Manufacturing method for high mechanical properties samarium cobalt permanent magnets

Abstract

To provide a preparation method of a samarium-cobalt permanent magnet with high mechanical properties which not only improves the magnetic properties, but also greatly enhances the mechanical properties of the samarium-cobalt magnet, achieving a synergistic improvement in the magnetic and mechanical properties of the samarium-cobalt magnet.SOLUTION: A method includes the steps of performing melting, pulverizing, orientation shaping, cold isostatic pressing, sintering, solution, aging and heat treatment sequentially on raw materials to obtain a samarium-cobalt permanent magnet. The heat treatment is performed under a protection of an inactive atmosphere. The number of heat treatment cycles ranges from 1 to 10, and an external magnetic field and an external stress are applied during one or multiple heat treatment cycles. The magnetic field intensity of the external magnetic field is 1-50 kOe, and the magnitude of the external stress is 5-500 MPa. Compared to the traditional process, this method not only improves the magnetic properties, but also greatly enhances the mechanical properties of the samarium-cobalt magnet by performing the heat treatment with the external magnetic field and the external stress after the aging process is finished., achieving a synergistic improvement in the magnetic and mechanical properties.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention belongs to the technical field of permanent magnetic materials and relates to a method for producing samarium-cobalt permanent magnets with high mechanical properties. [Background technology]

[0002] Samarium-cobalt permanent magnet materials have unique high-temperature stability, excellent corrosion resistance, and a low temperature coefficient of remanence, making them an essential material for the development of high technology, national defense weapons and equipment, modern communications, transportation, and intelligent manufacturing. However, due to the inherent characteristics of samarium-cobalt materials, such as a small number of slip systems and anisotropy, they lack ductility and are difficult to process into complex shapes. They are prone to corner chipping during product processing, process cycling, inspection, and magnetization, and are particularly susceptible to failure when exposed to external forces such as shock vibration and centrifugal force during use. Currently, samarium-cobalt magnets have a bending strength of only 80-140 MPa and a fracture toughness of 1.5-2.5 MPa.m. 1 / 2 However, production losses due to brittleness are high at 20-30%, which significantly increases processing costs and severely limits its application range and deep processing, which is detrimental to China's achievement of its strategic goal of developing a high-tech industrial chain as a country with a large amount of rare earths.

[0003] Researchers have conducted extensive research to improve the mechanical properties of samarium-cobalt permanent magnet materials. Adding high-melting-point oxides during the powdering process to form non-uniform powder mixtures effectively improves the mechanical properties of the magnets, but significantly degrades the magnetic properties. Coating the surface with a protective layer can improve the mechanical properties and consistency, but the improvement is limited and the magnetic properties are degraded.

[0004] Therefore, the current focus of research on samarium-cobalt permanent magnet materials is how to improve the mechanical properties of magnets while maintaining or improving their magnetic performance. Summary of the Invention [Problem to be solved by the invention]

[0005] In order to solve the above problems in the prior art, the present invention aims to provide a method for producing a samarium-cobalt permanent magnet with high mechanical properties. The produced samarium-cobalt permanent magnet has excellent mechanical properties, thereby solving the problems in the prior art.

[0006] One object of the present invention is achieved by the following technical solutions. A method for producing a samarium-cobalt permanent magnet with high mechanical properties, comprising the steps of: The process includes a step of sequentially subjecting the raw materials to smelting, pulverization, orientation molding, cold isostatic pressing, sintering, solution treatment, aging treatment, and heat treatment to obtain a samarium-cobalt permanent magnet, The heat treatment is carried out under the protection of an inert atmosphere, and the number of heat treatments is 1 to 10, and an external magnetic field and external stress are applied during one or more heat treatments. Here, "multiple times" means the number of heat treatments or less, and for example, when the number of heat treatments is three, "multiple times" here means two or three times.

[0007] The number of heat treatments is 1 to 10. When the number of heat treatments is ≥ 2, the temperature is lowered to 10 to 50°C after each heat treatment and then raised again for the remaining heat treatments. The temperature rise rate is preferably 0.8 to 1.2°C / min. The temperature and time for each heat treatment may be the same or different.

