A high remanence sintered Sm2Co 17 Methods for preparing permanent magnets

Abstract

The application relates to a high-remanence sintered Sm2Co 17 The application relates to a preparation method of a permanent magnet and belongs to the technical field of magnetic material preparation. 17 The application discloses a preparation method of a permanent magnet, and belongs to the technical field of magnetic material preparation. The technical problem of difficulty in forming a single 1:7H phase during solid solution of the permanent magnet and poor integrity of cellular structure of the magnet is solved. The application comprises the following steps: S1, preparing samarium-cobalt alloy particles; S2, preparing samarium-cobalt alloy powder; S3, magnetic field orientation forming and cold isostatic pressing; S4, sintering solid solution and aging treatment, and a samarium-cobalt cylindrical magnet with a diameter of 5-8 mm is prepared. In the step S2, auxiliary materials B and C are added and fully mixed. The application can effectively reduce the sintering temperature of the samarium-cobalt magnet, reduce the volatilization loss of rare earth elements during the sintering process, and the prepared magnet has high Fe content, can form a single 1:7H phase during solid solution, has complete cellular structure after aging, and finally has high comprehensive magnetic properties under high Fe content.

Description

Technical Field

[0001] This invention belongs to the field of magnetic material preparation technology, specifically relating to a high remanence sintered Sm2Co 17 Methods for preparing permanent magnets. Background Technology

[0002] Since their emergence in the 1960s, rare earth permanent magnet materials have been highly favored for their excellent magnetic properties, and have experienced rapid development in scientific research, production, and application. Among them, the 2:17 type samarium cobalt permanent magnet material, as a second-generation rare earth permanent magnet material, is widely used in many fields such as high-precision instruments, medical devices, microwave devices, sensors, various magnetic transmission devices, and high-end motors due to its high Curie temperature, excellent magnetic properties, good temperature stability, and outstanding oxidation and corrosion resistance.

[0003] The main steps in producing 2:17 type sintered SmCo magnets include sintering, solution treatment, and aging treatment. As is well known, solution treatment plays a crucial role in optimizing the magnetic properties of 2:17 type SmCo magnets. Through appropriate solution treatment, the magnet can form a single 1:7H phase. After aging treatment, the 1:7H phase decomposes into a 2:17R cell phase, a 1:5H cell wall phase, and a lamellar Zr-rich phase. The 2:17R cell phase provides high saturation magnetization, thereby enabling the magnet to achieve high remanence. B r and maximum magnetic energy product (BH) max The Cu-rich cell walls have a strong pinning effect relative to the domain walls, which can give the magnet high intrinsic coercivity. H cj Knee point magnetic field H knee .

[0004] Typically, increasing the Fe content improves the remanence of 2:17 sintered SmCo magnets because adding Fe to the 2:17R cellular phase replaces some Co, thus increasing the alloy's saturation magnetization and remanence. However, when the Fe content is high, more impurity phases tend to form during solid solution treatment, preventing the formation of a stable 1:7H phase. Consequently, a complete cellular structure cannot be formed during subsequent aging treatment, leading to deterioration of the magnet's magnetic properties. The challenge lies in how to increase the Fe content while simultaneously improving the remanence of Sm2Co magnets. 17 Obtaining ideal phase and cellular structure in permanent magnets to improve their overall magnetic properties is an urgent problem to be solved.

[0005] Currently, the Chinese patent document "A high remanence samarium cobalt permanent magnet material and its preparation method" (application number: 202211407292.1) discloses a method for preparing samarium cobalt permanent magnet material by rapid solidification melting of two alloys. 20 Nd80 ) 75 Ti 15 Cu 10 Adding auxiliary alloy castings to the main alloy castings alters the distribution of the magnet's cell wall phase composition. This compensates for the defects caused by the rapid growth and significant increase in volume fraction of the intracellular phase when the Fe content increases, leading to partial loss of the cell wall phase. It also improves the copper-poor phenomenon at grain boundaries, achieving grain boundary control, improving the magnet's microstructure, increasing remanence, and ultimately enhancing the product's overall magnetic properties. However, this Chinese patent document does not address the difficulty of forming a single 1:7H phase during the solid solution treatment of high-Fe-content magnets.

[0006] The Chinese patent "High Remanence and Low Coercivity Samarium-Cobalt Permanent Magnet Material and Preparation Method" (Patent No.: 201210258133.X) employs a dual-phase alloying method and rapid solidification process, requiring only two components in the rapid solidification zone to prepare magnets with high remanence and low coercivity. However, the Fe element content in the magnet in this Chinese patent document is only 17%~20% by mass, resulting in a low remanence of the prepared magnet. Summary of the Invention

[0007] The main objective of this invention is to overcome the shortcomings of the prior art and solve the problem of high Fe content Sm2Co 17 To address the technical problems of difficulty in forming a single 1:7H phase and poor integrity of the cellular structure during the solid solution treatment of permanent magnets, this invention provides a high-remanence sintered Sm2Co... 17 Methods for preparing permanent magnets.

