阅读说明：本技术 一种高渗氮效率制备高性能钐铁氮永磁材料的方法 (Method for preparing high-performance samarium-iron-nitrogen permanent magnet material with high nitriding efficiency ) 是由 赵宇 涂元浩 何馨怡 于京京 徐道兵 梁鹏 于 2021-09-28 设计创作，主要内容包括：本发明提供了一种高渗氮效率制备高性能钐铁氮永磁材料的方法,包括：将钐铁合金粉末进行分级筛选,使用真空泵将塔式真空氮化炉抽至低真空1×10～(-3)Pa,从塔式真空氮化炉底部持续充入高速高纯氮气气流进行氮化处理。本发明提供的高渗氮效率制备高性能钐铁氮永磁材料的方法,用氮气流冲刷SmFe合金粉末,使得SmFe合金粉末能够完全接触氮气,提高渗氮效率；进一步的,进行分级筛选,使料槽中的SmFe合金粉末处于最佳渗氮尺寸,利于后续渗氮处理。本发明提供的方法渗氮完成后SmFeN合金粉末氮含量高,相结构稳定,杂质少,磁性能优良且稳定；而且每次能进行氮化处理的原料量大产,制造成本低,经济效益转化率高。(The invention provides a method for preparing a high-performance samarium-iron-nitrogen permanent magnet material with high nitriding efficiency, which comprises the following steps: the samarium-iron alloy powder is graded and screened, and the tower type vacuum nitriding furnace is pumped to low vacuum of 1 x 10 by using a vacuum pump ‑3 And Pa, continuously filling high-speed high-purity nitrogen gas flow from the bottom of the tower type vacuum nitriding furnace for nitriding treatment. According to the method for preparing the high-performance samarium-iron-nitrogen permanent magnet material with high nitriding efficiency, provided by the invention, the SmFe alloy powder is flushed by nitrogen flow, so that the SmFe alloy powder can be in full contact with nitrogen, and the nitriding efficiency is improved; and further, carrying out grading screening to ensure that the SmFe alloy powder in the material groove is in the optimal nitriding size, so as to be beneficial to subsequent nitriding treatment. After nitriding is finished, the SmFeN alloy powder has high nitrogen content, stable phase structure, less impurities and excellent and stable magnetic performance; and the raw material amount capable of performing nitriding treatment each time is large, the manufacturing cost is low, and the economic benefit conversion rate is high.)

1. A method for preparing a high-performance samarium-iron-nitrogen permanent magnet material with high nitriding efficiency comprises the following steps:

and carrying out nitriding treatment on the samarium iron alloy powder in continuous nitrogen gas flow to obtain the high-performance samarium iron nitrogen permanent magnet material.

2. The method of claim 1 wherein the samarium iron alloy powder has a particle size of 300 to 2000 mesh.

3. The method according to claim 1, wherein the flow rate of the nitrogen gas flow during the nitriding treatment is 10 to 30 m/s.

4. The method according to claim 1, wherein the pressure during the nitriding treatment is 0.1 to 0.2 MPa.

5. The method according to claim 1, wherein the temperature during the nitriding treatment is 400 to 550 ℃.

6. The method according to claim 1, wherein the nitriding treatment is carried out for 10 to 30 hours.

7. The method of claim 1, wherein the nitridation process further comprises, prior to:

performing primary nitriding treatment on samarium-iron alloy powder; the preliminary nitridation treatment is performed in a high-energy ball milling tank.

8. The method according to claim 1, wherein the nitriding treatment is performed in a tower vacuum nitriding furnace; and the nitrogen gas flow is continuously filled from the bottom of the tower type vacuum nitriding furnace.

9. The method according to claim 8, wherein the tower vacuum nitriding furnace is provided with one or more fine-hole troughs;

samarium iron alloy powder with different granularities is put into respectively in a plurality of pore silos and is carried out the nitridation processing.

