A diffusion preparation method for Fe-rich high coercivity samarium cobalt magnet

Abstract

A diffusion preparation method for Fe-rich, high-coercivity samarium-cobalt magnets belongs to the field of magnetic material preparation technology and addresses the technical issues of Fe-rich samarium-cobalt magnets being difficult to form a good cellular structure and having a long process flow. The method comprises the following steps: S1, weighing samarium-cobalt permanent magnet alloy raw materials to prepare an alloy ingot; S2, mechanically crushing the alloy particles to prepare alloy powder; S3, subjecting the samarium-cobalt alloy powder to magnetic field orientation molding and cold isostatic pressing to prepare a green body; S4, sintering and solutionizing the green body to prepare a sintered samarium-cobalt permanent magnet blank, which is then processed into samarium-cobalt magnet slices; S5, subjecting the samarium-cobalt magnet slices to a primary diffusion treatment of PrCu; S6, subjecting the magnet slices to a secondary diffusion treatment of SnFe; and S7, subjecting the secondary diffused slices to an aging treatment to produce the samarium-cobalt permanent magnets. The preparation method provided by the present invention is easy to operate, control, and industrialize, and the resulting Fe-rich sintered samarium-cobalt magnets have excellent performance.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic material preparation, and in particular relates to a diffusion preparation method for an Fe-rich high-coercivity samarium-cobalt magnet. Background Art

[0002] Since its advent, the second-generation rare earth permanent magnet material 2:17 SmCo permanent magnet has been highly favored for its excellent magnetic properties. It has developed rapidly in scientific research, production and application, and is widely used in many fields such as national defense and military industry, aerospace, medical equipment, microwave devices, transportation, high-end motors, etc.

[0003] 2:17 SmCo permanent magnets have a typical cellular structure. The 2:17R cellular phase has a high solubility for Fe, providing a high saturation magnetization. The 1:5H cell wall has a high solubility for Cu. Through proper heat treatment, Cu can be enriched in the cell wall, forming a concentration gradient, resulting in a high coercivity. In addition to the cellular and cell wall phases, the magnet also contains a lamellar Zr-rich phase. This lamellar phase also plays an important role in the magnet, believed by many to provide pathways for element diffusion during aging. Precisely because of this complex microstructure, 2:17 sintered SmCo magnets exhibit excellent overall magnetic properties. Increasing the Fe content is a key process for producing high-performance SmCo magnets, but excessive Fe content can affect the magnet's microstructure, resulting in deteriorated magnetic properties. Improving the microstructure of Fe-rich SmCo magnets and optimizing the preparation process to enhance magnetic properties are of great significance to the development of the SmCo industry.

[0004] Currently, the patent document "2-17 type samarium cobalt permanent magnet material and its preparation method and application" (Publication No.: CN113593882 A) applies a metallic Cu layer to the surface of the samarium cobalt sintered body and diffuses it to improve the Cu content in the magnet grain boundaries and enhance the magnet's magnetic properties. However, Cu is a non-magnetic element, and diffusion of Cu reduces the magnet's remanence. The patent document "A method for improving the magnetic properties of samarium cobalt permanent magnet material" (Publication No.: CN 112038083 A) applies a low-melting-point phase diffusion source to the surface of the base material by coating and / or encapsulating it for diffusion treatment to enhance the magnet's magnetic properties. However, this does not address the problem of deteriorating magnet microstructure caused by excessive Fe content, and diffusing the low-melting-point phase RE-TM does not effectively increase the magnet's remanence and maximum magnetic energy product. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology and solve the technical problems that Fe-rich SmCo magnets are difficult to form a good cellular structure and the preparation process is long, the present invention provides a diffusion preparation method for Fe-rich high coercivity SmCo magnets, thereby improving the microstructure of Fe-rich SmCo magnets, improving production efficiency, and effectively improving the magnetic properties of 2:17 type SmCo magnets.

[0006] In order to achieve the above objectives, the present invention is implemented through the following technical solutions.

[0007] A diffusion preparation method for an Fe-rich high coercivity samarium-cobalt magnet comprises the following steps:

[0008] S1. First, weigh the samarium cobalt permanent magnet alloy raw materials according to the following composition and weight percentage: (Sm 1-x Re x ): 23% to 25.5%, Fe: 16% to 23%, Zr: 2.1% to 3%, Cu: 4% to 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; then, the weighed samarium-cobalt permanent magnet alloy raw material is melted in a vacuum medium-frequency induction melting furnace to obtain an alloy ingot with a thickness of 10 mm;

[0009] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5-2.5 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 3-5 μm;

[0010] S3, weighing the alloy powder prepared in step S2 in an air atmosphere, then orienting and shaping it in a 2T magnetic field, and finally cold isostatically pressing it at a pressure of 200 MPa to obtain a green body;

[0011] S4. First, the green body obtained in step S3 is sintered at a temperature of 1200-1215° C. for 1-2 hours. Then, the sintered blank is cooled to 1160-1180° C. with the furnace for solution treatment, and the heat preservation time is 4-10 hours. After the solution treatment, it is quickly cooled to room temperature to obtain a solid solution state blank of the samarium cobalt magnet. Through the solid solution treatment, the samarium cobalt magnet can form a uniform 1:7H phase, which prepares for subsequent diffusion and the formation of a good cellular structure. Finally, the solid solution state blank of the samarium cobalt magnet is processed into a samarium cobalt magnet slice using a slicer. Due to the influence of the element diffusion depth, when the magnet thickness is too large, the diffused elements cannot fully enter the interior of the magnet, resulting in poor diffusion effect. Therefore, the samarium cobalt magnet needs to be processed into a slice with a thickness of 3-7 mm.

