A high intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material and its preparation method

Abstract

The present invention provides a high intrinsic coercivity 2:17 type iron-rich samarium cobalt permanent magnet material and a preparation method thereof, belonging to the technical field of magnetic materials. The present invention sequentially performs magnetic field orientation molding and cold isostatic pressing molding on samarium cobalt magnet alloy powder, and sequentially performs sintering, solid solution treatment and cooling on the obtained green body to obtain a samarium cobalt magnet solid solution blank; under vacuum conditions, the samarium cobalt magnet solid solution blank is repeatedly heated and rapidly cooled to room temperature to obtain a blank after repeated rapid cooling treatment; then, isothermal aging treatment, cooling and slicing are performed to obtain samarium cobalt magnet sheets; a PrFeSn alloy powder suspension is applied to both sides of the samarium cobalt magnet sheet, and after drying, a slow cooling diffusion treatment is performed to obtain a high intrinsic coercivity 2:17 type iron-rich samarium cobalt permanent magnet material. The preparation method provided by the present invention can improve the cellular structure of the Fe-rich samarium cobalt magnet and effectively enhance the intrinsic coercivity of the 2:17 type iron-rich samarium cobalt permanent magnet material.

Description

Technical Field

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

[0002] Since its introduction, 2:17 SmCo, a second-generation rare earth permanent magnet material, has been highly sought after for its excellent magnetic properties, high Curie temperature, good temperature stability, and outstanding corrosion resistance. It is widely used in a wide range of fields, including defense and military industry, aerospace, medical equipment, microwave devices, transportation, and high-end motors. In recent years, as products in some fields have moved towards miniaturization and lightweighting, higher requirements have been placed on the magnetic properties of the magnets they require.

[0003] 2:17 SmCo permanent magnets (composed of Sm, Fe, Zr, Cu, and Co) exhibit a typical cellular microstructure. The 2:17R cellular phase has a high Fe content, contributing to the magnet's high saturation magnetization. The 1:5H cell wall phase has a high solubility for Cu, allowing it to accumulate in the cell walls, resulting in a high coercivity. In addition to the cellular and cell wall phases, the magnet also contains a lamellar Zr-rich phase, which provides pathways for element diffusion during aging. Precisely because of this complex microstructure, 2:17 sintered SmCo magnets exhibit excellent overall magnetic properties. Currently, increasing the Fe content is one of the primary methods for improving the magnetic properties of 2:17 SmCo permanent magnets. However, in the preparation of high-performance SmCo magnets, excessively high Fe content prevents the formation of a single, uniform 1:7H phase during the solid solution process. Consequently, a well-defined cellular microstructure is not formed during aging, resulting in deteriorated magnetic properties.

[0004] Currently, the Chinese patent document "A Method for Improving the Magnetic Properties of Samarium Cobalt Permanent Magnets" (Publication No.: CN112038083 A) uses a coating and / or encapsulation method to apply a low-melting-point phase diffusion source to the surface of the base material for diffusion treatment to improve the magnetic properties of the magnet. However, this method fails to address the problem of deterioration of the magnet's microstructure caused by excessive Fe content, and the diffusion of the low-melting-point phase RE-TM fails to effectively increase the magnet's remanence and maximum magnetic energy product. The Chinese patent document "A Diffusion Preparation Method for Fe-Rich High-Coercivity Samarium Cobalt Magnets" (Publication No.: CN119296941A) uses secondary diffusion of PrCu and SnFe to improve the magnet's magnetic properties. However, the Fe-rich magnets described in the patent cannot avoid excessive cell size during aging, resulting in a low Cu concentration at the cell wall and, consequently, a low intrinsic coercivity of the magnet. Summary of the Invention

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

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a high intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnetic material, comprising the following steps:

[0008] (1) Sm-Co permanent magnet material raw materials are smelted to obtain Sm-Co magnet alloy ingots; the Sm-Co permanent magnet material raw materials include, by weight percentage: (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, Re is one or more of Pr, Nd, Gd, Dy, Tb, Er, Y or Ho;

[0009] (2) crushing and grinding the samarium-cobalt magnet alloy ingot in sequence, and subjecting the obtained alloy powder to magnetic field orientation molding and cold isostatic pressing in sequence to obtain a samarium-cobalt magnet green body;

[0010] (3) sintering, solution treating and cooling the samarium cobalt magnet green body in sequence to obtain a samarium cobalt magnet solid solution blank;

[0011] (4) Under vacuum conditions, repeatedly heating the solid solution state blank of the samarium cobalt magnet to 830-850° C. and rapidly cooling it to room temperature to obtain a blank after repeated rapid cooling treatment;

[0012] (5) performing isothermal aging treatment and cooling on the blank after the repeated rapid cooling treatment to obtain a samarium-cobalt aged blank, and slicing the samarium-cobalt aged blank to obtain a samarium-cobalt magnet sheet;

[0013] (6) Applying a PrFeSn alloy powder suspension to both sides of the samarium cobalt magnet sheet, drying, and then performing a slow cooling diffusion treatment to obtain a high intrinsic coercive force 2:17 type iron-rich samarium cobalt permanent magnet material.

[0014] Preferably, the particle size of the alloy powder in step (2) is 3-5 μm;

[0015] The magnetic field intensity of the magnetic field orientation molding is 1.8~2T;

[0016] The cold isostatic pressing process is performed at a pressure of 200-230 MPa and a time of 20-30 seconds.

[0017] Preferably, the sintering temperature in step (3) is 1200-1210°C, and the holding time is 1-2 hours;

[0018] The temperature of the solution treatment is 1160-1180° C., and the time is 4-10 hours.

[0019] Preferably, in step (4), the temperature is heated to 830-850°C and then rapidly cooled to room temperature, and the rapid cooling method is air cooling; the time for rapidly cooling from 830-850°C to room temperature is 20-25 minutes;

[0020] The heating to 830-850° C. and rapid cooling to room temperature are repeated 1-2 times.

[0021] Preferably, the temperature of the isothermal aging treatment in step (5) is 830-850°C, and the holding time is 2-4 hours;

[0022] The samarium cobalt aged blank has a complete cellular structure, and the average cell size is 80-95 nm.

[0023] Preferably, the thickness of the samarium cobalt magnet sheet is 2-5 mm.