10. The method of claim 8, further comprising, prior to the nitridation process:

and (4) carrying out vacuum pumping treatment on the tower type vacuum nitriding furnace.

Technical Field

The invention belongs to the technical field of permanent magnet materials, and particularly relates to a method for preparing a high-performance samarium-iron-nitrogen permanent magnet material with high nitriding efficiency.

Background

With the rapid development of science and technology, especially in the fields of automobiles, aerospace and the like, under various extreme environmental conditions, more strict requirements are imposed on various materials. Permanent magnets are used as materials with the most important functions and are more and more widely applied in the fields of national economy and science and technology. The Nd-Fe-B rare earth permanent magnet has excellent magnetic property and mechanical property, but is expensive, so the use of the Nd-Fe-B rare earth permanent magnet at high temperature is greatly limited. In 1990, Coey et al prepared intermetallic compound R by gas-solid phase reaction₂Fe₁₇N_xWherein Sm₂Fe₁₇N_xAre attracting much attention. Magnetic property Sm₂Fe₁₇N_xThe saturation magnetization of the magnetic material can reach 1.54T, and is basically equivalent to NdFeB; sm₂Fe₁₇N_xThe Curie temperature of (A) is 470 ℃ and is higher than the Curie temperature of NdFeB (318 ℃; sm₂Fe₁₇N_xThe anisotropy field of (A) reached 14T, which is higher than 8T for NdFeB. Physical and chemical Properties of Sm₂Fe₁₇N_xThe key performances of corrosion resistance, oxidation resistance, high temperature resistance and the like are superior to those of NdFeB. In price, the samarium and iron raw materials have more resources and low price, wherein the samarium raw materials have surplus capacity in China and low cost. Development of Sm₂Fe₁₇N_xThe magnet has wide market prospect and higher market value.

At present Sm₂Fe₁₇N_xThere are various preparation processes such as melt rapid quenching (RS), Mechanical Alloying (MA), hydrogenation-disproportionation-dehydrogenation-recrystallization (HDDR), Powder Metallurgy (PM), Reduction Diffusion (RD), etc., and most of the above methods are two steps: firstly, preparing 2: 17 type samarium iron alloy carries out nitriding treatment to samarium iron alloy again. High-purity samarium-iron alloy is prepared by the existing method at present, but the Sm is prepared by aiming at the Sm in the second step of nitriding treatment₂Fe₁₇The problem of poor reaction kinetics of alloy nitriding, no good solution is provided in mass production at present, and the reaction kinetics of the alloy nitriding is closely related to nitriding environment; and SmFeN can be decomposed at the high temperature of 600 ℃,this results in the inability to promote the reaction by raising the nitrogen activity solely by raising the temperature, which results in lower nitridation efficiency and poorer nitridation effect by nitrogen diffusion in the nitrogen source-containing medium, and the SmFeN magnetic performance cannot reach the corresponding level.

Disclosure of Invention

In view of the above, the invention aims to provide a method for preparing a high-performance samarium iron nitrogen permanent magnet material with high nitriding efficiency.

The invention provides a method for preparing a high-performance samarium-iron-nitrogen permanent magnet material with high nitriding efficiency, which comprises the following steps:

and carrying out nitriding treatment on the samarium iron alloy powder in continuous nitrogen gas flow to obtain the high-performance samarium iron nitrogen permanent magnet material.

Preferably, the samarium-iron alloy powder has a particle size of 300 to 2000 meshes.

Preferably, the flow velocity of the nitrogen gas flow in the nitriding treatment process is 10-30 m/s.

Preferably, the pressure in the nitriding treatment process is 0.1-0.2 MPa.

Preferably, the temperature in the nitriding treatment process is 400-550 ℃.

Preferably, the nitriding treatment time is 10 to 30 hours.

Preferably, the nitriding treatment further comprises:

performing primary nitriding treatment on samarium-iron alloy powder; the preliminary nitridation treatment is performed in a high-energy ball milling tank.

