High-performance samarium-iron-nitrogen powder as well as preparation method and application thereof

Abstract

The invention relates to the technical field of magnetic materials, in particular to high-performance samarium-iron-nitrogen powder and a preparation method and application thereof. The invention provides a preparation method of samarium-iron-nitrogen powder, which comprises the following steps: (1) mixing Sm2O3 powder, Fe powder and a Ca reducing agent, and carrying out reduction reaction to obtain samarium-iron alloy; (2) mixing and crushing the samarium-iron alloy, mixing the crushed samarium-iron alloy with a dispersant and a passivation solution, carrying out ball milling, separating, and drying to obtain samarium-iron alloy powder; (3) nitriding the samarium-iron alloy powder to obtain samarium-iron-nitrogen powder; wherein the dispersing agent is selected from at least one of alkali metal phosphates; the passivation solution comprises chromium chloride, nitric acid, sulfuric acid and colloidal silicon dioxide. The samarium-iron-nitrogen powder prepared through the method has good magnetic performance.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic materials, and in particular to a high-performance samarium iron nitrogen powder and a preparation method and application thereof. Background Art

[0002] Permanent magnetic material is one of the core functional raw materials. As a unique permanent magnetic material, rare earth permanent magnets are widely used in many fields such as automobiles, wind power, electronics, aviation, etc., and with the rapid development of green industries, the global demand for rare earth permanent magnetic materials has increased rapidly. Samarium iron nitrogen has become a high-potential permanent magnetic material comparable to the "magnet king" NdFeB, with the huge advantages of high saturation magnetic polarization intensity, high Curie temperature (nearly 160°C higher than NdFeB), high magnetic anisotropy field, and low cost, and is superior to NdFeB in oxidation resistance and corrosion resistance.

[0003] SmFeN is the most valuable permanent magnet material after NdFeB due to its high Curie temperature, good temperature and chemical properties, and low price. In terms of physical and chemical properties, SmFeN has higher corrosion resistance, oxidation resistance, and high temperature resistance than NdFeB. It has important application value and broad market prospects in various extreme environmental conditions, especially in the automotive industry, consumer electronics, aerospace and other fields. In terms of price, samarium and iron raw materials are abundant and cheap, which has a good raw material cost advantage compared to NdFeB. Similar to sintered NdFeB, the particle size of SmFeN magnetic powder has a great influence on its performance. Too coarse powder will have a serious impact on coercivity and orientation.

[0004] The traditional reduction diffusion method uses samarium oxide and iron powder as raw materials and uses metal Ca or CaH 2 , CaCl 2 The disadvantage of reducing calcium-containing compounds is that the raw materials cannot be completely evenly dispersed and the prepared samarium-iron alloy particles are large in size and generally need to be crushed. However, after mechanical crushing, the powder morphology is mostly irregular and the particle size distribution is uneven. There will also be a large amount of Ca remaining between the particles, resulting in poor nitriding effect. At the same time, the powder is too fine after crushing, which will cause severe oxidation, resulting in a significant reduction in magnetic properties.

[0005] In summary, the samarium iron nitrogen powder prepared by the prior art has poor magnetic properties. Summary of the invention

[0006] The purpose of the present invention is to overcome the problem of poor magnetic properties of samarium iron nitrogen powder prepared by reduction diffusion method in the prior art, thereby providing a high-performance samarium iron nitrogen powder and a preparation method and application thereof.

[0007] The scheme adopted by the present invention is as follows:

[0008] The present invention provides a method for preparing high-performance samarium iron nitrogen powder, comprising the following steps:

[0009] (1) Sm 2 O 3 powder, Fe powder and Ca reducing agent are mixed and reduced to obtain samarium-iron alloy;

[0010] (2) mixing and crushing the samarium-iron alloy, mixing with a dispersant and a passivation solution, ball milling, separating, and drying to obtain a samarium-iron alloy powder;

[0011] (3) nitriding the samarium-iron alloy powder to obtain samarium-iron-nitrogen powder;

[0012] Wherein, the dispersant is selected from at least one of alkali metal phosphates;

[0013] The passivation solution includes chromium chloride, nitric acid, sulfuric acid and colloidal silica.

