Nitriding preparation method of easy-to-plane type rare earth alloy nitride soft magnetic material

Abstract

The invention discloses a nitriding preparation method of an easy-to-form rare earth alloy nitride soft magnetic material. The nitriding preparation method is high in nitriding efficiency (less than or equal to 120 minutes), large in nitriding depth (greater than or equal to 90 microns), wide in powder particle size range (less than or equal to 200 microns) and low in technological condition requirement (working air pressure is less than or equal to 0.1 Mpa), and is suitable for various RE2Fe17 easy-to-form rare earth alloy materials. The chemical component of the soft magnetic material prepared by the method is RE2Fe17N3-delta, RE is a rare earth element and is selected from one or more of Ce, Y, Pr and Nd, and delta is a nitrogen deficiency coefficient. The easy-to-face type rare earth soft magnetic nitride prepared by the method has good high-frequency magnetism. Compared with a flowing atmosphere and high-pressure atmosphere nitriding process, the nitriding method has the advantages that on one hand, the requirement for the small particle size of powder can be lowered, the powder manufacturing difficulty is lowered, and the oxidation problem is effectively avoided; on the other hand, flowing gases such as H2 and NH3 do not need to be provided in the nitriding process, so that the air pressure and the requirements on high-pressure reaction equipment can be obviously reduced.

Description

Technical Field

[0001] The invention relates to a nitriding preparation method for an easy-surface rare earth alloy nitride soft magnetic material, belonging to the field of metallic soft magnetic materials. Background Art

[0002] With the rapid development of the information industry, the functional requirements of electronic devices are increasing. For example, wireless network technology and wireless charging technology are widely used in mobile phones, computers, and even new energy vehicles. Electronic devices pursue higher transmission frequency and conversion density under high-frequency working conditions. In the existing technology, high-frequency soft magnetic materials are mostly ferrite materials, such as MnZn, NiZn and other materials. Subject to the high-frequency resonance limit, when the saturation magnetization intensity remains unchanged, increasing the resonant frequency of the material will inevitably cause the magnetic permeability of the magnet to decrease, resulting in these materials being unable to be used at higher frequencies. 17 Such materials can break through the high-frequency resonance limitation and form RE2Fe by nitridation 17 N materials have tuned high-frequency performance, exhibiting high resonant frequencies and high complex permeability in the MHz high-frequency band. Therefore, they have promising prospects for development and application in MHz-GHz high-frequency or power electromagnetic signal converters.

[0003] CN101699579A discloses a neodymium iron nitrogen high-frequency soft magnetic material. The preparation method comprises the following steps: 10 to 30 weight percent neodymium and 70 to 90 weight percent iron are smelted into an iron-based alloy, which is then crushed and ground into powder of less than or equal to 5 microns, and the powder is then nitrided at 250 to 550°C to obtain Nd2Fe 17 N 3-δ , where 0≤δ≤0.5. The disclosed nitriding method only provides the optimal nitriding temperature of 480°C, without disclosing more technical details. The composite material preparation method is to put the above-mentioned materials into an uncured adhesive material, and after fully mixing, put it into a mold made of non-magnetic material, and place the mold in a magnetic field, wherein the adhesive material is a polymer material such as resin or paraffin or polyethylene or polypropylene. The intermetallic compound material is mainly composed of metal elements, and its purpose is to improve the complex magnetic permeability and electromagnetic wave absorption performance of the obtained alloy.

[0004] CN101699578A discloses a rare earth iron nitrogen high frequency soft magnetic material, the general formula of which is R2Fe 17 N 3-δ, where R is any one or any combination of any two of Y, Ce, Pr, Gd, Tb, Dy, Ho, Er, Tm, and Lu among the rare earth elements, and 0≤δ≤0.5. The preparation method comprises smelting 10-30 wt% of rare earth and 70-90 wt% of iron into an iron-based alloy, then grinding the alloy into a powder of 5 microns or less, and then nitriding the powder at 250-550°C to obtain R2Fe 17 N 3-δ . The disclosed nitriding method only provides the optimal nitriding temperature of 480°C, without disclosing more technical details. The composite material preparation method is to put the above-mentioned materials into an uncured adhesive material, and after fully mixing, put it into a mold made of non-magnetic material, and place the mold in a magnetic field, wherein the adhesive material is a polymer material such as resin or paraffin or polyethylene or polypropylene. The intermetallic compound material uses metal elements as the main constituent elements, and its purpose is to improve the complex magnetic permeability and electromagnetic wave absorption performance of the obtained alloy.

