended raw materials were melted and refined in a vacuum high-frequency induction electric furnace, and high-purity argon gas was introduced. The melted raw materials formed a homogeneous alloy solution, which was then poured into a cooled copper mold to obtain an alloy ingot. Powder preparation: The ingots were mechanically crushed into powders of 100-300 μm, and the powders were further pulverized into powders with an average particle size of 4.6 μm using a jet mill process. Orientation compaction: Orientation compaction was performed under a magnetic field of 2 T, and after sealing, a cold isostatic press was used to maintain a pressure of 170 MPa for 20 seconds to compact the powder, thereby obtaining a green body. Sintering and solution treatment: The compact was sintered at 1206°C for 2 hours under argon gas protection, and then solution treated at 1190°C for 2 hours under argon gas protection, and then air-cooled to room temperature. First deep-freezing treatment: The molded body was placed in a deep-freezing treatment system and cooled to -190°C at a temperature drop rate of 5°C / min, then kept at that temperature for 0.5 hours, removed and placed in air to allow the temperature to rise naturally. Aging treatment: Under argon gas protection, the material was aged at 840°C for 12 hours, then cooled to 400°C at a rate of 0.5°C / min, kept at that temperature for 3 hours, and then air-cooled to room temperature to obtain a magnet. Second deep-freezing treatment: The molded body was placed in a deep-freezing treatment system and cooled to -190°C at a temperature drop rate of 10°C / min, then kept at that temperature for 0.5 hours, removed, placed in air, and allowed to warm naturally. Example 6

[0061] Raw material composition: Sm2Co used in this embodiment 17 The raw material composition of the samarium-cobalt permanent magnet material was, in weight percent, 24.75% samarium, 49.70% cobalt, 18.97% iron, 4.37% copper, and the remainder zirconium, with the purity of Sm, Co, and Cu being ≥ 99.9%, and the purity of Fe and Zr being ≥ 99.5%. Melting and refining: The blended raw materials were melted and refined in a vacuum high-frequency induction electric furnace, and high-purity argon gas was introduced. The melted raw materials formed a homogeneous alloy solution, which was then poured into a cooled copper mold to obtain an alloy ingot. Powder preparation: The ingots were mechanically crushed into powders of 100-300 μm, and the powders were further pulverized into powders with an average particle size of 4.6 μm using a jet mill process. Orientation compaction: Orientation compaction was performed under a magnetic field of 2 T, and after sealing, a cold isostatic press was used to maintain a pressure of 170 MPa for 20 seconds to compact the powder, thereby obtaining a green body. Sintering and solution treatment: The compact was sintered at 1206°C for 2 hours under argon gas protection, and then solution treated at 1190°C for 2 hours under argon gas protection, and then air-cooled to room temperature. First deep-freezing treatment: The molded body was placed in a deep-freezing treatment system and cooled to -190°C at a temperature drop rate of 10°C / min, then kept at that temperature for 0.5 hours, removed, placed in air, and allowed to warm up naturally. Aging treatment: Under argon gas protection, the material was aged at 840°C for 12 hours, then cooled to 400°C at a rate of 0.5°C / min, kept at that temperature for 3 hours, and then air-cooled to room temperature to obtain a magnet. Second deep-freezing treatment: The molded body was placed directly in liquid nitrogen and subjected to deep-freezing treatment for 0.5 hours, then removed and placed in the air to allow the temperature to rise naturally. Third deep-freezing treatment: The molded body was placed in a deep-freezing treatment system and cooled to -194°C at a temperature drop rate of 10°C / min, then kept at that temperature for 0.5 hours, removed, placed in air, and allowed to warm naturally. Example 7

[0062] The manufacturing method of the samarium-cobalt permanent magnet of Example 7 differs from Example 1 in that the compact is not subjected to a second deep-cooling treatment after the aging treatment, but the rest is the same as Example 1. Example 8