[0014] In the present invention, the chromium in the chromium chloride has a valence of +3.

[0015] Optionally, the passivation solution is prepared by mixing chromium chloride, nitric acid, sulfuric acid and colloidal silicon dioxide.

[0016] Preferably, the Sm 2 O 3 The mass ratio of Fe powder, Fe powder and Ca reducing agent is (300-400): (900-1000): (100-150);

[0017] Preferably, the Ca reducing agent is selected from Ca or CaH 2 , CaCl 2 At least one of;

[0018] Preferably, the reduction reaction temperature is 1000-1300°C and the time is 10-14h;

[0019] Preferably, the mass ratio of the samarium iron alloy, the dispersant, and the passivation solution after being crushed in the ball mill is 100:(0.5-3):(0.3-2);

[0020] Preferably, the crushing is carried out in a jaw crusher;

[0021] Preferably, the process of mixing and crushing the samarium-iron alloy is carried out under a nitrogen atmosphere;

[0022] Preferably, the particle size of the crushed samarium-iron alloy is 100-3000 μm;

[0023] Preferably, the ball milling is performed using water as a medium and steel balls;

[0024] Preferably, the ball milling frequency is 3-30 Hz;

[0025] Further preferably, the ball milling frequency is 5-20 Hz

[0026] Preferably, the ball milling time is 5-40h;

[0027] Further preferably, the ball milling time is 10-30h;

[0028] Preferably, the ball milling medium water is deionized water;

[0029] Preferably, the amount of deionized water added in the ball mill is such that the liquid level is 5 cm above the steel balls.

[0030] Preferably, the alkali metal phosphate is one or more of sodium tripolyphosphate, sodium pyrophosphate and sodium hexametaphosphate;

[0031] Preferably, the mass ratio of chromium chloride, nitric acid, sulfuric acid and colloidal silicon dioxide in the passivation solution is (7.5-8.5): (4.5-5.5): (1.5-2.5): (0.5-1.5);

[0032] Preferably, the mass ratio of chromium chloride, nitric acid, sulfuric acid and colloidal silicon dioxide in the passivation solution is 8:5:2:1;

[0033] Preferably, the concentration of the nitric acid is 7-15%;

[0034] Preferably, the concentration of the sulfuric acid is 5-10%.

[0035] Preferably, water and slurry need to be separated after ball milling, wherein the slurry needs to be dried;

[0036] Preferably, the drying is carried out in a vacuum drying oven;

[0037] Preferably, the drying temperature is 70-80°C;

[0038] Preferably, the nitriding is carried out in a tube furnace;

[0039] Preferably, the nitriding process is carried out in a nitrogen atmosphere;

[0040] Preferably, the nitriding temperature is 200-700°C

[0041] Further preferably, the nitriding temperature is 300-600°C;

[0042] Preferably, the nitriding time is 3-20h

[0043] Further preferably, the nitriding time is 5-15h;

[0044] Preferably, the particle size of the samarium iron nitrogen powder after nitriding is 1-10 μm.

[0045] The present invention also provides samarium iron nitrogen powder obtained by the above-mentioned preparation method of samarium iron nitrogen powder.

[0046] The present invention also provides an application of the samarium iron nitrogen powder obtained by the above-mentioned preparation method of the samarium iron nitrogen powder in electric motors and compressors.

[0047] Beneficial effects of the present invention:

[0048] The present invention provides a method for preparing samarium iron nitrogen powder, comprising the following steps: (1) 2 O 3 (1) mixing powder, Fe powder and Ca reducing agent, and subjecting them to reduction reaction to obtain samarium iron alloy; (2) mixing and crushing the samarium iron alloy, mixing it with a dispersant and a passivation solution, and then ball milling, separating and drying it to obtain samarium iron alloy powder; (3) nitriding the samarium iron alloy powder to obtain samarium iron nitrogen powder; wherein the dispersant is selected from at least one of alkali metal phosphates; and the passivation solution includes chromium chloride, nitric acid, sulfuric acid and colloidal silicon dioxide.

