A samarium-iron alloy, a samarium-iron-nitrogen permanent magnet material, and a preparation method and application thereof

Abstract

The application discloses a samarium-iron alloy, a samarium-iron-nitrogen permanent magnet material and a preparation method and application thereof. The preparation method of the samarium-iron alloy comprises the following steps: carrying out a reduction diffusion reaction and a crushing treatment on Sm2O3, Fe and Ca, and then obtaining the samarium-iron alloy; wherein the average particle size D50 of the Sm2O3 is 0.5-4 microns; the average particle size D50 of the Fe is 50-150 microns; and the porosity of the Fe is 10%-40%. In the preparation method, large-size iron powder is adopted, the cost is low, the samarium-iron-nitrogen permanent magnet material prepared has low impurity content, and the magnetic performance is excellent.

Description

Technical Field

[0001] This invention relates to a samarium iron alloy, a samarium iron nitrogen permanent magnet material, its preparation method and application. Background Technology

[0002] Iron-nitrogen-based rare-earth permanent magnet materials possess temperature stability comparable to samarium-cobalt. Their main components, samarium and iron, result in lower manufacturing costs, and minimal fluctuations in raw material prices make them an ideal choice for cost-effective permanent magnets in downstream applications. Iron-nitrogen-based rare-earth permanent magnet materials theoretically exhibit excellent magnetic properties. Based on the interstitial atom effect of nitrogen in rare-earth-transition metal compounds, their Curie temperature is more than 100°C higher than that of neodymium-iron-boron materials, making them a significant research hotspot in the field of rare-earth permanent magnets in recent years. (The text abruptly shifts to a seemingly unrelated topic about Sm2Fe...) 17 N3 magnetic powder exhibits high coercivity only when the grain size is no larger than a single-domain particle. In order to obtain fine grain structure economically and efficiently, the industry usually adopts melt quenching method, hydrogen disproportionation method, mechanical alloying method (CN1202537C), rapid solidification casting method (CN106312077B) or reduction diffusion method (CN1424165A). Among them, the reduction diffusion method has attracted the attention of researchers due to its advantages such as simple equipment, low raw material cost and easy implementation of process conditions.

[0003] In the reduction-diffusion process for preparing samarium iron nitrogen magnetic powder, to ensure a more complete diffusion reaction and obtain a small-particle-size product, the particle size of the raw iron powder is often reduced to promote the reduction-diffusion process. However, due to limitations in the uniformity of raw material mixing, some iron powder residue is unavoidable during the reduction-diffusion process. The residue of fine soft magnetic powder in the product is often difficult to separate effectively, leading to a decrease in the overall performance of the magnetic powder. Furthermore, finer iron powder is more prone to oxidation, causing a reduction in the performance of the alloy powder. Moreover, fine iron powder, especially nano-sized iron powder, is several times more expensive than ordinary iron powder, increasing manufacturing costs.

[0004] Therefore, there is an urgent need to provide an efficient and low-cost method for preparing samarium iron alloy and samarium iron nitrogen permanent magnet materials, and the prepared samarium iron nitrogen permanent magnets have low impurity content and excellent magnetic properties. Summary of the Invention

[0005] This invention addresses the shortcomings of existing samarium iron nitride (SFIN) permanent magnet preparation methods, such as the high cost and easy oxidation of fine iron powder, and the difficulty in separating residual fine iron powder, which deteriorates magnetic properties. It provides a samarium iron alloy, a samarium iron nitride permanent magnet material, its preparation method, and its applications. The preparation method of this invention uses large-particle iron powder, resulting in low cost and producing samarium iron nitride permanent magnet material with low impurity content and excellent magnetic properties.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] One of the technical solutions provided by this invention is: a method for preparing samarium-iron alloy, which includes the following steps: subjecting Sm2O3, Fe and Ca to a reduction-diffusion reaction and a crushing process;

[0008] The average particle size D50 of the Sm2O3 is 0.5–4 μm.

[0009] The average particle size D50 of the Fe is 50–150 μm; the porosity of the Fe is 10%–40%.

[0010] In this invention, the Sm2O3 can be conventional Sm2O3 powder in the art. The average particle size D50 of the Sm2O3 is preferably 1-2 μm.

[0011] The average particle size D50 of the Fe is preferably 80-120 μm.

[0012] The porosity of the Fe is preferably 25-40%. Porosity refers to the percentage of pore volume in a bulk material to the total volume of the material in its natural state (generally referring to a state without external force).

[0013] The Fe generally refers to iron powder with a porous structure, preferably porous iron powder or foamed iron powder. The porous iron powder and the foamed iron powder can be commercially available from sources commonly found in the art, such as Sega Microelectronics Technology Co., Ltd.

[0014] The Ca can be conventional in the art, such as commercially available metallic calcium. The physical form of the metallic calcium can be conventional in the art, such as metallic calcium particles. The particle size of the metallic calcium particles can be conventional in the art, such as 1-2 mm.

