A samarium iron nitrogen-based anisotropic permanent magnetic material and its preparation method and application

Abstract

The present invention provides a samarium iron nitrogen based anisotropic permanent magnetic material and its preparation method and application. The chemical composition of the permanent magnetic material expressed by the molar ratio of elements is: Sm2(Fe 1‑x Co x ) 17 N y ; Wherein, 0.01≤x≤0.2, 2.0≤y≤4.0. The preparation method comprises: (1) weighing an Sm source, an Fe source, a Co source and metal Ca according to the molar ratio of the elements, and mixing them uniformly to obtain a mixture; (2) subjecting the obtained mixture to a reduction diffusion reaction to obtain an alloy; (3) subjecting the obtained alloy to coarse crushing, nitriding and fine crushing in sequence to obtain magnetic powder; (4) subjecting the obtained magnetic powder to granulation and injection molding in sequence to obtain a samarium iron nitrogen-based anisotropic permanent magnetic material. The samarium iron nitrogen-based permanent magnetic material provided by the present invention significantly reduces the absolute value of the temperature coefficient of coercivity, has good high-temperature stability, and has a simple preparation process and low production cost, which is conducive to large-scale promotion and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic materials and relates to a rare earth permanent magnet material, in particular to a samarium iron nitrogen-based anisotropic permanent magnet material and a preparation method and application thereof. Background Art

[0002] Currently, the permanent magnet material with the highest magnetic properties is rare earth NdFeB. Sintered NdFeB permanent magnets have a maximum magnetic energy product exceeding 56 MGOe, making them highly suitable for miniaturization and lightweighting. In recent years, they have been widely used in wind power generation, new energy vehicles, elevators, and other fields. However, NdFeB has the disadvantage of poor high-temperature resistance, which severely limits its application in high-temperature applications.

[0003] In contrast, Sm2FeN magnets avoid the shortcomings of NdFeB magnets such as low Curie temperature, easy oxidation, and high cost, and have become a research hotspot for the new generation of rare earth permanent magnet materials. 17 N x The compound is very easy to undergo irreversible decomposition when the temperature exceeds 550℃, so it is difficult to prepare dense magnets through traditional sintering process. 17 N x The compound is generally mixed with plastic binders such as PA6 and PA12 at 200-300°C to form granules, and then injection molded to finally produce injection-molded magnets.

[0004] When permanent magnet materials are used in products such as motor rotors, their performance degrades significantly as the motor's temperature gradually rises to around 100°C after a period of operation. The material's temperature coefficient of coercivity, denoted by β, is generally used to measure its temperature stability. Its calculation formula is: β = 100% * [Hcj(T) - Hcj(T0)] / [(T - T0) * Hcj(T0)], where Hcj(T) and Hcj(T0) are the coercivity at temperature T and reference temperature T0, respectively. Room temperature or 20°C is typically used as T0, while the value for high-temperature T needs to be determined by both the supplier and the user based on the application environment. A positive β value indicates an increase in coercivity with increasing temperature; a negative value indicates a decrease. Therefore, a smaller absolute value of β indicates a better material's temperature stability.

[0005] In general, Sm2Fe 17 N xThe coercive force temperature coefficient of compound magnets is about -0.5% / ℃, that is, from about 20℃, the coercive force decreases by 0.5% for every 1℃ increase in temperature. When the temperature rises to about 100℃, the coercive force decreases by about 40%, which will cause the motor to fail or even become dangerous. The coercive force is related to the motor's anti-demagnetization ability, that is, the overload multiple and the air gap flux density and other indicators. The larger the coercive force value, the stronger the motor's anti-demagnetization ability, the greater the overload multiple, the stronger the adaptability to the strong demagnetization dynamic working environment, and the air gap flux density of the motor will also be improved. Therefore, it is necessary to increase the Sm2Fe 17 N x The temperature stability of magnetic materials is crucial to promoting the application of samarium iron nitride permanent magnet materials.