[0005] CN113871124A discloses a method for preparing high-performance samarium iron nitrogen permanent magnet material with high nitriding efficiency, wherein the method is as follows: Sm2Fe 17 The alloy powder was graded and screened from 300 to 2000 mesh, and the tower vacuum nitriding furnace was pumped to a low vacuum of 1×10 -3 Pa, continuously fill the bottom of the tower vacuum nitriding furnace with high-speed high-purity nitrogen gas flow (10-30m / s) for nitriding treatment for 10-30 hours. The invention provides a method for preparing high-performance samarium iron nitrogen permanent magnet materials with high nitriding efficiency, using nitrogen gas flow to flush Sm2Fe 17 Alloy powder, making Sm2Fe 17 The alloy powder can be fully exposed to nitrogen, improving the nitriding efficiency. This method uses high-pressure equipment and high-pressure N2 gas flow to implement the nitriding process, the purpose of which is to increase the nitrogen content and nitriding efficiency of the resulting alloy.

[0006] CN 114622155 A discloses a vacuum nitriding method for samarium iron nitrogen powder, the preparation method of which is as follows: (1) samarium iron (Sm2Fe 17 ) The powder is placed in the rotating powder barrel of a vacuum rotary nitriding furnace, and the rotating powder barrel is controlled to rotate alternately forward and reverse; (2) nitrogen is filled into the furnace body, and when the pressure in the furnace body reaches 0.2-0.5MPa, nitrogen is alternately filled and discharged, with a nitrogen flow rate of 15-20L / min, and the furnace body is heated for nitriding treatment, and the heating time is 8-16h; (4) After nitriding is completed, the powder is cooled, the gas is released, and the samarium iron nitrogen powder is taken out. This method uses a vacuum rotary nitriding furnace and a high-pressure N2 gas flow to implement the nitriding process, and its purpose is to increase the nitrogen content and nitriding efficiency of the resulting alloy.

[0007] Theoretically, Th2Zn has rhombohedral symmetry 17 Structure of RE2Fe 17 The alloy unit cell can introduce 3 interstitial N atoms, which has a nitriding limit. At the same time, the nitriding process has a great influence on the nitriding amount and magnetic properties of the material. At present, the flow atmosphere and high pressure atmosphere annealing nitriding process are widely used to achieve RE2Fe 17 The nitriding process of the material. The nitriding efficiency of the process using a single flow N2 atmosphere environment is low. In order to improve the nitriding efficiency, RE2Fe 17 The material has a particle size of less than 50 microns, while the smaller particle size RE2Fe 17 The powder is very easy to oxidize under air conditions, so additional anti-oxidation measures are needed, which increases costs. The high-temperature annealing process using a mixed atmosphere of flowing N2, H2 and NH3 can use the activity of H2 and NH3 at high temperatures to improve the nitriding efficiency. However, the flowing H2 and NH3 not only increase the safety requirements of the nitriding annealing process equipment, but also increase the difficulty of recovering the small amount of H2 and NH3 at the outlet, which limits the industrial application of the nitriding process and method using flowing gas, further affecting the RE2Fe 17 Large-scale preparation, development and utilization of N materials. However, the high-pressure atmosphere annealing nitriding process requires the use of high-pressure reaction equipment that can withstand 0.2-0.5MPa, which significantly increases the complexity of the equipment and process. Therefore, there is an urgent need for a nitriding process with high efficiency, large nitriding depth, wide requirements for powder particle size, simple process and low cost, and suitable for a variety of easy-to-surface rare earth metal alloys RE2Fe 17 Nitriding method for similar materials. Summary of the Invention

[0008] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing the nitridation of the surface-easy rare earth alloy nitride soft magnetic material, which is suitable for industrial preparation of the above-mentioned RE2Fe 17 N 3-δ The nitriding method is used to obtain RE2Fe with a high resonance frequency and high complex permeability in the MHz range. 17 N 3-δ Material.