[0012] S5. First, prepare a PrCu suspension solution. Then, evenly coat the PrCu suspension solution on the surface (top and bottom) of the SmCo magnet sheet and blow dry. Finally, perform a primary diffusion treatment on the coated SmCo magnet sheet in a tube furnace at a temperature of 1140-1150°C for 4-8 hours. The sheet is then cooled and removed from the furnace to produce diffused SmCo magnet sheets. After the solution treatment in step S4, a uniform 1:7H phase is obtained. Subsequently, a primary diffusion of PrCu is performed at a temperature slightly below the solution temperature of 1140-1150°C to promote the network segregation of the Cu element. When preparing Fe-rich SmCo magnets, due to the high Fe content, the magnet cell size becomes larger and a complete cellular structure is difficult to form. This prevents effective pinning of the magnetic domains, resulting in a decrease in the magnet's coercive force. The present invention diffuses PrCu compounds to allow a certain amount of Cu elements to enter the interior of the magnet and distribute them in a network-like segregation. These segregated Cu elements will become nucleation sites for the Cu-rich cell wall phase in the subsequent aging process, which is beneficial to the formation of cell walls. Therefore, it promotes the formation of a complete cellular structure of the Fe-rich magnet, thereby obtaining a higher coercive force. However, Cu is a non-magnetic element, and its entry will cause the saturation magnetization of the magnet to decrease, while the entry of Pr will form Pr2Co 17 phase, whose saturation magnetization is greater than that of Sm2Co 17 , thus increasing the saturation magnetization of the magnet, compensating for the decrease in magnetic properties of the magnet caused by the entry of non-magnetic Cu elements;

[0013] S6. First, prepare a SnFe suspension solution; then, evenly coat the SnFe suspension solution on the surface of the thin slice prepared in step S5 and blow dry; finally, perform a secondary diffusion treatment on the coated samarium cobalt magnet slice in a tubular furnace. The secondary diffusion treatment temperature is 850~900℃, the diffusion treatment time is 2~4h, and the slice is cooled and taken out of the furnace to obtain a samarium cobalt magnet secondary diffusion slice; the secondary diffusion treatment can allow the Fe element to enter the cell, increase the saturation magnetization intensity of the magnet, and promote the rapid formation of the cellular structure. By diffusing the SnFe compound, the excess Fe element is diffused into the magnet. Under the premise of not destroying the cellular structure formed by the magnet, the Fe element can replace the Co element, thereby increasing the saturation magnetization intensity of the magnet, thereby increasing the remanence and maximum magnetic energy product of the magnet. The addition of the Sn element is conducive to the full and rapid diffusion of the Fe element.

[0014] S7. The samarium cobalt magnet secondary diffusion sheet obtained after the treatment in step S6 is subjected to aging treatment. The aging treatment process is as follows: heating the samarium cobalt magnet secondary diffusion sheet to 800-850° C., keeping the temperature for 1-4 hours, then cooling the temperature to 400° C. at a rate of 1.5° C. / min, keeping the temperature for 1 hour, and then rapidly cooling the temperature to room temperature with air, thereby obtaining an Fe-rich high coercive force samarium cobalt magnet.

[0015] Furthermore, in step S4, the thickness of the samarium cobalt magnet sheet is 3-7 mm.

[0016] Furthermore, in step S5, the PrCu suspension solution is prepared by: 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 PrCu alloy powder with a particle size of 500-1000 nm by high-energy ball milling, which is conducive to its uniform coating on the surface of the magnet sheet and improves the diffusion uniformity, thereby making the magnetic properties of the magnet after diffusion more consistent; finally, the PrCu alloy powder is mixed and stirred evenly with anhydrous ethanol to obtain a PrCu suspension solution.

[0017] Furthermore, in step S5, the prepared samarium-cobalt magnet diffusion sheet has a network-like Cu element segregation structure.

[0018] Furthermore, in step S6, the SnFe suspension solution is prepared by: 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 SnFe alloy powder of 500-1000 nm by high-energy ball milling, which is conducive to uniform diffusion of elements; finally, the SnFe alloy powder is mixed and stirred evenly with anhydrous ethanol to obtain a SnFe suspension solution.

[0019] Furthermore, the PrCu alloy powder and the SnFe alloy powder were mixed with anhydrous ethanol at a mass ratio of 1:9.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention diffuses PrCu compounds in the solid solution samarium cobalt magnet slices. After the Cu element diffuses into the magnet, it is distributed in a network, which can become the nucleation site of the Cu-rich cell wall phase in the subsequent aging process, which is conducive to the formation of a good cellular structure of the Fe-rich magnet, thereby obtaining a higher coercive force; at the same time, the Pr element enters the magnet, and due to the Pr2Co 17 The saturation magnetization is greater than that of Sm2Co 17 , which can make up for the decrease in the saturation magnetization intensity of the magnet caused by the entry of non-magnetic Cu elements;

[0022] 2. The present invention diffuses SnFe compounds to allow excess Fe elements to enter the magnet, and the diffusion temperature is 850-900°C, thereby increasing the saturation magnetization 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 elements is conducive to the full and rapid diffusion of Fe elements.

