A samarium iron alloy, samarium iron nitrogen permanent magnet material, its manufacturing method, and its applications

Abstract

This invention discloses a samarium iron alloy, a samarium iron nitrogen permanent magnet material, its manufacturing method, and its applications. The manufacturing method of the samarium iron alloy includes the following steps: subjecting raw materials to reduction diffusion treatment and hydrogen crushing treatment, wherein the raw materials include iron powder, samarium oxide powder, and metallic calcium; the hydrogen crushing treatment includes hydrogen absorption and dehydrogenation steps, wherein the hydrogen absorption temperature is 200–300°C; and the dehydrogenation temperature is 300–550°C. The manufacturing method of the samarium iron nitrogen magnet material of this invention can obtain products with small particle sizes (0.2–4 μm) without being limited to the particle size of the raw materials. The prepared samarium iron nitrogen permanent magnet material has low iron impurity and oxygen content and exhibits good magnetic properties. The preparation method of this invention is characterized by high safety, low cost, and ease of production operation.

Description

Technical Field

[0001] This invention relates to a samarium iron alloy, a samarium iron nitrogen permanent magnet material, its manufacturing method, and its 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 that of uniaxial particles. In order to obtain fine grain structure economically and efficiently, the industry usually adopts melt quenching method, hydrogen disproportionation method, mechanical alloying method (e.g., Chinese invention patent CN1202537C), rapid solidification casting method (e.g., Chinese invention patent CN106312077B) or reduction diffusion method (e.g., Chinese invention patent application 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] For the preparation of samarium iron nitrogen magnetic powder by reduction diffusion method, industry theory and practice indicate that Sm2Fe with a particle size between 0.2-4 μm is suitable. 17 N3 magnetic powder has good performance, especially coercivity.

[0004] 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.

[0005] However, if non-fine powder raw materials are used instead of small-particle-size raw materials, the difficulty of the preparation process will be greatly increased. Although ball milling can be used to obtain small-particle-size products, the ball milling process has poor sealing, which will lead to adverse effects such as high iron impurity content, high oxygen content, and poor magnetic properties in the product.

[0006] Therefore, there is an urgent need to provide a method for preparing samarium iron nitrogen magnetic materials, which can obtain samarium iron nitrogen magnetic powder with small particle size and good magnetic properties without being limited by small particle size raw materials. Summary of the Invention

[0007] The technical problem this invention aims to solve is to overcome the shortcomings of existing methods for preparing samarium iron nitride (SMR) magnet materials, which are limited by the particle size of the raw materials and have difficulty in improving magnetic properties. This invention provides a samarium iron alloy, a samarium iron nitride permanent magnet material, its manufacturing method, and its applications. The samarium iron alloy of this invention is used to prepare samarium iron nitride magnet materials, enabling the acquisition of small-particle-size samarium iron nitride magnet materials without being limited by the particle size of the raw materials. The prepared samarium iron nitride permanent magnet materials exhibit excellent magnetic properties.

[0008] This invention reduces the particle size of the product by incorporating an appropriate hydrogen fragmentation process into the reduction-diffusion preparation of samarium iron alloys. This makes it easier to achieve complete nitridation in the subsequent preparation of samarium iron nitride magnet materials, thereby improving the magnetic properties of the samarium iron nitride magnet materials, especially their coercivity.

[0009] The present invention solves the above-mentioned technical problems through the following technical solution:

[0010] A method for manufacturing a samarium-iron alloy, comprising the following steps:

[0011] The raw materials are subjected to reduction diffusion treatment and hydrogen crushing treatment, among which...

[0012] The raw materials include iron powder, samarium oxide powder, and metallic calcium;

[0013] The hydrogen crushing process includes hydrogen absorption and dehydrogenation steps, wherein the temperature for hydrogen absorption is 200–300°C.

[0014] The dehydrogenation temperature is 300-550℃.

[0015] In this invention, the samarium-iron alloy is Sm2Fe. 17 alloy.

[0016] In this invention, the temperature during hydrogen absorption is preferably 250°C, 260°C, or 280°C.

[0017] In this invention, the hydrogen absorption time is preferably 2 to 5 hours, for example 3 hours.