Preferably, the nitriding treatment is performed in a tower type vacuum nitriding furnace; and the nitrogen gas flow is continuously filled from the bottom of the tower type vacuum nitriding furnace.

Preferably, the tower type vacuum nitriding furnace is provided with a plurality of fine-hole material tanks;

samarium iron alloy powder with different granularities is put into respectively in a plurality of pore silos and is carried out the nitridation processing.

Preferably, the method further comprises, before the nitriding treatment:

and (4) carrying out vacuum pumping treatment on the tower type vacuum nitriding furnace.

According to the method for preparing the high-performance samarium-iron-nitrogen permanent magnet material with high nitriding efficiency, provided by the invention, the SmFe alloy powder is flushed by nitrogen flow, so that the SmFe alloy powder can be in full contact with nitrogen, and the nitriding efficiency is improved; and further, carrying out grading screening to ensure that the SmFe alloy powder in the material groove is in the optimal nitriding size, so as to be beneficial to subsequent nitriding treatment. The SmFeN alloy powder after nitriding is high in nitrogen content, stable in phase structure, few in impurities, and excellent and stable in magnetic performance; and the raw material amount capable of performing nitriding treatment each time is large, the manufacturing cost is low, and the economic benefit conversion rate is high.

Drawings

FIG. 1 is a result of a measurement of the properties of samarium-iron-nitrogen permanent magnet material prepared in example 1 of the present invention;

FIG. 2 shows the measured results of the properties of samarium-iron-nitrogen permanent magnet material prepared in comparative example 1;

FIG. 3 is a result of a measurement of the properties of samarium-iron-nitrogen permanent magnet material prepared in example 2 of the present invention;

FIG. 4 shows the measured results of the properties of samarium-iron-nitrogen permanent magnet material prepared in comparative example 2;

FIG. 5 is a graph showing the results of measurements of the properties of samarium-iron-nitrogen permanent magnet materials prepared in example 3 of the present invention;

FIG. 6 shows the results of measurements of the properties of samarium-iron-nitrogen permanent magnet materials prepared in comparative example 3.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a method for preparing a high-performance samarium-iron-nitrogen permanent magnet material with high nitriding efficiency, which comprises the following steps:

and carrying out nitriding treatment on the samarium iron alloy powder in continuous nitrogen gas flow to obtain the high-performance samarium iron nitrogen permanent magnet material.

In the present invention, the chemical formula of the samarium iron alloy powder is preferably Sm₂Fe₁₇。

In the present invention, the samarium-iron alloy powder preferably has a particle size of 300 to 2000 mesh, more preferably 500 to 800 mesh, and most preferably 600 to 2000 mesh.

In the invention, preferably, the samarium iron alloy powder is subjected to classification treatment to obtain powder with different particle size ranges, the particle size of the samarium iron alloy powder is preferably classified into 3-5 grades according to the particle size range, more preferably 4 grades, the particle size range of the first grade is preferably 30-48 microns, more preferably 35-45 microns, more preferably 38-42 microns, and most preferably 40 microns; the particle size range of the second stage is preferably 10-20 micrometers, more preferably 12-18 micrometers, and most preferably 14-16 micrometers; the particle size range of the third stage is preferably 5-10 micrometers, and more preferably 6-8 micrometers; the fourth stage preferably has a particle size in the range of 0 to 5 microns, more preferably 1 to 4 microns, and most preferably 2 to 3 microns.

In the present invention, it is preferable that before subjecting the samarium-iron alloy powder to nitriding treatment, the samarium-iron alloy powder further comprises: performing primary nitriding treatment on samarium-iron alloy powder; the preliminary nitridation treatment method preferably includes:

samarium-iron alloy powder was treated with nitrogen gas.

In the present invention, the preliminary nitriding treatment (nitrogen-charging treatment) is preferably performed in a high-energy ball mill pot.