[0024] Preferably, the particle size of the PrFeSn alloy powder is 1000-5000 nm;

[0025] In the PrFeSn alloy, the mass content of Pr is 30-45%, the mass content of Fe is 50-65%, and the mass percentage of Sn is 1-5%.

[0026] Preferably, the mass concentration of the PrFeSn alloy powder in the PrFeSn alloy powder suspension is 10-20%;

[0027] The solvent of the PrFeSn alloy powder suspension is an alcohol solvent.

[0028] Preferably, the slow cooling diffusion treatment method comprises the following steps:

[0029] The samarium cobalt magnet sheet coated with a PrFeSn alloy powder suspension on both sides was heated to 830-850°C, then cooled to 400°C for 1 hour and then air-cooled to room temperature.

[0030] The cooling rate is 0.5-0.7°C / min.

[0031] The present invention provides a high intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnetic material prepared by the above preparation method.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention promotes the nucleation of 1:5H cell wall phase by repeatedly heating the solid solution blank to 830-850°C and then rapidly cooling it, thereby effectively shortening the cellular structure formation time in the subsequent processing process, greatly shortening the subsequent aging treatment time, and improving production efficiency; and because there are more 1:5H cell wall phase nucleation points, more cell wall phases can be formed, reducing the average cell size and narrowing the cell wall, so that a higher Cu concentration can be obtained at the cell wall, thereby improving the intrinsic coercivity of the iron-rich magnet.

[0034] (2) The present invention uses PrFeSn as a diffusion agent in the slow cooling stage. During the slow cooling diffusion treatment process, Fe element diffuses into the cell, and Cu element diffuses into the cell wall. Therefore, excess Fe element will directly diffuse into the magnet cell, and since a good cellular structure has been formed in the isothermal aging and heat preservation stage at 830~850℃, the excess Fe element can increase the saturation magnetization intensity of the magnet without destroying the cellular structure of the magnet, thereby increasing the remanence and maximum magnetic energy product of the magnet; the addition of Sn element is beneficial to lowering the melting point of PrFeSn and promoting the rapid diffusion of elements; in addition, Pr element enters the magnet cell to replace Sm element, and due to Pr2Co 17 The saturation magnetization is greater than that of Sm2Co 17 , thus also improving the magnet's remanence and maximum magnetic energy product. Compared to the prior art CN119296941A, the present invention avoids the secondary diffusion process and improves the cellular structure of the Fe-rich SmCo magnet through a single diffusion of PrFeSn, effectively increasing the intrinsic coercivity of the 2:17 iron-rich SmCo permanent magnet material while also improving production efficiency.

[0035] (3) Furthermore, in the present invention, the SmCo aged blank has a complete cellular structure with an average cell size of 80-95 nm. Due to the increase in the nucleation sites of the 1:5H phase, a cellular structure with an average cell size of 80-95 nm can be formed by isothermal aging. However, at this time, the Cu element is relatively low in the cell wall and needs to be enriched in the cell wall after diffusion during the subsequent slow cooling process.

[0036] (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

[0037] Figure 1 Schematic diagram of the process flow of the preparation method of the high intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material of the present invention;

[0038] Figure 2This is the cellular structure of the samarium cobalt permanent magnet material of Example 1 of the present invention;

[0039] Figure 3 This is the cellular structure of the samarium cobalt permanent magnet material of Example 2 of the present invention;

[0040] Figure 4 This is the cellular structure of the samarium cobalt permanent magnet material of Example 3 of the present invention;

[0041] Figure 5 This is the cellular structure of the samarium cobalt permanent magnet material of Example 4 of the present invention. DETAILED DESCRIPTION

[0042] The present invention provides a method for preparing a high intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnetic material, comprising the following steps:

[0043] (1) Sm-Co permanent magnet material raw materials are smelted to obtain Sm-Co magnet alloy ingots; the Sm-Co permanent magnet material raw materials include, by weight percentage: (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, Re is one or more of Pr, Nd, Gd, Dy, Tb, Er, Y or Ho;

[0044] (2) crushing and grinding the samarium-cobalt magnet alloy ingot in sequence, and subjecting the obtained alloy powder to magnetic field orientation molding and cold isostatic pressing in sequence to obtain a samarium-cobalt magnet green body;

[0045] (3) sintering, solution treating and cooling the samarium cobalt magnet green body in sequence to obtain a samarium cobalt magnet solid solution blank;

[0046] (4) Under vacuum conditions, repeatedly heating the solid solution state blank of the samarium cobalt magnet to 830-850° C. and rapidly cooling it to room temperature to obtain a blank after repeated rapid cooling treatment;

[0047] (5) performing isothermal aging treatment and cooling on the blank after the repeated rapid cooling treatment to obtain a samarium-cobalt aged blank, and slicing the samarium-cobalt aged blank to obtain a samarium-cobalt magnet sheet;

[0048] (6) Applying a PrFeSn alloy powder suspension to both sides of the samarium cobalt magnet sheet, drying, and then performing a slow cooling diffusion treatment to obtain a high intrinsic coercive force 2:17 type iron-rich samarium cobalt permanent magnet material.

[0049] Unless otherwise specified, the raw materials used in the present invention are commercially available.

[0050] The present invention melts the raw material of samarium cobalt permanent magnet material to obtain samarium cobalt magnet alloy ingot. In the present invention, the raw material of samarium cobalt permanent magnet material comprises, by weight percentage: (Sm 1-x Re x ) : 25% ~ 25.5%, Fe: 14% ~ 18%, Zr: 2.2% ~ 3%, Cu: 4% ~ 6%, the balance is Co; Sm 1-x Re x , 0≤x≤0.3, preferably 0.1-0.2, specifically 0, 0.1, 0.2 or 0.3; Re is one or more of Pr, Nd, Gd, Dy, Tb, Er, Y or Ho.

[0051] In the present invention, the Sm 1-x Re x The content of is preferably 25.2% to 25.4%, the content of Fe is preferably 15% to 17%, the content of Zr is preferably 2.4% to 2.8%, and the content of Cu is preferably 4.5% to 5%.