[0015] In this invention, the Sm2O3, the Fe, and the Ca can be expressed as Sm2O3 + 17Fe + 3Ca = Sm2Fe 17 The reaction equation for +3CaO determines the material ratio.

[0016] To ensure sufficient reduction of samarium oxide, metallic Ca is generally prepared at 1.05 to 1.5 times the theoretical amount determined by the equation (5% to 50% excess). Meanwhile, considering the volatilization of metallic Sm during the reduction diffusion reaction at high temperature, Sm2O3 is generally prepared at 1.05 to 1.3 times the theoretical amount determined by the above equation (5% to 30% excess).

[0017] Preferably, the molar ratio of Sm2O3 to Fe is 1:(13-17), for example 1:16.2.

[0018] Preferably, the molar ratio of Sm2O3 to Ca is 1:(2-5), for example 1:2.4, 1:3 or 1:4.3.

[0019] In this invention, the reduction-diffusion reaction can be conventional in the art and generally includes a reduction process and a diffusion process; the reduction process and the diffusion process can be independently a process of placing Sm2O3, Fe and Ca in a vacuum heat treatment furnace, raising the temperature from room temperature to the reaction temperature, and maintaining the reaction temperature for a period of time.

[0020] In this invention, the reaction temperature and reaction time of the reduction process and the diffusion process in the reduction-diffusion reaction can be the same or different.

[0021] For example, when the reaction temperatures of the reduction process and the diffusion process are the same, the reaction temperatures of the reduction process and the diffusion process are independently 1050 to 1180°C, for example 1120°C or 1140°C; the reaction times of the reduction process and the diffusion process are independently 2 to 13 hours, for example 5 hours, 6 hours, 8 hours, 9 hours or 10 hours.

[0022] For example, when the reaction temperatures of the reduction process and the diffusion process are different, the reaction temperature of the reduction process is 850-950°C, preferably 900°C, and the reaction time of the reduction process is 1-5 hours, for example, 2 hours or 3 hours; the reaction temperature of the diffusion process is 1050-1180°C, for example, 1100°C, 1120°C, 1140°C, 1150°C or 1160°C, and the reaction time of the diffusion process is 2-10 hours, for example, 4 hours, 6 hours or 8 hours.

[0023] In this invention, the reduction-diffusion reaction is more preferably carried out according to the following steps:

[0024] The reduction process involves maintaining mixture A at a temperature of 850–950°C for 1–5 hours to fully reduce Sm2O3, thereby obtaining mixture B; the mixture A consists of Sm2O3, Fe, and Ca.

[0025] The diffusion process involves maintaining the mixture B at 1050–1180°C for 2–10 hours, allowing the metal Sm to diffuse into the Fe powder and form a samarium-iron alloy.

[0026] In this invention, the samarium iron alloy generally refers to Sm2Fe 17 alloy.

[0027] In this invention, the reduction-diffusion reaction is more preferably carried out under the protection of an inert gas.

[0028] The inert gas can be a conventional inert gas in the art, such as argon. Generally, the vacuum level in the vacuum furnace can be maintained at <0.1 Pa before the mixture A is raised from room temperature to the reaction temperature of the reduction process. After the reaction temperature of the reduction process is reached, high-purity argon is introduced into the vacuum heat treatment furnace.

[0029] In this invention, the crushing process may include coarse crushing, air jet milling, and hydrogen crushing.

[0030] After the reduction-diffusion reaction is completed, the product is Sm2Fe. 17 The mixture of components such as CaO and Ca, which are mixed and agglomerated, can be coarsely crushed to reduce the size and improve the efficiency of subsequent hydrogen crushing.

[0031] The coarse crushing can be conventional in the art, generally involving mechanical crushing of the samarium-iron alloy obtained after the reduction-diffusion reaction, such as jaw crushing or disc milling. After coarse crushing, the average particle size D50 of the samarium-iron alloy is generally <2 mm.

[0032] The air jet milling is a conventional technique in the field, generally involving the use of an air jet mill to crush and sort the coarsely crushed samarium-iron alloy, thereby breaking down and dispersing the agglomerated products after the reaction.

[0033] After the airflow pulverization, the average particle size D50 of the samarium iron alloy can be 0.5 to 25 μm.

[0034] The air jet milling process can separate large, unreacted iron powder particles (>25μm) from the product, resulting in a mixed product free of iron powder.

[0035] The hydrogen crushing mentioned above is conventional in the field and generally refers to crushing using H2.

[0036] The hydrogen crushing can be carried out in a vacuum hydrogen crushing furnace.

[0037] The hydrogen crushing can be carried out in an atmosphere of 500–900 mbar H2 gas.

[0038] The hydrogen crushing can be carried out according to the following process: the samarium-iron alloy after air jet pulverization absorbs hydrogen at 150-250°C for 2-5 hours, and then dehydrogenates it under vacuum at 250-350°C.

[0039] The hydrogen breakage can remove Sm2Fe from the mixture. 17 The alloy undergoes hydrogen absorption and breakage, causing the remaining metallic Ca layer adhering to the product surface to transform into CaH2, which then pulverizes and peels off.