In the present invention, the method of the nitrogen-filling treatment preferably includes:

samarium-iron alloy powder and a solvent are subjected to ball milling and mixing in a high-energy ball milling tank under the nitrogen environment.

In the invention, the solvent is preferably one or more of ethanol, n-heptane and n-hexane; the ethanol is preferably anhydrous ethanol.

In the present invention, the pressure of the nitrogen gas is preferably 0.1 to 0.3MPa, more preferably 0.15 to 0.25MPa, and most preferably 0.2 MPa.

In the invention, non-magnetic steel balls are preferably added in the ball-milling mixing process; the ball-material ratio in the ball-milling mixing process is preferably (8-12): 1, more preferably (9-11): 1, most preferably 10: 1; the ball milling and mixing time is preferably 2-4 hours, more preferably 2.5-3.5 hours, and most preferably 3 hours; the rotating speed in the ball milling and mixing process is preferably 150-200 r/min, more preferably 160-190 r/min, and most preferably 170-180 r/min.

In the invention, the particle size of the samarium-iron alloy powder after the primary nitriding treatment is preferably 1-50 micrometers, more preferably 5-40 micrometers, more preferably 10-30 micrometers, and most preferably 20 micrometers.

In the invention, the preliminarily nitrided samarium iron alloy is preferably classified and screened to obtain the samarium iron alloy powder with the mesh number in the technical scheme, the samarium iron alloy powder is preferably screened according to the size in the classified particle size range of the samarium iron alloy powder in the technical scheme, and the preliminarily processed samarium iron alloy powder is divided into different grades according to the particle size range.

In the present invention, the nitriding treatment is preferably performed in a tower-type vacuum nitriding furnace; the tower vacuum nitriding furnace is preferably provided with one or more pore silos, preferably put into the samarium iron alloy powder of different particle size ranges respectively in a plurality of pore silos and carry out the nitridation and handle, preferably put into the pore silos of different mesh numbers with hierarchical different particle size ranges samarium iron alloy powder that above-mentioned technical scheme.

In the invention, the mesh number of the fine-hole trough is preferably 300-2000 meshes, more preferably 400-800 meshes, and most preferably 500-600 meshes; the number of the fine hole troughs and the mesh number of each fine hole trough are preferably adapted to the grading number and the grading particle size range of the samarium iron alloy powder in the technical scheme, and the number of the fine hole troughs is consistent with the grading grade number of the samarium iron alloy powder; the mesh number of pore silo is unanimous with the different grades of granularity scope of the samarium iron alloy powder of putting into, puts into the pore silo of different meshes with the samarium iron alloy powder of different grades of granularity scope.

In the invention, the fine-hole trough is preferably a 316 stainless steel screen; the loading amount of the fine-hole trough is preferably 1-10 kg, more preferably 2-8 kg, and most preferably 3-6 kg; the fine hole material grooves are preferably used in a multilayer overlapping mode, namely a plurality of porous material grooves with different meshes are sequentially arranged in the tower type vacuum furnace from the bottom position to the top position according to the mesh size, the mesh size of the porous material grooves arranged at the bottom is smaller, and the mesh size of the porous material grooves arranged at the top position is larger; the bigger the particle size of the samarium iron alloy powder is, the smaller the specific surface area is, the smaller the area in contact with nitrogen is, and the lower the nitriding efficiency is, the larger the particle size of the samarium iron alloy powder is firstly placed at the bottom of the vacuum furnace (placed by a fine hole trough with smaller mesh number), and then the smaller particle size of the samarium iron alloy powder is sequentially stacked upwards (placed by a fine hole trough with larger mesh number), so that the nitriding efficiency can be improved; in the invention, a plurality of porous material troughs with gradually increased granularity from 300-2000 meshes are preferably arranged from the bottom to the top of the vacuum furnace in sequence.