[0008] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0009] A high remanence sintered Sm2Co 17 The method for preparing a permanent magnet includes the following steps:

[0010] S1. Preparation of samarium-cobalt alloy particles:

[0011] S1-1. Weigh the samarium-cobalt alloy raw material according to the following chemical composition and weight percentage: (Sm 1-x Pr x ): 25%~25.5%, Fe: 18%~20%, Zr: 2%~2.5%, Cu: 4%~5%, the remainder is Co; where x ranges from 0 ≤ x ≤ 0.4;

[0012] S1-2. The samarium cobalt alloy raw material weighed in step S1-1 is smelted in a medium frequency induction melting furnace and cast in a single-sided water-cooled copper mold to obtain samarium cobalt alloy ingots.

[0013] S1-3. The samarium cobalt alloy ingot prepared in step S1-2 is mechanically crushed to a particle size of 0.4mm~2mm to obtain samarium cobalt alloy particles for later use.

[0014] S2. Preparation of samarium-cobalt alloy powder:

[0015] S2-1. The samarium-cobalt alloy particles obtained in step S1 are processed into alloy powder A with a particle size of 3.2μm~4μm by air jet milling.

[0016] S2-2. Nano FeSn particles are used as auxiliary material B, and nano Fe powder is used as auxiliary material C. The raw materials are weighed according to the following mass percentages: alloy powder A: 94%~99%, auxiliary material B: 1%, and the remainder is auxiliary material C.

[0017] S2-3. The raw materials weighed in step S2-2 are mixed in a nitrogen protective atmosphere for 1-2 hours to obtain samarium-cobalt alloy powder for later use.

[0018] S3, magnetic field orientation molding, cold isostatic pressing:

[0019] The samarium-cobalt alloy powder obtained in step S2 is subjected to magnetic orientation forming in a magnetic field orientation forming press with a magnetic field strength greater than 1.8T; then it is subjected to cold isostatic pressing with a forming pressure greater than 180MPa and an isostatic pressing holding time of 8s~10s to obtain a green blank.

[0020] S4. Sintering, solution treatment, and aging treatment:

[0021] S4-1. The green body obtained after cold isostatic pressing in step S3 is heated to 600°C under vacuum conditions and held for 15 min to 30 min until the organic matter and adsorbed gas in the green body are completely removed.

[0022] S4-2. First, green billet sintering: the heating temperature is 1180℃~1200℃, and the sintering time is 0.2h~0.5h to obtain sintered billet; then, the sintered billet undergoes a two-stage solution treatment, which includes the following two stages: the first stage: the sintered billet is cooled to 1170℃ and held for 4h; the second stage: the sintered billet is cooled to 1150℃ within 15min and held for 20h; finally, the sintered billet after the two-stage solution treatment is rapidly air-cooled to room temperature;

[0023] S4-3. Aging Treatment: First, reheat the sintered billet to 800℃~860℃ and hold for 6h~10h; then, cool the sintered billet to 400℃ at a cooling rate of 1℃ / min and hold for 1h; finally, rapidly air-cool to room temperature to obtain sintered Sm2Co. 17 Permanent magnet.

[0024] Furthermore, in step S2-1, the process of preparing alloy powder A by air jet milling is carried out in a nitrogen atmosphere, wherein the oxygen content in the nitrogen atmosphere is less than 500 ppm and the oxygen content in alloy powder A is less than 1000 ppm.

[0025] Furthermore, in step S2-2, the particle size of the nano FeSn particles is 30nm~100nm; the purity of the nano Fe powder is 99.9%, and the particle size is 30nm~100nm.

[0026] Furthermore, in steps S2-3, nitrogen gas is introduced into the system before powder mixing, with a nitrogen pressure of 0.2 MPa, and an antioxidant with a volume fraction of 1‰ is added during powder mixing.

[0027] Furthermore, in step S3, the magnetic field orientation molding is carried out under nitrogen protection, with an oxygen content of less than 500 ppm.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. By adding auxiliary material B: nano FeSn particles, this invention can effectively reduce the sintering temperature of sintered samarium cobalt magnets, reduce the volatilization loss of rare earth elements, reduce manufacturing costs, and increase the Fe content of the magnet, thereby increasing the saturation magnetization and optimizing the magnetic properties of the magnet; by adding auxiliary material C: nano Fe powder, the Fe content of the magnet is effectively increased, thereby increasing the remanence and maximum energy product of the magnet.

[0030] 2. By adding nano-FeSn particles and nano-Fe powder, and combining them with a two-stage solid solution treatment, the present invention can enable the magnet to form a single 1:7H phase when it is dissolved at a high Fe content, thus preventing the formation of impurity phases. Subsequently, the 1:7H phase decomposes into 2:17R and 1:5H phases during aging, forming a complete cellular structure, which enables the samarium cobalt magnet to obtain good comprehensive magnetic properties.

