High intrinsic coercive force 2 / 17 type iron-samarium-cobalt-rich permanent magnet material and preparation method thereof

Abstract

The invention provides a high intrinsic coercive force 2: 17 type iron-samarium-cobalt-rich permanent magnet material and a preparation method thereof, and belongs to the technical field of magnetic materials. Samarium cobalt magnet alloy powder is sequentially subjected to magnetic field orientation forming and cold isostatic pressing forming, an obtained green body is sequentially subjected to sintering, solution treatment and cooling, and a solid-solution-state samarium cobalt magnet blank is obtained; under the vacuum condition, the samarium-cobalt magnet solid solution state blank is repeatedly heated and rapidly cooled to the room temperature, and a blank subjected to repeated and rapid cooling treatment is obtained; carrying out isothermal aging treatment, cooling and slicing to obtain a samarium-cobalt magnet sheet; and applying the PrFeSn alloy powder turbid liquid to the double surfaces of the samarium-cobalt magnet sheet, drying, and carrying out slow cooling diffusion treatment to obtain the high intrinsic coercive force 2: 17 type iron-rich samarium-cobalt permanent magnet material. According to the preparation method provided by the invention, the cellular organization structure of the Fe-rich samarium-cobalt magnet can be improved, and the intrinsic coercive force of the 2: 17 type iron-rich samarium-cobalt permanent magnet material is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetic materials, and specifically relates to a 2:17 type iron-rich samarium cobalt permanent magnet material with high intrinsic coercivity and a preparation method thereof. Background Art

[0002] The second-generation rare-earth permanent magnet material, the 2:17 type SmCo permanent magnet, has excellent magnetic properties, a high Curie temperature, good temperature stability, and excellent corrosion resistance. Since its appearance, it has been highly favored and widely used in many fields such as national defense and military industry, aerospace, medical devices, microwave devices, transportation, and high-end motors. In recent years, as products in some fields have developed towards miniaturization and light weight, higher requirements have been put forward for the magnetic properties of the required magnets.

[0003] The 2:17 type SmCo permanent magnet (the composition includes Sm, Fe, Zr, Cu, and Co) has a typical cellular tissue structure. Among them, the 2:17R cellular phase has a high Fe element content, which can provide a high saturation magnetization intensity for the magnet; the 1:5H cell wall phase has a high solubility for the Cu element, and the Cu element can be enriched at the cell wall, enabling the magnet to obtain a high coercivity; in addition to the cellular phase and the cell wall phase, there is also a sheet-like Zr-rich phase structure in the magnet, which provides a channel for element diffusion during the aging process. It is precisely because of such a complex microstructure that the 2:17 type sintered SmCo magnet exhibits excellent comprehensive magnetic properties. At present, increasing the Fe content is one of the main methods to improve the magnetic properties of the 2:17 type SmCo permanent magnet. However, during the preparation of high-magnetic-property SmCo magnets, too high an Fe content will cause the magnet not to form a single and uniform 1:7H phase during the solution process, so that a good cellular tissue structure cannot be formed during the aging process of the magnet, resulting in the deterioration of the magnetic properties of the magnet.

[0004] At present, in the Chinese patent document "A Method for Improving the Magnetic Properties of Samarium Cobalt Permanent Magnet Materials" (Publication No.: CN112038083 A), a low-melting-point phase diffusion source is applied to the surface of the matrix material by coating and / or cladding for diffusion treatment to improve the magnetic properties of the magnet, but it cannot solve the problem of the deterioration of the microstructure of the magnet caused by too high an Fe content, and the diffusion of the low-melting-point phase RE-TM cannot effectively improve the remanence and maximum magnetic energy product of the magnet. In the Chinese patent document "A Diffusion Preparation Method for Fe-Rich High-Coercivity Samarium Cobalt Magnets" (Publication No.: CN119296941 A), secondary diffusion of PrCu and SnFe is used to improve the magnetic properties of the magnet. However, in the patent, the Fe-rich magnet cannot avoid the problem of too large cell size during the aging process, resulting in a relatively low Cu concentration at the cell wall, thus making the intrinsic coercivity of the magnet relatively low. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a 2:17 type Fe-rich SmCo permanent magnet material with high intrinsic coercivity and a preparation method thereof. The preparation method provided by the present invention can improve the cellular tissue structure of the Fe-rich SmCo magnet and effectively enhance the remanence, maximum magnetic energy product and intrinsic coercivity of the 2:17 type Fe-rich SmCo permanent magnet material.

[0006] In order to achieve the above object of the invention, the present invention provides the following technical solutions: The present invention provides a preparation method of a 2:17 type Fe-rich SmCo permanent magnet material with high intrinsic coercivity, comprising the following steps: (1) Melting the raw materials of the SmCo permanent magnet material to obtain a SmCo magnet alloy ingot; calculated by mass percentage, the raw materials of the SmCo permanent magnet material include: (Sm 1-x Re x ) : 25% - 25.5%, Fe: 14% - 18%, Zr: 2.2% - 3%, Cu: 4% - 6%, and the balance is Co; wherein, 0 ≤ x ≤ 0.3, and Re is one or more of Pr, Nd, Gd, Dy, Tb, Er, Y or Ho; (2) Crushing and grinding the SmCo magnet alloy ingot in sequence, and subjecting the obtained alloy powder to magnetic field orientation forming and cold isostatic pressing forming in sequence to obtain a SmCo magnet green body; (3) Sintering, solution treatment and cooling the SmCo magnet green body in sequence to obtain a SmCo magnet solution-state blank; (4) Under vacuum conditions, repeatedly heating the SmCo magnet solution-state blank to 830 - 850 °C and rapidly cooling it to room temperature to obtain a blank after repeated rapid cooling treatment; (5) Performing isothermal aging treatment and cooling on the blank after repeated rapid cooling treatment to obtain a SmCo aged-state blank, and slicing the SmCo aged-state blank to obtain a SmCo magnet sheet; (6) Applying a PrFeSn alloy powder suspension to both sides of the SmCo magnet sheet, drying and then performing slow-cooling diffusion treatment to obtain a 2:17 type Fe-rich SmCo permanent magnet material with high intrinsic coercivity.

[0007] Preferably, in the step (2), the particle size of the alloy powder is 3 - 5 μm; The magnetic field strength of the magnetic field orientation forming is 1.8 - 2 T; The pressure of the cold isostatic pressing forming is 200 - 230 MPa, and the time is 20 - 30 s.

[0008] Preferably, in the step (3), the sintering temperature is 1200 - 1210 °C, and the heat preservation time is 1 - 2 h; The temperature of the solution treatment is 1160 - 1180 °C, and the time is 4 - 10 h.

[0009] Preferably, in the step (4) of heating to 830 - 850 °C and then rapidly cooling to room temperature, the rapid cooling method is air cooling; the time for rapidly cooling from 830 - 850 °C to room temperature is 20 - 25 min; The number of repetitions of heating to 830 - 850 °C and then rapidly cooling to room temperature is 1 - 2 times.