In the invention, the tower type vacuum nitriding furnace can preferably provide a high-vacuum degree environment, and the ultimate vacuum degree is preferably 1 x 10^-3Pa; heating, wherein the highest temperature is 600 ℃; the nitrogen can be filled, and the maximum flow velocity of the nitrogen flow is preferably 4 m/s; the maximum pressure bearable in the cavity is preferably 0.2 MPa.

In the invention, before the nitriding treatment, the tower type vacuum nitriding furnace is preferably subjected to vacuum pumping treatment, preferably a vacuum pump is adopted to pump the vacuum to a low vacuum, and the vacuum degree of the vacuum treatment is preferably 2.5-3.5 multiplied by 10^-3Pa, more preferably 2.8 to 3.2X 10^-3Pa, most preferably 3X 10^-3Pa。

In the invention, the nitrogen gas flow is preferably continuously filled from the bottom of the tower type vacuum nitriding furnace and sequentially passes through a plurality of fine hole troughs with the mesh number from small to large, samarium-iron alloy powder with different particle size ranges is contained in the fine hole troughs, and the particle size of the samarium-iron alloy powder is gradually reduced from the bottom to the top of the vacuum furnace to carry out nitriding treatment on the samarium-iron alloy.

In the present invention, the nitrogen gas stream is preferably a high purity nitrogen gas stream.

The invention continuously fills nitrogen gas flow in the nitriding treatment process without rotating the nitriding furnaceThe cavity can make samarium iron alloy granule contact nitrogen gas completely, adverse factors such as reunion, cold welding can not take place among the samarium iron alloy granule, makes the nitrogen content mole ratio of the high performance samarium iron nitrogen permanent magnet material who obtains of preparation than higher, and the chemical formula of the high performance samarium iron nitrogen permanent magnet material who obtains is Sm₂Fe₁₇N_x，2.5≤x≤3。

In the invention, the flow velocity of the nitrogen gas flow in the nitriding treatment process is preferably 10-30 m/s, more preferably 15-25 m/s, and most preferably 20 m/s; the pressure in the nitriding treatment process is preferably 0.1-0.15 MPa, more preferably 0.15-0.2 MPa, and most preferably 0.2 MPa; the temperature in the nitriding treatment process is preferably 400-550 ℃, more preferably 450-500 ℃, and most preferably 500 ℃; the nitriding treatment time is 10 to 30 hours, and most preferably 20 to 30 hours.

In the present invention, it is preferable that the nitriding treatment further includes:

and cooling the product after the nitriding treatment to obtain the high-performance samarium-iron-nitrogen permanent magnet material.

In the invention, the method for preparing the high-performance samarium-iron-nitrogen permanent magnet material with high nitriding efficiency preferably comprises the following steps:

placing samarium-iron alloy powder into a high-energy ball-milling tank, and filling nitrogen to perform primary nitridation treatment, wherein the particle size of the samarium-iron alloy subjected to the primary nitridation treatment is 1-50 micrometers;

grading and screening the preliminarily treated samarium-iron alloy powder, wherein the screening grade is 300-2000 meshes, and the samarium-iron alloy powder is filled into a fine hole trough with a corresponding mesh number, and the mesh number of the fine hole trough is 300-800 meshes;

placing the sorted fine-pore material tanks into a tower type vacuum nitriding furnace, and pumping to low vacuum by using a vacuum pump, wherein the vacuum degree is 3 multiplied by 10^-3Pa, continuously filling high-speed high-purity nitrogen gas flow from the bottom of the tower type vacuum nitriding furnace, enabling the nitrogen gas to sequentially pass through a plurality of fine-hole material grooves with the mesh number from small to large, enabling the nitrogen gas flow rate to be 10-30 m/s, keeping the pressure in the furnace chamber within a certain range, enabling the pressure to be 0.1-0.2 MPa, heating to 400-550 ℃ and carrying out nitriding treatment for 10-30 hours;

and after the nitriding treatment is finished, cooling the furnace body, and taking out the nitride powder in an argon box to obtain the high-performance samarium-iron-nitrogen permanent magnet material.