[0009] The present invention achieves the above-mentioned purpose through the following technical solutions.

[0010] The present invention provides a nitriding preparation method of an easy-surface rare earth alloy nitride soft magnetic material, wherein the chemical composition of the easy-surface rare earth alloy nitride soft magnetic material is RE2Fe 17 N 3-δ ; wherein RE is selected from one or more of Ce, Y, Pr and Nd; δ is the nitrogen deficiency coefficient in the structure, 0<δ≤2;

[0011] The nitriding preparation method comprises the following steps:

[0012] 1) crushing and sieving the surface-easy rare earth alloy soft magnetic material to obtain uniform alloy powder;

[0013] 2) fully stirring the alloy powder and the nitrogen-rich compound to form a mixture;

[0014] 3) The mixture is subjected to nitriding treatment to obtain the easy-surface rare earth alloy nitride soft magnetic material.

[0015] According to a preferred embodiment of the present invention, the chemical composition of the easy-surface rare earth alloy soft magnetic material in step 1) is RE2Fe 17 , wherein RE is selected from one or more of Ce, Y, Pr and Nd, and the raw material purity is at least industrial pure.

[0016] According to a preferred embodiment of the present invention, the particle size of the alloy powder ranges from 50 microns to 300 microns. Preferably, the particle size of the alloy powder ranges from 100 to 150 microns.

[0017] According to a preferred embodiment of the present invention, the chemical structure of the nitrogen-rich compound is rich in -NH3 groups and can be pyrolyzed at 100-400°C to release NH3; the nitrogen-rich compound is selected from one or more of urea, melamine, dicyandiamide, ammonium bicarbonate, and amino acids, and has a purity of industrial purity or above.

[0018] According to a preferred embodiment of the present invention, the mass ratio of the alloy powder to the nitrogen-rich compound is 8 to 10:1.

[0019] According to a preferred embodiment of the present invention, step 3) is specifically as follows: placing the mixture into an inert atmosphere furnace or a heating device capable of providing inert atmosphere protection, and performing nitriding treatment at 450-600° C. under the condition that the initial pressure of the inert atmosphere is greater than or equal to 0.1 MPa. After reaching the target temperature, the nitriding process time is 20 minutes to 3 hours.

[0020] According to a preferred embodiment of the present invention, during the nitriding treatment at 450-600° C., no flowing nitrogen source gas or hydrogen gas flow is provided.

[0021] The present invention also provides a face-easy rare earth alloy nitride soft magnetic material prepared by the method.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention utilizes the thermal decomposition of nitrogen-rich compounds to release NH3 components, provides a static partial pressure of NH3, and cooperates with N2 to realize the nitriding process of rare earth alloy soft magnetic materials; on the one hand, compared with the flowing atmosphere nitriding method, the entire nitriding process in the present invention does not require the use of flowing gas to stabilize the gas pressure, thereby avoiding the safety of H2 use and exhaust gas treatment problems in the nitriding process; on the other hand, compared with the high-pressure (0.8Mpa) atmosphere nitriding method, the gas pressure of the entire nitriding process in the present invention does not exceed 0.2Mpa, and no high-pressure reaction equipment is used, which reduces the overall process complexity.