[0008] The temperature for each heat treatment is preferably 350°C≦T<Curie temperature, and more preferably 400°C≦T≦850°C.

[0009] The warming time for each heat treatment is preferably 3 to 90 minutes, and more preferably 5 to 60 minutes.

[0010] Preferably, the number of heat treatment stages is one or two, and an external magnetic field and an external stress are applied to one of the heat treatment stages or to both the first and second stages.

[0011] When the number of heat treatment stages is one, the temperature retention in the first heat treatment stage is 350° C.≦T<Curie temperature, and more preferably 400° C.≦T≦850° C. The temperature retention time in the first heat treatment stage is 3 to 90 minutes, and more preferably 5 to 60 minutes.

[0012] When the number of heat treatment stages is two, the first-stage heat treatment has a temperature retention of 350°C≦T<Curie temperature (more preferably 400°C≦T≦850°C) and a time retention of 3 to 90 minutes (more preferably 5 to 60 minutes), and the second-stage heat treatment has a temperature retention of 350°C≦T<Curie temperature (more preferably 400°C≦T≦850°C) and a time retention of 3 to 90 minutes (more preferably 5 to 60 minutes).

[0013] More preferably, when the number of heat treatment stages is two, the first-stage heat treatment has a temperature retention of 700 to 850°C and a time retention of 3 to 90 minutes (more preferably 5 to 60 minutes), and the second-stage heat treatment has a temperature retention of 350 to 600°C and a time retention of 3 to 90 minutes (more preferably 5 to 60 minutes).

[0014] Each heat treatment process includes a temperature increase step, a temperature maintenance step, and a temperature decrease step. Preferably, the external magnetic field and the external stress are applied in any one step, any two steps, or all steps in each heat treatment process.

[0015] The magnetic field strength of the external magnetic field is preferably 1 to 50 kOe, more preferably 3 to 20 kOe, and even more preferably 5 to 10 kOe.

[0016] Preferably, the external magnetic field is positioned on both sides of the sample, and the sample is positioned at the center of the magnetic field. Preferably, the direction of the external magnetic field is one of horizontal, vertical, and at any angle. Preferably, the direction of the external magnetic field is parallel to the easy axis of magnetization of the sample. The magnitude of the external stress is preferably 5 to 500 MPa, more preferably 30 to 300 MPa, and even more preferably 50 to 200 MPa.

[0017] The stress is applied directly to the magnet using a clamp, press or other mechanical device, and the medium of the external stress can be a magnetically permeable or non-magnetically permeable material, preferably a non-magnetically permeable material.

[0018] Preferably, the direction of the external stress is parallel to the direction of the external magnetic field.

[0019] Preferably, the inert atmosphere is nitrogen gas and / or argon gas, and the purity of the nitrogen gas and / or argon gas is ≧99.99%.

[0020] Another object of the present invention is achieved by the following technical solutions.

[0021] The samarium-cobalt permanent magnet produced by the above-mentioned production method has high mechanical properties.

[0022] Preferably, the samarium-cobalt permanent magnet has a maximum bending strength of ≧150 MPa, more preferably ≧220 MPa, and even more preferably 290 to 400 MPa. [Effects of the Invention]

[0023] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, after the aging process, heat treatment is performed using an external magnetic field and external stress. This not only improves the magnetic properties but also significantly improves the mechanical properties of the samarium-cobalt magnet compared to conventional processes, thereby achieving a combined improvement in the magnetic and mechanical performance of the samarium-cobalt magnet. 2. In the present invention, after the aging process is completed, heat treatment is performed multiple times using an external magnetic field and external stress, which significantly improves the coercive force and mechanical properties compared to when heat treatment is performed only once. 3. The improved bending strength of samarium-cobalt permanent magnets is advantageous for deep processing of magnets into complex shapes, reducing processing losses and costs, and greatly expanding their application range. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a process diagram showing the steps of sintering, solution treatment, aging treatment, and heat treatment of a samarium-cobalt permanent magnet. [Figure 2] 10 is a line graph showing the magnetic properties of the samarium-cobalt magnet of Example 7 of the present invention. [Figure 3] 1 is a line graph showing the magnetic properties of a samarium-cobalt magnet of Comparative Example 1 of the present invention. [Figure 4] FIG. 10 is a bending stress-strain curve of the samarium-cobalt magnet of Example 7 of the present invention. [Figure 5] FIG. 2 is a bending stress-strain diagram of a samarium-cobalt magnet of Comparative Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following describes in detail embodiments of the smelting, pulverization, orientation molding, cold isostatic pressing, sintering, solution treatment, aging treatment, and heat treatment steps involved in the production of a samarium-cobalt permanent magnet with high mechanical properties. However, these embodiments are merely illustrative, and the disclosure of the present invention is not limited thereto.