[0023] 3. In the present invention, the segregation of Cu elements is formed by primary diffusion, which is conducive to the rapid formation of a cellular structure during the aging process. In addition, in the secondary diffusion process, the diffusion temperature of 850-900°C promotes the formation of a cellular structure, thereby greatly shortening the subsequent aging treatment time and improving production efficiency.

[0024] In summary, the preparation method provided by the present invention is easy to operate, control and industrialize, and the prepared sintered samarium cobalt magnet has excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the process flow of the diffusion preparation method of the Fe-rich high coercivity samarium cobalt magnet of the present invention;

[0026] Figure 2 This is a typical network-like Cu element segregation microstructure of the samarium-cobalt thin sheet obtained after a single diffusion of PrCu in the present invention. DETAILED DESCRIPTION

[0027] The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention. Unless otherwise specified, the examples are based on conventional experimental conditions. Example 1

[0028] A diffusion preparation method for an Fe-rich high coercivity samarium-cobalt magnet comprises the following steps:

[0029] S1. First, weigh a samarium cobalt permanent magnet alloy raw material according to the following composition and its weight percentage: Sm: 23%, Fe: 16%, Zr: 2.5%, Cu: 5%, Co: 53.5%; then, melt the weighed samarium cobalt permanent magnet alloy raw material in a vacuum medium frequency induction melting furnace to produce an alloy ingot with a thickness of 10 mm;

[0030] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2.5 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;

[0031] S3, weighing the alloy powder prepared in step S2 in an air atmosphere, then orienting and shaping it in a 2T magnetic field, and finally cold isostatically pressing it at a pressure of 200 MPa to obtain a green body;

[0032] S4. First, the green body obtained in step S3 is sintered at 1215° C. for 2 h. Then, the sintered green body is furnace-cooled to 1180° C. for solution treatment, and the temperature is kept at this temperature for 4 h. After the solution treatment, the green body is rapidly cooled to room temperature by air to obtain a solid solution state of samarium cobalt magnet. Finally, the solid solution state of samarium cobalt magnet is processed into a samarium cobalt magnet slice with a thickness of 5 mm using a slicer.

[0033] S5. First, 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 evenly with anhydrous ethanol, and the mass ratio of the PrCu alloy powder to the anhydrous 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 sheet and blown dry; finally, the coated samarium cobalt magnet sheet is subjected to a primary diffusion treatment in a tube furnace, the primary diffusion treatment temperature is 1150° C., the diffusion treatment time is 4 h, and the sheet is cooled and taken out of the furnace to obtain a samarium cobalt magnet diffusion sheet, wherein the prepared samarium cobalt magnet diffusion sheet has a network Cu element segregation structure;

[0034] S6. First, prepare a SnFe suspension solution. The SnFe suspension solution is prepared as follows: 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 slice prepared in step S5 and blown dry; finally, the coated samarium cobalt magnet slice is subjected to a secondary diffusion treatment in a tube furnace, the secondary diffusion treatment temperature is 900°C, the diffusion treatment time is 4 hours, and the slice is cooled and taken out of the furnace to obtain a samarium cobalt magnet secondary diffusion slice;

[0035] S7. The samarium cobalt magnet secondary diffusion sheet obtained after the treatment in step S6 is subjected to aging treatment. The aging treatment process is as follows: heating the samarium cobalt magnet secondary diffusion sheet to 850° C., keeping the temperature for 4 hours, then cooling the temperature to 400° C. at a rate of 1.5° C. / min, keeping the temperature for 1 hour, and then rapidly cooling the temperature to room temperature with air, thereby obtaining an Fe-rich high coercive force samarium cobalt magnet.

[0036] The magnetic properties of the Fe-rich high coercivity samarium cobalt magnet prepared in Example 1 are as follows: remanence B r =11.41kGs, magnetic energy product (BH) m =31MGOe, intrinsic coercivity H cj =33.38kOe.

[0037] Comparative Example 1

[0038] Comparative Example 1 does not adopt the S5 primary diffusion and S6 secondary diffusion processes in Example 1, and other preparation processes are the same as those in Example 1.

[0039] A method for preparing a sintered samarium-cobalt permanent magnet comprises the following steps:

[0040] S1. First, weigh a samarium cobalt permanent magnet alloy raw material according to the following composition and its weight percentage: Sm: 23%, Fe: 16%, Zr: 2.5%, Cu: 5%, Co: 53.5%; then, melt the weighed samarium cobalt permanent magnet alloy raw material in a vacuum medium frequency induction melting furnace to produce an alloy ingot with a thickness of 10 mm;

[0041] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2.5 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;

[0042] S3, weighing the alloy powder prepared in step S2 in an air atmosphere, then orienting and shaping it in a 2T magnetic field, and finally cold isostatically pressing it at a pressure of 200 MPa to obtain a green body;

[0043] S4. First, the green body obtained in step S3 is sintered at 1215° C. for 2 h. Then, the sintered green body is furnace-cooled to 1180° C. for solution treatment, and the temperature is kept at this temperature for 4 h. After the solution treatment, the green body is rapidly cooled to room temperature by air to obtain a solid solution state of samarium cobalt magnet. Finally, the solid solution state of samarium cobalt magnet is processed into a samarium cobalt magnet slice with a thickness of 5 mm using a slicer.