[0024] (2) The preparation process of the present invention is simple and feasible. After reaching the nitriding treatment temperature, the nitriding depth is not less than 100 microns within a short time (20 minutes to 3 hours). Therefore, the required RE2M 17 The powder particle size can be selected from 50 to 200 microns, which significantly improves the nitriding efficiency. Compared with the existing nitriding technology, which requires the alloy powder particle size to be less than 30 microns and provides an oxygen-free environment during the treatment process to prevent the oxidation of the alloy powder, the present invention significantly reduces the powder particle size requirements and the cost of anti-oxidation measures. At the same time, the nitrogen-rich compounds required in the preparation process of the present invention are common and low-cost.

[0025] (3) Relevant experimental studies have shown that the easy-surface RE2Fe obtained by the nitriding method of the present invention 17 N 3-δ The material has high ferromagnetic properties at room temperature and high theoretical domain wall displacement resonance frequency (160 MHz) and domain wall spin resonance frequency (1 GHz).

[0026] (4) The present invention provides a simple, low-cost, and efficient preparation method for the easy-to-surface RE2Fe 17 N 3-δ The method of using this material has broad application prospects in the field of high-frequency inductance in the MHz range. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The X-ray diffraction spectra of the material of Example 1 of the present invention before and after nitridation, wherein (a) is before nitridation; (b) is after nitridation.

[0028] Figure 2 This is a diagram of the static magnetic properties of the material of Example 1 of the present invention before and after nitridation at room temperature.

[0029] Figure 3 This is a cross-sectional diagram of electron probe scanning nitriding of a bulk material under the same experimental conditions as Example 1 of the present invention.

[0030] Figure 4 Graph showing the relationship between the complex magnetic permeability and frequency after nitridation of Example 1 of the present invention, where (a) is before nitridation and (b) is after nitridation.

[0031] Figure 5 The X-ray diffraction spectra of the material of Example 2 of the present invention before and after nitridation, where (a) is before nitridation; (b) is after nitridation.

[0032] Figure 6 This is a diagram of the static magnetic properties of the material of Example 2 of the present invention before and after nitridation at room temperature.

[0033] Figure 7 This is an electron probe scanning nitriding cross-section diagram of the bulk material under the same experimental conditions as Example 2 of the present invention.

[0034] Figure 8 Graph showing the relationship between the complex magnetic permeability and frequency after nitridation of Example 2 of the present invention, where (a) is before nitridation and (b) is after nitridation. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0036] The present invention provides a surface-friendly rare earth alloy nitride soft magnetic material. The present invention found that by pyrolysis of nitrogen-rich compounds NH3 to solid-dissolve N into RE2M 17 The alloy has a high local NH3 partial pressure, which improves the nitriding efficiency and nitriding depth, and can obtain a face-change type rare earth alloy nitride soft magnetic material with a single nitriding depth of not less than 100 microns. It can also improve the domain wall displacement and natural resonance frequency of the face-change type rare earth alloy nitride soft magnetic material in the MHz range, thereby obtaining a face-change type rare earth alloy nitride soft magnetic material with better performance.

[0037] The chemical composition of the easy-surface rare earth alloy nitride soft magnetic material is RE2Fe 17 N 3-δ . It may contain unavoidable impurities. Wherein, RE is selected from one or more of Ce, Y, Pr and Nd; preferably, RE is selected from one of Ce, Y, Pr and Nd. According to one embodiment of the present invention, M is Ce. Wherein, δ is the nitrogen deficiency coefficient in the structure, 0<δ≤2, preferably 0<δ≤1, more preferably, 0<δ≤0.9, further preferably 0<δ≤0.1, for example, δ is 0.04;

[0038] According to a specific embodiment of the present invention, the chemical composition of the easy-surface rare earth alloy nitride soft magnetic material is RE2Fe 17 N 2.96 .

[0039] The method for preparing the easy-surface rare earth alloy nitride soft magnetic material of the present invention comprises the following steps: (1) preparing the easy-surface rare earth alloy soft magnetic material powder; (2) mixing the powder; and (3) annealing.

