Samarium cobalt permanent magnet and preparation method thereof

Abstract

The invention relates to a samarium-cobalt permanent magnet and a preparation method thereof, the preparation method comprises the steps of powder preparation, forming and heat treatment, in the step of powder preparation, coarse powder of samarium-cobalt alloy and inorganic materials are mixed and then subjected to jet milling treatment to obtain fine powder, the inorganic materials comprise fluorides and oxides, the addition amount of the fluorides is MF and # imgabs0 # of the mass of the coarse powder, k1 is equal to 0.1-2, and k2 is equal to 0.1-2; p is the pressure of the jet mill, v is the rotating speed of the jet mill, R is a numerical value obtained by multiplying the sum of the mass fractions of Fe and Co in the samarium-cobalt alloy by 100, d is the particle size of fluoride, the addition amount of the oxide is MO, # imgabs 1 # and k2 of the mass of the coarse powder, and the addition amount of the inorganic material is 1.5-10 wt% of the mass of the coarse powder. According to the invention, the microstructure of the magnet can be optimized by regulating and controlling the addition mode and the addition proportion of the fluoride and the oxide, so that the resistivity and the mechanical property of the samarium-cobalt permanent magnet can be improved on the basis of not sacrificing the magnetic property of the samarium-cobalt permanent magnet.

Description

Technical Field

[0001] The present invention relates to the technical field of permanent magnet materials, and particularly to a samarium cobalt permanent magnet and a preparation method thereof. Background Art

[0002] Due to the relatively low resistivity of samarium cobalt permanent magnets, in an alternating magnetic field working environment, circular induced currents (i.e., eddy currents) will be generated inside the magnet due to electromagnetic induction, causing the energy inside the magnet to continuously convert into heat energy, resulting in increased energy loss. At the same time, the continuously released heat will also cause the demagnetization of the magnet itself, thus greatly shortening the service life of the magnet and even causing incalculable economic losses. Currently, the general method to increase the resistivity of samarium cobalt permanent magnets is to add inorganic materials with high resistivity, such as fluorides, oxides, nitrides, sulfides, etc. among which the inertness between fluorides and rare earth permanent magnet materials is the best and the effect is better.

[0003] In addition, the poor mechanical properties of samarium cobalt permanent magnets are also the key problems restricting their application capabilities. It not only makes the magnet prone to cracking and chipping during the processing, greatly reducing the yield and processing accuracy of the magnet and increasing the processing cost of the magnet, but also makes its performance in terms of earthquake resistance and shock resistance relatively poor. Currently, the main method to improve the mechanical properties of samarium cobalt permanent magnets is to refine the magnet grains by adding high melting point oxides.

[0004] However, a large number of studies have shown that although the mechanical properties or resistivity of samarium cobalt permanent magnets can be improved by the above methods, the magnetic properties of samarium cobalt permanent magnets will be sacrificed. Summary of the Invention

[0005] Based on this, in view of the above problems, it is necessary to provide a samarium cobalt permanent magnet and a preparation method thereof, and the preparation method can improve its resistivity and mechanical properties without sacrificing the magnetic properties of the samarium cobalt permanent magnet.

[0006] A preparation method of a samarium cobalt permanent magnet includes powder making, shaping and heat treatment. In the step of powder making, the coarse powder of samarium cobalt alloy is mixed with inorganic materials and then subjected to jet milling treatment to obtain fine powder. Among them, the inorganic materials include fluorides and oxides, and the addition amount of the fluoride is M of the mass of the coarse powder F , , where k 1 = 0.1 - 2, P is the pressure of the jet mill, v is the rotation speed of the jet mill, R is the value obtained by multiplying the total mass fraction of Fe and Co in the samarium cobalt alloy by 100, d is the particle size of the fluoride, and the addition amount of the oxide is M of the mass of the coarse powder O , , where k 2= 0.15 - 0.5, and the addition amount of the inorganic material is 1.5 wt% - 10 wt% of the mass of the coarse powder.

[0007] In one embodiment, the preparation method satisfies the following conditions:

[0008] (1) During the air jet mill treatment, the pressure P = 400 MPa - 650 MPa, and the rotational speed v = 2800 rpm - 4500 rpm;

[0009] (2) The total mass fraction of Fe and Co in the samarium cobalt alloy is 40% - 70%;

[0010] (3) The particle size d of the fluoride is 0.5 μm - 2 μm.