[0040] The second technical solution provided by the present invention is: a samarium-iron alloy, which is prepared by the preparation method described above.

[0041] In this invention, the samarium-iron alloy is preferably in powder form.

[0042] In this invention, the average particle size D50 of the samarium iron alloy is preferably 0.2 to 4 μm, for example 1.7 μm, 1.8 μm, 2.1 μm, 2.3 μm or 2.5 μm.

[0043] The third technical solution provided by this invention is: the application of the samarium iron alloy as described above in the preparation of samarium iron nitrogen permanent magnet materials.

[0044] The fourth technical solution provided by the present invention is: a method for preparing samarium iron nitride permanent magnet material, which includes the following steps: subjecting the samarium iron alloy as described above to nitriding treatment.

[0045] In this invention, the nitriding process can be a conventional nitriding process in the art.

[0046] The temperature of the nitriding treatment can be conventional in the art, such as 450-550°C, or for example, 480°C, 500°C or 520°C.

[0047] The pressure of the nitriding treatment can be conventional in the art, such as 0.09MPa-1.5MPa, for example 0.2MPa, 0.5MPa, 0.8MPa, 0.9MPa, 1MPa, 1.2MPa or 1.5MPa.

[0048] The nitriding treatment time can be conventional in the art, preferably 4 to 20 hours, for example 5 hours, 6 hours, 10 hours, 12 hours or 15 hours. For example, nitriding can be performed for 5 to 20 hours under conditions of 0.09 MPa to 1.5 MPa.

[0049] The nitriding medium can be conventional in the art, such as N2 or NH3, or even a mixture of N2+H2, N2+NH3, NH3+H2, or N2+NH3+H2.

[0050] In this invention, during the nitriding process, Sm2Fe 17 Alloy nitriding forms Sm2Fe 17 N3 compounds.

[0051] In this invention, after the nitriding treatment, the process generally includes water washing and drying steps.

[0052] The water washing process can be conventional in the field and is used to remove impurities such as CaO, Ca, and CaH2 from the mixed product.

[0053] The washing solution used can be any conventional solution in the art, such as water. Preferably, a small amount of weak acid can be added to the washing solution to maintain the pH of the washing solution ≥ 6. The weak acid can be any conventional weak acid in the art, such as acetic acid.

[0054] The washing process may further include a dehydration step. The solvent used for dehydration may be conventional in the art, such as an organic solvent. The organic solvent may be alcohol or acetone.

[0055] The drying process can be conventional in the art, such as vacuum drying.

[0056] In this invention, preferably, after drying, the process further includes an airflow dispersion and classification step. This breaks down and disperses the dried and agglomerated product to obtain samarium iron nitrogen permanent magnet material with an appropriate particle size.

[0057] The process of airflow dispersion and classification can be carried out using an airflow mill.

[0058] The gas used in the air jet mill can be a conventional inert gas in the art. The inert gas can be helium, nitrogen, or argon.

[0059] Preferably, during the airflow dispersion and classification process, the product is simultaneously subjected to antioxidant and dispersion treatment.

[0060] The antioxidant treatment can be carried out by adding an organic antioxidant during the air jet milling process. The amount of the organic antioxidant added is preferably 0.2% to 2.5%, for example, 0.5%.

[0061] The dispersion treatment can be carried out by adding a dispersant during the air jet milling process. The amount of dispersant added is preferably 0.2% to 2.5%, for example, 0.5%.

[0062] Preferably, the sum of the amounts of the organic antioxidant and the dispersant is 0.8% to 4.0%, for example, 1% or 1.5%.

[0063] The fifth technical solution provided by the present invention is: a samarium iron nitrogen permanent magnet material, which is prepared by the preparation method of samarium iron nitrogen permanent magnet material as described above.

[0064] In this invention, the average particle size D50 of the samarium iron nitrogen permanent magnet material can be 0.2 to 4 μm, for example 1.7 μm, 1.8 μm, 2.1 μm, 2.3 μm or 2.5 μm.

[0065] The sixth technical solution provided by this invention is: the application of samarium iron nitrogen permanent magnet material as described above as an electromagnetic element.

[0066] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0067] The reagents and raw materials used in this invention are all commercially available.

[0068] The positive and progressive effects of this invention are as follows:

[0069] (1) In this invention, large-particle porous iron powder is used in combination with fine-particle samarium oxide powder. During the reduction process, after thorough mixing, a material accumulation state is formed in which samarium oxide powder coats the porous iron powder. During the diffusion process, metallic samarium diffuses fully into the interior of the iron powder through the pores of the porous iron powder, forming Sm2Fe. 17 The alloy causes porous iron powder undergoing a diffusion reaction to spontaneously break down into small particles, Sm2Fe. 17 The alloy is formed, while the unreacted iron powder retains its original large particle shape, which makes it possible to remove excess iron powder in subsequent airflow separation.