[0010] Preferably, in the step (5), the temperature of the isothermal aging treatment is 830 - 850 °C, and the holding time is 2 - 4 h; The SmCo aged blank has a complete cellular microstructure, and the average cell size is 80 - 95 nm.

[0011] Preferably, the thickness of the SmCo magnet sheet is 2 - 5 mm.

[0012] Preferably, the particle size of the PrFeSn alloy powder is 1000 - 5000 nm; In the PrFeSn alloy, the mass content of Pr is 30 - 45%, the mass content of Fe is 50 - 65%, and the mass percentage content of Sn is 1 - 5%.

[0013] Preferably, the mass concentration of the PrFeSn alloy powder in the PrFeSn alloy powder suspension is 10 - 20%; The solvent of the PrFeSn alloy powder suspension is an alcohol solvent.

[0014] Preferably, the slow cooling and diffusion treatment method includes the following steps: Heat the SmCo magnet sheet with PrFeSn alloy powder suspension applied on both sides to 830 - 850 °C, then cool it to 400 °C and hold for 1 h, and then air cool to room temperature; The cooling rate is 0.5 - 0.7 °C / min.

[0015] The present invention provides a 2:17 type Fe-rich SmCo permanent magnet material with high intrinsic coercivity prepared by the above preparation method.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By repeatedly heating the solution-treated blank to 830 - 850 °C and then rapidly cooling it, the present invention can promote the nucleation of the 1:5H cell wall phase, thereby effectively shortening the formation time of the cellular structure in the subsequent treatment process, greatly shortening the subsequent aging treatment time, and improving the production efficiency; and due to the presence of more 1:5H cell wall phase nucleation points, more cell wall phases can be formed, reducing the average cell size and narrowing the cell walls, so that a higher Cu concentration can be obtained at the cell walls, thereby improving the intrinsic coercivity of the Fe-rich magnet.

[0017] (2) In the slow cooling stage of the present invention, PrFeSn is used as a diffusing agent. During the slow cooling diffusion treatment process, Fe elements diffuse into the cells. Fe elements will diffuse into the cells, and Cu elements will diffuse into the cell walls. Therefore, excessive Fe elements will directly diffuse into the cells of the magnet. And because a good cellular tissue structure has been formed during the isothermal aging heat preservation stage at 830 - 850 °C, excessive Fe elements can improve the saturation magnetization intensity of the magnet without destroying the cellular tissue structure formed by the magnet, thereby improving the remanence and maximum magnetic energy product of the magnet; the addition of Sn elements is beneficial to reducing the melting point of PrFeSn and promoting the rapid progress of element diffusion; in addition, Pr elements enter the cells of the magnet to replace Sm elements. Since the saturation magnetization intensity of Pr2Co 17 is greater than that of Sm2Co 17 , so it can also improve the remanence and maximum magnetic energy product of the magnet. Compared with the prior art CN119296941A, the present invention avoids the secondary diffusion process and can improve the cellular tissue structure of the Fe-rich samarium cobalt magnet only by a single diffusion of PrFeSn, effectively improving the intrinsic coercivity of the 2:17 type Fe-rich samarium cobalt permanent magnetic material, and at the same time improving the production efficiency.

[0018] (3) Further, in the present invention, the samarium cobalt aged blank has a complete cellular tissue structure, and the average cell size is 80 - 95 nm. Due to the increase in the nucleation points of the 1:5H phase, an isothermal aging process can form a cellular tissue structure with an average cell size of 80 - 95 nm. However, at this time, there is less Cu element at the cell walls, and it needs to be enriched at the cell walls through diffusion during the subsequent slow cooling process.

[0019] (4) The preparation method provided by the present invention is easy to operate and control, and is easy to realize industrial mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a process flow schematic diagram of the preparation method of the 2:17 type Fe-rich samarium cobalt permanent magnetic material with high intrinsic coercivity of the present invention; Figure 2 is the cellular tissue structure of the samarium cobalt permanent magnetic material in Example 1 of the present invention; Figure 3 is the cellular tissue structure of the samarium cobalt permanent magnetic material in Example 2 of the present invention; Figure 4 is the cellular tissue structure of the samarium cobalt permanent magnetic material in Example 3 of the present invention; Figure 5 is the cellular tissue structure of the samarium cobalt permanent magnetic material in Example 4 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The present invention provides a preparation method of a 2:17 type Fe-rich samarium cobalt permanent magnetic material with high intrinsic coercivity, including the following steps: (1) The raw materials of the samarium-cobalt permanent magnet material are smelted to obtain a samarium-cobalt magnet alloy ingot; in terms of mass percentage, the raw materials of the samarium-cobalt permanent magnet material include: (Sm 1-x Re x ): 25% - 25.5%, Fe: 14% - 18%, Zr: 2.2% - 3%, Cu: 4% - 6%, and the balance is Co; where 0 ≤ x ≤ 0.3, and Re is one or more of Pr, Nd, Gd, Dy, Tb, Er, Y, or Ho; (2) The samarium-cobalt magnet alloy ingot is successively crushed and ground, and the obtained alloy powder is successively formed by magnetic field orientation and cold isostatic pressing to obtain a green body of the samarium-cobalt magnet; (3) The green body of the samarium-cobalt magnet is successively sintered, solution-treated, and cooled to obtain a solution-treated blank of the samarium-cobalt magnet; (4) Under vacuum conditions, the solution-treated blank of the samarium-cobalt magnet is repeatedly heated to 830 - 850 °C and rapidly cooled to room temperature to obtain a blank after repeated rapid cooling treatment; (5) The blank after repeated rapid cooling treatment is subjected to isothermal aging treatment and cooling to obtain an aged blank of the samarium-cobalt magnet, and the aged blank of the samarium-cobalt magnet is sliced to obtain samarium-cobalt magnet sheets; (6) A PrFeSn alloy powder suspension is applied to both sides of the samarium-cobalt magnet sheet, and after drying, slow-cooling diffusion treatment is carried out to obtain a 2:17 type iron-rich samarium-cobalt permanent magnet material with high intrinsic coercivity.

[0022] Unless otherwise specified, the raw materials used in the present invention are commercially available.

[0023] The present invention smelts the raw materials of the samarium-cobalt permanent magnet material to obtain a samarium-cobalt magnet alloy ingot. In the present invention, in terms of mass percentage, the raw materials of the samarium-cobalt permanent magnet material include: (Sm 1-x Re x ): 25% - 25.5%, Fe: 14% - 18%, Zr: 2.2% - 3%, Cu: 4% - 6%, and the balance is Co; in Sm 1-x Re x , 0 ≤ x ≤ 0.3, preferably 0.1 - 0.2, specifically can be 0, 0.1, 0.2, or 0.3; Re is one or more of Pr, Nd, Gd, Dy, Tb, Er, Y, or Ho.

[0024] In the present invention, in terms of mass percentage, the content of the Sm 1-x Re x is preferably 25.2% - 25.4%, the content of Fe is preferably 15% - 17%, the content of Zr is preferably 2.4% - 2.8%, and the content of Cu is preferably 4.5% - 5%.