[0052] In the present invention, the smelting is preferably vacuum medium frequency induction melting; the vacuum degree of the vacuum medium frequency induction melting is preferably 5×10 -2 ~5×10 -3 Pa, the melting temperature is preferably 1400~1500℃. In the present invention, after the alloy raw materials are melted, the present invention preferably continues to refine for 2~3min under insulation conditions. In the present invention, the thickness of the samarium cobalt magnet alloy ingot is preferably 10~20mm. After obtaining the samarium cobalt magnet alloy ingot, the present invention sequentially crushes and grinds the samarium cobalt magnet alloy ingot, and sequentially performs magnetic field orientation molding and cold isostatic pressing molding on the obtained alloy powder to obtain a samarium cobalt magnet green body. In the present invention, the crushing is preferably mechanical crushing, and the particle size after the crushing is preferably 0.5~2mm, more preferably 1~1.5mm. In the present invention, the grinding is preferably airflow grinding, and the average particle size of the alloy powder after grinding is preferably 3~5μm.

[0053] In the present invention, the magnetic field intensity of the magnetic field orientation molding is preferably 1.8~2T; by performing magnetic field orientation molding under the above conditions, the present invention can ensure that the green body obtains a higher orientation degree, and the orientation degree is proportional to the remanence of the magnet, so the final magnet can obtain a higher remanence.

[0054] In the present invention, the cold isostatic pressing pressure is preferably 200-230 MPa, and the time is preferably 20-30 seconds. Cold isostatic pressing under the above conditions can achieve a relatively high density for the green compact, which is beneficial for obtaining a dense structure during subsequent sintering of the magnet.

[0055] After obtaining the samarium cobalt magnet green body, the present invention sequentially sinters, solution treats and cools the samarium cobalt magnet green body to obtain a samarium cobalt magnet solid solution blank. In the present invention, the sintering atmosphere is preferably argon; the sintering temperature is preferably 1200~1210℃, specifically 1200℃, 1205℃ or 1210℃; the holding time is preferably 1~2h, specifically 1h, 1.5h or 2h. In the present invention, the heating rate to the sintering temperature is preferably 5~6℃ / min. By sintering under the above conditions, the present invention can enable the magnet to obtain a dense structure, thereby obtaining high remanence. After the sintering, the present invention preferably cools to the solution treatment temperature with the furnace.

[0056] In the present invention, the solution treatment is preferably carried out under an argon atmosphere, and the temperature of the solution treatment is preferably 1160~1180°C, specifically 1160°C, 1170°C or 1180°C, and the time is preferably 4~10h, more preferably 6~8h. In the present invention, the cooling method is preferably rapid air cooling to room temperature, and the time for cooling from the solution treatment to room temperature is preferably 25~30min. In the present invention, since the Fe content in the samarium cobalt alloy raw material is relatively low, the samarium cobalt magnet can form a uniform 1:7H phase through solution treatment, which is beneficial to the formation of a complete cellular structure after subsequent aging of the magnet.

[0057] After obtaining the solid solution state blank of the samarium cobalt magnet, the present invention repeatedly heats the solid solution state blank of the samarium cobalt magnet to 830-850°C and rapidly cools it to room temperature under vacuum conditions to obtain a blank after repeated rapid cooling treatment. In the present invention, the vacuum degree of the vacuum condition is preferably 10 -2 ~10 -3 Pa. In the present invention, the heating rate of heating to 830~850℃ is preferably 5~6℃ / min, and the present invention cools immediately after heating to 830~850℃. In the present invention, the rapid cooling method is air cooling, and the time from 830~850℃ to rapid cooling to room temperature is preferably 20~25min; in the present invention, the number of repetitions of heating to 830~850℃-rapid cooling to room temperature is preferably 1~2 times. The present invention promotes the nucleation of 1:5H cell wall phase by repeatedly heating to 830~850℃-rapid cooling to room temperature, thereby shortening the cellular structure formation time in the subsequent processing process, and because there are more 1:5H cell wall phase nucleation points, more cell wall phases can be formed, reducing the average cell size and narrowing the cell wall, so that a higher Cu concentration can be obtained at the cell wall.

[0058] After obtaining a blank after repeated rapid cooling, the present invention performs an isothermal aging treatment and cooling on the blank after repeated rapid cooling to obtain a samarium-cobalt aged blank. The samarium-cobalt aged blank is then sliced ​​to obtain samarium-cobalt magnet sheets. In the present invention, the atmosphere for the isothermal aging treatment is preferably argon, the temperature for the isothermal aging treatment is preferably 830-850°C, specifically 830°C, 840°C, or 850°C, and the holding time is preferably 2-4 hours, more preferably 2 hours, 3 hours, or 4 hours. The heating rate for the isothermal aging treatment is preferably 5-6°C / min. In the present invention, the cooling is preferably rapid cooling, more preferably air cooling, and the cooling time from the isothermal aging treatment temperature to room temperature is preferably 20-25 minutes. The present invention, through the isothermal failure treatment, can form a complete cellular structure in a relatively short period of time. In the present invention, the samarium-cobalt aged blank has a complete cellular structure, and the average cell size is preferably 80-95 nm.

[0059] The present invention preferably uses a slicer to perform the slicing process. In the present invention, the thickness of the samarium-cobalt magnet slice is preferably 2-5 mm, more preferably 3-4 mm. In the present invention, due to the influence of element diffusion depth, when the magnet thickness is too large, the diffusing elements cannot fully enter the magnet interior, resulting in poor diffusion effect. Therefore, the samarium-cobalt magnet needs to be processed into thin slices with a thickness of 2-5 mm.

[0060] After obtaining the samarium cobalt magnet sheet, the present invention applies a PrFeSn alloy powder suspension to both surfaces of the samarium cobalt magnet sheet, dries it, and then performs a slow cooling diffusion treatment to obtain a high intrinsic coercivity 2:17 iron-rich samarium cobalt permanent magnet material. In the present invention, the particle size of the PrFeSn alloy powder is preferably 1000-5000 nm, more preferably 2000-4000 nm. In the present invention, the mass content of Pr in the PrFeSn alloy is preferably 30-45%, more preferably 35-40%; the mass content of Fe is preferably 50-65%, more preferably 55-60%; and the mass percentage 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, more preferably one or more of ethanol, propanol, and glycerol.

[0061] In the present invention, the method for preparing the PrFeSn alloy powder suspension preferably comprises the following steps:

[0062] Smelting metal Pr, metal Fe and metal Sn to obtain a PrFeSn alloy ingot;

[0063] crushing and ball-milling the PrFeSn alloy ingot to obtain PrFeSn alloy powder;

[0064] The PrFeSn alloy powder is mixed with an alcohol solvent to obtain a PrFeSn alloy powder suspension.