[0006] CN107833726A discloses a Sm-Fe-N magnet material comprising: 7.0-12 atomic % of Sm; 0.1-1.5 atomic % of at least one element selected from the group consisting of Hf, Zr, and Sc; 0.1-0.5 atomic % of Mn; 10-20 atomic % of N; and 0-35 atomic % of Co, with the remainder being Fe and unavoidable impurities. The invention also relates to a Sm-Fe-N bonded magnet comprising powder of the Sm-Fe-N magnet material and a binder. The Sm-Fe-N magnet material and the Sm-Fe-N bonded magnet of the invention are isotropic and suitable for long-term use in high-temperature environments.

[0007] CN108630371A discloses a rare earth permanent magnet powder with high thermal stability, a preparation method thereof and a magnet containing the same. The composition of the rare earth permanent magnet material expressed in atomic percentage is: Sm x R a Fe 100-x-y-z-a M y N z , wherein R is at least one of Zr and Hf, M is at least one of Co, Ti, Cr, Nb, V, Mo, Ga, Mn, Si, Ni, and Al, x+a is 7-10%, a is 0-1.5%, y is 0-5%, and z is 10-14%. The rare earth permanent magnet material provided by the invention has excellent temperature resistance and corrosion resistance, facilitating further miniaturization of devices and facilitating their use in special environments.

[0008] However, the magnet materials disclosed in the above inventions are all isotropic and do not involve anisotropic samarium iron nitride permanent magnet materials, and the high temperature resistance of the magnets still has much room for improvement.

[0009] It can be seen from this that how to provide a samarium iron nitrogen-based anisotropic permanent magnet material with good high-temperature stability and a preparation method thereof, reduce the absolute value of the temperature coefficient of coercive force of the magnet as much as possible, and at the same time simplify the preparation process and reduce production costs has become an urgent problem that technical personnel in this field need to solve. Summary of the Invention

[0010] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a samarium iron nitrogen-based anisotropic permanent magnet material and its preparation method and application. The samarium iron nitrogen-based permanent magnet material significantly reduces the absolute value of the temperature coefficient of coercivity, has good high-temperature stability, and has a simple preparation process and low production cost, which is conducive to large-scale promotion and application.

[0011] To achieve this object, the present invention adopts the following technical solutions:

[0012] In a first aspect, the present invention provides a samarium iron nitrogen based anisotropic permanent magnet material, wherein the chemical composition of the samarium iron nitrogen based anisotropic permanent magnet material expressed by the molar ratio of elements is: Sm2(Fe 1-x Co x ) 17 N y ; Among them, 0.01≤x≤0.2, 2.0≤y≤4.0.

[0013] The present invention is to use the traditional samarium iron nitrogen magnet Sm2Fe 17 N x Doping metal Co in the magnet to replace part of Fe significantly improves the high-temperature stability of the magnet material, while maintaining a high coercive force and reducing the absolute value of the coercive force temperature coefficient as much as possible, thereby broadening the application field.

[0014] In the present invention, 0.01≤x≤0.2, for example, x=0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.12, 0.14, 0.16, 0.18 or 0.2, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] In the present invention, 2.0≤y≤4.0, for example, y can be 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8 or 4.0, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] In the present invention, the molar ratio x of the metallic Co element must be controlled within a reasonable range. When x < 0.01, the absolute value of the coercivity temperature coefficient of the magnetic material is similar to that of samarium iron nitride magnets, indicating no significant decrease. When x > 0.2, although the absolute value of the coercivity temperature coefficient decreases significantly, indicating good temperature stability, the coercivity of the magnetic material also decreases significantly, resulting in insufficient anti-demagnetization capability of the motor and low practical value.

[0017] Preferably, 0.1≤x≤0.15, for example, x=0.1, 0.105, 0.11, 0.115, 0.12, 0.125, 0.13, 0.135, 0.14, 0.145 or 0.15, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] In a second aspect, the present invention provides a method for preparing the samarium iron nitrogen-based anisotropic permanent magnetic material as described in the first aspect, the preparation method comprising the following steps:

[0019] (1) According to Sm2(Fe 1-x Co x ) 17 N y Sm source, Fe source, Co source and metal Ca are weighed and mixed uniformly to obtain a mixed material;

[0020] (2) The mixture obtained in step (1) is subjected to a reduction diffusion reaction to obtain Sm2(Fe 1-x Co x ) 17 alloy;

[0021] (3) The alloy obtained in step (2) is subjected to coarse crushing, nitriding and fine crushing in sequence to obtain Sm2(Fe 1-x Co x ) 17 N y Magnetic powder;

[0022] (4) The magnetic powder obtained in step (3) is granulated and injection molded in sequence to obtain a samarium iron nitrogen-based anisotropic permanent magnet material.