[0018] In this invention, the temperature during dehydrogenation is preferably 350, 380, 400, 450, 500 or 550°C.

[0019] In this invention, before the hydrogen absorption, the following steps can be performed according to conventional practices in the art: evacuation and hydrogen filling.

[0020] The pressure when filling with hydrogen is preferably 500 to 900 mbar, for example 700 mbar.

[0021] In this invention, the hydrogen crushing process can be carried out in a vacuum hydrogen crushing furnace as is conventional in the art.

[0022] In this invention, the iron powder can be commercially available iron powder in the art, and the particle size of the iron powder can be the particle size of conventional iron powder in the art, for example, the D50 particle size of the iron powder is 0.5 to 150 μm, or for example 0.5 μm, 5 μm, 10 μm, 15 μm, 25 μm, 40 μm, 50 μm, 80 μm or 100 μm.

[0023] In this invention, preferably, the iron powder is selected from one or more of spherical iron powder, porous iron powder and reduced iron powder, wherein the porous iron powder may be foamed iron powder.

[0024] The spherical iron powder refers to iron powder with a dense spherical shape, which can be purchased from MCC Xindun Company.

[0025] The porous iron powder refers to iron powder with a certain porosity, which can be purchased from Shijiaweier Technology Co., Ltd.

[0026] The reduced iron powder refers to loose iron powder that has been reduced to remanence by iron(III) oxide under high heat conditions in a hydrogen or carbon monoxide stream, and can be purchased from Guangzhou Metal Metallurgy Co., Ltd.

[0027] The porosity of the porous iron powder is preferably 10% to 40%, for example 20%, 25% or 30%.

[0028] In this invention, the samarium oxide powder can be commercially available samarium oxide powder conventionally in the art.

[0029] In this invention, preferably, the D50 particle size of the samarium oxide powder is 0.1 to 8 μm, for example 0.2 μm, 1.5 μm, 4 μm, 5 μm, 6 μm or 7 μm.

[0030] In this invention, the metallic calcium can be commercially available metallic calcium in the art. The physical form of the metallic calcium can be a conventional physical form in the art, for example, the metallic calcium can be metallic calcium particles. The particle size of the metallic calcium particles can be a conventional particle size of metallic calcium in the art, for example, 1-2 mm.

[0031] In this invention, the amount of the raw materials can be determined according to conventional methods in the art, based on the formula Sm₂O₃ + 17Fe + 3Ca ==Sm₂Fe. 17 The theoretical quantities of the reaction equation for +3CaO are used to make the proportions.

[0032] Preferably, the amount of metallic calcium is prepared according to 1.3 times the theoretical amount in the above reaction equation.

[0033] Preferably, the amount of samarium oxide powder is 1.1 times the theoretical amount according to the above reaction equation.

[0034] In this invention, the reduction-diffusion treatment can be performed according to conventional reduction-diffusion treatment steps in the art. Reduction-diffusion treatment in the art generally includes the following processes: reduction process: at a certain temperature, metallic calcium is melted and the samarium oxide powder is reduced to metallic samarium; diffusion process: metallic samarium diffuses into the iron powder and forms Sm2Fe. 17 alloy.

[0035] In this invention, the temperatures of the reduction process and the diffusion process in the reduction-diffusion treatment can be the same or different.

[0036] When the reduction and diffusion processes in the reduction-diffusion treatment are at the same temperature, the temperature of the reduction-diffusion treatment is preferably 1050-1180℃, for example 1120 or 1140℃.

[0037] The reduction diffusion treatment time is preferably 2-13 hours, for example 5, 6, 8, 9 or 10 hours.

[0038] When the temperatures of the reduction process and the diffusion process in the reduction-diffusion treatment are different, the reduction-diffusion treatment includes the following steps: performing a reduction treatment at 850–950°C and a diffusion treatment at 1050–1180°C.

[0039] The reduction treatment temperature is preferably 900°C.

[0040] The reduction process is preferably carried out over a period of 1-5 hours, for example, 2 hours or 3 hours.

[0041] The diffusion treatment temperature is preferably 1050–1180°C, for example 1100°C, 1120°C, 1140°C, 1150°C or 1160°C.