[0011] In one embodiment, the total mass fraction of Fe and Co in the samarium cobalt alloy is 50% - 60%.

[0012] In one embodiment, by mass fraction, the composition components of the samarium cobalt alloy include 22% - 35% of samarium, 30% - 60% of cobalt, 13% - 30% of iron, 3% - 10% of copper, and 1.5% - 8% of zirconium.

[0013] In one embodiment, the particle size of the oxide is 0.5 μm - 2 μm.

[0014] In one embodiment, the fluoride is selected from at least one of calcium fluoride, magnesium fluoride, samarium fluoride, cobalt fluoride, iron fluoride, barium fluoride; and / or, the oxide is selected from at least one of samarium oxide, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide.

[0015] In one embodiment, the particle size of the coarse powder is 0.1 mm - 2 mm, and the particle size of the fine powder is 3 μm - 5 μm.

[0016] In one embodiment, the forming step includes: orienting and forming the fine powder under a magnetic field strength of 1.5 T - 2 T, and then performing cold isostatic pressing in a fluid of 200 MPa - 300 MPa.

[0017] In one embodiment, the heat treatment step includes: sintering at 1180 °C - 1250 °C for 30 min - 120 min in an inert atmosphere, then performing solution treatment at 1130 °C - 1190 °C for 2 h - 48 h, cooling to room temperature, then performing isothermal aging treatment at 750 °C - 850 °C for 2 h - 30 h, then cooling to 380 °C - 420 °C at a rate of 0.5 °C / min - 1.5 °C / min and holding for 1 h - 20 h, and finally cooling to room temperature.

[0018] A samarium-cobalt permanent magnet obtained by the described preparation method.

[0019] In the present invention, by combining the process parameters of the jet mill and the mass fractions of Fe and Co in the samarium-cobalt alloy, the addition ratio of fluoride and oxide is regulated. At the same time, by regulating the addition methods of fluoride and oxide, the fluoride, oxide and coarse powder are mixed and jointly subjected to the jet mill to optimize the particle size matching between the fluoride, oxide and fine powder, and effectively promote the uniform distribution of fluoride and oxide in the magnet. Furthermore, the microstructure of the magnet can be optimized, so as to improve its resistivity and mechanical properties without sacrificing the magnetic properties of the samarium-cobalt permanent magnet. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is the scanning electron microscope (SEM) image of the samarium-cobalt permanent magnet in Example 1;

[0022] Figure 2 It is the scanning electron microscope (SEM) image of the samarium-cobalt permanent magnet in Comparative Example 1;

[0023] Figure 3 It is the optical photo of the mixture of coarse powder and inorganic material in Comparative Example 4;

[0024] Figure 4 It is the scanning electron microscope (SEM) image of the samarium-cobalt permanent magnet in Comparative Example 4. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] For the convenience of understanding the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing specific embodiments or examples only and are not intended to limit the present invention. The optional range of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of the related listed items. The any and all combinations include any two related listed items, any more related listed items, or the combination of all related listed items.

[0027] In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0028] The steps for preparing samarium-cobalt permanent magnets by powder metallurgy mainly include powder making, shaping, and heat treatment. Specifically, first, raw materials are configured according to the formula of samarium-cobalt alloy and melted into an alloy ingot under vacuum. The alloy ingot is coarsely crushed to obtain coarse powder, and the coarse powder is processed by a jet mill to obtain fine powder. Then, the fine powder is placed in a mold for magnetic pressing to form a shape, and cold isostatic pressing is carried out to obtain an alloy blank. Then, the alloy blank is sintered, solution-treated, and aged to obtain a samarium-cobalt permanent magnet.

[0029] In samarium-cobalt permanent magnets, adding fluoride and oxide can both increase the resistivity of samarium-cobalt permanent magnets. At the same time, adding oxide can significantly reduce the grain size of the magnet, achieve fine grain strengthening, and improve the mechanical properties of the magnet. However, while fluoride increases the coercivity, it causes a decrease in remanence and magnetic energy product. On the contrary, oxide basically does not deteriorate the remanence and magnetic energy product of the magnet, but it will reduce the coercivity.