[0025] In the present invention, the smelting is preferably vacuum intermediate frequency induction smelting; the vacuum degree of the vacuum intermediate frequency induction smelting is preferably 5×10 -2 ~5×10 -3 Pa, and the smelting temperature is preferably 1400~1500°C. In the present invention, after the alloy raw materials are completely melted, the present invention preferably continues to refine for 2~3 min under the condition of heat preservation. In the present invention, the thickness of the samarium cobalt magnet alloy ingot is preferably 10~20 mm. After obtaining the samarium cobalt magnet alloy ingot, the present invention successively crushes and grinds the samarium cobalt magnet alloy ingot, and successively subjects the obtained alloy powder to magnetic field orientation forming and cold isostatic pressing forming to obtain a samarium cobalt magnet green body. In the present invention, the crushing is preferably mechanical crushing, and the particle size after crushing is preferably 0.5~2 mm, more preferably 1~1.5 mm. In the present invention, the grinding is preferably air jet milling, and the average particle size of the alloy powder after grinding is preferably 3~5 μm.

[0026] In the present invention, the magnetic field strength of the magnetic field orientation forming is preferably 1.8~2 T; by carrying out magnetic field orientation forming under the above conditions, the present invention can ensure that the green body obtains a high degree of orientation, and the degree of orientation is proportional to the remanence of the magnet, so that the final magnet can obtain a high remanence.

[0027] In the present invention, the pressure of the cold isostatic pressing forming is preferably 200~230 MPa, and the time is preferably 20~30 s. By carrying out cold isostatic pressing forming under the above conditions, the present invention can make the green body obtain a relatively large density, which is beneficial to obtaining a dense tissue structure during the subsequent sintering of the magnet.

[0028] After obtaining the samarium cobalt magnet green body, the present invention successively sinters, solution-treats and cools the samarium cobalt magnet green body to obtain a samarium cobalt magnet solution-state blank. In the present invention, the atmosphere of the sintering is preferably argon; the sintering temperature is preferably 1200~1210°C, specifically it can be 1200°C, 1205°C or 1210°C; the heat preservation time is preferably 1~2 h, specifically it can be 1 h, 1.5 h or 2 h. In the present invention, the heating rate for heating to the sintering temperature is preferably 5~6°C / min. By carrying out sintering under the above conditions, the present invention can make the magnet obtain a dense structure, thereby obtaining a high remanence. After the sintering, the present invention preferably cools with the furnace to the temperature of the solution treatment.

[0029] In the present invention, the solution treatment is preferably carried out in an argon atmosphere. The temperature of the solution treatment is preferably 1160-1180 °C, specifically it can be 1160 °C, 1170 °C or 1180 °C, and the time is preferably 4-10 h, more preferably 6-8 h. In the present invention, the cooling method is preferably rapid air cooling to room temperature, and the time from the solution treatment to cooling to room temperature is preferably 25-30 min. In the present invention, since the Fe content in the samarium cobalt alloy raw material is small, through the solution treatment, the samarium cobalt magnet can form a uniform 1:7H phase, which is beneficial to the formation of a complete cellular tissue structure after the subsequent aging of the magnet.

[0030] After obtaining the solution-state blank of the samarium cobalt magnet, in the present invention, under vacuum conditions, the solution-state blank of the samarium cobalt magnet is repeatedly heated to 830-850 °C and rapidly cooled to room temperature to obtain a blank after repeated rapid cooling treatment. In the present invention, the vacuum degree of the vacuum conditions is preferably 10 -2 ~10 -3 Pa. In the present invention, the heating rate for heating to 830-850 °C is preferably 5-6 °C / min, and in the present invention, cooling is carried out immediately after heating to 830-850 °C. In the present invention, the rapid cooling method is air cooling, and the time from 830-850 °C to rapid cooling to room temperature is preferably 20-25 min; in the present invention, the number of repetitions of heating to 830-850 °C and rapid cooling to room temperature is preferably 1-2 times. By repeatedly heating to 830-850 °C and rapid cooling to room temperature, the present invention can promote the nucleation of the 1:5H cell wall phase, thereby shortening the formation time of the cellular tissue in the subsequent treatment process. And because there are more nucleation points of the 1:5H cell wall phase, more cell wall phases can be formed, the average cell size is reduced, and the cell wall becomes narrower, so that a higher Cu concentration can be obtained at the cell wall.

[0031] After obtaining the blank after repeated rapid cooling treatment, the present invention performs isothermal aging treatment and cooling on the blank after repeated rapid cooling treatment to obtain a samarium-cobalt aged blank, and performs slicing treatment on the samarium-cobalt aged blank to obtain a samarium-cobalt magnet sheet. In the present invention, the atmosphere of the isothermal aging treatment is preferably argon, the temperature of the isothermal aging treatment is preferably 830-850 °C, specifically it can be 830 °C, 840 °C or 850 °C, the holding time is preferably 2-4 h, more preferably 2 h, 3 h or 4 h; the heating rate to the isothermal aging treatment is preferably 5-6 °C / min. In the present invention, the cooling is preferably rapid cooling, further preferably air cooling, and the time for cooling from the isothermal aging treatment temperature to room temperature is preferably 20-25 min. Through the isothermal aging treatment of the present invention, a complete cellular tissue structure can be formed in a relatively short time. In the present invention, the samarium-cobalt aged blank has a complete cellular tissue structure, and the average cell size is preferably 80-95 nm.

[0032] The present invention preferably performs the slicing treatment by a slicing machine. In the present invention, the thickness of the samarium-cobalt magnet sheet is preferably 2-5 mm, more preferably 3-4 mm. In the present invention, affected by the element diffusion depth, when the magnet thickness is too large, the diffused elements cannot fully enter the interior of the magnet, resulting in a poor diffusion effect. Therefore, the samarium-cobalt magnet needs to be processed into a thin sheet with a thickness of 2-5 mm.

[0033] After obtaining the samarium-cobalt magnet sheet, the present invention applies a PrFeSn alloy powder suspension to both sides of the samarium-cobalt magnet sheet, dries it and then performs slow-cooling diffusion treatment to obtain a 2:17 type iron-rich samarium-cobalt permanent magnet material with high intrinsic coercivity. In the present invention, the particle size of the PrFeSn alloy powder is preferably 1000-5000 nm, more preferably 2000-4000 nm. In the PrFeSn alloy of the present invention, the mass content of Pr is preferably 30-45%, more preferably 35-40%; the mass content of Fe is preferably 50-65%, more preferably 55-60%; the mass percentage content of Sn is preferably 1-5%, more preferably 2-4%. In the present invention, the mass concentration of the PrFeSn alloy powder in the PrFeSn alloy powder suspension is preferably 10-20%, more preferably 12-15%; the solvent of the PrFeSn alloy powder suspension is preferably an alcohol solvent, further preferably one or more of ethanol, propanol and glycerol.