[0063] The composition of the neodymium-iron-boron alloy used in this embodiment is (PrNd) 32 (CoCuAlZr) 0.2 The manufacturing process used was: vacuum rapid solidification melting, hydrogen crushing, powder production by jet milling, magnetic field oriented compaction, cold isostatic pressing, sintering, first deep-freezing treatment, tempering, and second deep-freezing treatment. The jet-milled powder had an average particle size of 2.18 μm and was vacuum sintered at 1060°C for 5 hours. The compact was directly placed in liquid nitrogen and removed after 0.5 hours for the first deep-freezing treatment. It was then placed in air and allowed to warm naturally. It was then tempered at 900°C and 480°C for 3 hours each (cooling rate from 900°C to 480°C was 0.5°C / min). The compact was then directly placed in liquid nitrogen, removed after 1 hour, placed in air and allowed to warm naturally, and subjected to the second deep-freezing treatment. Example 9

[0064] The method for producing the neodymium iron boron permanent magnet of Example 9 differs from Example 8 in that the first deep-cooling treatment is not performed on the compact after sintering. The rest is the same as Example 8. Example 10

[0065] The manufacturing method of the neodymium iron boron permanent magnet of Example 10 differs from that of Example 8 in that the compact is not subjected to a second deep-freeze treatment after the tempering treatment. The rest is the same as that of Example 8. <Comparative Example 1>

[0066] The manufacturing method of the samarium-cobalt permanent magnet of Comparative Example 1 differs from that of Example 1 in that the compact is not subjected to a first deep-freeze treatment after sintering and solution treatment, and is not subjected to a second deep-freeze treatment after aging treatment. The rest is the same as that of Example 1. <Comparative Example 2>

[0067] The manufacturing method of the samarium-cobalt permanent magnet of Comparative Example 2 differs from that of Example 2 in that the compact is not subjected to the first deep-freeze treatment after sintering and solution treatment, and is not subjected to the second deep-freeze treatment after aging treatment. The rest is the same as that of Example 2. <Comparative Example 3>

[0068] The manufacturing method of the neodymium iron boron permanent magnet of Comparative Example 3 differs from that of Example 8 in that the compact is not subjected to a first deep-freeze treatment after sintering, and is not subjected to a second deep-freeze treatment after tempering. The rest is the same as that of Example 8.

[0069] The samarium-cobalt permanent magnets of Examples 1-7 and Comparative Examples 1-2 were tested for bending strength at room temperature. Five mechanical test samples were prepared under each condition, and the average value was calculated. The dimensions, orientation, and force direction of the three-point bending experiment samples are shown in Figure 1. At the same time, the magnetic properties of the samarium-cobalt permanent magnets of Examples 1-7 and Comparative Examples 1-2 were tested for bending strength and magnetic properties at room temperature. The test results for bending strength and magnetic properties are shown in Table 1.

[0070] Table 1. Bending strength and magnetic properties of samarium-cobalt permanent magnets of Examples 1 to 7 and Comparative Examples 1 and 2 JPEG0007763844000001.jpg57170

[0071] FIG. 2 shows three-point bending curves for the samarium-cobalt permanent magnet produced in Example 1 and Comparative Example 1. Referring to Table 1 and FIG. 2 together, it can be seen that the deep-freeze-treated samarium-cobalt permanent magnets have improved bending strength compared to magnets that have not been deep-freeze-treated. As can be seen from Table 1, the average bending strength of Examples 1 to 6 is greater than 150 MPa, while the average bending strength of Comparative Examples 1 and 2 is less than 140 MPa. These experimental results demonstrate that the mechanical properties of the samarium-cobalt permanent magnets of the present invention can be effectively improved after deep-freeze treatment. The samarium-cobalt permanent magnets of Examples 3 and 7 were deep-freeze-treated only once, and exhibited improved bending strength compared to Comparative Example 1, which was not deep-freeze-treated. However, the samarium-cobalt permanent magnet of Example 3, which was deep-freeze-treated once after aging treatment, exhibited better bending properties compared to the samarium-cobalt permanent magnet of Example 7, which was deep-freeze-treated once after sintering and solution treatment.

[0072] Figure 3 shows the demagnetization curves of the samarium-cobalt permanent magnets produced in Example 1 and Comparative Example 1. Referring to Table 1 and Figure 3 together, the magnetic properties of the deep-cooled samarium-cobalt permanent magnets are slightly improved compared to magnets that are not deep-cooled. The above experimental results demonstrate that the samarium-cobalt permanent magnets of the present invention maintain excellent magnetic properties even after deep-cooling. Among these, the samarium-cobalt permanent magnets of Examples 3 and 7 underwent deep-cooling only once, and their magnetic properties were relatively poor.