[0065] In the present invention, the smelting is preferably carried out in an arc induction melting furnace.

[0066] The present invention preferably uses an electromagnetic crusher for the crushing, and the particle size of the resulting alloy particles after crushing is preferably 0.1 to 1 mm. In the present invention, the ball milling is preferably a high-energy ball milling. The present invention has no particular requirements for the specific parameters of the ball milling, and the particle size of the PrFeSn alloy powder is preferably 1000 to 5000 nm.

[0067] In the present invention, the PrFeSn alloy powder and the alcohol solvent are preferably mixed by stirring.

[0068] In the present invention, the PrFeSn alloy powder suspension is applied to both sides of the samarium cobalt magnet sheet by coating, and the coating amount is preferably 10-30 mg / cm 3 , more preferably 20~30mg / cm 3 In the present invention, the drying method is preferably blow-drying.

[0069] In the present invention, the method of slow cooling diffusion treatment preferably includes the following steps:

[0070] The samarium cobalt magnet sheet coated with PrFeSn alloy powder suspension on both sides was heated to 830-850°C, then cooled to 400°C for 1 hour and then air-cooled to room temperature.

[0071] In the present invention, the slow cooling diffusion treatment is preferably performed in an inert gas atmosphere, preferably argon, with a pressure of 0.5 MPa. The present invention utilizes an inert gas (Ar) atmosphere at a certain pressure to prevent PrFeSn oxidation from hindering surface diffusion.

[0072] In the present invention, the heating rate to 830-850°C is preferably 5-6°C / min. After heating to 830-850°C, the present invention preferably immediately cools the temperature to 400°C at a rate of preferably 0.5-0.7°C / min. In the present invention, the holding time at 400°C is preferably 1 hour.

[0073] In the present invention, during the slow cooling and diffusion process, the Fe element diffuses into the cell, and under the premise of not destroying the cellular structure of the magnet, the Fe element replaces the Co element, thereby increasing the saturation magnetization intensity of the magnet, thereby increasing the remanence and maximum magnetic energy product of the magnet. At the same time, the Cu element in the magnet diffuses and enriches into the cell wall, so that the cell wall has a higher Cu concentration, thereby making the cell wall have a strong pinning effect on the domain wall, and the magnet can obtain a higher intrinsic coercive force. In addition, due to the Pr2Co 17 The saturation magnetization intensity is greater than that of Sm2Co 17 Therefore, the diffusion of Pr into the magnet can also increase the remanence and maximum magnetic energy product of the magnet. The addition of Sn can lower the melting point of the PrFeSn alloy powder, making diffusion easier. At the same time, Sn can reduce the diffusion activation energy of Cu, making it easier for Cu to accumulate in the cell wall, increasing the Cu concentration in the cell wall and giving the magnet a high intrinsic coercive force.

[0074] As a specific embodiment of the present invention, the process flow diagram of the method for preparing the high intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material is as follows: Figure 1 shown.

[0075] The present invention provides a high intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnetic material prepared by the above preparation method.

[0076] The high intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material and its preparation method provided by the present invention are described in detail below with reference to the examples, but they should not be construed as limiting the scope of protection of the present invention.

[0077] Example 1

[0078] A method for preparing a high intrinsic coercivity 2:17 iron-rich samarium-cobalt permanent magnetic material comprises the following steps:

[0079] S1. First, weigh the raw materials of samarium cobalt permanent magnet alloy according to the following composition and its weight percentage: Sm: 25%, Fe: 14%, Zr: 2.6%, Cu: 5.5%, Co: 52.9%; then, melt the weighed raw materials of samarium cobalt permanent magnet alloy in a vacuum medium frequency induction melting furnace at a vacuum degree of 5×10 -2 ~5×10 -3 Pa, the melting temperature is 1400~1500℃, the raw materials are melted and refined for 2~3min before casting to obtain an alloy ingot with a thickness of 10mm;

[0080] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 3.8 μm;

[0081] S3, weighing the alloy powder prepared in step S2 in an air atmosphere to a weight of 300 g per portion, then orienting and shaping the powder in a 1.8 T magnetic field, and finally cold isostatically pressing the powder under a pressure of 230 MPa for 30 seconds to obtain a green compact;

[0082] S4. First, the green body obtained in step S3 is sintered at 1210°C for 2 hours in an argon atmosphere at a heating rate of 6°C / min. Then, the sintered blank is furnace-cooled to 1180°C for solution treatment, the holding time is 4 hours, and the solid solution treatment is followed by rapid air cooling to room temperature to obtain a solid solution state blank of samarium cobalt magnet. Then, the solid solution state blank of samarium cobalt magnet is heated to 850°C under vacuum conditions (the heating rate is 6°C / min) and then rapidly air cooled to room temperature, and this process is repeated once. Then, the blank after repeated rapid cooling treatment is heated to 850°C again for isothermal aging treatment, the holding time is 2 hours, and the solid solution state blank is rapidly air cooled to room temperature after the isothermal aging treatment to obtain a samarium cobalt aged blank with an average cell size of 90 nm. Finally, the samarium cobalt aged blank is processed into 3 mm samarium cobalt magnet slices using a slicer.

[0083] S5. First, prepare a PrFeSn suspension solution. The preparation method of the PrFeSn suspension solution is as follows: first, 30% by mass of Pr, 65% by mass of Fe and 5% by mass of Sn are smelted in an arc induction melting furnace to obtain a PrFeSn alloy ingot; then, an electromagnetic crusher is used to crush the PrFeSn alloy ingot into PrFeSn alloy particles with a particle size of 0.1-1 mm; then, a high-energy ball mill is used to crush the PrFeSn alloy particles into PrFeSn alloy powder with a particle size of 1000-5000 nm; finally, the PrFeSn alloy powder is mixed and stirred evenly with anhydrous ethanol, and the mass ratio of PrFeSn alloy powder to anhydrous ethanol is 1:9 to obtain a PrFeSn suspension solution; then, the PrFeSn suspension solution is evenly coated on both sides of the samarium cobalt magnet sheet and blown dry, and the coating amount is 30 mg / cm 3 ; Finally, the coated samarium cobalt magnet slices are subjected to slow cooling diffusion treatment in a tube furnace. During the treatment, 0.5MPa argon gas is filled into the tube furnace. The slow cooling diffusion treatment process is as follows: the coated samarium cobalt magnet slices are heated to 850℃ with a heating rate of 6℃ / min; then cooled to 400℃ at a rate of 0.7℃ / min, kept warm for 1h, and then quickly air-cooled to room temperature to obtain a high intrinsic coercive force 2:17 type iron-rich samarium cobalt permanent magnet material.