[0034] In the present invention, the preparation method of the PrFeSn alloy powder suspension preferably includes the following steps: Melting metal Pr, metal Fe and metal Sn to obtain a PrFeSn alloy ingot; Crushing and ball milling the PrFeSn alloy ingot to obtain PrFeSn alloy powder; Mix the PrFeSn alloy powder with an alcohol solvent to obtain a PrFeSn alloy powder suspension.

[0035] In the present invention, the melting is preferably carried out in an arc induction melting furnace.

[0036] In the present invention, the crushing is preferably carried out using an electromagnetic crusher, and the particle size of the alloy particles obtained after crushing is preferably 0.1 - 1 mm. In the present invention, the ball milling is preferably high-energy ball milling, and there are no special requirements for the specific parameter conditions of the ball milling. It is only necessary to preferably make the particle size of the PrFeSn alloy powder reach 1000 - 5000 nm.

[0037] In the present invention, the mixing method of the PrFeSn alloy powder and the alcohol solvent is preferably stirring and mixing.

[0038] In the present invention, the application method of applying the PrFeSn alloy powder suspension to both sides of the samarium-cobalt magnet sheet is preferably coating, and the coating amount is preferably 10 - 30 mg / cm 3 , more preferably 20 - 30 mg / cm 3 . In the present invention, the drying method is preferably air drying.

[0039] In the present invention, the method of slow cooling and diffusion treatment preferably includes the following steps: Heat the samarium-cobalt magnet sheet with the PrFeSn alloy powder suspension applied on both sides to 830 - 850 °C, then cool it to 400 °C and hold for 1 h, and then air-cool to room temperature.

[0040] In the present invention, the slow cooling and diffusion treatment is preferably carried out in an inert gas atmosphere. The inert gas is preferably argon, and the pressure of the argon is preferably 0.5 MPa. In the present invention, treatment in an inert gas (Ar) atmosphere under a certain pressure can prevent the oxidation of PrFeSn from hindering the surface diffusion.

[0041] In the present invention, the heating rate for heating to 830 - 850 °C is preferably 5 - 6 °C / min. After heating to 830 - 850 °C, the present invention preferably immediately cools it to 400 °C, and the cooling rate is preferably 0.5 - 0.7 °C / min. In the present invention, the holding time at 400 °C is preferably 1 h.

[0042] In the present invention, during the slow cooling diffusion treatment, Fe elements diffuse into the cells. Without destroying the cellular tissue structure of the magnet, Fe elements replace Co elements to increase the saturation magnetization intensity of the magnet, thereby increasing the remanence and maximum magnetic energy product of the magnet. At the same time, Cu elements in the magnet diffuse and accumulate at the cell walls, resulting in a high Cu concentration at the cell walls of the magnet. Thus, the cell walls have a strong pinning effect on the domain walls, and the magnet can obtain a high intrinsic coercivity. Additionally, since the saturation magnetization intensity of Pr2Co 17 is greater than that of Sm2Co 17 , after Pr elements diffuse into the magnet, the remanence and maximum magnetic energy product of the magnet can also be increased. The addition of Sn elements can lower the melting point of the PrFeSn alloy powder, making the diffusion easier. At the same time, Sn elements can lower the diffusion activation energy of Cu elements, making it easier for Cu elements to accumulate at the cell walls, increasing the Cu concentration at the cell walls, and enabling the magnet to obtain a high intrinsic coercivity.

[0043] As a specific embodiment of the present invention, the process flow schematic diagram of the preparation method of the high-intrinsic-coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material is as shown in Figure 1 the figure.

[0044] The present invention provides a high-intrinsic-coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material prepared by the above preparation method.

[0045] The high-intrinsic-coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material and its preparation method provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0046] Example 1 A preparation method of a high-intrinsic-coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material includes the following steps: S1. First, weigh the samarium-cobalt permanent magnet alloy raw materials according to the following components and their weight percentages: Sm: 25%, Fe: 14%, Zr: 2.6%, Cu: 5.5%, Co: 52.9%; then, melt the weighed samarium-cobalt permanent magnet alloy raw materials in a vacuum medium-frequency induction melting furnace. During melting, the vacuum degree is 5×10 -2 ~5×10 -3 Pa, the melting temperature is 1400~1500 °C. After the raw materials are completely melted, refine for 2~3 min and then cast to obtain an alloy ingot with a thickness of 10 mm; S2. Mechanically crush the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5~2 mm; then, use the method of airflow milling to make the alloy particles into alloy powder with an average particle size of 3.8 μm; S3. Weigh the alloy powder prepared in step S2 in an air atmosphere, with each portion weighing 300 g. Then, perform orientation molding under a 1.8 T magnetic field, and finally, perform cold isostatic pressing at a pressure of 230 MPa for 30 s to obtain a green compact. S4. First, sinter the green compact obtained in step S3 at a temperature of 1210 °C for 2 h in an argon atmosphere, with a heating rate of 6 °C / min. Then, cool the sintered blank in the furnace to 1180 °C for solution treatment, with a holding time of 4 h. After solution treatment, quickly air-cool to room temperature to obtain a solution-state blank of the samarium-cobalt magnet. Then, heat the solution-state blank of the samarium-cobalt magnet to 850 °C (heating rate of 6 °C / min) under vacuum conditions and quickly air-cool to room temperature, and repeat this treatment once. Then, heat the blank after repeated rapid cooling treatment to 850 °C again for isothermal aging treatment, with a holding time of 2 h. After isothermal aging treatment, quickly air-cool to room temperature to obtain an isothermal-aged blank of the samarium-cobalt magnet, with an average cell size of 90 nm. Finally, process the isothermal-aged blank of the samarium-cobalt magnet into a 3-mm-thick samarium-cobalt magnet thin slice using a slicing machine. S5. First, prepare a PrFeSn suspension solution. The preparation method of the PrFeSn suspension solution is as follows: First, melt Pr with a mass percentage of 30%, Fe with a mass percentage of 65%, and Sn with a mass percentage of 5% in an arc induction melting furnace to obtain a PrFeSn alloy ingot. Then, use an electromagnetic crusher to crush the PrFeSn alloy ingot into PrFeSn alloy particles with a particle size of 0.1 - 1 mm. Next, use high-energy ball milling to crush the PrFeSn alloy particles into PrFeSn alloy powder with a particle size of 1000 - 5000 nm. Finally, mix and stir the PrFeSn alloy powder with absolute ethanol evenly, with the mass ratio of PrFeSn alloy powder to absolute ethanol being 1:9, to obtain a PrFeSn suspension solution. Then, evenly coat the PrFeSn suspension solution on both sides of the samarium-cobalt magnet thin slice and blow it dry, with the coating amount being 30 mg / cm 3 ; Finally, perform slow-cooling diffusion treatment on the coated samarium-cobalt magnet thin slice in a tube furnace. When processing, fill 0.5 MPa of argon into the tube furnace. The slow-cooling diffusion treatment process is as follows: Heat the coated samarium-cobalt magnet thin slice to 850 °C, with a heating rate of 6 °C / min; then, cool it at a rate of 0.7 °C / min to 400 °C, hold for 1 h, and then quickly air-cool to room temperature to obtain a 2:17-type iron-rich samarium-cobalt permanent magnet material with high intrinsic coercivity.