According to the method for preparing the high-performance samarium-iron-nitrogen permanent magnet material with high nitriding efficiency, provided by the invention, the SmFe alloy powder is flushed by nitrogen flow, so that the SmFe alloy powder can be in full contact with nitrogen, and the nitriding efficiency is improved; and further, carrying out grading screening to ensure that the SmFe alloy powder in the material groove is in the optimal nitriding size, so as to be beneficial to subsequent nitriding treatment. The SmFeN alloy powder after nitriding is high in nitrogen content, stable in phase structure, few in impurities, and excellent and stable in magnetic performance; and the raw material amount capable of performing nitriding treatment each time is large, the manufacturing cost is low, and the economic benefit conversion rate is high.

Example 1

Placing samarium iron alloy powder into a high-energy ball milling tank, charging nitrogen gas into the high-energy ball milling tank, performing primary nitridation treatment on the samarium iron alloy powder (Sm)₂Fe₁₇) Putting the mixture into absolute ethyl alcohol, putting a nonmagnetic steel ball, and filling nitrogen into the mixture, wherein the air pressure is 0.2 MPa; according to the ball-material ratio of 10:1, performing high-energy ball milling in a high-energy ball milling tank, controlling the time to be 3 hours, controlling the rotating speed to be 150-200 r/min, and controlling the particle size of the samarium-iron alloy subjected to primary nitridation to be 1-50 micrometers;

grading and screening the samarium iron alloy powder obtained by the primary treatment, wherein the screening and grading are 300-2000 meshes, the samarium iron alloy powder is divided into four grades according to the granularity, and the first grade granularity is 30-48 microns; the secondary particle size range is 10-20 microns; the third-level particle size range is 5-10 microns; the fourth-level particle size range is 0-5 microns; respectively loading samarium-iron alloy powder of different grades into fine hole material tanks of different meshes, and totally loading the samarium-iron alloy powder into four fine hole material tanks of corresponding meshes;

horizontally arranging the four sorted fine-hole material tanks from the bottom to the top of the tower type vacuum nitriding furnace according to the mesh number from small to large, and tightly fastening and linking each fine-hole material tank; pumping to low vacuum with a vacuum degree of 3 × 10^{- 3}Pa, continuously filling high-speed high-purity nitrogen gas flow into the bottom of the tower type vacuum nitriding furnace, keeping the flow rate of the nitrogen gas flow at 10m/s, keeping the pressure of 0.15MPa in the furnace chamber, and heating to 400 ℃ for nitriding treatment for 25 hours;

and after the nitriding treatment is completed, cooling the furnace body, and taking out the nitride powder in an argon box to obtain the high-performance samarium-iron-nitrogen permanent magnet material.

Comparative example 1

Placing samarium-iron alloy powder into a high-energy ball milling tank, and filling nitrogen into the high-energy ball milling tank to perform primary nitridation treatment (the treatment method is the same as that in example 1), wherein the particle size of the samarium-iron alloy subjected to the primary nitridation treatment is 1-50 micrometers;

nitriding the samarium iron alloy powder subjected to the primary nitriding treatment in a tubular annealing furnace containing nitrogen under the pressure of 400 ℃ for 25 hours at the nitriding temperature and the nitriding pressure of 0.05 MPa;

and after the nitriding treatment is completed, cooling the furnace body, and taking out the nitride powder in the nitrogen box to obtain the samarium-iron-nitrogen permanent magnet material.