[0040] (1) Preparation steps of easy-surface rare earth alloy soft magnetic material powder

[0041] In a specific embodiment of the present invention, the steps are as follows: RE and Fe metals are weighed according to a weight ratio calculated by measuring the molar ratio of 2:17, and a master alloy is obtained by using a smelting furnace, and then RE2Fe is obtained by annealing in a vacuum furnace. 17 Master alloy. RE2Fe 17 The master alloy is crushed and sieved to obtain alloy powder.

[0042] RE2Fe 17 The master alloy crushing and screening range is selected from 50 to 200 microns, preferably 100 to 150 microns.

[0043] In the present invention, the method for obtaining the alloy from the single metal is not particularly limited, and those known in the art can be used, for example, high-frequency arc melting, medium-frequency casting, and strip-spinning methods.

[0044] When using the medium frequency casting method, a Φ50mm*50mm copper mold can be used, and a quartz crucible can be used. In certain embodiments, the co-medium frequency casting method may include the following steps: weighing RE and Fe metals according to a weight ratio calculated by measuring the molar ratio of 2:17, and placing them in a crucible, increasing the coil power, and the alloy mixture begins to melt and continues to mix to obtain a master alloy; placing the cut master alloy in a vacuum furnace at 1000℃ for annealing for 10 days; after the annealing process is completed, RE2Fe 17 The master alloy is quenched and RE2Fe is obtained 17 alloy.

[0045] In the present invention, RE2Fe 17 The method for crushing and screening the master alloy to obtain alloy powder is not particularly limited, and any method known in the art may be used, for example, direct crushing and ball milling.

[0046] (2) Powder mixing step: fully stirring the alloy powder and the nitrogen-rich compound to form a mixture;

[0047] In the present invention, the nitrogen-rich compound may be a compound containing an -NH3 functional group that can be pyrolyzed at 100-400°C to release NH3. Preferably, the nitrogen-rich compound is selected from one or more of urea, melamine, dicyandiamide, ammonium bicarbonate, and amino acids. More preferably, the nitrogen-rich compound is selected from one of urea, melamine, dicyandiamide, ammonium bicarbonate, and amino acids. According to one embodiment of the present invention, the nitrogen-rich compound is urea.

[0048] The mass ratio of the nitrogen-rich compound to the alloy powder is 8 to 10:1, preferably 9 to 10:1, and more preferably 10:1.

[0049] (3) Annealing step: annealing the mixture to obtain a nitrided material.

[0050] Specifically, the mixture is placed in a heating device capable of providing inert atmosphere protection, and annealed at 400-600° C. for 20 minutes to 3 hours under the inert gas atmosphere. During the annealing process at 400-600° C., no flowing inert gas flow is provided.

[0051] Thus, on the one hand, the present invention utilizes the pyrolysis of nitrogen-rich compounds to release NH3 components, providing a local high-pressure active NH3 atmosphere to achieve N entering RE2Fe 17 On the other hand, in the process of heating and annealing the mixture, the pyrolysis of the nitrogen-rich compound provides local high-pressure NH3, which increases the penetration of N into RE2Fe 17 Compared to traditional flowing atmosphere reduction methods, the present invention eliminates the need for flowing gas to stabilize gas pressure during the entire nitriding process, thus avoiding the use of additional reducing agents or gas safety and tail gas treatment issues. Furthermore, the high efficiency and depth of the nitriding process reduce the particle size requirements of the alloy powder, thereby lowering the requirements for the powder's antioxidant properties. This reduces overall process complexity, making the process simpler and more cost-effective.

[0052] In the present invention, the inert atmosphere can be a protective gas atmosphere formed by nitrogen. The heating device capable of providing inert atmosphere protection according to the present invention can be an inert atmosphere furnace.

[0053] The annealing temperature may be 450 to 600° C., preferably 450 to 550° C., more preferably 450 to 500° C. The annealing time may be 20 minutes to 3 hours, preferably 1.5 to 3 hours, more preferably 2 to 3 hours.

[0054] The inventors of this application believe that RE2Fe begins to form when the temperature rises to 400-450°C. 17 N 3-δ Nano-grains are formed and then solid-solution is carried out to form an intermediate phase compound structure during the subsequent temperature-raising annealing process.