[0047] The cellular microstructure of the 2:17-type iron-rich samarium-cobalt permanent magnet material with high intrinsic coercivity prepared in Example 1 is as Figure 2 shown, and it can be seen from Figure 2 that the magnet has a complete cellular microstructure and a relatively small average cell size, about 90 nm.

[0048] Comparative Example 1 In Comparative Example 1, the solution-treated blank is not heated to 850°C and then rapidly air-cooled. Compared with Example 1, step S4 of Comparative Example 1 is as follows: First, the green compact obtained in step S3 is sintered at 1210°C for 2 h; then, the sintered blank is cooled in the furnace to 1180°C for solution treatment, with a holding time of 4 h. After the solution treatment, it is rapidly air-cooled to room temperature to obtain a samarium-cobalt magnet solution-treated blank; thereafter, the solution-treated blank is heated to 850°C for isothermal aging treatment, with a holding time of 2 h. After the isothermal aging treatment, it is again rapidly air-cooled to room temperature to obtain a samarium-cobalt aged blank, with an average cell size of 102 nm; finally, the samarium-cobalt aged blank is processed into a 3-mm-thick samarium-cobalt magnet thin sheet using a slicing machine.

[0049] For the operations of the remaining steps, refer to Example 1.

[0050] Comparative Example 2 In Comparative Example 2, the diffusion PrFeSn treatment in Example 1 is not adopted. Compared with Example 1, step S5 of Comparative Example 2 is as follows: The samarium-cobalt magnet thin sheet is heated to 850°C, and then cooled at a rate of 0.7°C / min to 400°C. After holding for 1 h, it is rapidly air-cooled to room temperature to obtain a samarium-cobalt magnet.

[0051] For the operations of the remaining steps, refer to Example 1.

[0052] Comparative Example 3 Compared with Example 1, in Comparative Example 3, the composition of the PrFeSn diffusing agent is changed. Compared with Example 1, step S5 of Comparative Example 3 is as follows: Prepare a PrCu suspension solution. The preparation method of the PrCu suspension solution is as follows: First, a PrCu alloy ingot is obtained by melting Pr with a mass percentage of 40% and Cu with a mass percentage of 60% in an arc induction melting furnace; then, the PrCu alloy ingot is crushed into PrCu alloy powder with a particle size of 500 - 1000 nm using high-energy ball milling; finally, the PrCu alloy powder is mixed and stirred evenly with absolute ethanol, and the mass ratio of the PrCu alloy powder to absolute ethanol is 1:9 to obtain a PrCu suspension solution; then, the PrCu suspension solution is evenly coated on the surface of the samarium-cobalt magnet thin sheet and dried; finally, the coated samarium-cobalt magnet thin sheet is subjected to a primary diffusion treatment in a tube furnace. The primary diffusion treatment temperature is 1150°C, and the diffusion treatment time is 4 h. After cooling and taking out of the furnace, a samarium-cobalt magnet diffusion thin sheet is obtained; Prepare a SnFe suspension solution. The preparation method of the SnFe suspension solution is as follows: First, melt Sn with a mass percentage of 5% and Fe with a mass percentage of 95% in an arc induction melting furnace to obtain a SnFe alloy ingot; then, use high-energy ball milling to crush the SnFe alloy ingot into SnFe alloy powder with a particle size of 500 - 1000 nm; finally, mix the SnFe alloy powder and absolute ethanol and stir evenly. The mass ratio of the SnFe alloy powder to absolute ethanol is 1:9 to obtain the SnFe suspension solution; then, evenly coat the SnFe suspension solution on the surface of the thin sheet prepared by the above primary diffusion treatment and blow it dry; finally, perform secondary diffusion treatment on the coated samarium-cobalt magnet thin sheet in a tube furnace. The temperature of the secondary diffusion treatment is 900 °C, the diffusion treatment time is 4 h, and after cooling and taking out of the furnace, a samarium-cobalt magnet secondary diffusion thin sheet is obtained; Perform aging treatment on the obtained samarium-cobalt magnet secondary diffusion thin sheet. The aging treatment process is as follows: Heat the samarium-cobalt magnet secondary diffusion thin sheet to 850 °C, hold for 4 h, then cool it to 400 °C at a rate of 1.5 °C / min, hold for 1 h, and then quickly air-cool to room temperature.

[0053] For the operations of the remaining steps, refer to Example 1.

[0054] Example 2 A preparation method of a 2:17 type iron-rich samarium-cobalt permanent magnet material with high intrinsic coercivity includes the following steps: S1. First, weigh the samarium-cobalt permanent magnet alloy raw materials according to the following components and their weight percentages: Sm: 25.5%, Fe: 18%, Zr: 2.2%, Cu: 5.8%, Co: 48.5%; then, melt the weighed samarium-cobalt permanent magnet alloy raw materials in a vacuum medium-frequency induction melting furnace. The vacuum degree during melting is 5×10 -2 ~5×10 -3 Pa, the melting temperature is 1400 - 1500 °C. After the raw materials are completely melted, refine for 2 - 3 min and then cast to obtain an alloy ingot with a thickness of 10 mm; S2. Mechanically crush the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 - 2 mm; then, use the method of airflow milling to make the alloy particles into alloy powder with an average particle size of 4 μm; S3. Weigh the alloy powder prepared in step S2 in an air atmosphere, with each portion weighing 300 g, then orient and form it under a 1.8 T magnetic field, and finally perform cold isostatic pressing at a pressure of 220 MPa for 25 s to obtain a green compact; S4. First, sinter the green body prepared in step S3 at 1200 °C for 1 h in an argon sintering atmosphere with a heating rate of 5 °C / min. Then, cool the sintered blank in the furnace to 1160 °C for solution treatment with a holding time of 10 h, and after solution treatment, quickly air-cool it to room temperature to obtain a solution-state blank of samarium cobalt magnet. After that, heat the solution-state blank of samarium cobalt magnet to 830 °C (heating rate is 5 °C / min) under vacuum conditions and then quickly air-cool it to room temperature, and repeat this treatment 2 times. After that, heat the blank after repeated rapid cooling treatment to 830 °C again for isothermal aging treatment with a holding time of 4 h, and after isothermal aging treatment, quickly air-cool it to room temperature to obtain an isothermal aging-state blank of samarium cobalt with an average cell size of 94.4 nm. Finally, process the isothermal aging-state blank of samarium cobalt into samarium cobalt magnet thin slices with a thickness of 2 mm using a slicing machine; S5. First, prepare a PrFeSn suspension solution. The preparation method of the PrFeSn suspension solution is as follows: First, melt Pr with a mass percentage of 30%, Fe with a mass percentage of 65%, and Sn with a mass percentage of 5% in an arc induction melting furnace to obtain a PrFeSn alloy ingot. Then, use an electromagnetic crusher to crush the PrFeSn alloy ingot into PrFeSn alloy particles with a particle size of 0.1 - 1 mm. Next, use high-energy ball milling to crush the PrFeSn alloy particles into PrFeSn alloy powder with a particle size of 1000 - 5000 nm. Finally, mix and stir the PrFeSn alloy powder with absolute ethanol evenly, and the mass ratio of PrFeSn alloy powder to absolute ethanol is 1:9 to obtain a PrFeSn suspension solution. Then, evenly coat the PrFeSn suspension solution on both sides of the samarium cobalt magnet thin slice and dry it, and the coating amount is 20 mg / cm 3 ; Finally, perform slow-cooling diffusion treatment on the coated samarium cobalt magnet thin slice in a tube furnace. When processing, fill 0.5 MPa argon into the tube furnace. The slow-cooling diffusion treatment process is: heat the coated samarium cobalt magnet thin slice to 830 °C with a heating rate of 5 °C / min; then cool it to 400 °C at a rate of 0.7 °C / min, hold for 1 h, and then quickly air-cool it to room temperature to obtain a 2:17 type high-intrinsic coercivity iron-rich samarium cobalt permanent magnet material.