[0044] S5. The samarium cobalt magnet slices obtained after the treatment in step S4 are subjected to aging treatment. The aging treatment process is as follows: heating the samarium cobalt magnet slices to 850° C., keeping the temperature for 4 hours, then cooling the temperature to 400° C. at a rate of 1.5° C. / min, keeping the temperature for 1 hour, and then rapidly cooling the temperature to room temperature to obtain sintered samarium cobalt permanent magnets.

[0045] The magnetic properties of the sintered samarium cobalt permanent magnet prepared in Comparative Example 1 are as follows: remanence B r =11.22kGs, magnetic energy product (BH) m =29.93MGOe, intrinsic coercivity H cj =33.42kOe. Example 2

[0046] A diffusion preparation method for an Fe-rich high coercivity samarium-cobalt magnet comprises the following steps:

[0047] S1. First, weigh a samarium cobalt permanent magnet alloy raw material according to the following composition and its weight percentage: Sm: 24%, Fe: 23%, Zr: 2.8%, Cu: 5.5%, Co: 44.7%; then, melt the weighed samarium cobalt permanent magnet alloy raw material in a vacuum medium frequency induction melting furnace to produce an alloy ingot with a thickness of 10 mm;

[0048] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2.5 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 3.4 μm;

[0049] S3, weighing the alloy powder prepared in step S2 in an air atmosphere, then orienting and shaping it in a 2T magnetic field, and finally cold isostatically pressing it at a pressure of 200 MPa to obtain a green body;

[0050] S4. First, the green body obtained in step S3 is sintered at 1200° C. for 1.5 hours. Then, the sintered green body is furnace-cooled to 1160° C. for solution treatment, and the temperature is kept at this temperature for 10 hours. After the solution treatment, the green body is rapidly cooled to room temperature by air to obtain a solid solution state of samarium cobalt magnet. Finally, the solid solution state of samarium cobalt magnet is processed into a samarium cobalt magnet slice with a thickness of 7 mm using a slicer.

[0051] S5. First, prepare a PrCu suspension solution. The preparation method of the PrCu suspension solution is the same as that in Example 1. Then, the PrCu suspension solution is evenly coated on the surface of the samarium cobalt magnet sheet and blown dry. Finally, the coated samarium cobalt magnet sheet is subjected to a diffusion treatment in a tube furnace at a diffusion treatment temperature of 1140° C. for 8 hours. The sheet is cooled and taken out of the furnace to obtain a samarium cobalt magnet diffusion sheet. The obtained samarium cobalt magnet diffusion sheet has a network-like Cu element segregation structure.

[0052] S6. First, prepare a SnFe suspension solution. The method for preparing the SnFe suspension solution is the same as that in Example 1. Then, evenly coat the SnFe suspension solution on the surface of the slice prepared in step S5 and blow dry. Finally, perform a secondary diffusion treatment on the coated samarium cobalt magnet slice in a tube furnace at a secondary diffusion treatment temperature of 850° C. for 2 hours. The slice is then cooled and taken out of the furnace to obtain a samarium cobalt magnet secondary diffusion slice.

[0053] S7. The samarium cobalt magnet secondary diffusion sheet obtained after the treatment in step S6 is subjected to aging treatment. The aging treatment process is as follows: heating the samarium cobalt magnet secondary diffusion sheet to 800° C., keeping the temperature for 3 hours, then cooling the temperature to 400° C. at a rate of 1.5° C. / min, keeping the temperature for 1 hour, and then rapidly cooling the temperature to room temperature with air, thereby obtaining an Fe-rich high coercive force samarium cobalt magnet.

[0054] The magnetic properties of the Fe-rich high coercivity samarium cobalt magnet prepared in Example 2 are as follows: remanence B r =11.84kGs, magnetic energy product (BH) m =33.18MGOe, intrinsic coercivity H cj =23.25kOe. Comparative Example 2

[0055] Comparative Example 2 does not adopt the S5 primary diffusion and S6 secondary diffusion processes in Example 2, and the other preparation processes are the same as those in Example 2.

[0056] A method for preparing a sintered samarium-cobalt permanent magnet comprises the following steps:

[0057] S1. First, weigh a samarium cobalt permanent magnet alloy raw material according to the following composition and its weight percentage: Sm: 24%, Fe: 23%, Zr: 2.8%, Cu: 5.5%, Co: 44.7%; then, melt the weighed samarium cobalt permanent magnet alloy raw material in a vacuum medium frequency induction melting furnace to produce an alloy ingot with a thickness of 10 mm;

[0058] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2.5 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 3.4 μm;

[0059] S3, weighing the alloy powder prepared in step S2 in an air atmosphere, then orienting and shaping it in a 2T magnetic field, and finally cold isostatically pressing it at a pressure of 200 MPa to obtain a green body;

[0060] S4. First, the green body obtained in step S3 is sintered at 1200° C. for 1.5 hours. Then, the sintered green body is furnace-cooled to 1160° C. for solution treatment, and the temperature is kept at this temperature for 10 hours. After the solution treatment, the green body is rapidly cooled to room temperature by air to obtain a solid solution state of samarium cobalt magnet. Finally, the solid solution state of samarium cobalt magnet is processed into a samarium cobalt magnet slice with a thickness of 7 mm using a slicer.