[0026] The samarium-cobalt permanent magnet includes 1-5 system and 2-17 system, and is not intended to limit the scope of protection of the present invention.

[0027] In the smelting process, the raw materials are weighed and mixed according to the molecular formula of the samarium-cobalt permanent magnet, and an offset amount is added to the Sm during the mixing process. The raw materials are placed in a vacuum smelting furnace, and the vacuum level in the furnace is less than 1×10 -1 The mixture is evacuated to a pressure of 0.1 Pa, an inert gas is injected, the temperature is raised to 1400-1500°C, smelting is performed, and the temperature is maintained for 1-30 minutes. Thereafter, the high-temperature alloy solution is poured into a water-cooled copper mold and cooled to form an alloy ingot. The above smelting process is merely illustrative and does not limit the scope of protection of the present invention.

[0028] In the powdering step, the alloy ingot obtained in the smelting step is coarsely pulverized to a particle size of 300 μm or less, and the coarsely pulverized coarse magnetic powder is jet milled to a magnetic powder having a particle size of 1 to 6 μm. The above powdering steps are merely illustrative and do not limit the scope of protection of the present invention.

[0029] In the orientation compaction and cold isostatic pressing steps, the magnetic powder obtained in the powdering step is placed in a magnetic field press with a magnetic field strength of 0.5 to 5 T under the protection of an inert atmosphere and orientation compacted, and the produced green body is vacuum packaged and placed in an isostatic press and held at a pressure of 50 to 300 MPa for 5 to 60 seconds to obtain a samarium-cobalt permanent magnet alloy blank. The above orientation compaction and cold isostatic pressing steps are merely illustrative and do not limit the scope of protection of the present invention.

[0030] 1 is a process diagram showing the sintering, solution treatment, aging treatment, and heat treatment steps for the samarium-cobalt permanent magnet of the present invention. The specific steps are as follows:

[0031] In the sintering process, the samarium-cobalt permanent magnet alloy blank obtained in the cold isostatic pressing process is first pre-sintered at 1100-1180°C for 0.5-2 hours, and then the temperature is increased to 1170-1250°C in an inert atmosphere and sintered for 1-5 hours. The above sintering process is merely illustrative and does not limit the scope of protection of the present invention.

[0032] In the solution treatment, the solution treatment temperature is 10 to 20°C lower than the sintering temperature, and the solution treatment is continued for 2 to 6 hours, followed by cooling to room temperature to obtain a samarium-cobalt permanent magnet solid solution. The above solution treatment process is merely illustrative and does not limit the scope of the present invention.

[0033] In the aging treatment step, the samarium-cobalt permanent magnet solid solution is isothermally aged in an inert atmosphere at a temperature of 750°C≦T<Curie temperature (more preferably 800°C≦T≦850°C) for 10 to 30 hours, then slowly cooled to 300 to 500°C at a rate of 0.3 to 1.0°C / min and kept at that temperature for 1 to 5 hours, and finally slowly cooled to room temperature in a furnace to obtain a samarium-cobalt sample.

[0034] The above aging treatment process is merely illustrative and does not limit the scope of the present invention. The aging treatment process may include multi-stage aging treatment or multiple aging treatments for 1-5 or 2-17 samarium-cobalt magnets.

[0035] Heat treatment process: The heat treatment is carried out under the protection of an inert atmosphere, and the number of heat treatments is 1 to 10 (or may be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10), and an external magnetic field and external stress are applied during one or more heat treatments. The "multiple times" here refers to the number of heat treatments or less. For example, if the number of heat treatments is 3, the "multiple times" here refers to 2 or 3. If the number of heat treatments is 10, the "multiple times" here may be 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0036] When the number of heat treatments is ≥ 2, the temperature is lowered to 10 to 50°C for each heat treatment, and then raised again for the remaining heat treatments. The temperature and time for each heat treatment may be the same or different.