[0023] The present invention uses reduction diffusion reaction, nitridation and other treatment processes to finally produce samarium iron nitrogen-based anisotropic permanent magnetic materials with excellent performance. The preparation process is simple and efficient, the production cost is low, the repeatability is good, and it is easy to promote and apply on a large scale.

[0024] Preferably, the Sm source in step (1) includes Sm2O3.

[0025] Preferably, the Fe source in step (1) comprises Fe powder.

[0026] Preferably, the Co source in step (1) includes Co2O3.

[0027] Preferably, the Sm source in step (1) is in an excess of 1-50% based on the molar ratio of the element, for example, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] Preferably, the metal Ca in step (1) is in an excess of 1-50% based on the element molar ratio, for example, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45% or 50%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0029] Preferably, the mixing in step (1) is carried out in a powder mixer.

[0030] Preferably, the reduction diffusion reaction in step (2) is carried out in a sintering furnace in an inert gas atmosphere.

[0031] Preferably, the inert gas includes helium and / or argon.

[0032] Preferably, the temperature of the reduction diffusion reaction in step (2) is 900-1100°C, for example, it can be 900°C, 920°C, 940°C, 960°C, 980°C, 1000°C, 1020°C, 1040°C, 1060°C, 1080°C or 1100°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0033] Preferably, the time of the reduction diffusion reaction in step (2) is 0.1-24h, for example, it can be 0.1h, 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or 24h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] In the present invention, the reduction diffusion reaction in step (2) specifically includes the following three-step reaction process:

[0035] (A) Reaction between Sm2O3 and metallic Ca

[0036] Sm2O3+3Ca=2Sm+3CaO;

[0037] (B) Reaction between Co2O3 and metallic Ca

[0038] Co2O3+3Ca=2Co+3CaO;

[0039] (C) Reaction between Sm obtained in step (A), Co obtained in step (B) and Fe powder

[0040] 2Sm+17[(1-x)Fe+xCo]=Sm2(Fe 1-x Co x ) 17 ;

[0041] The above three steps of reaction are carried out simultaneously during the whole reduction diffusion reaction process, and finally form Sm2(Fe 1-x Co x ) 17 alloy.

[0042] Preferably, the coarse crushing in step (3) crushes the alloy into particles with an average particle size of 0.1-1 mm, for example, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1 mm, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0043] Preferably, the nitriding in step (3) is carried out in a nitriding furnace in an ammonia atmosphere.

[0044] Preferably, the temperature of the nitriding in step (3) is 520-545°C, for example, it can be 520°C, 522°C, 524°C, 526°C, 528°C, 530°C, 532°C, 534°C, 536°C, 538°C, 540°C, 542°C, 544°C or 545°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0045] Preferably, the nitriding time in step (3) is 1-24 h, for example, it can be 1 h, 2 h, 4 h, 6 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h, 20 h, 22 h or 24 h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] Preferably, the fine crushing in step (3) crushes the particles into magnetic powder with an average particle size of 1-5 μm, for example, it can be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0047] Preferably, the granulation in step (4) includes mixing magnetic powder and polyamide resin for granulation.

[0048] Preferably, the polyamide resin accounts for 5-20% of the mass of the magnetic powder, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0049] Preferably, the granulation temperature in step (4) is 180-230°C, for example, it can be 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C or 230°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0050] Preferably, the injection molding temperature in step (4) is 210-300°C, for example, it can be 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C or 300°C, but is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0051] As a preferred technical solution of the second aspect of the present invention, the preparation method comprises the following steps:

[0052] (1) According to Sm2(Fe 1-x Co x ) 17 N y Sm2O3, Fe powder, Co2O3 and metallic Ca are weighed in an element molar ratio of 1-50%, and Sm2O3 and metallic Ca are respectively excessively added. The mixture is uniformly mixed in a powder mixer to obtain a mixed material;