[0042] The diffusion treatment time is preferably 2-10 hours, for example 4 hours, 6 hours or 8 hours.

[0043] More preferably, the reduction-diffusion treatment includes the following steps: reducing the raw material by holding it at 850–950°C for 1–5 hours to fully reduce Sm₂O₃; then diffusing the reduced material by holding it at 1050–1180°C for 2–10 hours to allow metallic Sm to diffuse into the iron powder and form Sm₂Fe. 17 alloy.

[0044] In this invention, preferably, the reduction diffusion process is carried out under the protection of an inert gas. The inert gas can be a conventional inert gas in the art, such as argon.

[0045] In this invention, preferably, a heating step is included before the reduction diffusion treatment, wherein the heating is performed under vacuum conditions, and the vacuum degree of the vacuum conditions is preferably <0.1 Pa.

[0046] In this invention, preferably, the equipment used for the reduction diffusion process can be conventional equipment for reduction diffusion processes in the art, such as a vacuum heat treatment furnace.

[0047] In this invention, preferably, a coarse crushing step is included after the reduction-diffusion treatment and before the hydrogen crushing treatment. The product at the end of the reduction-diffusion treatment is Sm2Fe. 17 A mixture of components such as CaO and Ca, in which these components are in a mixed and agglomerated state, can be coarsely crushed before hydrogen crushing to reduce the size and improve the hydrogen crushing efficiency.

[0048] The coarse crushing process can be a conventional coarse crushing process in the art, such as mechanical coarse crushing.

[0049] The mechanical coarse crushing can be a jaw crusher or a disc mill crusher.

[0050] After the coarse crushing, preferably, the particle size of the product is <2 mm.

[0051] Preferably, after the coarse crushing and before the hydrogen crushing treatment, a first airflow pulverization step is also included.

[0052] The first air jet milling process can be a conventional air jet milling process in the art.

[0053] The equipment used for the first air jet milling can be any conventional air jet milling equipment in the art, such as an air jet mill. This invention uses an air jet mill to further crush and sort the coarsely crushed powder, breaking down and dispersing the agglomerated products after the reaction, and sorting to obtain a mixed product with a particle size of 0.5–25 μm. It also separates unreacted large iron particles (>25 μm) from the product, resulting in a mixed product with no (or very little) iron powder, thus avoiding the formation of an α-Fe soft magnetic phase in the final magnet and further improving the coercivity of the permanent magnet material.

[0054] The present invention also provides a samarium-iron alloy, which is prepared by the aforementioned method for preparing samarium-iron alloy.

[0055] In this invention, the samarium-iron alloy is preferably in powder form.

[0056] In this invention, the particle size of the samarium iron alloy is preferably 0.2 to 4 μm, for example 1.5 μm, 1.8 μm, 2.8 μm, 3.1 μm, 3.2 μm, 3.5 μm or 3.8 μm.

[0057] The present invention also provides an application of the aforementioned samarium iron alloy in the preparation of samarium iron nitride magnet materials.

[0058] The present invention also provides a method for preparing samarium iron nitride magnet material, which includes the following steps: subjecting the samarium iron alloy prepared by the aforementioned preparation method to nitriding treatment.

[0059] In this invention, the nitriding process can be a conventional nitriding process in the art.

[0060] In this invention, the nitriding temperature is preferably 450–550°C, for example 480°C, 500°C, or 520°C.

[0061] In this invention, the pressure of the nitriding treatment is preferably 0.09 to 1.5 MPa, for example 0.2 MPa, 0.5 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, 1.2 MPa or 1.5 MPa.

[0062] In this invention, the nitriding treatment time is preferably 4 to 20 hours, for example 5, 6, 10, 12 or 15 hours.

[0063] In this invention, the medium used for nitriding in the nitriding treatment can be a medium conventionally used for nitriding in the art, such as a mixture of N2, NH3, N2+H2, N2+NH3, NH3+H2 or N2+NH3+H2.

[0064] In this invention, preferably, after the nitriding treatment, the process further includes water washing and drying steps.