[0031] In summary, the preparation method provided by this invention is easy to operate, control, and industrialize, and the sintered samarium cobalt magnets prepared have excellent performance, overcoming the problem of poor overall magnetic properties of traditional high-Fe content samarium cobalt magnets. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the preparation process of the present invention. Detailed Implementation

[0033] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the examples are conducted under conventional experimental conditions.

[0034] like Figure 1 A high remanence sintered Sm2Co is shown 17The method for preparing a permanent magnet includes the following steps:

[0035] S1. Preparation of samarium-cobalt alloy particles:

[0036] S1-1. Weigh the samarium-cobalt alloy raw material according to the following chemical composition and weight percentage: (Sm 1-x Pr x The composition of Pr is 25%~25.5%, Fe is 18%~20%, Zr is 2%~2.5%, Cu is 4%~5%, and the remainder is Co; where x ranges from 0 to x to 0.4; in this invention, 0~40% by mass of Pr is added to the samarium-cobalt alloy raw material, since Pr₂Co 17 The saturation magnetization is greater than that of Sm2Co. 17 Therefore, adding a certain amount of Pr can increase the saturation magnetization of the magnet, thereby increasing the remanence. However, when the Pr content is too high, the magnetic properties of the magnet will deteriorate. Therefore, the mass percentage of Pr added is controlled within 40%. To prepare a high-remanence samarium-cobalt magnet, the alloy raw material of this invention uses an Fe content of 18-20% by mass. Within this range, it is relatively easy for the magnet to form a single 1:7H phase through solid solution. To stabilize the formation of a single 1:7H phase during solid solution, this invention adds 2-2.5% by mass of Zr. However, excessive Zr and Cu will reduce the remanence of the magnet. Therefore, the Zr and Cu contents are controlled within the range required by this invention.

[0037] S1-2. The samarium cobalt alloy raw material weighed in step S1-1 is smelted in a medium frequency induction melting furnace and cast in a single-sided water-cooled copper mold to obtain samarium cobalt alloy ingots.

[0038] S1-3. The samarium cobalt alloy ingot prepared in step S1-2 is mechanically crushed to a particle size of 0.4mm~2mm to obtain samarium cobalt alloy particles for later use.

[0039] S2. Preparation of samarium-cobalt alloy powder:

[0040] S2-1. The samarium-cobalt alloy particles obtained in step S1 are processed into alloy powder A with a particle size of 3.2μm~4μm by air jet milling.

[0041] S2-2. Nano FeSn particles are used as auxiliary material B, and nano Fe powder is used as auxiliary material C. The raw materials are weighed according to the following mass percentages: alloy powder A: 94%~99%, auxiliary material B: 1%, and the remainder is auxiliary material C. Adding 1 wt.% of auxiliary material B (nano FeSn particles) can effectively reduce the sintering temperature and shorten the sintering time, allowing the magnet to be sintered densely in a shorter time, reducing rare earth burn-off, lowering costs, and preventing excessive and premature uniform entry of Fe elements into the grains, which would affect the formation of a single 1:7H phase in the solid solution. By adding auxiliary material C (nano Fe powder), the saturation magnetization of the magnet can be effectively improved through Fe element diffusion in the solid solution, thereby increasing its remanence.

[0042] S2-3. The raw materials weighed in step S2-2 are mixed in a nitrogen protective atmosphere for 1-2 hours to obtain samarium-cobalt alloy powder for later use.

[0043] S3, magnetic field orientation molding, cold isostatic pressing:

[0044] The samarium-cobalt alloy powder obtained in step S2 is subjected to magnetic orientation forming in a magnetic field orientation forming press with a magnetic field strength greater than 1.8T; then it is subjected to cold isostatic pressing with a forming pressure greater than 180MPa and an isostatic pressing holding time of 8s~10s to obtain a green blank.

[0045] S4. Sintering, solution treatment, and aging treatment:

[0046] S4-1. The green body obtained after cold isostatic pressing in step S3 is heated to 600°C under vacuum conditions and held for 15 min to 30 min until the organic matter and adsorbed gas in the green body are completely removed.

[0047] S4-2. First, green blank sintering: heating temperature is 1180℃~1200℃, sintering time is 0.2h~0.5h, to obtain sintered blank; then, the sintered blank undergoes a two-stage solution treatment, which includes the following two stages: first stage: the sintered blank is cooled to 1170℃ and held for 4h; second stage: the sintered blank is cooled to 1150℃ within 15min and held for 20h; finally, the sintered blank after the two-stage solution treatment is rapidly air-cooled to room temperature; this invention effectively reduces the sintering temperature and shortens the sintering time by adding nano-FeSn particles, making the magnet rapidly dense and preventing excessive Fe elements from entering the grains during sintering. The two-stage solution treatment can form a single 1:7H phase, which helps the magnet form a complete cellular structure during aging, obtaining good comprehensive magnetic properties; and it allows the added nano-Fe powder to fully diffuse into the phase, improving the remanence of the magnet;

[0048] S4-3. Aging Treatment: First, reheat the sintered billet to 800℃~860℃ and hold for 6h~10h; then, cool the sintered billet to 400℃ at a cooling rate of 1℃ / min and hold for 1h; finally, rapidly air-cool to room temperature to obtain sintered Sm2Co. 17 Permanent magnet. During the aging process, the 1:7H phase with a high Fe content decomposes into the 2:17R phase and the 1:5H phase, and the magnet forms a complete cellular structure. In the end, the magnet has a high Fe content and good comprehensive magnetic properties.