[0049] In the preparation method provided by the present invention, Sm 2 O 3 The process comprises the following steps: using Fe powder and Fe powder as raw materials, utilizing the strong reducing property of Ca reducing agent to adsorb the reduced Sm on the surface and inside of Fe powder particles to form a uniform and stable bulk samarium-iron alloy; then in step (2), when ball milling the obtained samarium-iron alloy, adding an alkali metal phosphate dispersant and a specific passivating solution, wherein the alkali metal phosphate dispersant has good solubility in water and is easily hydrolyzed into orthophosphate in water; there are residual ferrous ions and samarium ions in the samarium-iron alloy powder, and the phosphate ions can react with the ferrous ions in the water to form a positively charged colloid, and the colloid particles are deposited on the cathode to form a film and are tightly bound to the metal surface; the sulfate ions and nitrate ions in the passivating solution can also react with the metal ions on the alloy surface to form a protective film, which has a good effect of reducing the activity of the alloy and avoids the alloy particles from being damaged. The alkali metal phosphate is used as a dispersant to disperse the colloid formed by phosphate, ferrous ions and calcium ions and the metal powder in water without precipitation. At the same time, the alkali metal phosphate dispersant is easily soluble in water but insoluble in organic solvents such as ethanol and acetone. The carboxyl groups on its molecular chain stretch the twisted polymer chain due to electrostatic repulsion, which promotes the exposure of the adsorptive functional groups on the surface. These active points are adsorbed on the positively charged colloid and metal powder to form a bridge between the colloidal particles and the metal powder, thereby accelerating the coating of the colloidal particles. The surface oxidation of the alloy particles is further avoided. In addition, the calcium oxide and metallic calcium between the particles are removed during the ball milling process. In the subsequent nitriding process, step (3) can effectively carry out nitriding, and finally obtain samarium iron nitrogen powder with good magnetic properties.

[0050] Furthermore, the samarium iron nitrogen powder obtained by the preparation method provided by the present invention has high mechanical strength.

[0051] Furthermore, the preparation method provided by the present invention can avoid dangers in the production process. DETAILED DESCRIPTION

[0052] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0053] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0054] The colloidal silica used in the examples and comparative examples is fumed silica purchased from MacLean Reagent, model number S818465.

[0055] Example 1

[0056] This embodiment provides a method for preparing samarium iron nitrogen powder, comprising the following steps:

[0057] (1) Sm 2 O 3 Powder, Fe powder and metal Ca particles were mixed in a mass ratio of 348:952:120 and reacted at 1200°C for 12h to obtain samarium-iron alloy;

[0058] (2) Weigh 5 kg of samarium-iron alloy and crush it in a jaw crusher, while nitrogen is passed through the crushing process, and after crushing, obtain samarium-iron alloy particles with an average particle size of 1500 μm; take 2000 g of the crushed samarium-iron alloy particles and pour them into a ball mill equipped with 30 kg of steel balls, pour in an appropriate amount of deionized water so that the liquid level is 5 cm higher than the steel balls, and then add 30 g of dispersant (sodium hexametaphosphate) and 20 g of passivation solution (the mass ratio of chromium chloride, nitric acid, sulfuric acid and colloidal silica is 8:5:2:1, wherein the concentration of nitric acid is 10% and the concentration of sulfuric acid is 8%); ball mill the mixture in a ball mill at a frequency of 10 Hz for 20 hours, and separate the mixture after ball milling; place the separated material in a vacuum drying oven at 75° C. for drying to obtain samarium-iron alloy powder;

[0059] (3) The dried samarium-iron alloy powder is placed in a tubular furnace and nitrided under a nitrogen atmosphere at 400° C. for 10 h to obtain samarium-iron-nitrogen powder.

[0060] Example 2

[0061] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that 800 g of the samarium iron alloy particles obtained by crushing with a jaw crusher are poured into a ball mill for ball milling.

[0062] Example 3

[0063] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that 4000 g of the samarium iron alloy particles obtained by crushing with a jaw crusher are poured into a ball mill for ball milling.

[0064] Example 4

[0065] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the dispersant added during ball milling is 5 g of sodium hexametaphosphate.

[0066] Example 5

[0067] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the dispersant added during ball milling is 80 g of sodium hexametaphosphate.