[0065] The water washing process can be a conventional water washing process in the art. The nitrided product is washed with water to remove impurities such as CaO, Ca, and CaH2 from the mixed product.

[0066] The water washing solution used in the process can be a conventional water washing solution in the art, such as water.

[0067] Preferably, the washing solution contains a small amount of a weak acid, and the pH of the washing solution is ≥6. The weak acid can be a conventional weak acid in the art, such as acetic acid.

[0068] Preferably, after washing and before drying, a dehydration step is also included.

[0069] The solvent used for the dehydration process can be a solvent commonly used in the art for dehydration processes, such as an organic solvent.

[0070] The organic solvent may be alcohol or acetone.

[0071] The drying operation can be a conventional drying operation in the art, such as vacuum drying.

[0072] Preferably, after drying, a second air-jet milling step is included to break up and disperse the dried and agglomerated product, thereby obtaining a samarium iron nitrogen permanent magnet material with an appropriate particle size.

[0073] The second air jet milling process can be performed using an air jet mill.

[0074] The gas used in the air jet mill can be a conventional inert gas in the art. The inert gas can be nitrogen or argon.

[0075] Preferably, during the second air jet milling process, the product is simultaneously subjected to antioxidant and dispersion treatment.

[0076] The antioxidant treatment can be carried out by adding an organic antioxidant during the air jet milling process. The amount of organic antioxidant added is preferably 0.2% to 2.5%, for example, 0.5%.

[0077] 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%.

[0078] 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%.

[0079] A samarium iron nitrogen permanent magnet material is prepared by the aforementioned method for preparing samarium iron nitrogen permanent magnet materials.

[0080] In this invention, the particle size of the samarium iron nitrogen permanent magnet material is preferably 0.2-4 μm, for example 1.5 μm, 1.8 μm, 2.1 μm, 2.3 μm, 2.8 μm, 3.1 μm, 3.2 μm, 3.5 μm or 3.8 μm.

[0081] In this invention, the remanence B of the samarium iron nitrogen permanent magnet material r It can reach 13.4-14.8 kGs; coercivity H cj It can reach 8.3-26.7 kOe.

[0082] In this invention, the maximum magnetic energy product BH of the samarium iron nitrogen permanent magnet material is... max It can reach 37.4-45.6 MGOe.

[0083] In this invention, the α-Fe content of the samarium iron nitrogen permanent magnet material can be as low as 2.1 wt%, and the oxygen content can be as low as 2.4 wt%.

[0084] In this invention, "first time" and "second time" have no special meaning.

[0085] 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.

[0086] The reagents and raw materials used in this invention are all commercially available.

[0087] The positive and progressive effects of this invention are as follows:

[0088] (1) By combining hydrogen crushing treatment with reduction diffusion method, this invention can obtain products with small particle size (0.2-4μm) without being limited to the particle size of raw materials. The prepared samarium iron nitrogen permanent magnet material has low iron impurity and oxygen content, significantly improved coercivity, and good magnetic properties.

[0089] (2) In existing technologies, conventional methods such as the belt spinning method and rapid quenching method result in samarium-iron alloys with high reactivity after hydrogen breakage. These alloys are prone to oxidation during subsequent processes such as ball milling and can spontaneously combust in air. Therefore, they pose significant risks in production and application, requiring oxygen-isolated storage and transportation, resulting in stringent production conditions, high costs, and limited large-scale application. In contrast, the preparation method of this invention produces samarium-iron alloy powder that is coated with calcium oxide and residual metallic calcium in the product, resulting in low surface activity. This makes it less prone to oxidation after hydrogen breakage and does not generate heat. This method offers high safety, low cost, and ease of production operation.

[0090] (3) Further, the present invention may also include an air jet milling step before hydrogen crushing treatment of the reduction diffusion products to separate and obtain a mixed product with a particle size of 0.5 to 25 μm, and to separate the larger particles Sm2Fe with a particle size of 4 to 25 μm in the product. 17 The product was subsequently broken down into fine Sm2Fe particles of 0.2–4 μm by hydrogen absorption. 17 Fine alloy powder is beneficial for improving the efficiency and degree of subsequent nitriding, further enhancing the coercivity of the material. Furthermore, large-particle porous iron powder can be used in combination with fine-particle samarium oxide raw materials. During the reduction and diffusion process, after thorough mixing, a material accumulation state is formed where samarium oxide powder encapsulates porous iron powder. During reduction and diffusion, metallic samarium diffuses fully into the interior of the iron powder through the pores, 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.