[0055] Some of the test methods in the following examples and comparative examples are described as follows:

[0056] Electron probe image: Using JXA-IHP200F Hyper probe.

[0057] XRD pattern: Bruker D8 Advance was used.

[0058] Room temperature static magnetic properties diagram: using Quantum Design VersaLab.

[0059] High-frequency magnetic parameter diagram: Using KEYSIGHT Impedance Analyzer E4991B.

[0060] Example 1

[0061] The surface-friendly rare earth alloy nitride soft magnetic material in this embodiment is Ce2Fe 17 N 2.96 , that is, δ = 0.04.

[0062] The preparation method of the easy-surface rare earth alloy nitride soft magnetic material is as follows:

[0063] According to the molar ratio of Ce and Fe, the corresponding amount of metal was cast through a medium frequency induction furnace to obtain a master alloy; then, Ce2Fe was obtained by annealing at 1000℃ in a vacuum furnace for 10 days. 17 Master alloy; Ce2Fe 17 The master alloy is crushed and screened to select Ce2Fe with a particle size of 100-150 microns 17 Powder material 1g;

[0064] Take 10g of urea and mix it thoroughly with the alloy powder to obtain a mixture; place the mixture in an inert atmosphere annealing device, provide an initial N2 atmosphere of 0.1MPa; anneal at 490℃ for 2 hours to obtain Ce2Fe 17 N 2.96 Material.

[0065] X-ray diffraction spectra before and after nitriding are shown in Figure 1 , room temperature static magnetic properties can be seen Figure 2 , the electron probe scanning nitriding cross-section of the bulk material under the same nitriding conditions is shown in Figure 3 Under the same nitriding conditions, the high frequency magnetic properties of the powder composite material can be seen Figure 4 .

[0066] Depend on Figure 1 It can be seen that the material obtained by nitriding in this example 1 is Ce2Fe 17 N3 phase (XRD-Cobalt target), in accordance with standard card PDF#97-065-8561.

[0067] Depend on Figure 2 It can be seen that the Ce2Fe obtained by nitriding in Example 1 17 N 2.96 The static magnetic properties of powder material at room temperature reach 148.3emu / g. 17 The static magnetic properties of the material tested under the same conditions are 55emu / g.

[0068] Depend on Figure 3 It can be seen that the Ce2Fe obtained by nitriding in Example 1 17 N 2.96 For bulk materials, under the same nitriding conditions, the nitriding depth is greater than or equal to 165μm.

[0069] Depend on Figure 4 It can be seen that the material obtained by nitridation in Example 1 is compounded with polyurethane (30at.%) and oriented in a 0.7T magnetic field. The domain wall displacement resonance frequency in the range of 1-1000MHz is 160MHz, and the domain wall spin resonance frequency is 1GHz, which is a good high-frequency soft magnetic material. 17 The composite material, when tested under the same conditions, has a domain wall displacement resonance frequency of 31 MHz and a domain wall spin resonance frequency of 100 MHz.

[0070] Example 2

[0071] The surface-friendly rare earth alloy nitride soft magnetic material in this embodiment is Ce2Fe 17 N 2.11 , that is, δ = 0.89.

[0072] The preparation method of the easy-surface rare earth alloy nitride soft magnetic material is as follows:

[0073] According to the molar ratio of Ce and Fe, the corresponding amount of metal was cast through a medium frequency induction furnace to obtain a master alloy; then, Ce2Fe was obtained by annealing at 1000℃ in a vacuum furnace for 10 days. 17 Master alloy; Ce2Fe 17 The master alloy is crushed and screened to select Ce2Fe with a particle size of 63-100 microns 17 Powder material 1g;

[0074] Take 10g of urea and mix it thoroughly with the alloy powder to obtain a mixture; place the mixture in an inert atmosphere annealing device, provide an initial N2 atmosphere of 0.1MPa; anneal at 490℃ for 60 minutes to obtain Ce2Fe 17 N 2.11 Material.