[0084] The cellular structure of the high intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material prepared in Example 1 is as follows: Figure 2 As shown by Figure 2It can be seen that the magnet has a complete cellular structure and the average cell size is small, about 90nm.

[0085] Comparative Example 1

[0086] Comparative Example 1 does not use the method of heating the solid solution blank to 850° C. and then rapidly cooling it with air. Compared with Example 1, step S4 of Comparative Example 1 is:

[0087] First, the green body obtained in step S3 is sintered at 1210°C for 2 hours. Then, the sintered green body is furnace-cooled to 1180°C for solution treatment with a holding time of 4 hours. After the solution treatment, it is rapidly air-cooled to room temperature to obtain a solid solution state blank of a samarium-cobalt magnet. Thereafter, the solid solution state blank is heated to 850°C for isothermal aging treatment with a holding time of 2 hours. After the isothermal aging treatment, it is 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 3 mm samarium-cobalt magnet slices using a slicer.

[0088] The remaining steps are as in Example 1.

[0089] Comparative Example 2

[0090] Comparative Example 2 does not adopt the PrFeSn diffusion treatment in Example 1. Compared with Example 1, step S5 of Comparative Example 2 is:

[0091] The samarium cobalt magnet slice was heated to 850°C, then cooled to 400°C at a rate of 0.7°C / min, kept at this temperature for 1 hour, and then rapidly cooled to room temperature by air to obtain a samarium cobalt magnet.

[0092] The remaining steps are as in Example 1.

[0093] Comparative Example 3

[0094] Comparative Example 3 Compared with Example 1, the composition of the PrFeSn diffusing agent is changed. Compared with Example 1, step S5 of Comparative Example 3 is:

[0095] A PrCu suspension solution is prepared. The preparation method of the PrCu suspension solution is as follows: first, 40% by mass of Pr and 60% by mass of Cu are smelted in an arc induction melting furnace to obtain a PrCu alloy ingot; then, the PrCu alloy ingot is crushed into a PrCu alloy powder with a particle size of 500-1000 nm by high-energy ball milling; finally, the PrCu alloy powder is mixed and stirred uniformly with anhydrous ethanol, with the mass ratio of PrCu alloy powder to anhydrous ethanol being 1:9, to obtain a PrCu suspension solution; then, the PrCu suspension solution is evenly coated on the surface of a samarium cobalt magnet sheet and blown dry; finally, the coated samarium cobalt magnet sheet is subjected to a primary diffusion treatment in a tube furnace at a primary diffusion treatment temperature of 1150°C for a diffusion treatment time of 4 hours, and then cooled and removed from the furnace to obtain the samarium cobalt magnet diffusion sheet;

[0096] A SnFe suspension solution is prepared. The SnFe suspension solution is prepared by the following method: first, 5% by mass of Sn and 95% by mass of Fe are smelted in an arc induction melting furnace to obtain a SnFe alloy ingot; then, the SnFe alloy ingot is crushed into a SnFe alloy powder of 500-1000 nm by a high-energy ball mill; finally, the SnFe alloy powder is mixed and stirred evenly with anhydrous ethanol, wherein the mass ratio of the SnFe alloy powder to the anhydrous ethanol is 1:9, to obtain a SnFe suspension solution; then, the SnFe suspension solution is evenly coated on the surface of the thin slice prepared by the above-mentioned primary diffusion treatment and blown dry; finally, the coated samarium cobalt magnet thin slice is subjected to a secondary diffusion treatment in a tube furnace, wherein the secondary diffusion treatment temperature is 900°C and the diffusion treatment time is 4 hours, and the thin slice is cooled and taken out of the furnace to obtain a samarium cobalt magnet secondary diffusion thin slice;

[0097] The obtained samarium cobalt magnet secondary diffusion sheet was subjected to aging treatment. The aging treatment process was as follows: the samarium cobalt magnet secondary diffusion sheet was heated to 850°C, kept at this temperature for 4 hours, then cooled to 400°C at a rate of 1.5°C / min, kept at this temperature for 1 hour, and then quickly cooled to room temperature with air.

[0098] The remaining steps are as in Example 1.

[0099] Example 2

[0100] A method for preparing a high intrinsic coercivity 2:17 iron-rich samarium-cobalt permanent magnetic material comprises the following steps:

[0101] S1. First, weigh the raw materials of samarium cobalt permanent magnet alloy according to the following composition and its weight percentage: Sm: 25.5%, Fe: 18%, Zr: 2.2%, Cu: 5.8%, Co: 48.5%; then, melt the weighed raw materials of samarium cobalt permanent magnet alloy in a vacuum medium frequency induction melting furnace at a vacuum degree of 5×10 -2 ~5×10 -3Pa, the melting temperature is 1400~1500℃, the raw materials are melted and refined for 2~3min before casting to obtain an alloy ingot with a thickness of 10mm;

[0102] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 4 μm;

[0103] S3, weighing the alloy powder prepared in step S2 in an air atmosphere to a weight of 300 g per portion, then orienting and shaping the powder in a 1.8 T magnetic field, and finally cold isostatically pressing the powder under a pressure of 220 MPa for 25 seconds to obtain a green compact;

[0104] S4. First, the green body obtained in step S3 is sintered at 1200°C for 1 hour in an argon atmosphere at a heating rate of 5°C / min. Then, the sintered blank is furnace-cooled to 1160°C for solution treatment, which is held for 10 hours. After the solution treatment, it is rapidly air-cooled to room temperature to obtain a solid solution state blank of samarium-cobalt magnet. Then, the solid solution state blank of samarium-cobalt magnet is heated to 830°C under vacuum (at a heating rate of 5°C / min) and then rapidly air-cooled to room temperature. This process is repeated twice. Then, the blank after repeated rapid cooling treatment is heated to 830°C again for isothermal aging treatment, which is held for 4 hours. After the isothermal aging treatment, it is rapidly air-cooled to room temperature to obtain a samarium-cobalt aged blank with an average cell size of 94.4 nm. Finally, the samarium-cobalt aged blank is processed into 2 mm samarium-cobalt magnet slices using a slicer.