[0055] The cellular microstructure of the 2:17 type high-intrinsic coercivity iron-rich samarium cobalt permanent magnet material prepared in Example 2 is as Figure 3 shown, and it can be seen from Figure 3 that the magnet has a complete cellular microstructure with a relatively small average cell size of about 94.4 nm.

[0056] Comparative Example 4 In Comparative Example 4, the solution-state blank is not heated to 850 °C and then quickly air-cooled. Compared with Example 2, step S4 of Comparative Example 4 is as follows: First, sinter the green body obtained in step S3 at 1200 °C for 1 h; then, cool the sintered blank in the furnace to 1160 °C for solution treatment, with a holding time of 10 h. After solution treatment, quickly air-cool to room temperature to obtain a solution-state blank of samarium-cobalt magnet; thereafter, heat the solution-state blank to 830 °C for isothermal aging treatment, with a holding time of 4 h. After isothermal aging treatment, quickly air-cool to room temperature again to obtain an aged-state blank of samarium-cobalt, with an average cell size of 123 nm; finally, process the aged-state blank of samarium-cobalt into a 2-mm-thick samarium-cobalt magnet thin slice with a slicing machine.

[0057] For the operations of the remaining steps, refer to Example 2.

[0058] Comparative Example 5 Comparative Example 5 does not adopt the diffusion PrFeSn treatment in Example 2. Compared with Example 2, step S5 of Comparative Example 5 is as follows: S5. Heat the samarium-cobalt magnet thin slice to 830 °C, then cool it at a rate of 0.7 °C / min to 400 °C, hold for 1 h, and then quickly air-cool to room temperature to obtain a samarium-cobalt magnet.

[0059] For the operations of the remaining steps, refer to Example 2.

[0060] Example 3 A preparation method of a 2:17 type iron-rich samarium-cobalt permanent magnet material with high intrinsic coercivity includes the following steps: S1. First, weigh the raw materials of the samarium-cobalt permanent magnet alloy according to the following components and their weight percentages: Sm: 25.4%, Fe: 17.5%, Zr: 3%, Cu: 6%, Co: 48.1%; then, melt the weighed raw materials of the samarium-cobalt permanent magnet alloy in a vacuum medium-frequency induction melting furnace. During melting, the vacuum degree is 5×10 -2 ~5×10 -3 Pa, the melting temperature is 1400~1500 °C. After the raw materials are completely melted, refine for 2~3 min and then carry out casting to obtain an alloy ingot with a thickness of 10 mm; S2. Mechanically crush the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5~2 mm; then, use the method of airflow milling to make the alloy particles into alloy powder with an average particle size of 4.2 μm; S3. Weigh the alloy powder prepared in step S2 in an air atmosphere, with each portion weighing 300 g, then orient and form it under a 1.8 T magnetic field; finally, carry out cold isostatic pressing at a pressure of 230 MPa for 30 s to obtain a green body; S4. First, sinter the green body obtained in step S3 at a temperature of 1207 °C for 1 h in an argon sintering atmosphere with a heating rate of 6 °C / min. Then, cool the sintered blank in the furnace to 1170 °C for solution treatment with a holding time of 8 h, and then quickly air-cool to room temperature after solution treatment to obtain a solution-state blank of samarium-cobalt magnet. After that, heat the solution-state blank of samarium-cobalt magnet to 840 °C (heating rate: 6 °C / min) in a vacuum condition and then quickly air-cool to room temperature, and repeat this treatment twice. After that, heat the blank after repeated rapid cooling treatment to 840 °C again for isothermal aging treatment with a holding time of 3 h, and then quickly air-cool to room temperature after isothermal aging treatment to obtain an aged-state blank of samarium-cobalt magnet with an average cell size of 88.6 nm. Finally, machine the aged-state blank of samarium-cobalt magnet into a 5-mm-thick samarium-cobalt magnet thin slice with a slicing machine; S5. First, prepare a PrFeSn suspension solution. The preparation method of the PrFeSn suspension solution is as follows: First, melt Pr with a mass percentage of 30%, Fe with a mass percentage of 65%, and Sn with a mass percentage of 5% in an arc induction melting furnace to obtain a PrFeSn alloy ingot. Then, use an electromagnetic crusher to crush the PrFeSn alloy ingot into PrFeSn alloy particles with a particle size of 0.1 - 1 mm. Next, use high-energy ball milling to crush the PrFeSn alloy particles into PrFeSn alloy powder with a particle size of 1000 - 5000 nm. Finally, mix and stir the PrFeSn alloy powder with absolute ethanol evenly, and the mass ratio of the PrFeSn alloy powder to absolute ethanol is 1:9 to obtain a PrFeSn suspension solution. Then, evenly coat the double sides of the samarium-cobalt magnet thin slice with the PrFeSn suspension solution and dry it, and the coating amount is 30 mg / cm 3 ; Finally, perform slow-cooling diffusion treatment on the coated samarium-cobalt magnet thin slice in a tube furnace. When performing the treatment, fill 0.5 MPa of argon into the tube furnace. The slow-cooling diffusion treatment process is as follows: Heat the coated samarium-cobalt magnet thin slice to 840 °C with a heating rate of 6 °C / min. Then, cool it to 400 °C at a rate of 0.7 °C / min, hold for 1 h, and then quickly air-cool to room temperature to obtain a 2:17-type iron-rich samarium-cobalt permanent magnet material with high intrinsic coercivity.

[0061] The cellular microstructure of the 2:17-type iron-rich samarium-cobalt permanent magnet material with high intrinsic coercivity prepared in Example 3 is as shown in Figure 4 shown, and it can be seen from Figure 4 that the magnet has a complete cellular microstructure with a relatively small average cell size of about 88.6 nm.