[0030] In view of this, in the method for preparing a samarium-cobalt permanent magnet of the present invention, during the powder-making step, the coarse powder of the samarium-cobalt alloy is mixed with an inorganic material and then processed by a jet mill to obtain fine powder. Among them, the inorganic material includes fluoride and oxide, and the addition amount of the fluoride is M of the mass of the coarse powder F , , where k 1= 0.1 - 2, where P is the pressure of the jet mill, v is the rotational speed of the jet mill, R is the value obtained by multiplying the total mass fraction of Fe and Co in the samarium cobalt alloy by 100, d is the particle size of the fluoride. It can be understood that when calculating, the corresponding values of P, v, and d can be taken directly without considering the units. The addition amount of the oxide is M of the mass of the coarse powder O , , where k 2 = 0.15 - 0.5, and the addition amount of the inorganic material is 1.5 wt% - 10 wt% of the mass of the coarse powder.

[0031] Thus, by combining the process parameters of the jet mill and the mass fractions of Fe and Co in the samarium cobalt alloy, the addition ratios of the fluoride and the oxide are regulated. At the same time, by regulating the addition methods of the fluoride and the oxide, the fluoride, the oxide, and the coarse powder are mixed and jointly subjected to jet milling, optimizing the particle size matching between the fluoride, the oxide, and the fine powder, and effectively promoting the uniform distribution of the fluoride and the oxide in the magnet. Furthermore, the microstructure of the magnet can be optimized, so as to improve its resistivity and mechanical properties without sacrificing the magnetic properties of the samarium cobalt permanent magnet.

[0032] In addition, the method of adding the inorganic material to the coarse powder in the present invention can significantly improve the powder-making efficiency of the jet mill and improve the particle size distribution. Therefore, lubricants such as zinc stearate, aluminum stearate, and gasoline added in the conventional process can be cancelled, which can not only reduce the cost and improve the production efficiency, but also avoid the introduction of defects and harmful substances such as pores, oxidation, and carbonization caused by the decomposition of the lubricant during the sintering process.

[0033] Optionally, the fluoride is selected from at least one of calcium fluoride, magnesium fluoride, samarium fluoride, cobalt fluoride, iron fluoride, and barium fluoride, and the oxide is selected from at least one of samarium oxide, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, and magnesium oxide.

[0034] In the preparation method of the present invention, during the jet milling treatment, preferably the pressure P = 400 MPa - 650 MPa, the rotational speed v = 2800 rpm - 4500 rpm. The total mass fraction of Fe and Co in the samarium cobalt alloy is preferably 40% - 70%, more preferably 50% - 60%. The particle size d of the fluoride is preferably 0.5 μm - 2 μm, and the particle size of the oxide is preferably 0.5 μm - 2 μm.

[0035] Among them, taking the pressure P = 500 MPa, the rotational speed v = 3000 rpm, the total mass fraction of Fe and Co in the samarium cobalt alloy being 50%, and the particle size d of the fluoride being 1 μm as an example, .

[0036] The preparation method of the samarium cobalt permanent magnet of the present invention is suitable for 1:5 type (SmCo 5)Samarium Cobalt Permanent Magnet and 2:17 Type (Sm 2 Co 17 )Preparation of Samarium Cobalt Permanent Magnet. Preferably, by mass fraction, the composition components of the samarium cobalt alloy include 22% - 35% of samarium, 30% - 60% of cobalt, 13% - 30% of iron, 3% - 10% of copper, and 1.5% - 8% of zirconium.

[0037] Optionally, the particle size of the coarse powder obtained by coarse crushing of the samarium cobalt alloy ingot is 0.1 mm - 2 mm. After jet milling treatment, the particle size of the fine powder is 3 μm - 5 μm. It should be noted that the fine powder refers to the samarium cobalt alloy fine powder.

[0038] In the forming step of the present invention, preferably, the fine powder is oriented and formed under a magnetic field strength of 1.5 T - 2 T, and then cold isostatically pressed in a fluid of 200 MPa - 300 MPa. In the heat treatment step, preferably, it is sintered at 1180°C - 1250°C for 30 min - 120 min in an inert atmosphere, then solution-treated at 1130°C - 1190°C for 2 h - 48 h, cooled to room temperature, then isothermally aged at 750°C - 850°C for 2 h - 30 h, then cooled to 380°C - 420°C at a rate of 0.5°C / min - 1.5°C / min and held for 1 h - 20 h, and finally cooled to room temperature. Thus, by optimizing the forming and / or heat treatment conditions, the microstructure of the magnet can be further optimized.