[0068] Example 6

[0069] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that 4 g of passivation solution (the mass ratio of chromium chloride, nitric acid, sulfuric acid and colloidal silicon dioxide is 8:5:2:1) is added during ball milling.

[0070] Example 7

[0071] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that 50 g of passivation solution (the mass ratio of chromium chloride, nitric acid, sulfuric acid and colloidal silicon dioxide is 8:5:2:1) is added during ball milling.

[0072] Example 8

[0073] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the dispersant added during ball milling is 30 g of sodium tripolyphosphate.

[0074] Example 9

[0075] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the dispersant added during ball milling is 30 g of sodium pyrophosphate.

[0076] Example 10

[0077] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the dispersants added during ball milling are: 10 g of sodium hexametaphosphate, 10 g of sodium tripolyphosphate, and 10 g of sodium pyrophosphate.

[0078] Embodiment 11

[0079] This embodiment provides a method for preparing high-performance samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the ball milling frequency is 3 Hz.

[0080] Example 12

[0081] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the ball milling frequency is 30 Hz.

[0082] Example 13

[0083] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the ball milling time is 5 hours.

[0084] Embodiment 14

[0085] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the ball milling time is 40 hours.

[0086] Embodiment 15

[0087] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the nitriding temperature in the tube furnace is 100°C.

[0088] Example 16

[0089] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the nitriding temperature in the tube furnace is 800°C.

[0090] Embodiment 17

[0091] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the nitriding time in the tubular furnace is 3 hours.

[0092] Embodiment 18

[0093] This embodiment provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the nitriding time in the tube furnace is 20 hours.

[0094] Comparative Example 1

[0095] This comparative example provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that no dispersant is added during ball milling.

[0096] Comparative Example 2

[0097] This comparative example provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that no passivation solution is added during ball milling.

[0098] Comparative Example 3

[0099] This comparative example provides a method for preparing samarium iron nitrogen powder, comprising the following steps:

[0100] (1) Sm 2 O 3 The powder, Fe powder and Ca reducing agent were mixed in a mass ratio of 348:952:120 and reacted at 1200°C for 12h to obtain samarium-iron alloy;

[0101] (2) weighing 5 kg of samarium-iron alloy and crushing it in a jaw crusher, with nitrogen flowing during the crushing process, to obtain samarium-iron alloy particles with an average particle size of 1500 μm;

[0102] (3) The samarium-iron alloy particles are placed in a tubular furnace and nitrided in a nitrogen atmosphere at 400° C. for 10 h to obtain samarium-iron-nitrogen powder.

[0103] Comparative Example 4

[0104] This comparative example provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that there is no colloidal silica in the configured passivation solution, wherein the mass ratio of chromium chloride, nitric acid and sulfuric acid is 8:5:2, and no colloidal silica is added (the amount of passivation solution added remains unchanged).

[0105] Comparative Example 5

[0106] This comparative example provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the passivation solution does not contain chromium chloride, and the mass ratio of nitric acid, sulfuric acid and colloidal silicon dioxide is 5:2:1 (the amount of passivation solution added remains unchanged).

[0107] Comparative Example 6

[0108] This comparative example provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that the passivation solution does not contain nitric acid, and the mass ratio of chromium chloride, sulfuric acid and colloidal silicon dioxide is 8:2:1 (the amount of passivation solution added remains unchanged).

[0109] Comparative Example 7

[0110] This comparative example provides a method for preparing samarium iron nitrogen powder, which is basically the same as the method in Example 1, except that there is no sulfuric acid in the configured passivation solution, wherein the mass ratio of chromium chloride, nitric acid and colloidal silicon dioxide is 8:5:1 (the amount of passivation solution added remains unchanged).