[0053] (2) The mixture obtained in step (1) is subjected to reduction diffusion reaction in a sintering furnace in an inert gas atmosphere at a temperature of 900-1100°C for 0.1-24h to obtain Sm2(Fe 1-x Co x ) 17 alloy; the inert gas comprises helium and / or argon;

[0054] (3) The alloy obtained in step (2) is subjected to coarse crushing, nitriding and fine crushing in sequence to obtain Sm2(Fe 1-x Co x ) 17 N y Magnetic powder; the coarse crushing crushes the alloy into particles with an average particle size of 0.1-1 mm; the nitriding is carried out in a nitriding furnace in an ammonia atmosphere at a temperature of 520-545°C for 1-24 hours; the fine crushing crushes the particles into magnetic powder with an average particle size of 1-5 μm;

[0055] (4) The magnetic powder obtained in step (3) is sequentially subjected to granulation at 180-230° C. and injection molding at 210-300° C. to obtain a samarium iron nitrogen-based anisotropic permanent magnetic material; the granulation comprises granulating a mixture of the magnetic powder and a polyamide resin, and the polyamide resin accounts for 5-20% of the mass of the magnetic powder.

[0056] In a third aspect, the present invention provides an application of the samarium iron nitrogen-based anisotropic permanent magnet material as described in the first aspect, wherein the application includes use in preparing parts for wind power generation, new energy vehicles or elevators.

[0057] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] (1) The present invention is to use a conventional samarium iron nitrogen magnet Sm2Fe 17 N x Doping metal Co to replace part of Fe significantly improves the high-temperature stability of the magnet material. While maintaining a high coercive force, the absolute value of the coercive force temperature coefficient is reduced as much as possible, and the absolute value can be as low as 0.383, thereby broadening the application field.

[0060] (2) The present invention finally produces an anisotropic samarium iron nitrogen-based permanent magnet material with excellent performance through reduction diffusion reaction, nitridation and other treatment processes. The preparation process is simple and efficient, the production cost is low, the repeatability is good, and it is easy to promote and apply on a large scale. DETAILED DESCRIPTION

[0061] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0062] Example 1

[0063] This embodiment provides a samarium iron nitrogen based anisotropic permanent magnet material and a preparation method thereof. The chemical composition of the samarium iron nitrogen based anisotropic permanent magnet material expressed by the molar ratio of elements is: Sm2(Fe 0.99 Co 0.01 ) 17 N3; The preparation method comprises the following steps:

[0064] (1) According to Sm2(Fe 0.99 Co 0.01 ) 17 Sm2O3, Fe powder, Co2O3 and metallic Ca are weighed in an element molar ratio of 10%, and Sm2O3 and metallic Ca are respectively in an excess of 10%, and mixed uniformly in a powder mixer to obtain a mixed material;

[0065] (2) The mixture obtained in step (1) was subjected to reduction diffusion reaction in a sintering furnace in an argon atmosphere at a temperature of 950°C for 12 hours to obtain Sm2(Fe 0.99 Co 0.01 ) 17 alloy;

[0066] (3) The alloy obtained in step (2) is subjected to coarse crushing, nitriding and fine crushing in sequence to obtain Sm2(Fe 0.99 Co 0.01 ) 17 N3 magnetic powder; the coarse crushing crushes the alloy into particles with an average particle size of 0.5 mm; the nitriding is carried out in a nitriding furnace in an ammonia atmosphere at a temperature of 530°C for 10 hours; the fine crushing crushes the particles into magnetic powder with an average particle size of 2.5 μm;

[0067] (4) The magnetic powder obtained in step (3) is subjected to granulation at 200° C. and injection molding at 260° C. in sequence to obtain a samarium iron nitrogen-based anisotropic permanent magnetic material; the granulation comprises granulating the mixed magnetic powder and polyamide resin, and the polyamide resin accounts for 8% of the mass of the magnetic powder.