[0039] The present invention also provides a samarium cobalt permanent magnet obtained by the described preparation method. The samarium cobalt permanent magnet simultaneously has excellent resistivity, mechanical properties, and magnetic properties, and can be better applied to military equipment, nuclear magnetic energy, high-temperature motors, aerospace and other fields.

[0040] Hereinafter, the samarium cobalt permanent magnet and its preparation method will be further described through the following specific examples.

[0041] Example 1

[0042] By mass fraction, weigh 29% of Sm, 43% of Co, 13% of Fe, 9% of Cu, and 6% of Zr, and then carry out vacuum induction melting to obtain a samarium cobalt alloy ingot.

[0043] Crush the above samarium cobalt alloy ingot into coarse powder with an average particle size of 0.18 mm.

[0044] Mix the above coarse powder of samarium cobalt alloy with inorganic materials in a mixer for 2 h and then carry out jet milling treatment to obtain fine powder with an average particle size of 4.2 μm. Among them, the inorganic materials include CaF with a particle size d of 1 μm 2 and Sm with a particle size of 1.2 μm 2 O 3, the pressure P during the airflow milling process is 600 MPa, the rotational speed v is 3200 rpm, and k 1 takes 0.2. According to the calculated M F is 2.1%, and k 2 takes 0.3. According to the calculated M O is 0.63%.

[0045] The fine powder obtained above is filled into a mold, oriented and formed under a magnetic field intensity of 2 T, and then cold isostatically pressed in a fluid of 200 MPa to obtain an alloy blank.

[0046] The alloy blank obtained above is sintered at 1210 °C for 120 min in an inert atmosphere, then solution-treated at 1180 °C for 3 h, cooled to room temperature, then isothermally aged at 850 °C for 5 h, and then cooled to 400 °C at a rate of 0.7 °C / min and held for 8 h, and then cooled to room temperature to obtain a samarium-cobalt permanent magnet.

[0047] The microstructure of the samarium-cobalt permanent magnet obtained in this example is characterized. As Figure 1 shown, the distribution of additives inside the magnet is uniform.

[0048] Example 2

[0049] The difference between Example 2 and Example 1 is only that k 1 takes 0.5, and the calculated M F is 5.25%, and k 2 takes 0.4, and the calculated M O is 2.1%.

[0050] Example 3

[0051] The difference between Example 3 and Example 1 is only that k 1 takes 0.8, and the calculated M F is 8.4%, and k 2 takes 0.15, and the calculated M O is 1.26%.

[0052] Example 4

[0053] By mass fraction, 32% of Sm, 40% of Co, 15% of Fe, 8% of Cu, and 5% of Zr are weighed, and then vacuum induction melting is carried out to obtain a samarium-cobalt alloy ingot.

[0054] The above samarium-cobalt alloy ingot is crushed into coarse powder with an average particle size of 0.35 mm.

[0055] The above-mentioned coarse powder of samarium cobalt alloy and inorganic materials are mixed in a mixer for 2 h and then subjected to jet milling to obtain fine powder with an average particle size of 3.8 μm. Among them, the inorganic materials include MgF with a particle size d of 0.8 μm 2 and Al with a particle size of 1.1 μm 2 O 3 . When performing jet milling, the pressure P is 650 MPa, the rotation speed v is 3800 rpm, k 1 is taken as 0.15. According to the calculated M F is 1.13%. k 2 is taken as 0.3. According to the calculated M O is 0.34%.

[0056] The above-mentioned obtained fine powder is loaded into a mold, oriented and formed under a magnetic field strength of 1.8 T, and then cold isostatically pressed in a fluid of 250 MPa to obtain an alloy blank.

[0057] The above-mentioned obtained alloy blank is sintered at 1206 °C for 120 min in an inert atmosphere, then solution-treated at 1180 °C for 2 h, cooled to room temperature, then isothermally aged at 810 °C for 6 h, then cooled to 400 °C at a rate of 0.5 °C / min and held for 10 h, and then cooled to room temperature to obtain a samarium cobalt permanent magnet.

[0058] Example 5

[0059] The difference between Example 5 and Example 4 is only that k 1 is taken as 0.5, and the calculated M F is 3.76%. k 2 is taken as 0.2, and the calculated M O is 0.75%.

[0060] Example 6

[0061] The difference between Example 6 and Example 4 is only that k 1 is taken as 1, and the calculated M F is 7.53%. k 2 is taken as 0.15, and the calculated M O is 1.13%.