[0070] (2) The present invention can use an inert gas jet mill to further crush and sort the coarse crushed product after reduction and diffusion, so that the remaining large iron powder particles that have not undergone reduction and diffusion reaction are separated from the product, and a product with very few iron impurities is obtained, thus avoiding the appearance of α-Fe soft magnetic phase in the final magnet and ensuring that the magnetic powder has high coercivity.

[0071] (3) The present invention can perform hydrogen crushing treatment on the reduction diffusion products after the first air jet milling, so that the larger particles Sm2Fe with a particle size of 4-25 μm in the products are reduced. 17 The product further absorbs hydrogen and breaks down into fine Sm2Fe particles of 0.2–4 μm. 17 Alloy powder. Fine alloy powder is beneficial for improving the efficiency and degree of subsequent nitriding, while also possessing high coercivity.

[0072] (4) In this invention, the reduction diffusion products can be nitrided first to reduce the Sm2Fe in the mixed products. 17 Nitriding to form Sm2Fe 17 The N3 compound is then subjected to water washing to remove impurities, avoiding the Sm2Fe contamination that occurs in the traditional method of washing first and then nitriding. 17 Water washing corrosion and oxidation of the alloy, followed by nitriding to form Sm2Fe 17 N3 compounds have high room temperature stability, are not easily oxidized or corroded, and facilitate thorough water washing to remove impurities from the mixed products. The final product has low Ca and O content and high magnetic properties. Attached Figure Description

[0073] Figure 1 This is an SEM image of the fine-grained samarium oxide feedstock in Example 1.

[0074] Figure 2 This is a SEM image of the porous iron powder raw material in Example 1.

[0075] Figure 3 This is a SEM image of samarium metal permeation and encapsulation formed after large porous iron powder particles in Example 1 are reduced by fine samarium oxide.

[0076] Figure 4 This is a SEM image of the mixed product after reduction and diffusion in Example 1.

[0077] Figure 5 This is a particle size distribution diagram of the mixed product after reduction and diffusion in Example 1.

[0078] Figure 6 This is a particle size distribution diagram of the reduction-diffusion mixture after airflow crushing and iron removal in Example 1. Detailed Implementation

[0079] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0080] In the following examples and comparative examples, the porous iron powder was purchased from Sega Microelectronics Technology Co., Ltd.; spherical iron powder refers to iron powder with a dense spherical shape (its density is 7.8 g / cm³). 3 Purchased from MCC Xindun Company.

[0081] Example 1

[0082] The preparation process of samarium iron nitrogen magnetic powder in Example 1 is as follows: batching - reduction diffusion - coarse crushing of product - air separation of product - hydrogen crushing - nitriding - impurity washing - product drying - air dispersion and classification - finished magnetic powder.

[0083] The specific steps are as follows:

[0084] (1) Porous iron powder with a particle size of 50 μm (D50) was used as the raw material for the reduction-diffusion reaction. The porosity of the porous iron powder was 10%. The high porosity of the porous iron powder resulted in high reactivity, which allowed the reaction to proceed fully and rapidly, and the reaction material was easily broken. Porosity refers to the percentage of pore volume in a bulk material to the total volume of the material in its natural state (generally referring to the state without external force).

[0085] (2) Samarium oxide powder is used as raw material with a particle size of 0.5 μm (D50).

[0086] (3) Prepare the ingredients according to the molar ratio of each component in Table 1: Specifically, the material ratio is Sm2O3 + 17Fe + 3Ca = Sm2Fe 17The reaction equation for +3CaO was determined. To ensure the full reduction of samarium oxide, metallic Ca was added at 1.1 times the theoretical amount determined by the equation (10% excess). Meanwhile, considering the volatilization of metallic Sm during the reduction diffusion reaction at high temperature, Sm2O3 was added at 1.05 times the theoretical amount determined by the above equation (5% excess). After addition, the raw materials were placed in a mixer for thorough mixing.

[0087] Table 1

[0088]

[0089]

[0090] (4) Reduction diffusion:

[0091] Reduction process: The thoroughly mixed raw materials are placed in a vacuum heat treatment furnace and heated. During the temperature rise from room temperature to the reduction treatment temperature, the vacuum degree in the furnace is maintained at <0.1 Pa. After the material reaches the reduction temperature, high-purity argon gas is introduced into the furnace at a pressure of 600 mbar. The material is then held at 950℃ for 2 hours for reduction treatment, which melts the metallic calcium and reduces Sm2O3 to metallic samarium.

[0092] Diffusion process: After reduction treatment, the material is heated to 1155℃ and held for 6 hours for diffusion treatment. The diffusion atmosphere is argon gas at a pressure of 900 mbar, which allows metallic Sm to diffuse into the porous iron powder and form Sm2Fe. 17 The alloy spontaneously breaks into alloy powder of 2–25 μm.

[0093] (5) Coarse crushing: The product after reduction and diffusion is mechanically coarsely crushed to make the product particle size <2mm. Coarse crushing can be done by jaw crusher or disc mill crusher.