The samarium iron nitrogen permanent magnet materials prepared in example 1 and comparative example 1 were measured for magnetic properties using a united states Lake Shore vibration sample magnetometer (model 7400 series) and the results are shown in table 1, fig. 1 and fig. 2:

table 1 results of performance tests of samarium-iron-nitrogen permanent magnet materials prepared in inventive example 1 and comparative example 1

Serial number	Categories	Saturation magnetization Ms(emu/g)	Intrinsic coercive force Hic(kOe)
				Example 1	Tower type vacuum nitriding furnace	118.5	14.7
Comparative example 1	Tubular vacuum annealing furnace	105.3	5.6

FIG. 1 is a hysteresis loop obtained by testing the product prepared in example 1; FIG. 2 is a hysteresis loop obtained by testing the product prepared in comparative example 1.

Example 2

Placing samarium-iron alloy powder into a high-energy ball milling tank, and filling nitrogen into the high-energy ball milling tank to perform primary nitridation treatment (the treatment method is the same as that in example 1), wherein the particle size of the samarium-iron alloy subjected to the primary nitridation treatment is 1-50 micrometers;

grading and screening the samarium iron alloy powder obtained by the primary treatment, wherein the screening and grading are 300-2000 meshes, the samarium iron alloy powder is divided into four grades according to the granularity, and the first grade granularity is 30-48 microns; the secondary particle size range is 10-20 microns; the third-level particle size range is 5-10 microns; the fourth-level particle size range is 0-5 microns; respectively loading samarium-iron alloy powder of different grades into fine hole material tanks of different meshes, and totally loading the samarium-iron alloy powder into four fine hole material tanks of corresponding meshes;

horizontally arranging the four sorted fine-hole material tanks from the bottom to the top of the tower type vacuum nitriding furnace according to the mesh number from small to large, and tightly fastening and linking each fine-hole material tank; pumping to low vacuum with a vacuum degree of 3 × 10^{- 3}Pa, continuously filling high-speed high-purity nitrogen gas flow from the bottom of the tower type vacuum nitriding furnace, keeping the nitrogen flow at 20m/s, keeping the pressure of 0.2MPa in the furnace chamber, and heating to 450 ℃ for nitriding treatment for 20 hours;

and after the nitriding treatment is completed, cooling the furnace body, and taking out the nitride powder in an argon box to obtain the high-performance samarium-iron-nitrogen permanent magnet material.

Comparative example 2

Placing samarium-iron alloy powder into a high-energy ball milling tank, and filling nitrogen into the high-energy ball milling tank to perform primary nitridation treatment (the treatment method is the same as that in example 1), wherein the particle size of the samarium-iron alloy subjected to the primary nitridation treatment is 1-50 micrometers;

putting the preliminarily treated samarium-iron alloy powder into a nitrogen-containing tubular annealing furnace for nitriding at the nitriding temperature of 450 ℃ for 30 hours at the nitriding pressure of 0.08 MPa;

and after the nitriding treatment is completed, cooling the furnace body, and taking out the nitride powder in the nitrogen box to obtain the samarium-iron-nitrogen permanent magnet material.

The samarium iron nitrogen permanent magnet materials prepared in example 2 of the present invention and comparative example 2 were tested for magnetic properties according to the method of example 1, and the results are shown in table 2, fig. 3 and fig. 4:

table 2 results of performance tests of samarium-iron-nitrogen permanent magnet materials prepared in example 2 of the present invention and comparative example 2

Serial number	Categories	Saturation magnetization Ms (emu/g)	Intrinsic coercivity (kOe)
				Example 2	Tower type vacuum nitriding furnace	120.1	13.6
Comparative example 2	Tubular vacuum annealing furnace	118.4	8.3