[0068] Example 2

[0069] This embodiment provides a samarium iron nitrogen based anisotropic permanent magnet material and a preparation method thereof. The chemical composition of the samarium iron nitrogen based anisotropic permanent magnet material expressed by the molar ratio of elements is: Sm2(Fe 0.99 Co 0.01 ) 17 N3; The preparation method comprises the following steps:

[0070] (1) According to Sm2(Fe 0.99 Co 0.01 ) 17 Sm2O3, Fe powder, Co2O3 and metallic Ca are weighed in an element molar ratio of 50%, and Sm2O3 and metallic Ca are respectively in excess of 50%, and mixed uniformly in a powder mixer to obtain a mixed material;

[0071] (2) The mixture obtained in step (1) was subjected to reduction diffusion reaction in a sintering furnace in a helium atmosphere at a temperature of 900°C for 24 hours to obtain Sm2(Fe 0.99 Co 0.01 ) 17 alloy;

[0072] (3) The alloy obtained in step (2) is subjected to coarse crushing, nitriding and fine crushing in sequence to obtain Sm2(Fe 0.99 Co 0.01 ) 17N3 magnetic powder; the coarse crushing crushes the alloy into particles with an average particle size of 0.1 mm; the nitriding is carried out in a nitriding furnace in an ammonia atmosphere at a temperature of 520°C for 24 hours; the fine crushing crushes the particles into magnetic powder with an average particle size of 1 μm;

[0073] (4) The magnetic powder obtained in step (3) is sequentially subjected to granulation at 180° C. and injection molding at 210° C. to obtain a samarium iron nitrogen-based anisotropic permanent magnetic material; the granulation comprises granulating a mixture of the magnetic powder and a polyamide resin, and the polyamide resin accounts for 5% of the mass of the magnetic powder.

[0074] Example 3

[0075] This embodiment provides a samarium iron nitrogen based anisotropic permanent magnet material and a preparation method thereof. The chemical composition of the samarium iron nitrogen based anisotropic permanent magnet material expressed by the molar ratio of elements is: Sm2(Fe 0.99 Co 0.01 ) 17 N3; The preparation method comprises the following steps:

[0076] (1) According to Sm2(Fe 0.99 Co 0.01 ) 17 Sm2O3, Fe powder, Co2O3 and metallic Ca are weighed in an element molar ratio of 1%, with Sm2O3 and metallic Ca respectively in an excess of 1%, and mixed uniformly in a powder mixer to obtain a mixed material;

[0077] (2) The mixture obtained in step (1) was subjected to reduction diffusion reaction in a sintering furnace in an argon atmosphere at a temperature of 1100°C for 0.1 h to obtain Sm2(Fe 0.99 Co 0.01 ) 17 alloy;

[0078] (3) The alloy obtained in step (2) is subjected to coarse crushing, nitriding and fine crushing in sequence to obtain Sm2(Fe 0.99 Co 0.01 ) 17 N3 magnetic powder; the coarse crushing crushes the alloy into particles with an average particle size of 1 mm; the nitriding is carried out in a nitriding furnace in an ammonia atmosphere at a temperature of 545°C for 1 hour; the fine crushing crushes the particles into magnetic powder with an average particle size of 5 μm;

[0079] (4) The magnetic powder obtained in step (3) is subjected to granulation at 230° C. and injection molding at 300° C. in sequence to obtain a samarium iron nitrogen-based anisotropic permanent magnetic material; the granulation comprises granulating a mixture of the magnetic powder and a polyamide resin, and the polyamide resin accounts for 20% of the mass of the magnetic powder.

[0080] Example 4

[0081] This embodiment provides a samarium iron nitrogen based anisotropic permanent magnetic material and a preparation method thereof, except that the molar ratio of each element in the mixture is adjusted to obtain a chemical composition of the permanent magnetic material of Sm2 (Fe 0.95 Co 0.05 ) 17 N3, the remaining steps and conditions are the same as those in Example 1, and therefore are not described here in detail.

[0082] Example 5

[0083] This embodiment provides a samarium iron nitrogen based anisotropic permanent magnetic material and a preparation method thereof, except that the molar ratio of each element in the mixture is adjusted to obtain a chemical composition of the permanent magnetic material of Sm2 (Fe 0.9 Co 0.1 ) 17 N3, the remaining steps and conditions are the same as those in Example 1, and therefore are not described here in detail.

[0084] Example 6

[0085] This embodiment provides a samarium iron nitrogen based anisotropic permanent magnetic material and a preparation method thereof, except that the molar ratio of each element in the mixture is adjusted to obtain a chemical composition of the permanent magnetic material of Sm2 (Fe 0.85 Co 0.15 ) 17 N3, the remaining steps and conditions are the same as those in Example 1, and therefore are not described here in detail.