[0037] The temperature for each heat treatment is preferably 350° C.≦T<Curie temperature, and more preferably 400° C.≦T≦850° C. The temperature retention time for each heat treatment is preferably 3 to 90 minutes, and more preferably 5 to 60 minutes.

[0038] Preferably, the number of heat treatment stages per treatment is one or two, and an external magnetic field and external stress are applied to one of the heat treatment stages or to both the first and second stages. When the number of heat treatment stages is one, the first heat treatment stage has a temperature retention of 350°C≦T<Curie temperature, more preferably 400°C≦T≦850°C, and a time retention period of 3 to 90 minutes, more preferably 5 to 60 minutes. When the number of heat treatment stages is two, the first heat treatment stage has a temperature retention of 350°C≦T<Curie temperature (more preferably 400°C≦T≦850°C) and a time retention period of 3 to 90 minutes (more preferably 5 to 60 minutes), and the second heat treatment stage has a temperature retention of 350°C≦T<Curie temperature (more preferably 400°C≦T≦850°C) and a time retention period of 3 to 90 minutes (more preferably 5 to 60 minutes).

[0039] More preferably, when the number of heat treatment stages is two, the first-stage heat treatment has a temperature retention of 700 to 850°C and a time retention of 3 to 90 minutes (more preferably 5 to 60 minutes), and the second-stage heat treatment has a temperature retention of 350 to 600°C and a time retention of 3 to 90 minutes (more preferably 5 to 60 minutes).

[0040] Each heat treatment step includes a temperature-raising step, a temperature-holding step, and a temperature-lowering step. The temperature-raising rate is 0.8 to 1.2°C / min, and the temperature-lowering rate may be 1 to 50°C / min, or may be achieved by cooling in a furnace. Each heat treatment step may be the same or different. Preferably, the external magnetic field and external stress are applied in any one, any two, or all of the steps in each heat treatment step.

[0041] The magnetic field strength of the external magnetic field is preferably 1 to 50 kOe, more preferably 3 to 20 kOe, and even more preferably 5 to 10 kOe. The magnitude of the external stress is preferably 5 to 500 MPa, more preferably 30 to 300 MPa, and even more preferably 50 to 200 MPa. Preferably, the inert atmosphere is nitrogen gas and / or argon gas. The purity of the nitrogen gas and / or argon gas is ≧99.99%.

[0042] Preferably, the external magnetic field is positioned on both sides of the sample, and the sample is positioned at the center of the magnetic field. Preferably, the direction of the external magnetic field is one of horizontal, vertical, and at any angle. Preferably, the direction of the external magnetic field is parallel to the easy axis of magnetization of the sample.

[0043] The stress is applied directly to the magnet using a clamp, press or other mechanical device, and the medium of the external stress is a magnetically permeable or non-magnetically permeable material, preferably a non-magnetically permeable material. Preferably, the direction of the external stress is parallel to the direction of the external magnetic field.

[0044] The technical solutions of the present invention will be further described below with reference to specific examples and drawings. However, it should be understood that the specific examples described herein are merely intended to aid in understanding the present invention and do not specifically limit the present invention. Furthermore, the drawings used in this specification are merely intended to better explain the contents disclosed in the present invention and do not limit the scope of protection. Unless otherwise specified, all materials used in the examples of the present invention are common materials in the art, and all methods used in the examples are common methods in the art.