[0105] S5. First, prepare a PrFeSn suspension solution. The preparation method of the PrFeSn suspension solution is as follows: first, 30% by mass of Pr, 65% by mass of Fe and 5% by mass of Sn are smelted in an arc induction melting furnace to obtain a PrFeSn alloy ingot; then, an electromagnetic crusher is used to crush the PrFeSn alloy ingot into PrFeSn alloy particles with a particle size of 0.1-1 mm; then, a high-energy ball mill is used to crush the PrFeSn alloy particles into PrFeSn alloy powder with a particle size of 1000-5000 nm; finally, the PrFeSn alloy powder is mixed and stirred evenly with anhydrous ethanol, and the mass ratio of PrFeSn alloy powder to anhydrous ethanol is 1:9 to obtain a PrFeSn suspension solution; then, the PrFeSn suspension solution is evenly coated on both sides of the samarium cobalt magnet sheet and blown dry, and the coating amount is 20 mg / cm 3; Finally, the coated samarium cobalt magnet slices are subjected to slow cooling diffusion treatment in a tube furnace. During the treatment, 0.5MPa argon gas is filled into the tube furnace. The slow cooling diffusion treatment process is as follows: the coated samarium cobalt magnet slices are heated to 830℃ at a heating rate of 5℃ / min; then cooled to 400℃ at a rate of 0.7℃ / min, kept warm for 1h, and then quickly air-cooled to room temperature to obtain a high intrinsic coercive force 2:17 type iron-rich samarium cobalt permanent magnet material.

[0106] The cellular structure of the high intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material prepared in Example 2 is as follows: Figure 3 As shown by Figure 3 It can be seen that the magnet has a complete cellular structure and the average cell size is small, about 94.4nm.

[0107] Comparative Example 4

[0108] Comparative Example 4 does not adopt the method of heating the solid solution blank to 850° C. and then rapidly cooling it with air. Compared with Example 2, step S4 of Comparative Example 4 is as follows:

[0109] First, the green body obtained in step S3 is sintered at 1200°C for 1 hour. Then, the sintered green body is furnace-cooled to 1160°C for solution treatment, which is held for 10 hours. After the solution treatment, it is rapidly air-cooled to room temperature to obtain a solid solution state blank of a samarium-cobalt magnet. Thereafter, the solid solution state blank is heated to 830°C for isothermal aging treatment, which is held for 4 hours. After the isothermal aging treatment, it is rapidly air-cooled to room temperature to obtain a samarium-cobalt aged blank with an average cell size of 123 nm. Finally, the samarium-cobalt aged blank is processed into 2 mm samarium-cobalt magnet slices using a slicer.

[0110] The remaining steps are as in Example 2.

[0111] Comparative Example 5

[0112] Comparative Example 5 does not adopt the PrFeSn diffusion treatment in Example 2. Compared with Example 2, step S5 of Comparative Example 5 is:

[0113] S5. The samarium cobalt magnet sheet was heated to 830° C., then cooled to 400° C. at a rate of 0.7° C. / min, kept at this temperature for 1 hour, and then rapidly cooled to room temperature by air to obtain a samarium cobalt magnet.

[0114] The remaining steps are as in Example 2.

[0115] Example 3

[0116] A method for preparing a high intrinsic coercivity 2:17 iron-rich samarium-cobalt permanent magnetic material comprises the following steps:

[0117] S1. First, weigh the raw materials of samarium cobalt permanent magnet alloy according to the following composition and its weight percentage: Sm: 25.4%, Fe: 17.5%, Zr: 3%, Cu: 6%, Co: 48.1%; then, melt the weighed raw materials of samarium cobalt permanent magnet alloy in a vacuum medium frequency induction melting furnace at a vacuum degree of 5×10 -2 ~5×10 -3 Pa, the melting temperature is 1400~1500℃, the raw materials are melted and refined for 2~3min before casting to obtain an alloy ingot with a thickness of 10mm;

[0118] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 4.2 μm;

[0119] S3, weighing the alloy powder prepared in step S2 in an air atmosphere, each weighing 300 g, and then orienting and molding the powder in a 1.8 T magnetic field; finally, cold isostatic pressing is performed at a pressure of 230 MPa for 30 seconds to obtain a green body;

[0120] S4. First, the green body obtained in step S3 is sintered at 1207°C for 1 hour in an argon atmosphere at a heating rate of 6°C / min. Then, the sintered blank is furnace-cooled to 1170°C for solution treatment, which is held for 8 hours. After the solution treatment, it is rapidly air-cooled to room temperature to obtain a solid solution state blank of samarium-cobalt magnet. Then, the solid solution state blank of samarium-cobalt magnet is heated to 840°C under vacuum (at a heating rate of 6°C / min) and then rapidly air-cooled to room temperature. This process is repeated twice. Then, the blank after repeated rapid cooling is heated to 840°C again for isothermal aging treatment, which is held for 3 hours. After the isothermal aging treatment, it is rapidly air-cooled to room temperature to obtain a samarium-cobalt aged blank with an average cell size of 88.6 nm. Finally, the samarium-cobalt aged blank is processed into 5 mm samarium-cobalt magnet slices using a slicer.

[0121] S5. First, prepare a PrFeSn suspension solution. The preparation method of the PrFeSn suspension solution is as follows: first, 30% by mass of Pr, 65% by mass of Fe and 5% by mass of Sn are smelted in an arc induction melting furnace to obtain a PrFeSn alloy ingot; then, an electromagnetic crusher is used to crush the PrFeSn alloy ingot into PrFeSn alloy particles with a particle size of 0.1-1 mm; then, a high-energy ball mill is used to crush the PrFeSn alloy particles into PrFeSn alloy powder with a particle size of 1000-5000 nm; finally, the PrFeSn alloy powder is mixed and stirred evenly with anhydrous ethanol, and the mass ratio of PrFeSn alloy powder to anhydrous ethanol is 1:9 to obtain a PrFeSn suspension solution; then, the PrFeSn suspension solution is evenly coated on both sides of the samarium cobalt magnet sheet and blown dry, and the coating amount is 30 mg / cm 3 ; Finally, the coated samarium cobalt magnet slices are subjected to slow cooling diffusion treatment in a tube furnace. During the treatment, 0.5MPa argon gas is filled into the tube furnace. The slow cooling diffusion treatment process is as follows: the coated samarium cobalt magnet slices are heated to 840℃ with a heating rate of 6℃ / min; then cooled to 400℃ at a rate of 0.7℃ / min, kept warm for 1h, and then quickly air-cooled to room temperature to obtain a high intrinsic coercive force 2:17 type iron-rich samarium cobalt permanent magnet material.