[0086] Example 7

[0087] This embodiment provides a samarium iron nitrogen based anisotropic permanent magnetic material and a preparation method thereof, except that the molar ratio of each element in the mixture is adjusted to obtain a chemical composition of the permanent magnetic material of Sm2 (Fe 0.8 Co 0.2 ) 17 N3, the remaining steps and conditions are the same as those in Example 1, and therefore are not described here in detail.

[0088] Comparative Example 1

[0089] This comparative example provides a samarium iron nitrogen permanent magnet material and a preparation method thereof, except that the molar ratio of each element in the mixture is adjusted to obtain a permanent magnet material having a chemical composition of Sm2Fe 17 N3, that is, no metal Co doping is performed, and the remaining steps and conditions are the same as those in Example 1, so they are not described here in detail.

[0090] Comparative Example 2

[0091] This comparative example provides a samarium iron nitrogen based anisotropic permanent magnetic material and its preparation method, except that the molar ratio of each element in the mixture is adjusted to the chemical composition of the obtained permanent magnetic material is Sm2 (Fe 0.7 Co 0.3 ) 17N3, the remaining steps and conditions are the same as those in Example 1, and therefore are not described here in detail.

[0092] The coercive force at 20°C, the coercive force at 100°C and the coercive force temperature coefficient β of the permanent magnetic materials obtained in Examples 1-7 and Comparative Examples 1-2 are shown in Table 1 below.

[0093] Table 1

[0094]

[0095] In the table above, the coercive force test method is as follows: After granulation, the magnetic powder is injection-molded into a φ24×10mm standard sample column. The test is performed using the NIM2000 permanent magnetic performance measurement system tester in accordance with the method specified in GB / T 3217 at 20±2℃ and 100±2℃ respectively.

[0096] Table 1 shows that the permanent magnet materials obtained in Examples 1-7 all minimized the absolute value of the coercivity temperature coefficient while maintaining high coercivity, with the lowest absolute value reaching 0.383. Since the Co addition levels in Examples 2 and 3 were identical, their β values ​​were relatively close. However, powder particle size significantly influences coercivity, with finer powders exhibiting higher coercivity. Therefore, at 20°C, Example 2 exhibited the highest coercivity, while Example 3 exhibited the lowest. Furthermore, coarser powders are less susceptible to oxidation at high temperatures, resulting in a lower absolute value of β for Example 3 at 100°C.

[0097] Compared with Example 1, Comparative Example 1 does not perform metal Co doping, resulting in an absolute value of its coercive force temperature coefficient as high as 0.585; although Comparative Example 2 performs metal Co doping, its coercive force decreases significantly due to excessive doping, which in turn leads to insufficient anti-demagnetization ability of the motor and low practical value.

[0098] It can be seen that the present invention is achieved by replacing the traditional samarium iron nitrogen magnet Sm2Fe 17 N x Doping metal Co in the magnet to replace part of Fe significantly improves the high-temperature stability of the magnet material. While maintaining a high coercive force, the absolute value of the coercive force temperature coefficient is reduced as much as possible, and the absolute value can be as low as 0.383, thereby broadening the application field.

[0099] In addition, the present invention finally produces an excellent-performance samarium iron nitrogen-based anisotropic permanent magnet material through reduction diffusion reaction, nitridation and other treatment processes. The preparation process is simple and efficient, the production cost is low, the repeatability is good, and it is easy to promote and apply on a large scale.

[0100] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a samarium iron nitrogen based anisotropic permanent magnetic material, characterized in that: The chemical composition of the samarium iron nitrogen based anisotropic permanent magnet material expressed by the molar ratio of elements is: Sm2(Fe 1-x Co x ) 17 N y ; Among them, 0.01≤x≤0.2, 2.0≤y≤4.0; The preparation method comprises the following steps: (1) According to Sm2(Fe 1-x Co x ) 17 N y Sm source, Fe source, Co source and metal Ca are weighed and mixed uniformly to obtain a mixed material; (2) The mixture obtained in step (1) is subjected to a reduction diffusion reaction at a temperature of 900-1100°C to obtain Sm2(Fe 1-x Co x ) 17 alloy; (3) The alloy obtained in step (2) is subjected to coarse crushing, nitriding and fine crushing in sequence to obtain Sm2(Fe 1-x Co x ) 17 N y Magnetic powder; the coarse crushing crushes the alloy into particles with an average particle size of 0.1-1 mm; the fine crushing crushes the particles into magnetic powder with an average particle size of 1-5 μm; (4) The magnetic powder obtained in step (3) is granulated and injection molded in sequence to obtain a samarium iron nitrogen-based anisotropic permanent magnet material.