[0091] (4) Furthermore, the present invention may first nitrid the reduction diffusion product to reduce the Sm2Fe in the mixed product. 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 good magnetic properties. Attached Figure Description

[0092] Figure 1 This is a SEM image of the raw material iron powder (porous iron powder) in Example 1 of the present invention.

[0093] Figure 2 This is a SEM image of the mixed product after reduction and diffusion in Example 1 of the present invention.

[0094] Figure 3 This is a SEM image of the final samarium iron nitrogen magnetic powder obtained in Example 1 of the present invention.

[0095] Figure 4 This is a SEM image of the raw material iron powder (spherical iron powder) in Example 4 of the present invention.

[0096] Figure 5 This is the particle size distribution curve of the mixed product after reduction and diffusion in Example 1 of the present invention.

[0097] Figure 6 This is the particle size distribution curve of the mixed product after reduction and diffusion in Example 1 of the present invention after iron removal. Detailed Implementation

[0098] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0099] Spherical iron powder was purchased from MCC Xindun Company; porous iron powder was purchased from Shijiaweier Technology Co., Ltd.; reduced iron powder was purchased from Guangzhou Metal Metallurgy Co., Ltd.

[0100] Example 1

[0101] A method for preparing samarium iron nitrogen magnetic powder, the preparation process is as follows: batching - reduction diffusion - coarse crushing of product - airflow separation of product - hydrogen crushing - nitriding - impurity washing - product drying - airflow dispersion and classification - finished magnetic powder.

[0102] The specific steps are as follows:

[0103] (1) Porous iron powder or foamed iron powder with a particle size of 80μm (D50) is used as the raw material for the reduction diffusion reaction. The porosity of the porous iron powder or foamed iron powder is 10%. Porous iron powder has high porosity and high reactivity, which can make the reaction proceed fully and quickly. It is easy to break after the reaction.

[0104] (2) Samarium oxide powder is used as raw material with a particle size of 0.2 μm (D50).

[0105] (3) Ingredients: The material ratio is as follows: Sm2O3 + 17Fe + 3Ca = Sm2Fe 17 The reaction equation for +3CaO was determined. To ensure the full reduction of samarium oxide, metallic Ca (particles, particle size 1-2 mm) was added at 1.3 times the theoretical amount determined by the equation (30%). Meanwhile, considering the volatilization of metallic Sm during the reduction diffusion reaction at high temperature, Sm2O3 was added at 1.1 times the theoretical amount determined by the above equation (10% excess). After addition, the raw materials were placed in a mixer for thorough mixing.

[0106] (4) Reduction-Diffusion: Reduction Treatment: The thoroughly mixed raw materials are placed in a vacuum heat treatment furnace and heated. During the temperature increase 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. The material is held at 900℃ for 2 hours for reduction treatment, which melts the metallic calcium and reduces Sm2O3 to metallic samarium. Diffusion Treatment: After the reduction treatment, the material is heated to 1140℃ and held for 6 hours for diffusion treatment, 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.

[0107] (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.

[0108] (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.

[0109] (7) Hydrogen Crushing: The powder after air jet milling is placed in a vacuum hydrogen crushing furnace for hydrogen crushing. After evacuating the furnace, 900 mbar H2 gas is introduced, and the temperature is raised to 260℃ to absorb hydrogen for 3 hours. Then, the furnace is evacuated at 550℃ 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.

[0110] (8) Nitriding: The product after hydrogen crushing was nitrided at 500℃ and 1.2MPa. The nitriding medium was an 8:2 mixture of N2 and H2, and the nitriding time was 6h, so that the Sm2Fe in the mixed product was reduced. 17 Alloy nitriding forms Sm2Fe 17 N3 compounds.

[0111] (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 acetic acid is also added during the washing process to keep the pH of the washing solution ≥ 6. After washing, alcohol is used to dehydrate the washed product.