[0094] (6) Air jet milling: The coarsely crushed powder is further crushed and sorted using an air jet mill to break and disperse the agglomerated product after the reaction, and to obtain a mixed product with a particle size of 0.5 to 25 μm. The large iron powder particles (>25 μm) that have not been fully reacted are separated from the product to obtain a mixed product without iron powder.

[0095] (7) Hydrogen Crushing: The powder after air jet milling is placed in a vacuum hydrogen crushing furnace for hydrogen crushing. After evacuating the furnace body, 800 mbar H2 gas is introduced, and the temperature is raised to 150℃ to absorb hydrogen for 2 hours. Then, the furnace is evacuated at 300℃ (vacuum degree <0.1 Pa) to remove hydrogen, so that the Sm2Fe in the mixed product is removed. 17 The alloy undergoes hydrogen absorption and breakage, causing the remaining metallic Ca layer adhering to the product surface to transform into CaH2, which then pulverizes and peels off.

[0096] (8) Nitriding: The hydrogen-crushed products are nitrided at 450℃ and 1.5MPa. The nitriding medium can be N2, and the nitriding time is 20h, so that the Sm2Fe in the mixed products is reduced. 17 Alloy nitriding forms Sm2Fe 17 N3 compounds.

[0097] (9) Washing: The nitrided product is washed with water to remove impurities such as CaO, Ca, and CaH2 from the mixed product. A small amount of weak acid such as acetic acid can also be added during the washing process to keep the pH of the washing solution ≥ 6. After washing, alcohol is used to dehydrate the washed product.

[0098] (10) The product after thorough washing and dehydration is vacuum dried.

[0099] (11) The vacuum-dried powder is subjected to nitrogen or argon gas flow milling to break up and disperse the dried and agglomerated product, resulting in Sm2Fe with a particle size (D50) of approximately 2.5 μm. 17 N3 magnetic powder can be treated with antioxidants and dispersants during the grinding process to resist oxidation and disperse the magnetic powder. The amount of additives added is 1.0%.

[0100] Examples 2-4 and Comparative Examples 1-5

[0101] Except for the process conditions listed in Tables 1 and 2, all other conditions are the same as in Example 1.

[0102] Table 2

[0103]

[0104]

[0105] Effect Example

[0106] 1. SEM observation and particle size distribution of the material

[0107] Figure 1 , Figure 2 , Figure 3 and Figure 4 The images show the SEM images of the samarium metal permeation and encapsulation state formed by the reduction of fine-grained samarium oxide raw material, porous iron powder raw material, and large-particle porous iron powder by fine-grained samarium oxide in Example 1, as well as the mixed product of reduction and diffusion.

[0108] Depend on Figures 1-4It is known that when large-particle porous iron powder and fine-particle samarium oxide raw materials work together, after thorough mixing during the reduction and diffusion process, a material accumulation state is formed in which samarium oxide powder coats the porous iron powder. During the reduction and diffusion process, the reduced samarium metal fully coats the iron powder particles and diffuses rapidly and fully into the interior of the iron powder through the pores of the porous iron powder, forming Sm2Fe. 17 The alloy eventually breaks spontaneously into samarium-iron alloy powder, while the incompletely reacted iron powder particles cannot break spontaneously enough and ultimately exist in the mixed product as large particles.

[0109] Figure 5 This is a particle size distribution diagram of the mixed product after reduction and diffusion in Example 1. Figure 6 This is a particle size distribution diagram of the reduction-diffusion mixture after airflow crushing and sorting for iron removal in Example 1. As shown in the diagram, after airflow crushing and sorting, large unreacted residual iron particles in the mixture are completely removed.

[0110] 2. The composition of the samarium iron nitrogen permanent magnet materials prepared in the above embodiments and comparative examples was determined. The results showed that Sm2Fe 17 Apart from the unavoidable samarium volatilization during the reduction and diffusion process (designed to be 5%) and differences in impurity content, the remaining components of the alloy material are similar to those of Sm2Fe. 17 The stoichiometric ratio remained unchanged during subsequent air jet milling, hydrogen crushing, and nitriding processes, except for Fe and oxygen impurities. After water washing, components such as Ca and CaO in the mixture were removed, yielding relatively pure Sm2Fe. 17 N3 powder (Sm2Fe in Examples 1-5) 17 The purity of N3 powder is >98%.

[0111] 3. The performance of the samarium iron nitrogen permanent magnet materials prepared in the above embodiments and comparative examples was tested, and the test results are shown in Table 3 below:

[0112] The magnetic properties were measured using a vibrating sample magnetometer (VSM), model LakeShore 7411.

[0113] Particle size was tested using a laser particle size analyzer, specifically a Malvern Mastersizer2000.

[0114] Component analysis was performed using an X-ray fluorescence spectrometer, specifically the Panalytical Axios Max.

[0115] Oxygen content was measured using an oxygen-nitrogen analyzer, model Horiba EMGA-620W.

[0116] α-Fe was detected using an X-ray diffractometer, specifically a Bruker D8DISCOVER.