[0049] This invention employs a two-stage solution treatment method. In the first stage, the magnet rapidly dissolves to form a 1:7H phase. Afterward, the temperature is lowered and the magnet is held at that temperature for an extended period, which helps stabilize the 1:7H phase and allows the Fe element to fully diffuse into the grains. After aging, the magnet can form a complete cellular structure, achieving the goal of having good overall magnetic properties despite high Fe content.

[0050] Furthermore, in step S2-1, the process of preparing alloy powder A by air jet milling is carried out in a nitrogen atmosphere, wherein the oxygen content in the nitrogen atmosphere is less than 500 ppm and the oxygen content in alloy powder A is less than 1000 ppm, so that the samarium cobalt alloy powder has a low oxygen content, which is beneficial to improving the remanence of the magnet.

[0051] Furthermore, in step S2-2, the particle size of the nano FeSn particles is 30nm~100nm; the purity of the nano Fe powder is 99.9%, and the particle size is 30nm~100nm.

[0052] Furthermore, in steps S2-3, nitrogen gas is introduced into the system before powder mixing, with a nitrogen pressure of 0.2 MPa. An antioxidant with a volume fraction of 1‰ is added during powder mixing to prevent the samarium cobalt alloy powder and auxiliary powder from being oxidized.

[0053] Furthermore, in step S3, the magnetic field orientation molding is carried out under nitrogen protection, with an oxygen content of less than 500 ppm.

[0054] The following will provide further details with reference to specific embodiments. Example 1

[0055] A high remanence sintered Sm2Co 17 The method for preparing a permanent magnet includes the following steps:

[0056] S1. Preparation of samarium-cobalt alloy particles:

[0057] S1-1. Weigh the samarium-cobalt alloy raw material according to the following chemical composition and weight percentage: Sm: 15.3%, Pr: 10.2%, Fe: 20%, Zr: 2%, Cu: 4%, and the remainder is Co;

[0058] S1-2. The samarium cobalt alloy raw material weighed in step S1-1 is smelted in a medium frequency induction melting furnace and cast in a single-sided water-cooled copper mold to obtain samarium cobalt alloy ingots.

[0059] S1-3. The samarium cobalt alloy ingot prepared in step S1-2 is mechanically crushed to a particle size of 0.4mm~2mm to obtain samarium cobalt alloy particles for later use.

[0060] S2. Preparation of samarium-cobalt alloy powder:

[0061] S2-1. The samarium cobalt alloy particles obtained in step S1 are processed into alloy powder A with a particle size of 3.2μm~4μm by air jet milling. The process of preparing alloy powder A by air jet milling is carried out in a nitrogen atmosphere, wherein the oxygen content in the nitrogen atmosphere is less than 500ppm and the oxygen content in alloy powder A is less than 1000ppm.

[0062] S2-2. Nano FeSn particles are used as auxiliary material B, with a particle size of 30nm~100nm; nano Fe powder is used as auxiliary material C, with a purity of 99.9% and a particle size of 30nm~100nm; the raw materials are weighed according to the following mass percentages: alloy powder A: 94%, auxiliary material B: 1%, auxiliary material C: 5%;

[0063] S2-3. The raw materials weighed in step S2-2 are mixed in a nitrogen protective atmosphere for 2 hours. Before mixing, nitrogen is introduced into the system at a pressure of 0.2 MPa. An antioxidant with a volume fraction of 1‰ is added during mixing to obtain samarium cobalt alloy powder for later use.

[0064] S3, magnetic field orientation molding, cold isostatic pressing:

[0065] The samarium-cobalt alloy powder obtained in step S2 is subjected to magnetic orientation forming in a magnetic field orientation forming press with a magnetic field strength greater than 1.8T. The magnetic field orientation forming is carried out under nitrogen protection with an oxygen content of less than 500ppm. Then, cold isostatic pressing is performed with a cold isostatic pressing forming pressure greater than 180MPa and an isostatic pressing holding time of 8s to obtain a cylindrical green blank.

[0066] S4. Sintering, solution treatment, and aging treatment:

[0067] S4-1. The cylindrical green body obtained after cold isostatic pressing in step S3 is heated to 600°C under vacuum conditions and held for 15 minutes until the organic matter and adsorbed gas in the cylindrical green body are completely removed.