[0062] Comparative Example 6 In Comparative Example 6, the solution-state blank is not heated to 840 °C and then quickly air-cooled. Compared with Example 3, the step S4 in Comparative Example 6 is as follows: S4. First, sinter the green body prepared in step S3 at 1207 °C for 1 h; then, cool the sintered blank in the furnace to 1170 °C for solution treatment, with a holding time of 8 h. After solution treatment, quickly air-cool it to room temperature to obtain a solution-state blank of samarium cobalt magnet; thereafter, heat the solution-state blank to 840 °C for isothermal aging treatment, with a holding time of 3 h. After isothermal aging treatment, quickly air-cool it to room temperature to obtain an isothermal aging-state blank of samarium cobalt, with an average cell size of 101 nm; finally, process the isothermal aging-state blank of samarium cobalt into a 5-mm-thick samarium cobalt magnet thin slice with a slicing machine.

[0063] For the operations of the remaining steps, refer to Example 3.

[0064] Comparative Example 7 Comparative Example 7 does not adopt the diffusion PrFeSn treatment in Example 3. Compared with Example 3, step S5 of Comparative Example 7 is as follows: S5. Heat the samarium cobalt magnet thin slice to 840 °C, and then cool it at a rate of 0.7 °C / min to 400 °C. After holding for 1 h, quickly air-cool it to room temperature to obtain a samarium cobalt magnet.

[0065] For the operations of the remaining steps, refer to Example 3.

[0066] Example 4 A preparation method of a 2:17 type iron-rich samarium cobalt permanent magnet material with high intrinsic coercivity includes the following steps: S1. First, weigh the raw materials of the samarium cobalt permanent magnet alloy according to the following components and their weight percentages: Sm: 23%, Gd: 2.3%, Fe: 16%, Zr: 2.6%, Cu: 5.8%, Co: 50.3%; then, melt the weighed raw materials of the samarium cobalt permanent magnet alloy in a vacuum medium-frequency induction melting furnace. During melting, the vacuum degree is 5×10 -2 ~5×10 -3 Pa, the melting temperature is 1400 - 1500 °C. After the raw materials are completely melted, refine for 2 - 3 min and then carry out casting to obtain an alloy ingot with a thickness of 10 mm; S2. Mechanically crush the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 - 2 mm; then, use the method of airflow milling to make the alloy particles into alloy powder with an average particle size of 4.8 μm; S3. Weigh the alloy powder prepared in step S2 in an air atmosphere, with each portion weighing 300 g. Then, orient and form it under a 1.8 T magnetic field, and finally carry out cold isostatic pressing and forming under a pressure of 230 MPa to obtain a green body; S4. First, sinter the green body prepared in step S3 at a temperature of 1205 °C for 1 h. The sintering atmosphere is argon, and the heating rate is 6 °C / min. Then, cool the sintered blank in the furnace to 1170 °C for solution treatment. The holding time is 8 h. After solution treatment, quickly air-cool it to room temperature to obtain a solution-state blank of samarium-cobalt magnet. After that, heat the solution-state blank of samarium-cobalt magnet to 840 °C (heating rate is 6 °C / min) under vacuum conditions and then quickly air-cool it to room temperature, and repeat this treatment 2 times. After that, heat the blank after repeated rapid cooling treatment to 840 °C again for isothermal aging treatment. The holding time is 3 h. After isothermal aging treatment, quickly air-cool it to room temperature to obtain a samarium-cobalt aged-state blank with an average cell size of 87.6 nm. Finally, process the samarium-cobalt aged-state blank into a 4-mm-thick samarium-cobalt magnet thin slice with a slicing machine; S5. First, prepare a PrFeSn suspension solution. The preparation method of the PrFeSn suspension solution is as follows: First, melt Pr with a mass percentage of 30%, Fe with a mass percentage of 65%, and Sn with a mass percentage of 5% in an arc induction melting furnace to obtain a PrFeSn alloy ingot. Then, use an electromagnetic crusher to crush the PrFeSn alloy ingot into PrFeSn alloy particles with a particle size of 0.1 - 1 mm. Next, use high-energy ball milling to crush the PrFeSn alloy particles into PrFeSn alloy powder with a particle size of 1000 - 5000 nm. Finally, mix and stir the PrFeSn alloy powder with absolute ethanol evenly. The mass ratio of the PrFeSn alloy powder to absolute ethanol is 1:9 to obtain a PrFeSn suspension solution. Then, evenly coat the PrFeSn suspension solution on both sides of the samarium-cobalt magnet thin slice and dry it. The coating amount is 20 mg / cm 3 ; Finally, perform slow-cooling diffusion treatment on the coated samarium-cobalt magnet thin slice in a tube furnace. When processing, fill 0.5 MPa of argon into the tube furnace. The slow-cooling diffusion treatment process is as follows: Heat the coated samarium-cobalt magnet thin slice to 840 °C with a heating rate of 6 °C / min. Then, cool it to 400 °C at a rate of 0.7 °C / min, hold for 1 h, and then quickly air-cool it to room temperature to obtain a 2:17-type iron-rich samarium-cobalt permanent magnet material with high intrinsic coercivity.

[0067] The cellular microstructure of the 2:17-type iron-rich samarium-cobalt permanent magnet material with high intrinsic coercivity prepared in Example 4 is as Figure 5 shown. It can be seen from Figure 5 that the magnet has a complete cellular microstructure with a relatively small average cell size of about 87.6 nm.

[0068] Comparative Example 8 In Comparative Example 8, the solution-state blank is not heated to 840 °C and then quickly air-cooled. Compared with Example 4, step S4 of Comparative Example 6 is as follows: S4. First, sinter the green body obtained in step S3 at a temperature of 1205 °C for 1 h; then, cool the sintered blank in the furnace to 1170 °C for solution treatment, with a holding time of 8 h. After solution treatment, quickly air-cool to room temperature to obtain a solution-state blank of the samarium-cobalt magnet; thereafter, heat the solution-state blank to 840 °C for isothermal aging treatment, with a holding time of 3 h. After isothermal aging treatment, quickly air-cool to room temperature to obtain an aged-state blank of the samarium-cobalt magnet, with an average cell size of 102.5 nm; finally, process the aged-state blank of the samarium-cobalt magnet into a 4-mm-thick samarium-cobalt magnet sheet with a slicing machine. For the operations of the remaining steps, refer to Example 4.

[0069] Comparative Example 9 Comparative Example 9 does not adopt the diffusion PrFeSn treatment in Example 4. Compared with Example 4, step S5 of Comparative Example 9 is as follows: S5. Heat the samarium-cobalt magnet sheet to 840 °C, then cool it at a rate of 0.7 °C / min to 400 °C, hold for 1 h, and then quickly air-cool to room temperature to obtain the samarium-cobalt magnet.

[0070] For the operations of the remaining steps, refer to Example 4.

[0071] Performance Test Use a PFM magnetic property measuring instrument to test the magnetic properties of the samarium-cobalt permanent magnetic materials obtained in Examples 1 to 4 and Comparative Examples 1 to 9. The obtained results are shown in Table 1.

