A samarium cobalt permanent magnet and its preparation method

Abstract

The present invention belongs to the technical field of rare earth permanent magnet materials and relates to a samarium cobalt permanent magnet and a preparation method thereof. While maintaining good magnetic properties, the present invention significantly improves the toughness and impact resistance of the samarium cobalt permanent magnet by adding only 0.5-2% of Cu. Homogenization of the cast sheet at 1000-1100°C improves grain size and component segregation, making it easier to crush during the subsequent pulverizing process, ensuring the consistency of the crushed powder and further guaranteeing the excellent magnetic properties of the final samarium cobalt permanent magnet.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth permanent magnetic materials and relates to a samarium cobalt permanent magnet and a preparation method thereof. Background Art

[0002] Samarium cobalt (SmCo) possesses excellent permanent magnetic properties and is primarily used in aerospace and military applications. However, its development has been significantly limited by the high cost of raw materials, resource shortages, and the consumption of strategic cobalt. In recent years, SmCo permanent magnets have become irreplaceable in modern industrial aerospace due to their excellent temperature stability, good corrosion resistance, and high magnetic properties. However, current SmCo permanent magnets suffer from poor toughness, making them prone to cracking and chipping during processing. This significantly reduces the yield and precision of the magnets, increases processing costs, and limits their application in the high-precision instrumentation industry.

[0003] Therefore, as the magnetic properties of samarium cobalt permanent magnet materials continue to improve, shortcomings such as poor plasticity and toughness, difficulty in machining, and poor resistance to impact and vibration have become the fatal weaknesses of rare earth permanent magnet materials. Summary of the Invention

[0004] The purpose of the present invention is to address the above problems existing in the prior art and to provide a samarium cobalt permanent magnet with strong toughness and good magnetic properties.

[0005] The object of the present invention can be achieved through the following technical solutions: a samarium cobalt permanent magnet, which comprises the following raw materials in mass percentage: 28-35% Sm, 0.5-2% Cu, and 63-71% Co.

[0006] Preferably, the samarium cobalt permanent magnet comprises the following raw materials in the following mass percentages: 30% Sm, 0.8% Cu, and 69.2% Co.

[0007] The present invention also provides a method for preparing a samarium cobalt permanent magnet, which comprises the following steps: batching, smelting, homogenizing the casting, powdering, orientation molding, sintering, and aging, wherein the casting homogenizing temperature is 1000-1100° C. and the time is 10-15 hours.

[0008] The invention increases the Sm content in the samarium cobalt permanent magnet to 30% to improve the high-temperature performance of the magnet, adjusts the microstructure of the samarium cobalt permanent magnet by adding only a trace amount of Cu (0.8%) to improve the mechanical properties of the material, and achieves the purpose of significantly improving the toughness and impact resistance of the permanent magnet while ensuring good magnetic properties of the samarium cobalt permanent magnet by coordinating a homogenization process.

[0009] In the above-mentioned method for preparing samarium cobalt permanent magnets, the powder making process is as follows: firstly, the easily breakable uniform samarium cobalt casting sheet is crushed into coarse powder, and then the coarse powder is ground into fine powder, wherein the particle size of the fine powder is 4-5 μm.

[0010] In the above-mentioned method for preparing a samarium cobalt permanent magnet, the orientation molding is specifically as follows: pre-orientation is performed in a magnetic field with an intensity of 2-3T, followed by adding a momentary pulse magnetic field with an intensity of 4T for complete orientation, followed by molding at a pressure of 3-4MPa, and finally isostatic pressing at 200-230MPa to obtain a blank.

[0011] In the above-mentioned method for preparing a samarium cobalt permanent magnet, the blank is heated to 900-1100° C. under vacuum, then filled with argon gas, and sintered at 1100-1200° C. for 2-8 hours.

[0012] In the above-mentioned method for preparing a samarium cobalt permanent magnet, the cooling is specifically as follows: firstly, the temperature is lowered to 700-900°C at a rate of 1-2°C / min, kept at that temperature for 1-3 hours, and finally, oil-cooled to room temperature.