[0111] Test Case

[0112] The nitrided samarium iron nitrogen powder was filled with nitrogen and stored at room temperature and pressure. A small amount of the nitrided powder was taken to test the oxygen content, nitrogen content, D50, SEM electron microscope and intrinsic coercivity; wherein the powder D50 was tested by a laser particle size distribution instrument; the gas analysis was performed by an ONH-2000 oxygen, nitrogen and hydrogen measuring instrument to obtain the N and O element contents in the powder; the thickness of the surface coated phosphating film was tested by SEM scanning; the intrinsic coercivity was tested by a NIM-2000 tester; the test results are shown in Table 1:

[0113] Table 1

[0114]

[0115] From Table 1 we can see that:

[0116] (1) The SmFeN powder obtained by the method provided in Example 1 of the present invention has an oxygen content of 0.88%, a nitrogen content of 3.36%, a powder particle size D50 of 1.32 μm, an average thickness of the coating film of 0.26 μm, a low degree of powder oxidation, no explosion occurs during the preparation process, and the intrinsic coercive force of the SmFeN powder is ≥16.73 KOe. This shows that the preparation method of the present invention ensures the activity and magnetism of the product while the coating of sodium polymetaphosphate effectively improves the safety.

[0117] (2) By comparing Example 1 with Examples 2-3, it can be seen that, when the mass of the steel ball is constant, the mass of the samarium iron alloy particles added during ball milling will greatly affect the powder particle size after ball milling and nitriding. The particle size of the SmFeN powder has a greater influence on the magnetic properties. The larger the powder particle size, the lower the magnetic properties. The smaller the powder particle size, the higher the magnetic properties. However, a small powder particle size will cause the powder to be easily oxidized, which will reduce the performance. If the powder particle size is too coarse, it will also affect the nitriding efficiency, resulting in a low powder nitrogen content and thus affecting the magnetic properties.

[0118] (3) By comparing Example 1 with Examples 4-5, it can be seen that the addition of sodium hexametaphosphate during ball milling affects the powder particle size. If too little sodium hexametaphosphate is added as a dispersant, the samarium iron alloy powder is easy to agglomerate during ball milling, affecting the passivation coating effect of the passivation solution. The powder is easy to oxidize, resulting in reduced performance. Excessive sodium hexametaphosphate will cause the powder particle size to become larger, thereby resulting in reduced performance.

[0119] (4) From the comparison between Example 1 and Examples 6-7, it can be seen that the addition of passivation liquid during ball milling will also affect the powder performance. Excessive amount of passivation liquid will cause the powder particle size to become larger, thereby reducing the performance. Insufficient amount of passivation liquid will result in poor powder coating effect and easy oxidation, resulting in reduced performance.

[0120] (5) From the comparison between Example 1 and Examples 8-10, it can be seen that sodium hexametaphosphate, sodium pyrophosphate, and sodium tripolyphosphate can all be used as dispersants in the ball milling process, and the effects are not much different.

[0121] (6) By comparing Example 1 with Examples 11-12, it can be seen that, under the conditions of constant ball milling time, steel ball mass, powder mass and added additives, the ball milling frequency will affect the powder particle size, resulting in reduced powder performance. Too coarse powder particle size will also affect the nitriding efficiency, resulting in a low powder nitrogen content and thus affecting the magnetic properties.

[0122] (7) By comparing Example 1 with Examples 13-14, it can be seen that, under the conditions of constant ball milling frequency, steel ball mass, powder mass and added additives, the ball milling time will affect the powder particle size, resulting in reduced powder performance. Too coarse powder particle size will also affect the nitriding efficiency, resulting in a low powder nitrogen content and thus affecting the magnetic properties.

[0123] (8) From the comparison between Example 1 and Examples 15-16, it can be seen that temperature has a great influence on the nitriding of samarium-iron alloys. If the temperature is too low, nitriding is almost impossible, and if the temperature is too high, SmFeN will be generated and then decomposed at high temperature.

[0124] (9) From the comparison between Example 1 and Examples 17-18, it can be seen that the nitriding time has a great influence on the formation of SmFeN from samarium-iron alloy. Insufficient time cannot completely complete the nitriding, while too long time will cause the decomposition of SmFeN.

[0125] (10) From the comparison between Example 1 and Comparative Example 1, it can be seen that the alkali metal phosphate dispersant promotes the passivation coating of the chromium passivation solution, can reduce the activity of the samarium iron alloy particles, reduce oxidation, and improve the magnetic properties.

[0126] (11) From the comparison between Example 1 and Comparative Example 2, it can be seen that the passivation solution can passivate and coat the SmFeN powder, reduce its activity, reduce oxidation, and improve magnetic properties.