[0072] Table 1 Magnetic Properties of Samarium-Cobalt Permanent Magnetic Materials Obtained in Examples 1 to 4 and Comparative Examples 1 to 9

[0073] As can be seen from Table 1, Examples 1 to 4 of the present invention can effectively improve the remanence, maximum magnetic energy product, and intrinsic coercivity of the 2:17 type iron-rich samarium-cobalt permanent magnetic material. Compared with Comparative Examples 1, 4, 6, and 8, in Examples 1 to 4 of the present invention, by repeatedly heating the solution-state blank to 830 - 850 °C and then quickly cooling, the nucleation of the 1:5H cell wall phase can be promoted, more cell wall phases can be formed, the average cell size can be reduced, and the cell wall can be narrowed, so that a higher Cu concentration can be obtained at the cell wall, and the intrinsic coercivity of the iron-rich magnet can be improved. Compared with Comparative Examples 2, 5, and 7, in Examples 1 to 3 of the present invention, the diffusion PrFeSn treatment is adopted. During the diffusion PrFeSn treatment, Fe enters the magnet cells to increase the saturation magnetization intensity, so that the magnet can obtain a higher remanence and magnetic energy product. However, when Fe enters the magnet structure, it will inevitably reduce the anisotropy field of the cell structure, resulting in a slight decrease in the intrinsic coercivity Hcj. The intrinsic coercivity of Comparative Example 9 is similar to that of Example 4 within the error range, because when the Fe content is lower than a certain value, the magnet is prone to obtain high coercivity, and as the Fe content decreases, the coercivity tends to be stable and will not continue to increase.

[0074] Comparative Example 3: The diffusion of PrCu was carried out at a high temperature of 1150°C, which inevitably caused the oxidation of rare earth Pr (rare earths are easily oxidized) and Cu oxidation, resulting in poor diffusion effect. Pr could not effectively enter the magnet, and Pr2Co was formed. 17 Therefore, Pr2Co was formed. 17 The effect of improving the remanence was poor, so the remanence was lower than that of Example 1. After Cu oxidation, the diffusion effect was poor, and the amount of Cu element entering the magnet became less, which could not effectively increase the Cu concentration at the cell wall, and the increase in coercivity was limited. Therefore, the coercivity of Comparative Example 3 was relatively low. In the present invention, PrFeSn was diffused during the slow cooling process after the samarium cobalt magnet sheet was heated to 830 - 850°C, which could avoid high-temperature oxidation and enable effective element diffusion, facilitating the obtaining of higher coercivity.

[0075] In the present invention, the addition of Sn element was beneficial to reducing the melting point of PrFeSn and promoting the entry of Pr element into the magnet cells to replace Sm element. Since the saturation magnetization intensity of Pr2Co 17 was greater than that of Sm2Co 17 , the remanence and maximum magnetic energy product of the magnet could be increased. The poor diffusion effect of PrCu in Comparative Example 3 was one of the reasons for the lower remanence than that of Example 1.

[0076] In addition, Comparative Example 3 carried out secondary diffusion at 1150°C and 900°C. The present invention has no additional diffusion process, and the diffusion of PrFeSn is directly carried out during the aging and slow cooling stage, greatly shortening the process flow, saving time, and improving the product preparation efficiency.

[0077] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a 2:17 type iron-rich samarium cobalt permanent magnet material with high intrinsic coercivity, characterized in that, It includes the following steps: (1) Melting the raw materials of samarium-cobalt permanent magnet materials to obtain a samarium-cobalt magnet alloy ingot; In terms of mass percentage, the raw materials of the samarium cobalt permanent magnet material include: (Sm 1-x Re x ): 25% - 25.5%, Fe: 14% - 18%, Zr: 2.2% - 3%, Cu: 4% - 6%, and the balance is Co; where 0 ≤ x ≤ 0.3, and Re is one or more of Pr, Nd, Gd, Dy, Tb, Er, Y, or Ho; (2) Crushing and grinding the samarium-cobalt magnet alloy ingot in sequence, and subjecting the obtained alloy powder to magnetic field orientation forming and cold isostatic pressing forming in sequence to obtain a green body of samarium-cobalt magnet; (3) Sintering, solution treatment and cooling the green body of samarium-cobalt magnet in sequence to obtain a solution-treated blank of samarium-cobalt magnet; (4) Under vacuum conditions, repeatedly heating the solution-treated blank of samarium-cobalt magnet to 830-850 °C and rapidly cooling it to room temperature to obtain a blank after repeated rapid cooling treatment; (5) Performing isothermal aging treatment and cooling on the blank after repeated rapid cooling treatment to obtain a samarium-cobalt aged blank, and performing slicing treatment on the samarium-cobalt aged blank to obtain samarium-cobalt magnet slices; (6) Applying a PrFeSn alloy powder suspension to both sides of the samarium-cobalt magnet slice, drying and then performing slow-cooling diffusion treatment to obtain a high-intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material.

2. The preparation method according to claim 1, characterized in that, In the step (2), the particle size of the alloy powder is 3-5 μm; The magnetic field strength of the magnetic field orientation forming is 1.8-2 T; The pressure of the cold isostatic pressing forming is 200-230 MPa, and the time is 20-30 seconds.

3. The preparation method according to claim 1, wherein In the step (3), the sintering temperature is 1200-1210 °C, and the holding time is 1-2 h; The temperature of the solution treatment is 1160-1180 °C, and the time is 4-10 h.

4. The preparation method according to claim 1, characterized in that, In the heating to 830-850 °C - rapid cooling to room temperature in the step (4), the rapid cooling method is air cooling, and the time from 830-850 °C to rapid cooling to room temperature is 20-25 min; The number of repetitions of heating to 830-850 °C - rapid cooling to room temperature is 1-2 times.

5. The preparation method according to claim 1, characterized in that, In the step (5), the temperature of the isothermal aging treatment is 830-850 °C, and the holding time is 2-4 h; The samarium-cobalt aged blank has a complete cellular tissue structure, and the average cell size is 80-95 nm.

6. The preparation method according to claim 1 or 5, characterized in that, The thickness of the samarium-cobalt magnet slice is 2-5 mm.

7. The preparation method according to claim 1, characterized in that, The particle size of the PrFeSn alloy powder is 1000-5000 nm; In the PrFeSn alloy, the mass content of Pr is 30-45%, the mass content of Fe is 50-65%, and the mass percentage content of Sn is 1-5%.

8. The preparation method according to claim 1 or 7, characterized in that The mass concentration of the PrFeSn alloy powder in the PrFeSn alloy powder suspension is 10-20%; The solvent of the PrFeSn alloy powder suspension is an alcohol solvent.

9. The preparation method according to claim 1, characterized in that, The method of the slow-cooling diffusion treatment includes the following steps: Heating the samarium-cobalt magnet slice with the PrFeSn alloy powder suspension applied on both sides to 830-850 °C, then cooling it to 400 °C and holding for 1 h, and air cooling to room temperature; The cooling rate is 0.5-0.7 °C / min.

10. A high-intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material prepared by the preparation method according to any one of claims 1-9.

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