[0112] (10) The product after thorough washing and dehydration is vacuum dried.

[0113] (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 of approximately 2.8 μm. 17 N3 magnetic powder, organic antioxidants and dispersants are added during the grinding process to treat the magnetic powder for anti-oxidation and dispersion, and the amount of organic antioxidants and dispersants added is 0.5% respectively.

[0114] The raw materials and processes for Examples 1-9 are as shown in Table 1 below, and other conditions are the same as in Example 1.

[0115] Table 1 Raw materials and processes of Examples 1-9

[0116]

[0117]

[0118] Example of effect:

[0119] 1. SEM observation and particle size distribution of the material

[0120] Figure 1 , Figure 2 , Figure 3 The images show a comparison of SEM images of the raw material iron powder (porous iron powder), the reduction-diffusion mixture, and the final samarium iron nitrogen magnetic powder in Example 1. Figure 4 This is a SEM image of the iron powder (spherical iron powder) used in the reduction-diffusion reaction of Example 4. Figure 1-3 It 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 spontaneously breaks down into samarium-iron alloy powder.

[0121] Figure 5 The particle size distribution of the reduction-diffusion mixture obtained in Example 1 is shown. Figure 6 The figure shows the particle size distribution of the reduction-diffusion mixture after airflow crushing and sorting for iron removal in Example 1. As can be seen from the figure, after airflow crushing and sorting, large unreacted residual iron particles in the mixture were completely removed.

[0122] 2. The properties of the prepared magnetic powder were tested, and the typical properties of the magnetic powder in each embodiment are shown in Table 2 below. The test methods are as follows:

[0123] The magnetic properties were measured using a vibrating sample magnetometer (VSM), model LakeShore 7411.

[0124] Particle size was measured using a laser particle size analyzer, specifically a Malvern Mastersizer 2000.

[0125] Oxygen content was measured using an oxygen-nitrogen analyzer, model Horiba EMGA-620W.

[0126] α-Fe was detected using an X-ray diffractometer, specifically a Bruker D8 DISCOVER.

[0127] Calcium content was measured using an inductively coupled plasma optical emission spectrometer (ICP-OES), model SPECTROBLUE FMX36.

[0128] Table 2 Typical magnetic powder properties of Examples 1-9

[0129]

[0130]

[0131] 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 for manufacturing a samarium-iron alloy, characterized in that, It includes the following steps: The raw materials are subjected to reduction diffusion treatment and hydrogen crushing treatment, among which... The raw materials include iron powder, samarium oxide powder, and metallic calcium; The hydrogen decomposition process includes hydrogen absorption and dehydrogenation steps. The process prior to hydrogen absorption includes the following steps: evacuating the vacuum and filling it with hydrogen gas; the pressure during hydrogen filling is 500~900 mbar. The temperature for hydrogen absorption is 200~300℃; The dehydrogenation temperature is 300-550℃.

2. The method for manufacturing samarium-iron alloy as described in claim 1, characterized in that, The samarium iron alloy is Sm2Fe. 17 alloy; And / or, the temperature during hydrogen absorption is 250°C, 260°C, or 280°C; And / or, the hydrogen absorption time is 2-5 hours; And / or, the temperature during dehydrogenation is 350, 380, 400, 450, 500 or 550°C; And / or, the pressure when filling with hydrogen is 700 mbar.

3. The method for manufacturing samarium-iron alloy as described in claim 2, characterized in that, The hydrogen absorption time is 3 hours.

4. The method for manufacturing samarium-iron alloy as described in claim 1, characterized in that, The D50 particle size of the iron powder is 0.5~150μm; And / or, the iron powder is porous iron powder; And / or, the D50 particle size of the samarium oxide powder is 0.1~8μm; And / or, the metallic calcium is metallic calcium particles.

5. The method for manufacturing samarium-iron alloy as described in claim 1, characterized in that, The iron powder is spherical iron powder.

6. The method for manufacturing samarium-iron alloy as described in claim 1, characterized in that, The iron powder is reduced iron powder.