[0013] Compared with the prior art, the present invention has the following beneficial effects: while ensuring good magnetic properties of the samarium cobalt permanent magnet, the present invention only adds 0.5-2% of Cu, thereby significantly improving the toughness and impact resistance of the samarium cobalt permanent magnet; after the casting sheet is homogenized at 1000-1100°C, the grain size and component segregation are improved, and the casting sheet is easier to crush in the subsequent powder making process, thereby ensuring the consistency of the powder particles after crushing, and further ensuring the excellent magnetic properties of the final samarium cobalt permanent magnet. DETAILED DESCRIPTION

[0014] The following are specific embodiments of the present invention, which further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0015] Example 1:

[0016] S1. Prepare raw materials according to the following mass percentages: 30% Sm, 0.8% Cu, and the balance Co.

[0017] S2. The raw materials are melted in a vacuum rapid solidification belt furnace at a melting temperature of 1500°C, then kept warm and refined for 10 minutes, and then cast and rapidly cooled to obtain a cast sheet.

[0018] S3, homogenizing the slab at 1000°C for 15h;

[0019] S4. First, crush the easily breakable uniform samarium cobalt flakes into coarse powder, and then grind the coarse powder into fine powder, the average particle size of the fine powder is 5μm.

[0020] S5. Pre-orientation is carried out in a magnetic field with an intensity of 3 T, and then a momentary pulse magnetic field with an intensity of 4 T is added for complete orientation, and then molding is carried out under a pressure of 3 MPa, and finally isostatic pressing is carried out at 210 MPa to obtain a blank.

[0021] S6. Heat the blank to 1000℃ at a heating rate of 3℃ / min under vacuum, then fill it with argon and continue heating it, and sinter it at 1150℃ for 4h.

[0022] S7. Reduce the temperature to 800°C at a rate of 2°C / min, then keep it at that temperature for 2 hours, and finally oil-cool to room temperature to obtain a samarium cobalt permanent magnet.

[0023] Example 2:

[0024] S1. Prepare raw materials according to the following mass percentages: 28% Sm, 0.5% Cu, and the balance Co.

[0025] S2. The raw materials are melted in a vacuum rapid solidification belt furnace at a melting temperature of 1500°C, then kept warm and refined for 10 minutes, and then cast and rapidly cooled to obtain a cast sheet.

[0026] S3, homogenizing the slab at 1000°C for 10 hours;

[0027] S4. First, crush the easily breakable uniform samarium cobalt flakes into coarse powder, and then grind the coarse powder into fine powder, the average particle size of the fine powder is 4μm.

[0028] S5. Pre-orientation is carried out in a magnetic field with an intensity of 2T, and then a momentary pulse magnetic field with an intensity of 4T is added for complete orientation, followed by molding at a pressure of 3MPa, and finally isostatic pressing is performed at 200MPa to obtain a blank.

[0029] S6. Heat the blank to 900°C at a heating rate of 3°C / min under vacuum, then fill it with argon and continue heating it, and sinter it at 1100°C for 2 hours.

[0030] S7. Reduce the temperature to 800℃ at a rate of 1℃ / min, then keep it at that temperature for 1h, and finally oil cool to room temperature to obtain the samarium cobalt permanent magnet.

[0031] Example 3:

[0032] S1. Prepare raw materials according to the following mass percentages: 35% Sm, 2.0% Cu, and the balance Co.

[0033] S2. The raw materials are melted in a vacuum rapid solidification belt furnace at a melting temperature of 1500°C, then kept warm and refined for 10 minutes, and then cast and rapidly cooled to obtain a cast sheet.

[0034] S3, homogenizing the slab at 1100°C for 15h;

[0035] S4. First, crush the easily breakable uniform samarium cobalt flakes into coarse powder, and then grind the coarse powder into fine powder, the average particle size of the fine powder is 5μm.

[0036] S5. Pre-orientation is carried out in a magnetic field with an intensity of 3 T, and then a momentary pulse magnetic field with an intensity of 4 T is added for complete orientation, and then molding is carried out under a pressure of 4 MPa, and finally isostatic pressing is carried out at 230 MPa to obtain a blank.