[0061] S5. The samarium cobalt magnet slices obtained after the treatment in step S4 are subjected to aging treatment. The aging treatment process is as follows: heating the samarium cobalt magnet slices to 800° C., keeping the temperature for 3 hours, then cooling the temperature to 400° C. at a rate of 1.5° C. / min, keeping the temperature for 1 hour, and then rapidly cooling the temperature to room temperature to obtain sintered samarium cobalt permanent magnets.

[0062] The magnetic properties of the sintered samarium cobalt permanent magnet prepared in Comparative Example 2 are as follows: remanence B r =11.65kGs, magnetic energy product (BH) m =32.23MGOe, intrinsic coercive force H cj =30.18kOe. Example 3

[0063] A diffusion preparation method for an Fe-rich high coercivity samarium-cobalt magnet comprises the following steps:

[0064] S1. First, weigh a samarium cobalt permanent magnet alloy raw material according to the following composition and its weight percentage: Sm: 25.5%, Fe: 22%, Zr: 2.1%, Cu: 6%, Co: 44.4%; then, melt the weighed samarium cobalt permanent magnet alloy raw material in a vacuum medium frequency induction melting furnace to produce an alloy ingot with a thickness of 10 mm;

[0065] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2.5 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 4.5 μm;

[0066] S3, weighing the alloy powder prepared in step S2 in an air atmosphere, then orienting and shaping it in a 2T magnetic field, and finally cold isostatically pressing it at a pressure of 200 MPa to obtain a green body;

[0067] S4. First, the green body obtained in step S3 is sintered at 1205° C. for 1 hour. Then, the sintered green body is furnace-cooled to 1165° C. for solution treatment, and the temperature is kept at this temperature for 10 hours. After the solution treatment, the green body is rapidly cooled to room temperature by air to obtain a solid solution state of samarium cobalt magnet. Finally, the solid solution state of samarium cobalt magnet is processed into a samarium cobalt magnet slice with a thickness of 6 mm using a slicer.

[0068] S5. First, prepare a PrCu suspension solution. The preparation method of the PrCu suspension solution is the same as that in Example 1. Then, the PrCu suspension solution is evenly coated on the surface of the samarium cobalt magnet sheet and blown dry. Finally, the coated samarium cobalt magnet sheet is subjected to a diffusion treatment in a tube furnace at a diffusion treatment temperature of 1140° C. for 8 hours. The sheet is cooled and taken out of the furnace to obtain a samarium cobalt magnet diffusion sheet. The obtained samarium cobalt magnet diffusion sheet has a network-like Cu element segregation structure.

[0069] S6. First, prepare a SnFe suspension solution. The method for preparing the SnFe suspension solution is the same as that in Example 1. Then, evenly coat the SnFe suspension solution on the surface of the slice prepared in step S5 and blow dry. Finally, perform a secondary diffusion treatment on the coated samarium cobalt magnet slice in a tube furnace at a secondary diffusion treatment temperature of 860° C. for 2 hours. The slice is then cooled and taken out of the furnace to obtain a samarium cobalt magnet secondary diffusion slice.

[0070] S7. The samarium cobalt magnet secondary diffusion sheet obtained after the treatment in step S6 is subjected to aging treatment. The aging treatment process is as follows: heating the samarium cobalt magnet secondary diffusion sheet to 810° C., keeping the temperature for 3 hours, then cooling the temperature to 400° C. at a rate of 1.5° C. / min, keeping the temperature for 1 hour, and then rapidly cooling the temperature to room temperature with air, thereby obtaining an Fe-rich high coercive force samarium cobalt magnet.

[0071] The magnetic properties of the Fe-rich high coercivity samarium cobalt magnet prepared in Example 3 are as follows: remanence Br =11.75kGs, magnetic energy product (BH) m =32.75MGOe, intrinsic coercive force H cj =29.96kOe. Comparative Example 3

[0072] Comparative Example 3 does not adopt the S5 primary diffusion and S6 secondary diffusion processes in Example 3, and the other preparation processes are the same as those in Example 3.