7. The method for manufacturing samarium-iron alloy as described in claim 4, characterized in that, The D50 particle size of the iron powder is 0.5μm, 5μm, 10μm, 15μm, 25μm, 40μm, 50μm, 80μm or 100μm; And / or, the porous iron powder is foamed iron powder; And / or, the porosity of the porous iron powder is 10%~40%; And / or, the D50 particle size of the samarium oxide powder is 0.2 μm, 1.5 μm, 4 μm, 5 μm, 6 μm or 7 μm; And / or, the particle size of the metallic calcium particles is 1-2 mm; And / or, the amount of said metallic calcium is in accordance with the formula Sm₂O₃ + 17Fe + 3Ca == Sm₂Fe 17 The reactants in the +3CaO reaction equation are prepared at 1.3 times the theoretical amount of the ingredients. And / or, the amount of samarium oxide powder used is in accordance with the formula: Sm₂O₃ + 17Fe + 3Ca == Sm₂Fe 17 The reactants are prepared at 1.1 times the theoretical amount of the reaction equation for +3CaO.

8. The method for manufacturing samarium-iron alloy as described in claim 7, characterized in that, The porosity of the porous iron powder is 20%, 25%, or 30%.

9. The method for manufacturing samarium-iron alloy as described in claim 1, characterized in that, The reduction and diffusion processes in the reduction-diffusion treatment are carried out at the same temperature.

10. The method for manufacturing samarium-iron alloy as described in claim 9, characterized in that, The temperature for the reduction diffusion treatment is 1050-1180℃; And / or, the reduction diffusion treatment lasts for 2-13 hours.

11. The method for manufacturing samarium-iron alloy as described in claim 10, characterized in that, The temperature of the reduction diffusion treatment is 1120 or 1140°C; And / or, the reduction diffusion treatment time is 5, 6, 8, 9 or 10 hours.

12. The method for manufacturing samarium-iron alloy as described in claim 1, characterized in that, The reduction and diffusion processes in the reduction-diffusion treatment are carried out at different temperatures; the reduction-diffusion treatment includes a reduction process at 850~950℃ and a diffusion process at 1050~1180℃.

13. The method for manufacturing samarium-iron alloy as described in claim 12, characterized in that, The reduction treatment temperature is 900℃; And / or, the reduction process takes 1-5 hours; And / or, the diffusion treatment time is 2-10 hours.

14. The method for manufacturing samarium-iron alloy as described in claim 13, characterized in that, The reduction process takes 2 hours or 3 hours; And / or, the diffusion treatment temperature is 1100°C, 1120°C, 1140°C, 1150°C, or 1160°C; And / or, the diffusion treatment time is 4h, 6h or 8h.

15. The method for manufacturing samarium-iron alloy as described in claim 1, characterized in that, The reduction-diffusion treatment is carried out under inert gas protection; And / or, prior to the reduction diffusion treatment, a heating step is included; And / or, the equipment used for the reduction diffusion treatment is a vacuum heat treatment furnace; And / or, after the reduction diffusion treatment and before the hydrogen crushing treatment, a coarse crushing step is also included.

16. The method for manufacturing samarium-iron alloy as described in claim 15, characterized in that, The inert gas is argon; And / or, the heating is performed under vacuum conditions; And / or, the coarse crushing process is mechanical coarse crushing.

17. The method for manufacturing samarium-iron alloy as described in claim 16, characterized in that, The vacuum level of the vacuum condition is <0.1 Pa; And / or, the mechanical coarse crushing method is jaw crushing or disc mill crushing.

18. The method for manufacturing samarium-iron alloy as described in claim 15, characterized in that, After coarse crushing, the particle size of the product is <2mm.

19. The method for manufacturing samarium-iron alloy as described in claim 15, characterized in that, The process includes a first air jet milling step after the coarse crushing and before the hydrogen crushing treatment.

20. The method for manufacturing samarium-iron alloy as described in claim 19, characterized in that, After the first air jet milling, a mixed product with a particle size of 0.5~25μm is obtained.

21. The method for manufacturing samarium-iron alloy as described in claim 20, characterized in that, The equipment used for the first air jet milling is an air jet mill.

22. A samarium-iron alloy, which is prepared by the method of manufacturing samarium-iron alloy as described in any one of claims 1-21.