2. The preparation method according to claim 1, characterized in that 0.1≤x≤0.15。 3. The preparation method according to claim 1, characterized in that The Sm source in step (1) includes Sm2O3.

4. The preparation method according to claim 1, characterized in that The Fe source in step (1) includes Fe powder.

5. The preparation method according to claim 1, characterized in that The Co source in step (1) includes Co2O3.

6. The preparation method according to claim 1, characterized in that In terms of element molar ratio, the Sm source in step (1) is in excess of 1-50%.

7. The preparation method according to claim 1, characterized in that In terms of element molar ratio, the metal Ca in step (1) is in excess of 1-50%.

8. The preparation method according to claim 1, characterized in that The mixing in step (1) is carried out in a powder mixer.

9. The preparation method according to claim 1, characterized in that The reduction diffusion reaction in step (2) is carried out in a sintering furnace in an inert gas atmosphere.

10. The preparation method according to claim 9, characterized in that The inert gas includes helium and / or argon.

11. The preparation method according to claim 1, characterized in that The time of the reduction diffusion reaction in step (2) is 0.1-24h.

12. The preparation method according to claim 1, characterized in that The nitriding in step (3) is carried out in a nitriding furnace in an ammonia atmosphere.

13. The preparation method according to claim 1, characterized in that The temperature of the nitriding in step (3) is 520-545°C.

14. The preparation method according to claim 1, characterized in that The nitriding time in step (3) is 1-24h.

15. The preparation method according to claim 1, characterized in that The granulation in step (4) includes mixing magnetic powder and polyamide resin for granulation.

16. The preparation method according to claim 15, characterized in that The polyamide resin accounts for 5-20% of the mass of the magnetic powder.

17. The preparation method according to claim 1, characterized in that The granulation temperature in step (4) is 180-230°C.

18. The preparation method according to claim 1, characterized in that The injection molding temperature in step (4) is 210-300°C.

19. The preparation method according to claim 1, characterized in that The preparation method comprises the following steps: (1) According to Sm2(Fe 1-x Co x ) 17 N y Sm2O3, Fe powder, Co2O3 and metallic Ca are weighed in an element molar ratio of 1-50%, and Sm2O3 and metallic Ca are respectively excessively added. The mixture is uniformly mixed in a powder mixer to obtain a mixed material; (2) The mixture obtained in step (1) is subjected to reduction diffusion reaction in a sintering furnace in an inert gas atmosphere at a temperature of 900-1100°C for 0.1-24h to obtain Sm2(Fe 1-x Co x ) 17 alloy; the inert gas comprises helium and / or argon; (3) The alloy obtained in step (2) is subjected to coarse crushing, nitriding and fine crushing in sequence to obtain Sm2(Fe 1-x Co x ) 17 N y Magnetic powder; the coarse crushing crushes the alloy into particles with an average particle size of 0.1-1 mm; the nitriding is carried out in a nitriding furnace in an ammonia atmosphere at a temperature of 520-545°C for 1-24 hours; the fine crushing crushes the particles into magnetic powder with an average particle size of 1-5 μm; (4) The magnetic powder obtained in step (3) is sequentially subjected to granulation at 180-230° C. and injection molding at 210-300° C. to obtain a samarium iron nitrogen-based anisotropic permanent magnetic material; the granulation comprises granulating a mixture of the magnetic powder and a polyamide resin, and the polyamide resin accounts for 5-20% of the mass of the magnetic powder.

20. Use of a samarium iron nitrogen based anisotropic permanent magnetic material obtained by the method for preparing the samarium iron nitrogen based anisotropic permanent magnetic material according to any one of claims 1 to 19, characterized in that: The applications include the preparation of parts for wind power generation, new energy vehicles or elevators.

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