[0062] Example 7

[0063] Weigh 27% of Sm, 43% of Co, 14% of Fe, 10% of Cu, and 6% of Zr by mass fraction, and then perform vacuum induction melting to obtain a samarium cobalt alloy ingot.

[0064] The above-mentioned samarium cobalt alloy ingot is crushed into coarse powder with an average particle size of 0.32 mm.

[0065] The coarse powder of the above samarium cobalt alloy and the inorganic material are mixed in a mixer for 2 h and then subjected to jet milling to obtain fine powder with an average particle size of 3.5 μm. Among them, the inorganic material includes BaF with a particle size d of 0.75 μm 2 and ZrO with a particle size of 0.83 μm 2 . During the jet milling process, the pressure P is 550 MPa, the rotation speed v is 4200 rpm, and k 1 is taken as 0.5. According to the calculated value of M F is 2.8%, and k 2 is taken as 0.3. According to the calculated value of M O is 0.84%.

[0066] The obtained fine powder is loaded into a mold, oriented and formed under a magnetic field intensity of 2 T, and then cold isostatically pressed in a fluid with a pressure of 300 MPa to obtain an alloy blank

[0067] The obtained alloy blank is sintered at 1210 °C for 120 min in an inert atmosphere, then solution-treated at 1180 °C for 3 h, cooled to room temperature, then isothermally aged at 830 °C for 5 h, then cooled to 400 °C at a rate of 0.7 °C / min and held for 10 h, and then cooled to room temperature to obtain a samarium cobalt permanent magnet

[0068] Example 8

[0069] The difference between Example 8 and Example 7 is only that k 1 is taken as 1, and the calculated value of M F is 5.6%, and k 2 is taken as 0.2, and the calculated value of M O is 1.12%.

[0070] Example 9

[0071] The difference between Example 9 and Example 7 is only that k 1 is taken as 0.2, and the calculated value of M F is 1.12%, and k 2 is taken as 0.5, and the calculated value of M O is 0.56%.

[0072] Comparative Example 1

[0073] The difference between Comparative Example 1 and Example 1 is only that CaF 2 and Sm 2 O 3 are not added

[0074] Comparative Example 2

[0075] The difference between Comparative Example 2 and Example 1 is only that k1 Take 1 and calculate to obtain M F is 10.5%, k 2 Take 0.2 and calculate to obtain M O is 2.1%.

[0076] Comparative Example 3

[0077] The difference between Comparative Example 3 and Example 1 is only that k 1 Take 0.1 and calculate to obtain M F is 1.05%, k 2 Take 0.2 and calculate to obtain M O is 0.21%.

[0078] Comparative Example 4

[0079] The difference between Comparative Example 4 and Example 1 is only that the addition amount of CaF 2 is 1 wt% of the coarse powder, and the addition amount of Sm 2 O 3 is 1.73 wt% of the coarse powder.

[0080] Comparative Example 5

[0081] The difference between Comparative Example 5 and Example 1 is only that the addition amount of CaF 2 is 0.5 wt% of the coarse powder, and the addition amount of Sm 2 O 3 is 2.23 wt% of the coarse powder.

[0082] Comparative Example 6

[0083] The difference between Comparative Example 6 and Example 1 is only that the addition amount of CaF 2 is 1.5 wt% of the coarse powder, and the addition amount of Sm 2 O 3 is 1.23 wt% of the coarse powder.

[0084] Comparative Example 7

[0085] The difference between Comparative Example 7 and Example 1 is only that the coarse powder is first prepared into fine powder with an average particle size of 4.2 μm by a jet mill, and then CaF 2 and Sm 2 O 3 are added for mixing. The mixed powder is as shown in Figure 3 where the white particles are the inorganic materials and are significantly agglomerated. Therefore, as shown in Figure 4 the obtained samarium cobalt permanent magnet in this comparative example has agglomeration and uneven distribution of the inorganic materials inside.

[0086] The magnetic properties, resistivity, and flexural strength of the samarium-cobalt permanent magnets in the above-mentioned examples and comparative examples were detected using a permanent magnet measuring instrument, the four-probe method, and a universal testing machine (three-point bending). The results are shown in Table 1.