[0068] S4-2. First, green billet sintering: The heating temperature is 1180℃, and the sintering time is 0.2h to obtain a cylindrical sintered billet; then, the cylindrical sintered billet undergoes a two-stage solution treatment, which includes the following two stages: Stage 1: The sintered billet is cooled to 1170℃ and held for 4h; Stage 2: The sintered billet is cooled to 1150℃ within 15min and held for 20h; finally, the sintered billet after the two-stage solution treatment is rapidly air-cooled to room temperature.

[0069] S4-3. Aging Treatment: First, the sintered billet is reheated to 800℃ and held for 10 hours; then, the sintered billet is cooled to 400℃ at a cooling rate of 1℃ / min and held for 1 hour; finally, it is rapidly air-cooled to room temperature to obtain sintered Sm2Co with a diameter of 5mm. 17 Cylindrical permanent magnet.

[0070] The high remanence sintered Sm2Co prepared in Example 1 17 The magnetic properties of permanent magnets are: remanence B r = 12.15 kGs, Magnetic Energy Product (BH) max =34.68MGOe, intrinsic coercivity H cj =18.12kOe, knee magnetic field H knee =12.28kOe. Example 2

[0071] A high remanence sintered Sm2Co 17 The method for preparing a permanent magnet includes the following steps:

[0072] S1. Preparation of samarium-cobalt alloy particles:

[0073] S1-1. Weigh the samarium-cobalt alloy raw material according to the following chemical composition and weight percentage: Sm: 25%, Fe: 18%, Zr: 2.5%, Cu: 5%, and the remainder is Co;

[0074] S1-2. The samarium cobalt alloy raw material weighed in step S1-1 is smelted in a medium frequency induction melting furnace and cast in a single-sided water-cooled copper mold to obtain samarium cobalt alloy ingots.

[0075] S1-3. The samarium cobalt alloy ingot prepared in step S1-2 is mechanically crushed to a particle size of 0.4mm~2mm to obtain samarium cobalt alloy particles for later use.

[0076] S2. Preparation of samarium-cobalt alloy powder:

[0077] S2-1. The samarium cobalt alloy particles obtained in step S1 are processed into alloy powder A with a particle size of 3.2μm~4μm by air jet milling. The process of preparing alloy powder A by air jet milling is carried out in a nitrogen atmosphere, wherein the oxygen content in the nitrogen atmosphere is less than 500ppm and the oxygen content in alloy powder A is less than 1000ppm.

[0078] S2-2. Nano FeSn particles are used as auxiliary material B, with a particle size of 30nm~100nm; nano Fe powder is used as auxiliary material C, with a purity of 99.9% and a particle size of 30nm~100nm; the raw materials are weighed according to the following mass percentages: alloy powder A: 99%, auxiliary material B: 1%;

[0079] S2-3. The raw materials weighed in step S2-2 are mixed in a nitrogen protective atmosphere for 1 hour. Before mixing, nitrogen is introduced into the system at a pressure of 0.2 MPa. An antioxidant with a volume fraction of 1‰ is added during mixing to obtain samarium cobalt alloy powder for later use.

[0080] S3, magnetic field orientation molding, cold isostatic pressing:

[0081] The samarium-cobalt alloy powder obtained in step S2 is subjected to magnetic orientation forming in a magnetic field orientation forming press with a magnetic field strength greater than 1.8T. The magnetic field orientation forming is carried out under nitrogen protection with an oxygen content of less than 500ppm. Then, cold isostatic pressing is performed with a cold isostatic pressing forming pressure greater than 180MPa and an isostatic pressing holding time of 9s to obtain a cylindrical green blank.

[0082] S4. Sintering, solution treatment, and aging treatment:

[0083] S4-1. The cylindrical green body obtained by cold isostatic pressing in step S3 is heated to 600°C under vacuum conditions and held for 30 minutes until the organic matter and adsorbed gas in the cylindrical green body are completely removed.

[0084] S4-2. First, green billet sintering: The heating temperature is 1200℃, and the sintering time is 0.5h to obtain a cylindrical sintered billet; then, the cylindrical sintered billet undergoes a two-stage solution treatment, which includes the following two stages: Stage 1: The sintered billet is cooled to 1170℃ and held for 4h; Stage 2: The sintered billet is cooled to 1150℃ within 15min and held for 20h; finally, the sintered billet after the two-stage solution treatment is rapidly air-cooled to room temperature.

[0085] S4-3. Aging Treatment: First, the sintered billet is reheated to 860℃ and held for 6 hours; then, the sintered billet is cooled to 400℃ at a cooling rate of 1℃ / min and held for 1 hour; finally, it is rapidly air-cooled to room temperature to obtain sintered Sm2Co with a diameter of 8mm. 17 Cylindrical permanent magnet.