[0127] (12) From the comparison between Example 1 and Comparative Example 3, it can be seen that if nitriding is carried out directly without ball milling and passivation treatment, the samarium-iron alloy particles are too large to cause nitriding to proceed, and since the calcium between the samarium-iron alloys is not removed, the magnetic properties are extremely low and cannot be measured.

[0128] (12) From the comparison between Example 1 and Comparative Examples 4, 5, 6, and 7, it can be seen that the components of the passivation solution are indispensable, especially colloidal silicon dioxide and chromium chloride. If they are missing, the passivation effect will not be achieved at all. Although sulfuric acid and nitric acid play an auxiliary role, they also affect the passivation effect to a large extent.

[0129] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing samarium iron nitrogen powder, characterized in that: The steps include: (1) Sm2O3 powder, Fe powder and Ca reducing agent are mixed and subjected to reduction reaction to obtain samarium-iron alloy; (2) mixing and crushing the samarium-iron alloy, mixing with a dispersant and a passivation solution, ball milling, separating, and drying to obtain a samarium-iron alloy powder; (3) nitriding the samarium-iron alloy powder to obtain samarium-iron-nitrogen powder; Wherein, the dispersant is selected from at least one of alkali metal phosphates; The passivation solution includes chromium chloride, nitric acid, sulfuric acid and colloidal silica.

2. The method for preparing the samarium iron nitrogen powder according to claim 1, characterized in that: The mass ratio of Sm2O3 powder, Fe powder and Ca reducing agent in step (1) is (300-400): (900-1000): (100-150); Preferably, the Ca reducing agent is selected from at least one of Ca or CaH2, CaCl2; Preferably, the reduction reaction temperature is 1000-1300° C. and the time is 10-14 h.

3. The method for preparing samarium iron nitrogen powder according to claim 1 or 2, characterized in that: In step (2), the mass ratio of the crushed samarium-iron alloy, the dispersant, and the passivation solution in the ball mill is 100:(0.5-3):(0.3-2); Preferably, the ball milling frequency is 3-30 Hz; Further preferably, the ball milling frequency is 5-20 Hz Preferably, the ball milling time is 5-40h; Further preferably, the ball milling time is 10-30h; Preferably, the process of mixing and crushing the samarium-iron alloy is carried out under a nitrogen atmosphere; Preferably, the particle size of the crushed samarium-iron alloy is 100-3000 μm.

4. The method for preparing samarium iron nitrogen powder according to any one of claims 1 to 3, characterized in that: In step (2), water is used as the medium for ball milling, and steel balls are used for ball milling.

5. The method for preparing samarium iron nitrogen powder according to claim 1, characterized in that: The alkali metal phosphate is one or more of sodium tripolyphosphate, sodium pyrophosphate and sodium hexametaphosphate.

6. The method for preparing samarium iron nitrogen powder according to claim 1, characterized in that: The mass ratio of chromium chloride, nitric acid, sulfuric acid and colloidal silicon dioxide in the passivation solution is (7.5-8.5): (4.5-5.5): (1.5-2.5): (0.5-1.5); Preferably, the mass ratio of chromium chloride, nitric acid, sulfuric acid and colloidal silicon dioxide in the passivation solution is 8:5:2:1; Preferably, the concentration of the nitric acid is 7-15%; Preferably, the concentration of the sulfuric acid is 5-10%.

7. The method for preparing samarium iron nitrogen powder according to claim 1, characterized in that: The drying temperature is 70-80°C.

8. The method for preparing samarium iron nitrogen powder according to claim 1, characterized in that: The nitriding process in step (3) is carried out in a nitrogen atmosphere; Preferably, the nitriding temperature is 200-700°C; Further preferably, the nitriding temperature is 400-600°C; Preferably, the nitriding time is 5-15h; The particle size D50 of the samarium iron nitrogen powder after nitriding is 1-10 μm.

9. A samarium iron nitrogen powder obtained according to the method for preparing samarium iron nitrogen powder according to any one of claims 1 to 8.

10. Use of the samarium iron nitrogen powder prepared by the preparation method according to any one of claims 1 to 8 or the samarium iron nitrogen powder according to claim 9 in electric motors and compressors.

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