[0045] Example 1 The method for producing the high mechanical properties samarium cobalt permanent magnet material of this embodiment includes the following steps. (1) Melting: Molecular formula Sm(Co bal Fe 0.21 Cu 0.062 Zr 0.024 ) 7.36 The material was mixed by adding an offset amount of 4% (mass percent) to Sm during the material mixing process, and the material was placed in a vacuum smelting furnace. The vacuum in the furnace was 3 × 10 -2 The system is evacuated to a vacuum of 100 Pa, high-purity argon gas is injected, the temperature is raised to 1450°C, smelting is carried out, and the temperature is maintained for 5 minutes. The hot alloy solution is then poured into a water-cooled copper mold, and after cooling, an alloy ingot is formed. (2) Powdering: The alloy ingot obtained in step (1) is subjected to coarse pulverization and then fine pulverization using a jet mill. The alloy ingot is coarsely pulverized to a particle size of 300 μm or less, and the coarsely pulverized coarse magnetic powder is further ground into a magnetic powder with a particle size of approximately 4 μm. (3) Orientation molding, cold isostatic pressing: The magnetic powder obtained in step (2) is placed in a magnetic field press with a magnetic field strength of 2 T under a nitrogen gas protection environment and oriented molded. The resulting green body is vacuum packaged and placed in an isostatic press, where it is held at a pressure of 180 MPa for 30 seconds to obtain a samarium-cobalt permanent magnet alloy blank. (4) The samarium-cobalt permanent magnet alloy blank obtained in step (3) is first pre-sintered at a temperature of 1180°C for 1 hour, and then sintered at a temperature of 1200°C for 2 hours under the protection of argon gas. (5) After sintering, the mixture is subjected to a solution heat treatment at 1190°C for 4 hours, and after the solution treatment, the mixture is cooled to obtain a samarium-cobalt permanent magnet solid solution. (6) The samarium-cobalt permanent magnet solid solution obtained in step (5) is isothermally heat-treated at 830°C for 20 hours under argon gas protection, then slowly cooled to 400°C at a rate of 0.7°C / min and kept at that temperature for 3 hours, and finally slowly cooled to room temperature in a furnace to obtain a samarium-cobalt sample. (7) The samarium-cobalt sample obtained in step (6) is isothermally heat-treated in a high-purity argon gas atmosphere at a temperature of 810°C at a rate of 1°C / min for 10 minutes. While the temperature is increasing, an external magnetic field of 10 kOe is applied (the external magnetic field is positioned on both sides of the sample, the sample is positioned at the center of the magnetic field, and the direction of the external magnetic field is parallel to the easy axis of magnetization of the sample) and an external stress of 100 MPa is applied (the direction of the external stress is parallel to the direction of the magnetic field). Finally, the sample is slowly cooled to room temperature in a furnace, and the magnetic field and stress are removed to obtain the final samarium-cobalt product.

[0046] <Example 2> Example 2 differs from Example 1 only in step (7). In step (7) of Example 2, the samarium-cobalt sample is isothermally heat-treated in a high-purity argon gas atmosphere at a temperature of 810°C at a rate of 1°C / min for 30 minutes. Simultaneously with the temperature increase, an external magnetic field of 10 kOe and an external stress of 100 MPa are applied. Finally, the sample is slowly cooled to room temperature in a furnace, and the magnetic field and stress are removed to obtain the final samarium-cobalt product.

[0047] Example 3 Example 3 differs from Example 1 only in step (7). In step (7) of Example 3, the samarium-cobalt sample is isothermally heat-treated in a high-purity argon gas atmosphere at a temperature of 810°C at a rate of 1°C / min for 60 minutes. Simultaneously with the temperature increase, an external magnetic field of 10 kOe and an external stress of 100 MPa are applied. Finally, the sample is slowly cooled to room temperature in a furnace, and the magnetic field and stress are removed to obtain the final samarium-cobalt product.

[0048] Example 4 Example 4 differs from Example 1 only in step (7). In step (7) of Example 4, the samarium-cobalt sample is isothermally heat-treated in a high-purity argon gas atmosphere at a temperature of 600°C at a rate of 1°C / min for 10 minutes. Simultaneously with the temperature increase, an external magnetic field of 10 kOe and an external stress of 100 MPa are applied. Finally, the sample is slowly cooled to room temperature in a furnace, and the magnetic field and stress are removed to obtain the final samarium-cobalt product.

[0049] <Example 5> Example 5 differs from Example 1 only in step (7). In step (7) of Example 5, the samarium-cobalt sample is isothermally heat-treated in a high-purity argon gas atmosphere at a temperature of 400°C at a rate of 1°C / min for 10 minutes. Simultaneously with the temperature increase, an external magnetic field of 10 kOe and an external stress of 100 MPa are applied. Finally, the sample is slowly cooled to room temperature in a furnace, and the magnetic field and stress are removed to obtain the final samarium-cobalt product.