[0086] The high remanence sintered Sm2Co prepared in Example 2 17 The magnetic properties of permanent magnets are: remanence B r = 11.73 kGs, Magnetic Energy Product (BH) max =32.85MGOe, intrinsic coercivity H cj =29.65kOe, knee magnetic field H knee =16.82kOe. Example 3

[0087] A high remanence sintered Sm2Co 17 The method for preparing a permanent magnet includes the following steps:

[0088] S1. Preparation of samarium-cobalt alloy particles:

[0089] S1-1. Weigh the samarium-cobalt alloy raw material according to the following chemical composition and weight percentage: Sm: 20.2%, Pr: 5%, Fe: 19%, Zr: 2.3%, Cu: 4.6%, with the remainder being Co;

[0090] S1-2. The samarium cobalt alloy raw material weighed in step S1-1 is smelted in a medium frequency induction melting furnace and cast in a single-sided water-cooled copper mold to obtain samarium cobalt alloy ingots.

[0091] S1-3. The samarium cobalt alloy ingot prepared in step S1-2 is mechanically crushed to a particle size of 0.4mm~2mm to obtain samarium cobalt alloy particles for later use.

[0092] S2. Preparation of samarium-cobalt alloy powder:

[0093] S2-1. The samarium cobalt alloy particles obtained in step S1 are processed into alloy powder A with a particle size of 3.2μm~4μm by air jet milling. The process of preparing alloy powder A by air jet milling is carried out in a nitrogen atmosphere, wherein the oxygen content in the nitrogen atmosphere is less than 500ppm and the oxygen content in alloy powder A is less than 1000ppm.

[0094] S2-2. Nano FeSn particles are used as auxiliary material B, with a particle size of 30nm~100nm; nano Fe powder is used as auxiliary material C, with a purity of 99.9% and a particle size of 30nm~100nm; the raw materials are weighed according to the following mass percentages: alloy powder A: 97%, auxiliary material B: 1%, auxiliary material C: 2%;

[0095] S2-3. The raw materials weighed in step S2-2 are mixed in a nitrogen protective atmosphere for 1.5 hours. Before mixing, nitrogen is introduced into the system at a pressure of 0.2 MPa. An antioxidant with a volume fraction of 1‰ is added during mixing to obtain samarium cobalt alloy powder for later use.

[0096] S3, magnetic field orientation molding, cold isostatic pressing:

[0097] The samarium-cobalt alloy powder obtained in step S2 is subjected to magnetic orientation forming in a magnetic field orientation forming press with a magnetic field strength greater than 1.8T. The magnetic field orientation forming is carried out under nitrogen protection with an oxygen content of less than 500ppm. Then, cold isostatic pressing is performed with a cold isostatic pressing forming pressure greater than 180MPa and an isostatic pressing holding time of 10s to obtain a cylindrical green blank.

[0098] S4. Sintering, solution treatment, and aging treatment:

[0099] S4-1. The cylindrical green body obtained by cold isostatic pressing in step S3 is heated to 600°C under vacuum conditions and held for 25 minutes until the organic matter and adsorbed gas in the cylindrical green body are completely removed.

[0100] S4-2. First, green billet sintering: The heating temperature is 1195℃, and the sintering time is 0.4h to obtain a cylindrical sintered billet; then, the cylindrical sintered billet undergoes a two-stage solution treatment, which includes the following two stages: Stage 1: The sintered billet is cooled to 1170℃ and held for 4h; Stage 2: The sintered billet is cooled to 1150℃ within 15min and held for 20h; finally, the sintered billet after the two-stage solution treatment is rapidly air-cooled to room temperature;

[0101] S4-3. Aging Treatment: First, the sintered billet is reheated to 830℃ and held for 8 hours; then, the sintered billet is cooled to 400℃ at a cooling rate of 1℃ / min and held for 1 hour; finally, it is rapidly air-cooled to room temperature to obtain sintered Sm2Co with a diameter of 7mm. 17 Cylindrical permanent magnet.

[0102] The high remanence sintered Sm2Co prepared in Example 3 17 The magnetic properties of permanent magnets are: remanence B r = 12.02 kGs, Magnetic Energy Product (BH) max =34.13MGOe, intrinsic coercivity H cj =21.71kOe, knee magnetic field H knee =14.86kOe. Example 4

[0103] A high remanence sintered Sm2Co17 The method for preparing a permanent magnet includes the following steps:

[0104] S1. Preparation of samarium-cobalt alloy particles:

[0105] S1-1. Weigh the samarium-cobalt alloy raw material according to the following chemical composition and weight percentage: Sm: 18%, Pr: 7.4%, Fe: 20%, Zr: 2.5%, Cu: 4.2%, with the remainder being Co;

[0106] S1-2. The samarium cobalt alloy raw material weighed in step S1-1 is smelted in a medium frequency induction melting furnace and cast in a single-sided water-cooled copper mold to obtain samarium cobalt alloy ingots.