23. The samarium-iron alloy as described in claim 22, characterized in that, The samarium-iron alloy is in powder form.

24. The samarium-iron alloy as described in claim 23, characterized in that, The samarium-iron alloy has a particle size of 0.2~4μm.

25. The samarium-iron alloy as described in claim 24, characterized in that, The samarium-iron alloy has a particle size of 1.5μm, 1.8μm, 2.8μm, 3.1μm, 3.2μm, 3.5μm or 3.8μm.

26. The application of the samarium iron alloy as described in any one of claims 22-25 in the preparation of samarium iron nitrogen magnet materials.

27. A method for preparing a samarium iron nitride magnet material, characterized in that, It includes the following steps: subjecting the samarium-iron alloy as described in any one of claims 22-25 to nitriding treatment.

28. The method for preparing the samarium iron nitride magnet material as described in claim 27, characterized in that, The nitriding treatment temperature is 450~550℃; And / or, the pressure of the nitriding treatment is 0.09~1.5MPa; And / or, the nitriding treatment time is 4~20h; And / or, the medium used for nitriding in the nitriding treatment is selected from N2, NH3, N2+H2, N2+NH3, NH3+H2 or a mixture of N2+NH3+H2 gases; And / or, after the nitriding treatment, the process may further include a water washing and drying step.

29. The method for preparing samarium iron nitride magnet material as described in claim 28, characterized in that, The nitriding treatment temperature is 480℃, 500℃, or 520℃. And / or, the pressure of the nitriding treatment is 0.2 MPa, 0.5 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, 1.2 MPa or 1.5 MPa; And / or, the nitriding treatment time is 5, 6, 10, 12 or 15 hours; And / or, the washing solution used in the water washing is water; And / or, after the washing and before drying, a dehydration step is also included; And / or, the drying operation is vacuum drying; And / or, after the drying process, a second airflow pulverization step is also included.

30. The method for preparing samarium iron nitride magnet material as described in claim 29, characterized in that, The washing solution contains a small amount of weak acid, and the pH of the washing solution is ≥6; And / or, the solvent used in the dehydration treatment is an organic solvent; And / or, the second air jet milling process is performed using an air jet mill; And / or, during the second air jet milling process, the product is simultaneously subjected to antioxidant treatment and dispersion treatment.

31. The method for preparing samarium iron nitride magnet material as described in claim 30, characterized in that, The weak acid is acetic acid; And / or, the organic solvent is alcohol or acetone; And / or, the gas used in the air jet mill is an inert gas; And / or, the antioxidant treatment is performed by adding an organic antioxidant during the second air jet milling process; And / or, the dispersion treatment is carried out by adding a dispersant during the second air jet milling process.

32. The method for preparing the samarium iron nitride magnet material as described in claim 31, characterized in that, The inert gas is nitrogen or argon; And / or, the amount of organic antioxidant added is 0.2~2.5%; And / or, the amount of the dispersant added is 0.2~2.5%.

33. The method for preparing the samarium iron nitride magnet material as described in claim 32, characterized in that, The sum of the amounts of the organic antioxidant and the dispersant added is 0.8-4.0%.

34. The method for preparing samarium iron nitride magnet material as described in claim 33, characterized in that, The sum of the amounts of the organic antioxidant and the dispersant is 1% or 1.5%.

35. A samarium iron nitrogen permanent magnet material, characterized in that, It is prepared by the method for preparing samarium iron nitrogen permanent magnet material according to any one of claims 27-34.

36. A samarium iron nitrogen permanent magnet material as described in claim 35, characterized in that, The samarium iron nitrogen permanent magnet material has a particle size of 0.2~4μm; And / or, the α-Fe content of the samarium iron nitrogen permanent magnet material is less than 2.1 wt%, and the oxygen content is less than 2.4 wt%.

37. A samarium iron nitrogen permanent magnet material as described in claim 36, characterized in that, The samarium iron nitrogen permanent magnet material has a particle size of 1.5μm, 1.8μm, 2.1μm, 2.3μm, 2.8μm, 3.1μm, 3.2μm, 3.5μm or 3.8μm.

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