[0122] The cellular structure of the high intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material prepared in Example 3 is as follows: Figure 4 As shown by Figure 4 It can be seen that the magnet has a complete cellular structure and the average cell size is small, about 88.6nm.

[0123] Comparative Example 6

[0124] Comparative Example 6 does not adopt the method of rapid air cooling after heating the solid solution blank to 840° C. Compared with Example 3, step S4 of Comparative Example 6 is:

[0125] S4. First, the green body obtained in step S3 is sintered at 1207°C for 1 hour; then, the sintered green body is furnace-cooled to 1170°C for solution treatment, the holding time is 8 hours, and the green body is rapidly air-cooled to room temperature after the solution treatment to obtain a solid solution state blank of samarium cobalt magnet; then, the solid solution state blank is heated to 840°C for isothermal aging treatment, the holding time is 3 hours, and the green body is rapidly air-cooled to room temperature after the isothermal aging treatment to obtain a samarium cobalt aged green body with an average cell size of 101 nm; finally, the samarium cobalt aged green body is processed into 5 mm samarium cobalt magnet slices using a slicer.

[0126] The remaining steps are as in Example 3.

[0127] Comparative Example 7

[0128] Comparative Example 7 does not adopt the PrFeSn diffusion treatment in Example 3. Compared with Example 3, step S5 of Comparative Example 7 is:

[0129] S5. The samarium cobalt magnet sheet was heated to 840°C, then cooled to 400°C at a rate of 0.7°C / min, kept at this temperature for 1 hour, and then rapidly cooled to room temperature by air to obtain a samarium cobalt magnet.

[0130] The remaining steps are as in Example 3.

[0131] Example 4

[0132] A method for preparing a high intrinsic coercivity 2:17 iron-rich samarium-cobalt permanent magnetic material comprises the following steps:

[0133] S1. First, weigh the raw materials of samarium cobalt permanent magnet alloy according to the following composition and its weight percentage: Sm: 23%, Gd: 2.3%, Fe: 16%, Zr: 2.6%, Cu: 5.8%, Co: 50.3%; then, melt the weighed raw materials of samarium cobalt permanent magnet alloy in a vacuum medium frequency induction melting furnace at a vacuum degree of 5×10 -2 ~5×10 -3 Pa, the melting temperature is 1400~1500℃, the raw materials are melted and refined for 2~3min before casting to obtain an alloy ingot with a thickness of 10mm;

[0134] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 4.8 μm;

[0135] S3, weighing the alloy powder prepared in step S2 in an air atmosphere, with each portion weighing 300 g, then orienting and shaping the powder in a 1.8 T magnetic field, and finally cold isostatically pressing the powder under a pressure of 230 MPa to obtain a green compact;

[0136] S4. First, the green body obtained in step S3 is sintered at 1205°C for 1 hour in an argon atmosphere at a heating rate of 6°C / min. Then, the sintered blank is furnace-cooled to 1170°C for solution treatment, which is held for 8 hours. After the solution treatment, it is rapidly air-cooled to room temperature to obtain a solid solution state SmCo magnet blank. Then, the solid solution state SmCo magnet blank is heated to 840°C under vacuum (at a heating rate of 6°C / min) and then rapidly air-cooled to room temperature. This process is repeated twice. Then, the blank after repeated rapid cooling treatment is heated to 840°C again for isothermal aging treatment, which is held for 3 hours. After the isothermal aging treatment, it is rapidly air-cooled to room temperature to obtain a SmCo aged blank with an average cell size of 87.6 nm. Finally, the SmCo aged blank is processed into 4 mm SmCo magnet slices using a slicer.

[0137] S5. First, prepare a PrFeSn suspension solution. The preparation method of the PrFeSn suspension solution is as follows: first, 30% by mass of Pr, 65% by mass of Fe and 5% by mass of Sn are smelted in an arc induction melting furnace to obtain a PrFeSn alloy ingot; then, an electromagnetic crusher is used to crush the PrFeSn alloy ingot into PrFeSn alloy particles with a particle size of 0.1-1 mm; then, a high-energy ball mill is used to crush the PrFeSn alloy particles into PrFeSn alloy powder with a particle size of 1000-5000 nm; finally, the PrFeSn alloy powder is mixed and stirred evenly with anhydrous ethanol, and the mass ratio of PrFeSn alloy powder to anhydrous ethanol is 1:9 to obtain a PrFeSn suspension solution; then, the PrFeSn suspension solution is evenly coated on both sides of the samarium cobalt magnet sheet and blown dry, and the coating amount is 20 mg / cm 3 ; Finally, the coated samarium cobalt magnet slices are subjected to slow cooling diffusion treatment in a tube furnace. During the treatment, 0.5MPa argon gas is filled into the tube furnace. The slow cooling diffusion treatment process is as follows: the coated samarium cobalt magnet slices are heated to 840℃ with a heating rate of 6℃ / min; then cooled to 400℃ at a rate of 0.7℃ / min, kept warm for 1h, and then quickly air-cooled to room temperature to obtain a high intrinsic coercive force 2:17 type iron-rich samarium cobalt permanent magnet material.

[0138] The cellular structure of the high intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material prepared in Example 4 is as follows: Figure 5 As shown by Figure 5 It can be seen that the magnet has a complete cellular structure and the average cell size is small, about 87.6nm.