[0107] S1-3. The samarium cobalt alloy ingot prepared in step S1-2 is mechanically crushed to a particle size of 0.4mm~2mm to obtain samarium cobalt alloy particles for later use.

[0108] S2. Preparation of samarium-cobalt alloy powder:

[0109] S2-1. The samarium cobalt alloy particles obtained in step S1 are processed into alloy powder A with a particle size of 3.2μm~4μm by air jet milling. The process of preparing alloy powder A by air jet milling is carried out in a nitrogen atmosphere, wherein the oxygen content in the nitrogen atmosphere is less than 500ppm and the oxygen content in alloy powder A is less than 1000ppm.

[0110] S2-2. Nano FeSn particles are used as auxiliary material B, with a particle size of 30nm~100nm; nano Fe powder is used as auxiliary material C, with a purity of 99.9% and a particle size of 30nm~100nm; the raw materials are weighed according to the following mass percentages: alloy powder A: 98%, auxiliary material B: 1%, auxiliary material C: 1%;

[0111] S2-3. The raw materials weighed in step S2-2 are mixed in a nitrogen protective atmosphere for 1.5 hours. Before mixing, nitrogen is introduced into the system at a pressure of 0.2 MPa. An antioxidant with a volume fraction of 1‰ is added during mixing to obtain samarium cobalt alloy powder for later use.

[0112] S3, magnetic field orientation molding, cold isostatic pressing:

[0113] The samarium-cobalt alloy powder obtained in step S2 is subjected to magnetic orientation forming in a magnetic field orientation forming press with a magnetic field strength greater than 1.8T. The magnetic field orientation forming is carried out under nitrogen protection with an oxygen content of less than 500ppm. Then, cold isostatic pressing is performed with a cold isostatic pressing forming pressure greater than 180MPa and an isostatic pressing holding time of 8s to obtain a cylindrical green blank.

[0114] S4. Sintering, solution treatment, and aging treatment:

[0115] S4-1. The cylindrical green body obtained by cold isostatic pressing in step S3 is heated to 600°C under vacuum conditions and held for 20 minutes until the organic matter and adsorbed gas in the cylindrical green body are completely removed.

[0116] S4-2. First, green billet sintering: The heating temperature is 1180℃, and the sintering time is 0.4h to obtain a cylindrical sintered billet; then, the cylindrical sintered billet undergoes a two-stage solution treatment, which includes the following two stages: Stage 1: The sintered billet is cooled to 1170℃ and held for 4h; Stage 2: The sintered billet is cooled to 1150℃ within 15min and held for 20h; finally, the sintered billet after the two-stage solution treatment is rapidly air-cooled to room temperature.

[0117] S4-3. Aging Treatment: First, the sintered billet is reheated to 830℃ and held for 8 hours; then, the sintered billet is cooled to 400℃ at a cooling rate of 1℃ / min and held for 1 hour; finally, it is rapidly air-cooled to room temperature to obtain sintered Sm2Co with a diameter of 6mm. 17 Cylindrical permanent magnet.

[0118] The high remanence sintered Sm2Co prepared in Example 4 17 The magnetic properties of permanent magnets are: remanence B r = 12 kGs, Magnetic Energy Product (BH) max =33.98MGOe, intrinsic coercivity H cj =22.2kOe, knee magnetic field H knee =15kOe. Comparative Example 1

[0119] S1. Preparation of samarium-cobalt alloy particles:

[0120] First, the samarium-cobalt alloy raw materials are prepared according to the following weight percentages: Sm: 15.3%, Pr: 10.2%, Fe: 20%, Zr: 2%, Cu: 4%, with the balance being Co;

[0121] Then, the weighed samarium-cobalt alloy raw materials are smelted in a medium-frequency induction melting furnace and cast in a single-sided water-cooled copper mold to obtain samarium-cobalt alloy ingots.

[0122] Finally, the samarium cobalt alloy ingot is mechanically crushed into samarium cobalt alloy particles with a particle size of 0.4~2mm;

[0123] S2. Preparation of samarium-cobalt alloy powder: The samarium-cobalt alloy particles obtained in step S1 are processed into alloy powder with a size of 3.2~4μm using air jet milling technology;

[0124] S3. Magnetic field orientation forming and cold isostatic pressing: The samarium cobalt alloy powder obtained in step S2 is oriented in a magnetic field orientation forming press with a magnetic field greater than 1.8T, and then cold isostatic pressing is performed with a pressure greater than 180MPa to obtain a cylindrical green blank.

[0125] S4. Sintering, solution treatment, and aging treatment:

[0126] First, the cylindrical green blank obtained after cold isostatic pressing in step S3 is heated to 1210℃ and sintered for 1 hour; then, it is cooled to 1170℃ and held for 20 hours; finally, it is rapidly air-cooled to room temperature.