[0073] A method for preparing a sintered samarium-cobalt permanent magnet comprises the following steps:

[0074] S1. First, weigh a samarium cobalt permanent magnet alloy raw material according to the following composition and its weight percentage: Sm: 25.5%, Fe: 22%, Zr: 2.1%, Cu: 6%, Co: 44.4%; then, melt the weighed samarium cobalt permanent magnet alloy raw material in a vacuum medium frequency induction melting furnace to produce an alloy ingot with a thickness of 10 mm;

[0075] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2.5 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 4.5 μm;

[0076] S3, weighing the alloy powder prepared in step S2 in an air atmosphere, then orienting and shaping it in a 2T magnetic field, and finally cold isostatically pressing it at a pressure of 200 MPa to obtain a green body;

[0077] S4. First, the green body obtained in step S3 is sintered at 1205° C. for 1 hour. Then, the sintered green body is furnace-cooled to 1165° C. for solution treatment, and the temperature is kept at this temperature for 10 hours. After the solution treatment, the green body is rapidly cooled to room temperature by air to obtain a solid solution state of samarium cobalt magnet. Finally, the solid solution state of samarium cobalt magnet is processed into a samarium cobalt magnet slice with a thickness of 6 mm using a slicer.

[0078] S5. The samarium cobalt magnet slices obtained after the treatment in step S4 are subjected to aging treatment. The aging treatment process is as follows: heating the samarium cobalt magnet slices to 810° C., keeping the temperature for 3 hours, then cooling the temperature to 400° C. at a rate of 1.5° C. / min, keeping the temperature for 1 hour, and then rapidly cooling the temperature to room temperature to obtain sintered samarium cobalt permanent magnets.

[0079] The magnetic properties of the sintered samarium cobalt permanent magnet prepared in this comparative example 3 are: remanence B r =11.58kGs, magnetic energy product (BH) m =31.88MGOe, intrinsic coercivity H cj =31.26kOe. Example 4

[0080] A diffusion preparation method for an Fe-rich high coercivity samarium-cobalt magnet comprises the following steps:

[0081] S1. First, weigh a samarium cobalt permanent magnet alloy raw material according to the following composition and its weight percentage: Sm: 24.5%, Fe: 20%, Zr: 3%, Cu: 4%, Co: 48.5%; then, melt the weighed samarium cobalt permanent magnet alloy raw material in a vacuum medium frequency induction melting furnace to produce an alloy ingot with a thickness of 10 mm;

[0082] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2.5 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 4 μm;

[0083] S3, weighing the alloy powder prepared in step S2 in an air atmosphere, then orienting and shaping it in a 2T magnetic field, and finally cold isostatically pressing it at a pressure of 200 MPa to obtain a green body;

[0084] S4. First, the green body obtained in step S3 is sintered at 1210° C. for 1.5 hours. Then, the sintered green body is furnace-cooled to 1170° C. for solution treatment, and the temperature is kept at this temperature for 6 hours. After the solution treatment, the green body is rapidly cooled to room temperature by air to obtain a solid solution state of samarium cobalt magnet. Finally, the solid solution state of samarium cobalt magnet is processed into a samarium cobalt magnet slice with a thickness of 5 mm using a slicer.

[0085] S5. First, prepare a PrCu suspension solution. The preparation method of the PrCu suspension solution is the same as that in Example 1. Then, the PrCu suspension solution is evenly coated on the surface of the 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 1145° C. for 6 hours. The sheet is cooled and removed from the furnace to obtain a samarium cobalt magnet diffusion sheet. The obtained samarium cobalt magnet diffusion sheet has a network-like Cu element segregation structure.

[0086] S6. First, prepare a SnFe suspension solution. The method for preparing the SnFe suspension solution is the same as that in Example 1. Then, evenly coat the SnFe suspension solution on the surface of the slice prepared in step S5 and blow dry. Finally, perform a secondary diffusion treatment on the coated samarium cobalt magnet slice in a tube furnace at a secondary diffusion treatment temperature of 870° C. for 3 hours. The slice is then cooled and taken out of the furnace to obtain a samarium cobalt magnet secondary diffusion slice.

[0087] S7. The samarium cobalt magnet secondary diffusion sheet obtained after the treatment in step S6 is subjected to aging treatment. The aging treatment process is as follows: heating the samarium cobalt magnet secondary diffusion sheet to 830° C., keeping the temperature for 3 hours, then cooling the temperature to 400° C. at a rate of 1.5° C. / min, keeping the temperature for 1 hour, and then rapidly cooling the temperature to room temperature to obtain an Fe-rich high coercive force samarium cobalt magnet.

[0088] The magnetic properties of the Fe-rich high coercivity samarium cobalt magnet prepared in Example 4 are as follows: remanence B r =11.68kGs, magnetic energy product (BH) m =32.41MGOe, intrinsic coercivity H cj =31.2kOe. Comparative Example 4

[0089] Comparative Example 4 does not adopt the S5 primary diffusion and S6 secondary diffusion processes in Example 4, and the other preparation processes are the same as those in Example 4.

[0090] A method for preparing a sintered samarium-cobalt permanent magnet comprises the following steps:

[0091] S1. First, weigh a samarium cobalt permanent magnet alloy raw material according to the following composition and its weight percentage: Sm: 24.5%, Fe: 20%, Zr: 3%, Cu: 4%, Co: 48.5%; then, melt the weighed samarium cobalt permanent magnet alloy raw material in a vacuum medium frequency induction melting furnace to produce an alloy ingot with a thickness of 10 mm;

[0092] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2.5 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 4 μm;

[0093] S3, weighing the alloy powder prepared in step S2 in an air atmosphere, then orienting and shaping it in a 2T magnetic field, and finally cold isostatically pressing it at a pressure of 200 MPa to obtain a green body;

[0094] S4. First, the green body obtained in step S3 is sintered at 1210° C. for 1.5 hours. Then, the sintered green body is furnace-cooled to 1170° C. for solution treatment, and the temperature is kept at this temperature for 6 hours. After the solution treatment, the green body is rapidly cooled to room temperature by air to obtain a solid solution state of samarium cobalt magnet. Finally, the solid solution state of samarium cobalt magnet is processed into a samarium cobalt magnet slice with a thickness of 5 mm using a slicer.