[0139] Comparative Example 8

[0140] Comparative Example 8 does not adopt the method of rapid air cooling after heating the solid solution blank to 840° C. Compared with Example 4, step S4 of Comparative Example 6 is:

[0141] S4. First, the green body produced in step S3 was sintered at 1205°C for 1 hour. The sintered body was then furnace-cooled to 1170°C for solution treatment, held at this temperature for 8 hours, and rapidly air-cooled to room temperature to produce a solid-solution-state SmCo magnet blank. The solid-solution-state blank was then heated to 840°C for isothermal aging treatment, held at this temperature for 3 hours, and rapidly air-cooled to room temperature to produce an aged SmCo blank with an average cell size of 102.5 nm. Finally, the aged SmCo blank was sliced ​​into 4 mm SmCo magnet slices.

[0142] The remaining steps are as in Example 4.

[0143] Comparative Example 9

[0144] Comparative Example 9 does not adopt the PrFeSn diffusion treatment in Example 4. Compared with Example 4, step S5 of Comparative Example 9 is:

[0145] S5. The samarium cobalt magnet sheet was heated to 840°C, then cooled to 400°C at a rate of 0.7°C / min, kept at this temperature for 1 hour, and then rapidly cooled to room temperature by air to obtain a samarium cobalt magnet.

[0146] The remaining steps are as in Example 4.

[0147] Performance Testing

[0148] The magnetic properties of the samarium cobalt permanent magnet materials obtained in Examples 1 to 4 and Comparative Examples 1 to 9 were tested using a PFM magnetic property measuring instrument. The results are shown in Table 1.

[0149] Table 1 Magnetic properties of samarium cobalt permanent magnet materials obtained in Examples 1 to 4 and Comparative Examples 1 to 9

[0150]

[0151] 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 2:17 iron-rich samarium-cobalt permanent magnet materials. Compared with Comparative Examples 1, 4, 6, and 8, Examples 1 to 4 of the present invention promote the nucleation of the 1:5H cell wall phase by repeatedly heating the solid solution blank to 830-850°C and then rapidly cooling it, which can form more cell wall phases, reduce the average cell size, and narrow the cell wall, thereby obtaining a higher Cu concentration at the cell wall and improving the intrinsic coercivity of the iron-rich magnet. Compared with Comparative Examples 2, 5, and 7, Examples 1 to 3 of the present invention use a diffused PrFeSn treatment. During the diffused PrFeSn treatment, Fe enters the magnet cell, increasing the saturation magnetization intensity, thereby enabling the magnet to obtain a higher remanence and magnetic energy product. However, at the same time, after Fe enters the magnet tissue, it will inevitably reduce the anisotropy field of the cell tissue, resulting in a slight decrease in the intrinsic coercivity Hcj. The intrinsic coercivity of Comparative Example 9 is similar to that of Example 4 and is within the error range. This is because when the Fe content is lower than a certain value, the magnet easily obtains a high coercivity. As the Fe content decreases, the coercivity tends to be stable and will not continue to increase.

[0152] Comparative Example 3: The diffusion of PrCu was carried out at a high temperature of 1150°C, which inevitably caused oxidation of rare earth Pr (rare earth is easily oxidized) and Cu, resulting in poor diffusion effect. Pr could not effectively enter the magnet, generating Pr2Co 17 , thus forming Pr2Co 17The effect of improving remanence was poor, resulting in a lower remanence than in Example 1. Cu diffusion after oxidation was poor, resulting in less Cu entering the magnet and failing to effectively increase the Cu concentration at the cell wall. This limited coercivity improvement led to a lower coercivity in Comparative Example 3. However, the present invention diffuses PrFeSn during the slow cooling process after heating the samarium-cobalt magnet sheet to 830-850°C, avoiding high-temperature oxidation and enabling efficient element diffusion, which is beneficial for achieving higher coercivity.

[0153] The addition of Sn element in the present invention is beneficial to lowering the melting point of PrFeSn and promoting the entry of Pr element into the magnet cell to replace Sm element. 17 The saturation magnetization is greater than that of Sm2Co 17 , thus the remanence and maximum magnetic energy product of the magnet can be improved, while the PrCu diffusion effect in comparative example 3 is poor, which is one of the reasons why the remanence is lower than that in embodiment 1.

[0154] In addition, comparative example 3 carried out secondary diffusion at 1150°C and 900°C. The present invention does not have an additional diffusion process, and the diffusion of PrFeSn is directly carried out during the aging and slow cooling stage, which greatly shortens the process flow, saves time, and improves product preparation efficiency.

[0155] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a high intrinsic coercivity 2:17 type iron-rich samarium-cobalt permanent magnet material, characterized in that: The following steps are involved: (1) Smearing the raw materials of samarium cobalt permanent magnet material to obtain samarium cobalt magnet alloy ingots; In terms of mass percentage, the raw materials of 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; wherein 0≤x≤0.3, 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 molding and cold isostatic pressing in sequence to obtain a samarium-cobalt magnet green body; (3) sintering, solution treating and cooling the samarium cobalt magnet green body in sequence to obtain a samarium cobalt magnet solid solution blank; (4) Under vacuum conditions, repeatedly heating the solid solution state blank of the 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 the repeated rapid cooling treatment to obtain a samarium-cobalt aged blank, and slicing the samarium-cobalt aged blank to obtain a samarium-cobalt magnet sheet; (6) applying a PrFeSn alloy powder suspension to both sides of the samarium cobalt magnet sheet, drying it, and then performing a slow cooling diffusion treatment to obtain a high intrinsic coercivity 2:17 type iron-rich samarium cobalt permanent magnet material; The method for slow cooling and diffusion treatment comprises the following steps: The samarium cobalt magnet sheet coated with a PrFeSn alloy powder suspension on both sides was heated to 830-850°C, then cooled to 400°C for 1 hour and then air-cooled to room temperature. The cooling rate is 0.5-0.7°C / min.

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

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

4. The preparation method according to claim 1, characterized in that The step (4) is heating to 830-850°C and rapidly cooling to room temperature, wherein the rapid cooling method is air cooling, and the time for rapidly cooling from 830-850°C to room temperature is 20-25 minutes; The heating to 830-850° C. and rapid cooling to room temperature are repeated 1-2 times.

5. The preparation method according to claim 1, characterized in that The temperature of the isothermal aging treatment in step (5) is 830-850°C, and the holding time is 2-4 hours; The samarium cobalt aged blank has a complete cellular 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 sheet 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 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. A high intrinsic coercivity 2:17 iron-rich samarium-cobalt permanent magnet material prepared by the preparation method according to any one of claims 1 to 8.

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