[0117] Table 3

[0118]

[0119] The test results above show that:

[0120] Examples 1-5: Sm2Fe prepared 17 N3 magnetic powder exhibits excellent properties: Br ≥ 13.5 kGs, Hcj ≥ 14.8 kOe, BHmax ≥ 38 MGOe; α-Fe content ≤ 0.56 wt%, oxygen content ≤ 0.78 wt%, and residual Ca content ≤ 0.03 wt%. It is evident that porous iron powder with an average particle size D50 of 50–150 μm and a porosity of 10%–40%, as well as Sm2O3 with an average particle size D50 of 0.5–4 μm, can effectively reduce Sm2Fe. 17 The impurity content of N3 magnetic powder is reduced, and its magnetic properties are improved;

[0121] Meanwhile, compared with Example 4, Example 5 has a slightly higher molar ratio of porous iron powder during the batching process. However, since the average particle size D50 and porosity of the porous iron powder are within the range of protection claimed in this application, even if the molar ratio of porous iron powder is "excessive", the residual excess iron powder can be completely separated from the product.

[0122] Comparative Example 1: Compared with Examples 1-5, the average particle size D50 of the porous iron powder is less than 50 μm, which cannot effectively utilize the particle size difference to separate and remove the residual iron powder in the air jet milling stage. The final magnetic powder has a high α-Fe content and poor magnetic properties, especially Hcj and BHmax, which are significantly inferior to those in Examples 1-5.

[0123] Comparative Example 2: Compared with Examples 1-5, the average particle size D50 of the porous iron powder was greater than 150 μm, which meant that the fine-grained samarium oxide could not completely encapsulate the excessively large iron powder particles. Furthermore, the porosity of the porous iron powder was less than 25%, resulting in insufficient penetration of the reduced samarium metal into the iron powder. Consequently, the reaction product contained incompletely formed Sm2Fe. 17 The small-particle α-Fe core of the alloy results in a high iron content and poor magnetic properties, especially Hcj and BHmax, which are significantly inferior to those in Examples 1-5.

[0124] Comparative Example 3: Compared with Examples 1-5, Sm2Fe was prepared using spherical iron powder. 17 The N3 magnetic powder has a significantly higher α-Fe impurity content and poorer magnetic properties, especially Hcj and BHmax, which are significantly inferior to those in Examples 1-5.

[0125] Comparative Example 4: Compared with Examples 1-5, the porosity of the porous iron powder is greater than 40%, resulting in excessive samarium filling the pores and affecting Sm2Fe. 17 Insufficient samarium content in the synthesis reaction resulted in the production of Sm2Fe. 17 The remanence and coercivity of N3 magnetic powder are significantly lower than those in Examples 1-5;

[0126] Comparative Example 5: Compared with Examples 1-5, the average particle size D50 of the samarium oxide powder was 10 μm, which is not in the range of 0.5-4 μm. The reduction reaction was incomplete, and there was not enough metallic samarium to participate in the Sm2Fe reduction. 17 The synthesis reaction of samarium oxide is problematic because its large particle size prevents it from forming a good coating on the iron powder, resulting in insufficient diffusion of metallic samarium into the iron powder and thus hindering the production of Sm2Fe. 17 The remanence and coercivity of N3 magnetic powder are significantly lower than those in Examples 1-5.

[0127] Comparative Example 6: Compared with Examples 1-5, the average particle size D50 of the porous iron powder is less than 50 μm, making it difficult to effectively utilize particle size differences to separate and remove residual iron powder during the air jet milling stage. Furthermore, compared to Comparative Example 1, the iron powder content in the ingredients of Comparative Example 6 is higher, resulting in a lower yield of Sm2Fe. 17 The N3 magnetic powder also has a higher residual α-Fe content; and its magnetic properties are poor, especially Hcj and BHmax, which are far inferior to those in Examples 1-5.

[0128] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method of producing a samarium-iron alloy, characterized by, The preparation method of the samarium-iron alloy includes the following steps: Sm2O3, Fe and Ca are subjected to a reduction diffusion reaction and crushing treatment; wherein Ca is metallic calcium. The average particle size D50 of the Sm2O3 is 0.5~4μm; The Fe is porous iron powder or foamed iron powder; the average particle size D50 of the Fe is 50~150μm; the porosity of the Fe is 10%~40%; The crushing process includes coarse crushing, air jet milling, and hydrogen crushing; The coarse crushing is performed by jaw crushing or disc milling; after coarse crushing, the average particle size D50 of the samarium iron alloy is <2mm. The air jet milling process involves using an air jet mill to crush and sort the coarsely crushed samarium-iron alloy, thereby breaking down and dispersing the agglomerated products after the reaction. After air jet milling, the average particle size D50 of the samarium-iron alloy is 0.5~25μm. The hydrogen crushing is carried out in a vacuum hydrogen crushing furnace; The hydrogen crushing is carried out in an atmosphere of 500-900 mbar H2 gas; The hydrogen crushing is carried out according to the following process: the samarium-iron alloy after air jet pulverization is subjected to hydrogen absorption at 150~250℃ for 2~5 hours, and then dehydrogenated by vacuuming at 250~350℃.