[0050] Example 6 Example 6 differs from Example 1 only in step (7). In step (7) of Example 6, the samarium-cobalt sample is isothermally heat-treated in a high-purity argon gas atmosphere at a temperature of 400°C at a rate of 1°C / min for 30 minutes. Simultaneously with the temperature increase, an external magnetic field of 10 kOe and an external stress of 100 MPa are applied. Finally, the sample is slowly cooled to room temperature in a furnace, and the magnetic field and stress are removed to obtain the final samarium-cobalt product.

[0051] Example 7 Example 7 differs from Example 1 only in step (7). In step (7) of Example 7, the samarium-cobalt sample is isothermally heat-treated in a high-purity argon gas atmosphere at a temperature of 810°C at a rate of 1°C / min for 30 minutes. Simultaneously with the temperature increase, an external magnetic field of 10 kOe and an external stress of 100 MPa are applied. The sample is then slowly cooled to 400°C and isothermally heat-treated for 60 minutes. Finally, the sample is slowly cooled to room temperature in a furnace, and the magnetic field and stress are removed to obtain the final samarium-cobalt product.

[0052] Example 8 Example 8 differs from Example 1 only in step (7). In step (7) of Example 8, the samarium-cobalt sample is isothermally heat-treated in a high-purity argon gas atmosphere at a temperature of 810°C at a rate of 1°C / min for 30 minutes. Simultaneously with the temperature increase, an external magnetic field of 10 kOe and an external stress of 100 MPa are applied. After the isothermal heat-treatment for 30 minutes, the magnetic field and stress are removed. The sample is then slowly cooled to 400°C and isothermally heat-treated for 60 minutes. Finally, the sample is slowly cooled to room temperature in a furnace to obtain the final samarium-cobalt product.

[0053] Example 9 Example 9 differs from Example 1 only in step (7). In step (7) of Example 9, the samarium-cobalt sample is isothermally heat-treated in a high-purity argon gas atmosphere at a temperature of 700°C at a rate of 1.2°C / min for 20 minutes. Simultaneously with the temperature increase, an external magnetic field of 5 kOe and an external stress of 200 MPa are applied. After the isothermal heat-treatment for 20 minutes, the magnetic field and stress are removed, and the sample is finally cooled to room temperature in a furnace to obtain the final samarium-cobalt product.

[0054] Example 10 Example 10 differs from Example 1 only in step (7). In step (7) of Example 10, the samarium-cobalt sample is isothermally heat-treated in a high-purity argon gas atmosphere at a temperature of 810°C at a rate of 0.8°C / min for 40 minutes. Simultaneously with the temperature increase, an external magnetic field of 15 kOe and an external stress of 150 MPa are applied. Finally, the sample is slowly cooled to room temperature in a furnace, and the magnetic field and stress are removed to obtain the final samarium-cobalt product.

[0055] <Comparative Example 1> Comparative Example 1 differs from Example 1 only in that Comparative Example 1 does not include step (7).

[0056] <Comparative Example 2> Comparative Example 2 differs from Example 1 only in that in step (7) of Comparative Example 2, the samarium-cobalt sample was isothermally heat-treated in a high-purity argon gas atmosphere at a temperature of 810°C at a rate of 1°C / min for 10 minutes, without any external magnetic field strength or external stress during the heat treatment, and finally cooled to room temperature in a furnace to obtain a final samarium-cobalt product.

[0057] <Comparative Example 3> Comparative Example 3 differs from Example 1 only in that in step (7) of Comparative Example 3, the samarium-cobalt sample was isothermally heat-treated in a high-purity argon gas atmosphere at a temperature of 810°C at a rate of 1°C / min for 10 minutes, and simultaneously with the temperature increase, an external magnetic field of 10 kOe was applied without applying any external stress, and finally, the sample was slowly cooled to room temperature in a furnace, and the magnetic field was removed to obtain the final samarium-cobalt product.