[0087] Table 1

[0088]

[0089] Comparing the samarium-cobalt permanent magnets of Examples 1-3 with Comparative Example 1, it can be seen that there is no obvious change in the magnetic properties of the samarium-cobalt permanent magnets in Examples 1-3, while the resistivity has increased by 49.66%, 58.91%, and 65.31% respectively, and the mechanical properties have increased by 13.68%, 19.88%, and 18.07% respectively. In addition, comparing the samarium-cobalt permanent magnets of Examples 1-3 with Comparative Examples 2 and 3, it can be seen that too high an addition amount of inorganic materials will deteriorate the magnetic properties of the magnet, and too low an addition amount cannot effectively improve the resistivity and mechanical properties of the magnet; comparing the samarium-cobalt permanent magnets of Examples 1-3 with Comparative Examples 4-6, it can be seen that the ratio of fluoride to oxide is crucial for the magnetic properties, resistivity, and mechanical properties of the magnet. An inappropriate ratio not only cannot significantly improve the resistivity and mechanical properties of the magnet, but may also lead to a decrease in magnetic properties; comparing the samarium-cobalt permanent magnets of Examples 1-3 with Comparative Example 7, it can be seen that different addition methods of coarse powder and inorganic materials will cause agglomeration and uneven distribution of inorganic materials inside the magnet, thereby resulting in an insignificant optimization effect on the resistivity and magnetic properties of the magnet.

[0090] The technical features of the above-mentioned embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0091] The above-mentioned embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A method for preparing a samarium cobalt permanent magnet, comprising powder making, molding and heat treatment, characterized in that: In the powder making step, the coarse powder of samarium-cobalt alloy is mixed with inorganic materials and then subjected to jet milling to obtain fine powder, wherein the inorganic materials include fluoride and oxide, and the amount of fluoride added is M of the mass of the coarse powder. F , , where k1=0.1-2, P is the pressure of the jet mill, v is the speed of the jet mill, R is the value obtained by multiplying the sum of the mass fractions of Fe and Co in the samarium-cobalt alloy by 100, d is the particle size of the fluoride, and the addition amount of the oxide is M of the mass of the coarse powder. O , , wherein k2=0.15-0.5, and the amount of the inorganic material added is 1.5wt%-10wt% of the mass of the coarse powder.

2. The method for preparing a samarium cobalt permanent magnet according to claim 1, characterized in that: The preparation method meets the following conditions: (1) During the jet mill treatment, the pressure P = 400MPa-650MPa, the speed v = 2800rpm-4500rpm; (2) The total mass fraction of Fe and Co in the samarium-cobalt alloy is 40%-70%; (3) The particle size d of the fluoride is 0.5 μm-2 μm.

3. The method for preparing a samarium cobalt permanent magnet according to claim 2, characterized in that: The total mass fraction of Fe and Co in the samarium-cobalt alloy is 50%-60%.

4. The method for preparing a samarium cobalt permanent magnet according to claim 2, characterized in that: In terms of mass fraction, the samarium-cobalt alloy comprises 22%-35% samarium, 30%-60% cobalt, 13%-30% iron, 3%-10% copper and 1.5%-8% zirconium.

5. The method for preparing a samarium cobalt permanent magnet according to claim 1, characterized in that: The particle size of the oxide is 0.5 μm-2 μm.

6. The method for preparing a samarium cobalt permanent magnet according to claim 1, characterized in that: The fluoride is selected from at least one of calcium fluoride, magnesium fluoride, samarium fluoride, cobalt fluoride, iron fluoride and barium fluoride; and / or the oxide is selected from at least one of samarium oxide, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide and magnesium oxide.

7. The method for preparing a samarium cobalt permanent magnet according to claim 1, characterized in that: The particle size of the coarse powder is 0.1 mm-2 mm, and the particle size of the fine powder is 3 μm-5 μm.

8. The method for preparing a samarium cobalt permanent magnet according to claim 1, characterized in that: The molding step comprises: orienting and molding the fine powder under a magnetic field strength of 1.5T-2T, and then cold isostatic pressing in a fluid of 200MPa-300MPa.

9. The method for preparing a samarium cobalt permanent magnet according to claim 1, characterized in that: The heat treatment steps include: sintering at 1180°C-1250°C for 30min-120min under an inert atmosphere, then solution treating at 1130°C-1190°C for 2h-48h, cooling to room temperature, then isothermal aging treatment at 750°C-850°C for 2h-30h, then cooling to 380°C-420°C at a rate of 0.5°C / min-1.5°C / min and keeping warm for 1h-20h, and finally cooling to room temperature.

10. A samarium cobalt permanent magnet obtained by the preparation method according to any one of claims 1 to 9.

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