Example 3

Placing samarium-iron alloy powder into a high-energy ball milling tank, and filling nitrogen into the high-energy ball milling tank to perform primary nitridation treatment (the treatment method is the same as that in example 1), wherein the particle size of the samarium-iron alloy subjected to the primary nitridation treatment is 1-50 micrometers;

grading and screening the samarium iron alloy powder obtained by the primary treatment, wherein the screening and grading are 300-2000 meshes, the samarium iron alloy powder is divided into four grades according to the granularity, and the first grade granularity is 30-48 microns; the secondary particle size range is 10-20 microns; the third-level particle size range is 5-10 microns; the fourth-level particle size range is 0-5 microns; respectively loading samarium-iron alloy powder of different grades into fine hole material tanks of different meshes, and totally loading the samarium-iron alloy powder into four fine hole material tanks of corresponding meshes;

horizontally arranging the four sorted fine-hole material tanks from the bottom to the top of the tower type vacuum nitriding furnace according to the mesh number from small to large, and tightly fastening and linking each fine-hole material tank; pumping to low vacuum with a vacuum degree of 3 × 10^{- 3}Pa, continuously filling high-speed high-purity nitrogen gas flow from the bottom of the tower type vacuum nitriding furnace at the flow rate of 20m/s, keeping the pressure of 0.15MPa in the furnace chamber, and heating to 500 ℃ for nitriding treatment for 10 hours;

and after the nitriding treatment is completed, cooling the furnace body, and taking out the nitride powder in an argon box to obtain the high-performance samarium-iron-nitrogen permanent magnet material.

Comparative example 3

Placing samarium-iron alloy powder into a high-energy ball milling tank, and filling nitrogen into the high-energy ball milling tank to perform primary nitridation treatment (the treatment method is the same as that in example 1), wherein the particle size of the samarium-iron alloy subjected to the primary nitridation treatment is 1-50 micrometers;

putting the samarium iron alloy powder subjected to the primary nitriding treatment into a nitrogen-containing tubular annealing furnace for nitriding treatment, wherein the nitriding temperature is 500 ℃, the nitriding time is 10 hours, and the nitriding pressure is 0.05 MPa;

and after the nitriding treatment is completed, cooling the furnace body, and taking out the nitride powder in the nitrogen box to obtain the samarium-iron-nitrogen permanent magnet material.

The samarium iron nitrogen permanent magnet materials prepared in example 3 of the present invention and comparative example 3 were tested for magnetic properties according to the method of example 1 and the results are shown in table 3, fig. 5 and fig. 6:

TABLE 3 results of measurements of properties of samarium iron nitrogen permanent magnet materials prepared in inventive example 3 and comparative example 3

Serial number	Categories	Saturation magnetization Ms (emu/g)	Intrinsic coercivity (kOe)
				Example 3	Tower type vacuum nitriding furnace	125.4	14.7
Comparative example 3	Tubular vacuum annealing furnace	111.5	4.4

According to the embodiment, the method for preparing the high-performance samarium-iron-nitrogen permanent magnet material with high nitriding efficiency provided by the invention has the advantages that the SmFe alloy powder is flushed by nitrogen flow, so that the SmFe alloy powder can be in full contact with nitrogen, and the nitriding efficiency is improved; and further, carrying out grading screening to ensure that the SmFe alloy powder in the material groove is in the optimal nitriding size, so as to be beneficial to subsequent nitriding treatment. The SmFeN alloy powder after nitriding is high in nitrogen content, stable in phase structure, few in impurities, and excellent and stable in magnetic performance; and the raw material amount capable of performing nitriding treatment each time is large, the manufacturing cost is low, and the economic benefit conversion rate is high.

While the invention has been described and illustrated with reference to specific embodiments thereof, such description and illustration are not intended to limit the invention. It will be clearly understood by those skilled in the art that various changes in form and details may be made therein without departing from the true spirit and scope of the invention as defined by the appended claims, to adapt a particular situation, material, composition of matter, substance, method or process to the objective, spirit and scope of this application. All such modifications are intended to be within the scope of the claims appended hereto. Although the methods disclosed herein have been described with reference to particular operations performed in a particular order, it should be understood that these operations may be combined, sub-divided, or reordered to form equivalent methods without departing from the teachings of the present disclosure. Accordingly, unless specifically indicated herein, the order and grouping of the operations is not a limitation of the present application.