[0058] <Comparative Example 4> Comparative Example 4 differs from Example 1 only in that in step (7) of Comparative Example 4, the samarium-cobalt sample was isothermally heat-treated in a high-purity argon gas atmosphere by increasing the temperature to 810°C at a rate of 1°C / min for 10 minutes, and simultaneously applying an external stress of 100 MPa without applying an external magnetic field, and finally slowly cooling to room temperature in a furnace, and the external force was removed to obtain a final samarium-cobalt product.

[0059] The magnetic and mechanical properties of the samarium-cobalt permanent magnet materials obtained in the above examples and comparative examples were characterized at room temperature. To perform magnetic property tests, the samarium-cobalt permanent magnet materials were machined to φ10 × 10 mm. To perform bending strength tests on the samarium-cobalt permanent magnet materials, standard samples were machined to h × b × l = 5 × 6 × 20 mm, with the height direction parallel to the easy axis of magnetization, i.e., h / / c. The results are shown in Table 1. Table 1. Magnetic properties and bending strength of samarium-cobalt permanent magnet materials obtained in Examples and Comparative Examples JPEG0007801407000001.jpg85170

[0060] Figure 3 is a line graph of the magnetic properties of the samarium-cobalt magnet of Comparative Example 1, and Figure 5 is a bending stress-strain diagram of the samarium-cobalt magnet of Comparative Example 1. Compared to the performance of Comparative Example 1, which uses a conventional process solution, the samarium-cobalt magnets of Examples 1 to 10 exhibit improved coercivity and magnetic energy product, with the maximum value in Example 1, where the magnetic energy product is 29.33 MGOe. They also exhibit significantly improved bending strength, with improvements ranging from 24.6 to 131.7%, with the maximum value in Example 7. This is due to the addition of a two-stage isothermal heat treatment at 400°C for 60 minutes. Both coercivity and mechanical properties are improved, with a high bending strength of 292 MPa, as shown in Figures 2 and 4. Examples 1 to 3 were subjected to isothermal heat treatment at 810°C for different lengths of time. As the aging time increased, mechanical properties improved and then declined, and magnetic properties gradually declined, but both were greater than those of the comparative examples. Example 4 was isothermal heat treated at 600°C for 10 minutes, which clearly reduced the mechanical properties compared to 10 minutes isothermal heat treated at 810°C. Examples 5 and 6 were isothermal heat treated at 400°C for different times, and although the mechanical properties improved with increasing aging time, the magnetic properties did not change significantly. This may be because the coercive force of the samarium-cobalt magnet was still very high at 400°C, and the external magnetic field was too small to magnetize the magnet to saturate it, resulting in little effect on the magnetic properties.

[0061] In Comparative Example 2, only heat treatment was performed, and no magnetic field or stress was applied. As can be seen from the experimental results of Comparative Examples 1 and 2, heat treatment without applying a magnetic field or stress does not have a significant effect on the magnetic properties and bending strength of the magnet. In Comparative Examples 3 and 4, only a magnetic field or stress was applied, and as can be seen from the experimental results of Comparative Examples 1, 3, and 4, when only a magnetic field or stress is applied during heat treatment, the degree of improvement in bending strength is limited.

[0062] As can be seen from the above analysis, the magnetic and mechanical properties of samarium-cobalt magnets were all improved by applying a magnetic field, stress, and isothermal heat treatment. One possible reason for this is that the application of a magnetic field and pressure imparts an external driving force to the magnet, promoting lattice distortion within the magnet and accelerating the diffusion of elements between the cells and the cell walls. Compared to conventional manufacturing processes, the addition of a magnetic field, stress, and isothermal heat treatment results in more complete element diffusion within the magnet, increasing the number of precipitates and strengthening the effect of the precipitates being pinned down by the cell walls. Furthermore, by appropriately selecting the temperature, magnetic field strength, aging time, and stress magnitude, the grain size can be refined, the number of grain boundaries can be increased, and crack propagation can be significantly inhibited, thereby improving the mechanical properties of the magnet. Within a certain range, increasing the heat treatment temperature also significantly improved the mechanical properties.