[0073] The NdFeB rare earth permanent magnet materials of Examples 8-10 and Comparative Example 3 were tested for bending strength at room temperature. Five mechanical test samples were prepared under each condition, and the average value was calculated. At the same time, the NdFeB rare earth permanent magnet materials of Examples 8-10 and Comparative Example 3 were tested for magnetic properties at room temperature. The test results for bending strength and magnetic properties are shown in Table 1.

[0074] Table 2: Bending strength and magnetic properties of neodymium iron boron rare earth permanent magnet materials of Examples 8 to 10 and Comparative Example 3 JPEG0007763844000002.jpg29170

[0075] Table 2 shows that the deep-freeze-treated neodymium iron boron rare earth permanent magnet material does not have a large difference in magnetic properties compared to magnets that have not been deep-freeze-treated, but does have improved mechanical properties.

[0076] Each aspect, example, and feature of the present invention should be considered in all respects as illustrative and not limiting of the invention, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0077] In the manufacturing method of the present invention, the order of each step is not limited to the order listed, and variations in the order of each step are within the scope of protection of the present invention without requiring creative efforts by those skilled in the art. Also, two or more steps or operations may be performed simultaneously.

[0078] Finally, it should be noted that the specific examples described in this specification do not limit the embodiments of the present invention, but are merely for illustrating the present invention. Those skilled in the art can make various modifications and additions to the specific examples described, or replace them in a similar manner, and it is not necessary or possible to list complete examples of all embodiments here. These obvious modifications or variations derived from the essential spirit of the present invention still belong to the protection scope of the present invention, and interpreting them as additional restrictions would be contrary to the spirit of the present invention.

Claims

1. The rare earth permanent magnet material is Sm ２ Co １７ rare earth permanent magnet material alloys, It includes raw material blending, melting and refining, powder production, oriented powder compaction, sintering, tempering, and deep-freezing. At least one deep-cooling treatment is performed between the sintering treatment and the tempering treatment, and at the same time, at least one deep-cooling treatment is performed after the tempering treatment; The deep-freezing step includes placing the compact into a deep-freezing system, cooling it to a deep-freezing temperature, and then removing the compact, the deep-freezing temperature being ≦−130°C and the deep-freezing time being 10 to 400 minutes. ２ Co １７ A method for producing rare earth permanent magnet materials based on the ZnO system.

2. The manufacturing method includes blending raw materials, melting and smelting, powder preparation, oriented powder compaction, sintering, a first deep-cooling treatment, a tempering treatment, and a second deep-cooling treatment; Or, it includes raw material blending, melting and refining, powder production, oriented powder compaction, sintering, first deep-freezing treatment, tempering treatment, second deep-freezing treatment, and third deep-freezing treatment. Alternatively, the manufacturing method according to claim 1, further comprising blending raw materials, melting and smelting, powder production, oriented powder compaction, sintering, a first deep-freezing treatment, a second deep-freezing treatment, a tempering treatment, and a third deep-freezing treatment.

3. A manufacturing method as described in claim 1 or claim 2, characterized in that the deep-freezing treatment step includes placing the molded body directly into liquid nitrogen for deep-freezing treatment, and then removing it.

4. 3. The method according to claim 1, wherein the deep-cooling temperature is ≦−190° C. and / or the deep-cooling time is 20 to 300 minutes.

5. 3. The manufacturing method according to claim 1, wherein the tempering treatment is one of a tempering diffusion treatment, an aging treatment, and a nitriding treatment.

6. The tempering and diffusion treatment includes a first tempering at 800 to 950°C for 2 to 6 hours, followed by a second tempering at a cooling rate of 0.3 to 1.3°C / min to 400 to 650°C for 2 to 6 hours; The aging treatment comprises maintaining the temperature at 800 to 950°C for 10 to 25 hours, then decreasing the temperature to 400 to 550°C at a cooling rate of 0.3 to 1.3°C / min, and maintaining the temperature for 2 to 12 hours; 6. The method according to claim 5, wherein the nitriding treatment comprises maintaining the temperature at 400 to 650° C. for 1 to 20 hours in nitrogen gas and / or ammonia gas.

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