2. The method of producing a samarium iron alloy according to claim 1, wherein The average particle size D50 of the Sm2O3 is 1~2μm; And / or, the physical form of the metallic calcium is metallic calcium particles; and / or, the Sm2O3, the Fe and the Ca are determined in the proportions Sm2O3 + 17Fe + 3Ca = Sm2Fe 17 + 3CaO according to the reaction equation. The Ca is prepared at 1.05 to 1.5 times the theoretical amount determined by the reaction equation; the Sm2O3 is prepared at 1.05 to 1.3 times the theoretical amount determined by the reaction equation.

3. The method of producing a samarium iron alloy according to claim 2, wherein The particle size of the metallic calcium particles is 1~2 mm.

4. The method of producing a samarium iron alloy according to claim 2, wherein The molar ratio of Sm2O3 to Fe is 1:(13~17).

5. The method of producing a samarium iron alloy according to claim 4, wherein The molar ratio of Sm2O3 to Fe is 1:16.

2.

6. The method of producing a samarium iron alloy according to claim 2, wherein The molar ratio of Sm2O3 to Ca is 1:(2~5).

7. The method of producing a samarium iron alloy according to claim 6, wherein The molar ratio of Sm2O3 to Ca is 1:2.4, 1:3, or 1:4.

3.

8. The method of producing a samarium iron alloy according to claim 1, wherein The average particle size D50 of the Fe is 80~120μm.

9. The method of producing a samarium iron alloy according to claim 1, wherein The porosity of the Fe is 25-40%.

10. The method of producing a samarium iron alloy according to claim 1, wherein The reduction-diffusion reaction includes a reduction process and a diffusion process; And / or, the reduction-diffusion reaction is carried out according to the following steps: the reduction process involves keeping mixture A at a temperature of 850~950℃ for 1~5h to allow Sm2O3 to be fully reduced, resulting in mixture B; the mixture A consists of Sm2O3, Fe, and Ca; the diffusion process involves keeping mixture B at a temperature of 1050~1180℃ for 2~10h to allow metallic Sm to diffuse into the Fe powder and form a samarium-iron alloy; And / or, the reduction-diffusion reaction is carried out under the protection of an inert gas.

11. The method of producing a samarium iron alloy according to claim 10, wherein In the reduction-diffusion reaction, the reaction temperature and reaction time of the reduction process and the diffusion process may be the same or different; When the reaction temperatures of the reduction process and the diffusion process are the same, the reaction temperature of the reduction process and the diffusion process is 1050~1180℃; the reaction time of the reduction process and the diffusion process is 2~13h. When the reaction temperatures of the reduction process and the diffusion process are different, the reaction temperature of the reduction process is 850-950℃, and the reaction time of the reduction process is 1-5h; the reaction temperature of the diffusion process is 1050-1180℃, and the reaction time of the diffusion process is 2-10h.

12. The method of producing a samarium iron alloy according to claim 11, wherein When the reaction temperatures of the reduction process and the diffusion process are the same, the reaction temperature of the reduction process and the diffusion process is 1120℃ or 1140℃.

13. The method of producing a samarium-iron alloy according to claim 11, wherein When the reaction temperatures of the reduction process and the diffusion process are the same, the reaction time of the reduction process and the diffusion process is 5h, 6h, 8h, 9h or 10h.

14. The method of producing a samarium-iron alloy according to claim 11, wherein When the reaction temperatures of the reduction process and the diffusion process are different, the reaction temperature of the reduction process is 900℃.

15. The method of producing a samarium-iron alloy according to claim 11, wherein When the reaction temperatures of the reduction process and the diffusion process are different, the reaction time of the reduction process is 2h or 3h.

16. The method of producing a samarium-iron alloy according to claim 11, wherein When the reaction temperatures of the reduction process and the diffusion process are different, the reaction temperature of the diffusion process is 1100℃, 1120℃, 1140℃, 1150℃ or 1160℃.

17. The method of producing a samarium-iron alloy according to claim 11, wherein When the reaction temperatures of the reduction process and the diffusion process are different, the reaction time of the diffusion process is 4h, 6h or 8h.

18. The method of producing a samarium iron alloy according to claim 10, wherein The inert gas is argon.

19. A samarium-iron alloy characterized by, The samarium-iron alloy is prepared by the method of any one of claims 1-18.

20. A samarium-iron alloy as claimed in claim 19, characterized in that The samarium-iron alloy is in powder form.

21. A samarium-iron alloy as claimed in claim 19, wherein The average particle size D50 of the samarium-iron alloy is 0.2-4μm.

22. The samarium-iron alloy of claim 21, wherein, The average particle size D50 of the samarium-iron alloy is 1.7μm, 1.8μm, 2.1μm, 2.3μm or 2.5μm.