[0095] S5. The samarium cobalt magnet slices obtained after the treatment in step S4 are subjected to aging treatment. The aging treatment process is as follows: heating the samarium cobalt magnet slices to 830° C., keeping the temperature for 3 hours, then cooling the temperature to 400° C. at a rate of 1.5° C. / min, keeping the temperature for 1 hour, and then rapidly cooling the temperature to room temperature to obtain sintered samarium cobalt permanent magnets.

[0096] The magnetic properties of the sintered samarium cobalt permanent magnet prepared in this comparative example 4 are: remanence B r =11.52kGs, magnetic energy product (BH) m =31.59MGOe, intrinsic coercivity H cj =33.29kOe. Example 5

[0097] A diffusion preparation method for an Fe-rich high coercivity samarium-cobalt magnet comprises the following steps:

[0098] S1. First, weigh a samarium cobalt permanent magnet alloy raw material according to the following composition and its weight percentage: Sm: 22.5%, Gd: 2%, Fe: 19%, Zr: 2.8%, Cu: 5.5%, Co: 48.2%; then, melt the weighed samarium cobalt permanent magnet alloy raw material in a vacuum medium frequency induction melting furnace to produce an alloy ingot with a thickness of 10 mm;

[0099] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2.5 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 3.9 μm;

[0100] S3, weighing the alloy powder prepared in step S2 in an air atmosphere, then orienting and shaping it in a 2T magnetic field, and finally cold isostatically pressing it at a pressure of 200 MPa to obtain a green body;

[0101] 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 1175° C. for solution treatment, and the temperature is kept at this temperature for 5 hours. After the solution treatment, the green body is rapidly cooled to room temperature by air to obtain a solid solution state of samarium cobalt magnet. Finally, the solid solution state of samarium cobalt magnet is processed into a samarium cobalt magnet slice with a thickness of 5 mm using a slicer.

[0102] S5. First, prepare a PrCu suspension solution. The preparation method of the PrCu suspension solution is the same as that in Example 1. Then, the PrCu suspension solution is evenly coated on the surface of the 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 4 hours. The sheet is cooled and removed from the furnace to obtain a samarium cobalt magnet diffusion sheet. The obtained samarium cobalt magnet diffusion sheet has a network-like Cu element segregation structure.

[0103] S6. First, prepare a SnFe suspension solution. The method for preparing the SnFe suspension solution is the same as that in Example 1. Then, evenly coat the SnFe suspension solution on the surface of the slice prepared in step S5 and blow dry. Finally, perform a secondary diffusion treatment on the coated samarium cobalt magnet slice in a tube furnace at a secondary diffusion treatment temperature of 850° C. for 4 hours. The slice is then cooled and taken out of the furnace to obtain a samarium cobalt magnet secondary diffusion slice.

[0104] S7. The samarium cobalt magnet secondary diffusion sheet obtained after the treatment in step S6 is subjected to aging treatment. The aging treatment process is as follows: heating the samarium cobalt magnet secondary diffusion sheet to 830° C., keeping the temperature for 4 hours, then cooling the temperature to 400° C. at a rate of 1.5° C. / min, keeping the temperature for 1 hour, and then rapidly cooling the temperature to room temperature with air, thereby obtaining an Fe-rich high coercive force samarium cobalt magnet.

[0105] The magnetic properties of the Fe-rich high coercivity samarium cobalt magnet prepared in Example 5 are as follows: remanence B r =11.36kGs, magnetic energy product (BH) m =30.71MGOe, intrinsic coercive force H cj =35.25kOe. Comparative Example 5

[0106] Comparative Example 5 does not adopt the S5 primary diffusion and S6 secondary diffusion processes in Example 5, and the other preparation processes are the same as those in Example 5.

[0107] A method for preparing a sintered samarium-cobalt permanent magnet comprises the following steps:

[0108] S1. First, weigh a samarium cobalt permanent magnet alloy raw material according to the following composition and its weight percentage: Sm: 22.5%, Gd: 2%, Fe: 19%, Zr: 2.8%, Cu: 5.5%, Co: 48.2%; then, melt the weighed samarium cobalt permanent magnet alloy raw material in a vacuum medium frequency induction melting furnace to produce an alloy ingot with a thickness of 10 mm;

[0109] S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5 to 2.5 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 3.9 μm;

[0110] S3, weighing the alloy powder prepared in step S2 in an air atmosphere, then orienting and shaping it in a 2T magnetic field, and finally cold isostatically pressing it at a pressure of 200 MPa to obtain a green body;

[0111] 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 1175° C. for solution treatment, and the temperature is kept at this temperature for 5 hours. After the solution treatment, the green body is rapidly cooled to room temperature by air to obtain a solid solution state of samarium cobalt magnet. Finally, the solid solution state of samarium cobalt magnet is processed into a samarium cobalt magnet slice with a thickness of 5 mm using a slicer.