[0127] Then, aging treatment: the temperature is raised to 860℃ and held for 6 hours; then, it is cooled to 400℃ at a cooling rate of 1℃ / min and held for 1 hour, followed by rapid air cooling to room temperature to obtain samarium cobalt magnets.

[0128] Sintered Sm2Co prepared in Comparative Example 1 17 The magnetic properties of permanent magnets are: remanence B r = 11.91 kGs, Magnetic Energy Product (BH) max =26.39 MGOe, intrinsic coercivity H cj =15.16kOe, knee magnetic field H knee =5.67kOe.

[0129] As can be seen from Examples 1-4 and Comparative Example 1, the present invention can produce products with high comprehensive magnetic properties through corresponding formulas and processes, meeting the needs of various commercial applications. Moreover, the method is simple, has good economic benefits, and has broad application prospects.

[0130] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high remanence sintered Sm2Co 17 A method for producing a permanent magnet of the type defined in the preamble of claim 1, characterized in that The method comprises the following steps: S1, preparing samarium-cobalt alloy particles: S1-1, according to the following chemical components and their weight percentages, samarium-cobalt alloy raw materials are weighed: (Sm 1-x Pr x ): 25%~25.5%, Fe: 18%~20%, Zr: 2%~2.5%, Cu: 4%~5%, and the rest is Co; wherein, the value range of x is 0≤x≤0.4; S1-2, smelting the samarium-cobalt alloy raw material weighed in step S1-1 in a medium-frequency induction smelting furnace, and casting in a single-face water-cooled copper mold to obtain a samarium-cobalt alloy ingot; S1-3, mechanically crushing the samarium-cobalt alloy ingot prepared in step S1-2 to a particle size of 0.4mm-2mm to obtain samarium-cobalt alloy particles for standby use; S2, preparing samarium-cobalt alloy powder: S2-1, using an air flow milling method to mill the samarium-cobalt alloy particles prepared in step S1 into alloy powder A with a particle size of 3.2μm-4μm; S2-2, using nano FeSn particles as auxiliary material B and nano Fe powder as auxiliary material C, and weighing the raw materials according to the following mass percentage: alloy powder A: 94%-98%, auxiliary material B: 1%, and the rest is auxiliary material C; S2-3, mixing the raw materials weighed in step S2-2 under a nitrogen protective atmosphere, and the mixing time is 1h-2h to obtain samarium-cobalt alloy powder for standby use; S3, magnetic field orientation forming and cold isostatic pressing: The samarium-cobalt alloy powder prepared in step S2 is subjected to magnetic field orientation forming in a magnetic field orientation forming press, and the magnetic field strength is greater than 1.8T; then cold isostatic pressing is performed, and the cold isostatic pressing forming pressure is greater than 180MPa, and the isostatic pressing holding time is 8s-10s to obtain a green body; S4, sintering, solid solution and aging treatment: S4-1, heating the green body prepared after the cold isostatic pressing in step S3 to 600℃ under vacuum conditions, and the holding time is 15min-30min until the organic matter and adsorbed gas in the green body are completely removed; S4-2, first, green body sintering: the heating temperature is 1180℃-1200℃, and the sintering time is 0.2h-0.5h to obtain a sintered blank; then, the sintered blank is subjected to two-stage solid solution treatment, which comprises the following two stages: first stage: the sintered blank is cooled to 1170℃ and held for 4h; second stage: the sintered blank is cooled to 1150℃ within 15min and held for 20h; finally, the sintered blank after the two-stage solid solution treatment is rapidly air-cooled to room temperature; S4-3, aging treatment: firstly, the sintered blank is reheated to 800-860℃, and kept for 6-10h; then, the sintered blank is cooled to 400℃ at a cooling rate of 1℃ / min, and kept for 1h; finally, it is rapidly air-cooled to room temperature to obtain a sintered Sm2Co 17 permanent magnet.

2. A high-remanence sintered Sm2Co 17 The method for producing a permanent magnet is characterized by comprising: In the step S2-1, the process of preparing the alloy powder A by the air flow milling method is carried out in a nitrogen atmosphere, wherein the oxygen content in the nitrogen atmosphere is less than 500ppm, and the oxygen content in the alloy powder A is less than 1000ppm.

3. A high-remanence sintered Sm2Co 17 The method for manufacturing a permanent magnet is characterized by comprising: In the step S2-2, the particle size of the nano FeSn particles is 30nm-100nm; the purity of the nano Fe powder is 99.9%, and the particle size is 30nm-100nm.

4. A high-remanence sintered Sm2Co 17 The method for producing a permanent magnet is characterized by comprising: In the step S2-3, nitrogen is filled into the system before mixing, and the nitrogen pressure is 0.2MPa; 1‰ of an antioxidant is added during mixing.

5. A high-remanence sintered Sm2Co 17 The method for producing a permanent magnet is characterized by comprising: In the step S3, the magnetic field orientation forming is carried out under a nitrogen protective atmosphere, and the oxygen content is less than 500ppm.

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