[0063] Each aspect, embodiment, and feature of the present invention is to be considered in all respects as illustrative and not limiting of the invention, the scope of which is defined by the appended claims. Other embodiments, modifications, and uses may occur to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0064] In the manufacturing method of the present invention, the order of each step is not limited to the one described above, and any change in the order of each step made by a person skilled in the art without any creative effort is also included within the scope of protection of the present invention. In addition, two or more steps or operations may be performed simultaneously.

[0065] Finally, it should be noted that the specific examples described herein do not limit the embodiments of the present invention, but are merely for the purpose of illustrating the present invention. Those skilled in the art can make various modifications or additions to the specific examples described, or replace them in similar ways, and it is not necessary or possible to list all the embodiments here. Obvious changes or modifications derived from the essential spirit of the present invention still fall within the protection scope of the present invention, and interpreting them as any additional restrictions would violate the spirit of the present invention.

Claims

1. The method includes a process of sequentially subjecting raw materials to smelting, pulverization, orientation molding, cold isostatic pressing, sintering, solution treatment, and aging treatment, and then subjecting the raw materials to heat treatment after the aging treatment to obtain a samarium-cobalt permanent magnet as a final product, The heat treatment is carried out under the protection of an inert atmosphere, and the number of heat treatments is 1 to 10, and an external magnetic field and an external stress are applied during one or more heat treatments. A method for producing a samarium-cobalt permanent magnet with high mechanical properties, characterized by the following:

2. 2. The method for producing a samarium-cobalt permanent magnet with high mechanical properties as set forth in claim 1, wherein the number of heat treatments is 1 to 10, and when the number of heat treatments is ≥ 2, the temperature is lowered to 10 to 50°C and then raised for each heat treatment.

3. 2. The method for producing a samarium-cobalt permanent magnet with high mechanical properties as set forth in claim 1, wherein the temperature for each heat treatment is 350°C≦T<Curie temperature, and the heat-holding time for each heat treatment is 3 to 90 minutes.

4. The number of heat treatment stages each time is one or two, and an external magnetic field and an external stress are applied to one of the heat treatment stages or to both the first and second stages; When the number of heat treatment stages is one, the temperature of the first heat treatment stage is 350° C.≦T<Curie temperature, and the time of the first heat treatment stage is 3 to 90 minutes.

2. The method for producing a samarium-cobalt permanent magnet with high mechanical properties according to claim 1, wherein the number of heat treatment stages is two, and the first heat treatment stage has an insulation temperature of 350°C≦T<Curie temperature and an insulation time of 3 to 90 minutes, and the second heat treatment stage has an insulation temperature of 350°C≦T<Curie temperature and an insulation time of 3 to 90 minutes.

5. 5. The method for producing a samarium-cobalt permanent magnet with high mechanical properties according to claim 4, wherein the number of heat treatment stages is two, and the first heat treatment stage has an insulation temperature of 700 to 850°C and an insulation time of 3 to 90 minutes, and the second heat treatment stage has an insulation temperature of 350 to 600°C and an insulation time of 3 to 90 minutes.

6. 2. The method for producing a samarium-cobalt permanent magnet with high mechanical properties according to claim 1, wherein the magnetic field strength of the external magnetic field is 1 to 50 kOe.

7. 2. The method for manufacturing a samarium-cobalt permanent magnet with high mechanical properties according to claim 1, wherein the magnitude of the external stress is 5 to 500 MPa.

8. 2. The method for producing a samarium-cobalt permanent magnet with high mechanical properties according to claim 1, wherein the magnetic field strength of the external magnetic field is 5 to 10 kOe, and the magnitude of the external stress is 50 to 200 MPa.

9. The external magnetic field is positioned on both sides of the sample, and the sample is positioned at the center of the magnetic field; 2. The method for producing a samarium-cobalt permanent magnet with high mechanical properties according to claim 1, wherein the direction of the external magnetic field is one of horizontal, vertical, and at any angle.

10. 2. The method for producing a high mechanical property samarium-cobalt permanent magnet according to claim 1, wherein the direction of the external magnetic field is parallel to the easy axis of magnetization of the sample.

11. 2. The method for producing a samarium-cobalt permanent magnet with high mechanical properties according to claim 1, wherein the direction of the external stress is parallel to the direction of the external magnetic field.

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