23. Use of the samarium-iron alloy of any one of claims 19-22 in the preparation of a samarium-iron-nitrogen permanent magnetic material.

24. A method of producing a samarium iron nitride permanent magnet material, characterized by, The preparation method of the samarium-iron-nitrogen permanent magnetic material comprises the following step: subjecting the samarium-iron alloy of any one of claims 19-22 to a nitriding treatment.

25. The method of producing a samarium iron nitride permanent magnet material according to claim 24, wherein the sintering is performed at a temperature of 1,100 to 1,300°C for 1 to 10 hours. The temperature of the nitriding treatment is 450-550℃. And / or, the pressure of the nitriding treatment is 0.09MPa-1.5MPa. And / or, the time of the nitriding treatment is 4-20h. And / or, the medium of the nitriding treatment is N2, NH3, a mixed gas of N2+H2, a mixed gas of N2+NH3, a mixed gas of NH3+H2, or a mixed gas of N2+NH3+H2. And / or, after the nitriding treatment, the steps of water washing and drying are further included.

26. The method of producing a samarium iron nitride permanent magnet material according to claim 25, wherein The temperature of the nitriding treatment is 480℃, 500℃ or 520℃. And / or, the pressure of the nitriding treatment is 0.2MPa, 0.5MPa, 0.8MPa, 0.9MPa, 1MPa, 1.2MPa or 1.5MPa. And / or, the time of the nitriding treatment is 5h, 6h, 10h, 12h or 15h.

27. The method for preparing samarium iron nitrogen permanent magnet material as described in claim 25, characterized in that, The water washing solution used in the water washing is water.

28. The method for preparing samarium iron nitrogen permanent magnet material as described in claim 25, characterized in that, After the water washing, the step of dehydration treatment is further included.

29. The method for preparing samarium iron nitrogen permanent magnet material as described in claim 28, characterized in that, The solvent of the dehydration treatment is an organic solvent.

30. The method of producing a samarium iron nitride permanent magnet material according to claim 29, wherein The organic solvent is alcohol or acetone.

31. The method of producing a samarium iron nitride permanent magnet material according to claim 25, wherein The drying process is vacuum drying.

32. The method of producing a samarium iron nitride permanent magnet material according to claim 25, wherein After the drying, the steps of airflow dispersion and classification are further included.

33. The method of producing a samarium iron nitride permanent magnet material according to claim 32, wherein the sintering is performed at a temperature of 1,100 to 1,300°C for 1 to 10 hours. The airflow dispersion and classification process adopts an airflow mill.

34. The method of producing a samarium iron nitride permanent magnet material according to claim 33, wherein In the airflow dispersion and classification process, the product is simultaneously subjected to antioxidant treatment and dispersion treatment.

35. The method of producing a samarium iron nitride permanent magnet material according to claim 34, wherein the sintering is performed at a temperature of 1,100 to 1,300°C for 1 to 10 hours. 35 The antioxidant treatment is performed by adding an organic antioxidant during the airflow milling process.

36. The method of producing a samarium iron nitride permanent magnet material according to claim 35, wherein The amount of the organic antioxidant added is 0.2-2.5%.

37. The method of producing a samarium iron nitride permanent magnet material according to claim 36, wherein The amount of the organic antioxidant added is 0.5%.

38. The method of producing a samarium iron nitride permanent magnet material according to claim 34, wherein The dispersion treatment is performed by adding a dispersant during the airflow milling process.

39. The method of producing a samarium iron nitride permanent magnet material according to claim 38, wherein The amount of the dispersant added is 0.2-2.5%.

40. The method of producing a samarium iron nitride permanent magnet material according to claim 39, wherein The amount of the dispersant added is 0.5%.

41. The method for preparing samarium iron nitrogen permanent magnet material as described in claim 34, characterized in that, The antioxidant treatment is performed by adding an organic antioxidant during the airflow milling process, and the dispersion treatment is performed by adding a dispersant during the airflow milling process, and the sum of the amounts of the organic antioxidant and the dispersant added is 0.8-4.0%.

42. The method of producing a samarium iron nitride permanent magnet material according to claim 41, wherein The sum of the amounts of the organic antioxidant and the dispersant added is 1% or 1.5%.

43. A samarium iron nitride permanent magnetic material, characterized by, The samarium-iron-nitrogen permanent magnetic material is prepared by the method for preparing a samarium-iron-nitrogen permanent magnetic material according to any one of claims 24-42.

44. A samarium iron nitride permanent magnetic material as claimed in claim 43, wherein, The average particle size D50 of the samarium-iron-nitrogen permanent magnetic material is 0.2-4 μm. ​ 45. A samarium iron nitride permanent magnetic material as claimed in claim 44, wherein, The average particle size D50 of the samarium-iron-nitrogen permanent magnetic material is 1.7 μm, 1.8 μm, 2.1 μm, 2.3 μm or 2.5 μm. ​ 46. Use of the samarium-iron-nitrogen permanent magnetic material according to any one of claims 43-45 as an electromagnetic element.

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