[0037] S6. Heat the blank to 1100°C at a heating rate of 3°C / min under vacuum, then fill it with argon and continue heating it, and sinter it at 1200°C for 8 hours.

[0038] S7. Reduce the temperature to 900°C at a rate of 2°C / min, then keep it at that temperature for 3 hours, and finally oil-cool to room temperature to obtain a samarium cobalt permanent magnet.

[0039] Example 4:

[0040] The only difference from Example 1 is that the homogenization treatment temperature is 900°C.

[0041] Example 5:

[0042] The only difference from Example 1 is that the homogenization treatment temperature is 1200°C.

[0043] Example 6:

[0044] The only difference from Example 1 is that no homogenization treatment is performed.

[0045] Comparative Example 1:

[0046] The only difference from Example 1 is that no Cu element is added to the samarium cobalt permanent magnet raw material.

[0047] Comparative Example 2:

[0048] The only difference from Example 1 is that the Cu content in the samarium cobalt permanent magnet raw material is 5%.

[0049] Table 1: Performance test results of samarium cobalt permanent magnets of Examples 1-6 and Comparative Examples 1-2

[0050]

[0051] From the above results, it can be seen that the present invention significantly improves the toughness and impact resistance of the samarium cobalt permanent magnet by adding only a trace amount of Cu element while ensuring the good magnetic properties of the samarium cobalt permanent magnet; the cast sheet of the present invention improves the grain size and component segregation after homogenization at 1000-1100°C, is easier to crush in the subsequent powder making process, ensures the consistency of the powder particles after crushing, and further ensures the excellent magnetic properties of the final samarium cobalt permanent magnet.

[0052] The parts of the embodiment herein that are not exhaustive of the midpoint values ​​of the technical scope claimed for protection by the present invention and the new technical solutions formed by equivalent replacement of single or multiple technical features in the technical solutions of the embodiments are also within the scope claimed for protection by the present invention; at the same time, in all the embodiments listed or not listed in the solutions of the present invention, each parameter in the same embodiment merely represents an example of its technical solution (i.e., a feasible solution), and there is no strict coordination and limitation relationship between the parameters, wherein the parameters can be replaced with each other without violating the axioms and the claims of the present invention, unless otherwise stated.

[0053] The technical means disclosed in the solutions of the present invention are not limited to the technical means disclosed in the above technical means, but also include technical solutions composed of any combination of the above technical features. The above is a specific embodiment of the present invention. It should be noted that for those skilled in the art, various improvements and modifications can be made without departing from the principles of the present invention, and such improvements and modifications are also considered to be within the scope of protection of the present invention.

[0054] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A samarium cobalt permanent magnet, characterized in that: The samarium cobalt permanent magnet is made of the following raw materials by mass percentage: 30% Sm, 0.8% Cu, and 69.2% Co; The preparation method of the samarium cobalt permanent magnet comprises the following steps: S1. The raw materials are melted in a vacuum rapid solidification belt furnace at a melting temperature of 1500°C, then kept warm and refined for 10 minutes, and then cast and rapidly cooled to obtain a cast sheet; S2, homogenizing the slab at 1000°C for 15h; S3, first crushing the easily broken uniform samarium cobalt flakes into coarse powder, and then grinding the coarse powder into fine powder, the average particle size of the fine powder is 5 μm; S4, pre-orienting in a magnetic field with an intensity of 3T, then adding a momentary pulse magnetic field with an intensity of 4T for complete orientation, then forming at a pressure of 3MPa, and finally isostatic pressing at 210MPa to obtain a blank; S5. Raise the temperature of the blank to 1000°C at a heating rate of 3°C / min under vacuum, then fill with argon and continue to raise the temperature, and sinter at 1150°C for 4 hours; S6. Reduce the temperature to 800°C at a rate of 2°C / min, then keep it at that temperature for 2 hours, and finally oil-cool to room temperature to obtain a samarium cobalt permanent magnet.

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