[0112] S5. The samarium cobalt magnet slices obtained after the treatment in step S4 are subjected to aging treatment. The aging treatment process is as follows: heating the samarium cobalt magnet slices to 830° C., keeping the temperature for 4 hours, then cooling the temperature to 400° C. at a rate of 1.5° C. / min, keeping the temperature for 1 hour, and then rapidly cooling the temperature to room temperature to obtain sintered samarium cobalt permanent magnets.

[0113] The magnetic properties of the sintered samarium cobalt permanent magnet prepared in Example 5 are as follows: remanence B r =11.22kGs, magnetic energy product (BH) m =29.95MGOe, intrinsic coercivity H cj =35.12kOe.

[0114] It can be seen that the present invention can prepare sintered samarium cobalt products in production through secondary diffusion technology to meet various commercial application needs, and has a short process flow, low energy consumption, good economic benefits, and broad application prospects.

[0115] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A diffusion preparation method for Fe-rich high coercivity samarium cobalt magnets, characterized in that: The following steps are involved: S1. First, weigh the samarium cobalt permanent magnet alloy raw materials according to the following composition and weight percentage: (Sm 1-x Re x ): 23% to 25.5%, Fe: 16% to 23%, Zr: 2.1% to 3%, Cu: 4% to 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; then, the weighed samarium-cobalt permanent magnet alloy raw material is melted in a vacuum medium-frequency induction melting furnace to obtain an alloy ingot with a thickness of 10 mm; S2. Mechanically crushing the alloy ingot prepared in step S1 into alloy particles with a particle size of 0.5-2.5 mm; then, using a jet milling method to prepare the alloy particles into an alloy powder with an average particle size of 3-5 μm; S3, weighing the alloy powder prepared in step S2 in an air atmosphere, then orienting and shaping it in a 2T magnetic field, and finally cold isostatically pressing it at a pressure of 200 MPa to obtain a green body; S4. First, the green body obtained in step S3 is sintered at a temperature of 1200-1215° C. for 1-2 hours. Then, the sintered green body is furnace-cooled to 1160-1180° C. for solution treatment, and the temperature is kept at this temperature for 4-10 hours. After the solution treatment, the green body is rapidly cooled to room temperature by air to obtain a solid solution state of samarium cobalt magnet. Finally, the solid solution state of samarium cobalt magnet is processed into samarium cobalt magnet slices using a slicer. S5. First, prepare a PrCu suspension solution; then, evenly coat the PrCu suspension solution on the surface of the samarium cobalt magnet sheet and blow dry; finally, perform a primary diffusion treatment on the coated samarium cobalt magnet sheet in a tube furnace at a primary diffusion treatment temperature of 1140-1150° C. for 4-8 hours, and cool the sheet out of the furnace to obtain a samarium cobalt magnet diffusion sheet; S6. First, prepare a SnFe suspension solution; then, evenly coat the SnFe suspension solution on the surface of the sheet prepared in step S5 and blow dry; finally, perform a secondary diffusion treatment on the coated samarium cobalt magnet sheet in a tube furnace at a secondary diffusion treatment temperature of 850-900° C. for 2-4 hours, and cool the sheet out of the furnace to obtain a samarium cobalt magnet secondary diffusion sheet; S7. The samarium cobalt magnet secondary diffusion sheet obtained after the treatment in step S6 is subjected to aging treatment. The aging treatment process is as follows: heating the samarium cobalt magnet secondary diffusion sheet to 800-850° C., keeping the temperature for 1-4 hours, then cooling the temperature to 400° C. at a rate of 1.5° C. / min, keeping the temperature for 1 hour, and then rapidly cooling the temperature to room temperature with air, thereby obtaining an Fe-rich high coercive force samarium cobalt magnet.

2. The diffusion preparation method of a Fe-rich high coercivity samarium-cobalt magnet according to claim 1, characterized in that: In step S4, the thickness of the samarium cobalt magnet sheet is 3-7 mm.

3. The diffusion preparation method of a Fe-rich high coercivity samarium-cobalt magnet according to claim 1, characterized in that: In step S5, the PrCu suspension solution is prepared by: 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 with anhydrous ethanol and stirred to obtain a PrCu suspension solution.

4. The diffusion preparation method of a Fe-rich high coercivity samarium-cobalt magnet according to claim 1 or 3, characterized in that: In step S5, the prepared samarium-cobalt magnet diffusion sheet has a network-like Cu element segregation structure.

5. The diffusion preparation method of a Fe-rich high coercivity samarium-cobalt magnet according to claim 1, characterized in that: In step S6, the SnFe suspension solution is prepared by: 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 SnFe alloy powder of 500-1000 nm by high-energy ball milling; finally, the SnFe alloy powder is mixed and stirred with anhydrous ethanol to obtain a SnFe suspension solution.

6. The diffusion preparation method of a Fe-rich high coercivity samarium-cobalt magnet according to claim 3 or 5, characterized in that: The PrCu alloy powder and the SnFe alloy powder were mixed with anhydrous ethanol in a mass ratio of 1:9.

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