[0075] X-ray diffraction spectra before and after nitriding are shown in Figure 5 , room temperature static magnetic properties can be seen Figure 6 , the electron probe scanning nitriding cross-section of the bulk material under the same nitriding conditions is shown in Figure 7 Under the same nitriding conditions, the high frequency magnetic properties of the powder composite material can be seen Figure 8 The performance test method is the same as that in Example 1.

[0076] Depend on Figure 5 It can be seen that the material obtained by nitriding in Example 2 is Ce2Fe17 N3 phase (XRD-Cobalt target), in accordance with standard card PDF#97-065-8561.

[0077] Depend on Figure 6 It can be seen that the Ce2Fe obtained by nitriding in Example 2 17 N 2.11 The static magnetic properties of the powder material at room temperature reach 131emu / g.

[0078] Depend on Figure 7 It can be seen that the Ce2Fe obtained by nitriding in Example 2 17 N 2.11 For bulk materials, under the same nitriding conditions, the nitriding depth is greater than or equal to 165μm.

[0079] Depend on Figure 8 It can be seen that after the material obtained by nitridation in Example 2 is compounded with polyurethane (30at.%) and oriented in a 0.7T magnetic field, the initial value of 1MHz magnetic permeability can be achieved, the domain wall displacement resonance frequency is 107MHz, and the domain wall spin resonance frequency is 316MHz, which is a good high-frequency soft magnetic material.

[0080] Examples 3-7

[0081] Examples 3-7 used the same raw materials and preparation method as Example 2, differing from Example 2 in terms of δ, nitriding temperature, nitriding time, and urea dosage. The static magnetic properties of the materials obtained by nitriding Examples 3-7 at room temperature are shown in the Ms column of Table 1. Comparative Examples 1-5 used a conventional nitriding method (specifically, the nitriding process involved flowing a nitrogen-source atmosphere at the gas flow rate and pressure specified in Table 2 at the temperature specified for each comparative example, for the specified duration). The static magnetic properties of the materials obtained by nitriding at room temperature are shown in the Ms column of Table 2.

[0082] Table 1 Performance data list of materials in Examples 3-7

[0083]

[0084] Table 2 Performance data list of materials in comparative examples 1-5

[0085]

[0086] As can be seen from Table 1 above, the nitriding condition window provided by the present invention can be used to adjust Ce2Fe 17 N 3-δThe nitrogen content and Ms of Ce2Fe2O3 are improved, and it can be seen from Table 2 that the traditional large-flow gas nitriding method, such as N2 or NH3 atmosphere, requires a longer time, higher temperature and higher initial gas pressure to adjust the 17 N 3-δ The nitrogen content and its Ms, therefore, the nitriding efficiency is low and the high pressure and tail gas treatment equipment cost requirements increase.

[0087] The present invention is not limited to the above-mentioned embodiments. Any modification, improvement, or substitution that can be conceived by those skilled in the art without departing from the essential content of the present invention shall fall within the scope of the present invention.

Claims

1. A nitriding preparation method for a surface-easy rare earth alloy nitride soft magnetic material, wherein the chemical composition of the surface-easy rare earth alloy nitride soft magnetic material is RE2Fe 17 N 3-δ ;in, RE is selected from one or more of Ce, Y, Pr and Nd; δ is the nitrogen deficiency coefficient in the structure, 0<δ≤2; It is characterized in that the nitriding preparation method comprises the following steps: 1) crushing and sieving the surface-easy rare earth alloy soft magnetic material to obtain uniform alloy powder; 2) fully stirring the alloy powder and the nitrogen-rich compound to form a mixture; 3) The mixture is subjected to nitriding treatment to obtain the easy-surface rare earth alloy nitride soft magnetic material.

2. The preparation method according to claim 1, characterized in that Step 1) The chemical composition of the surface-friendly rare earth alloy soft magnetic material is RE2Fe 17 , wherein RE is selected from one or more of Ce, Y, Pr and Nd, and the raw material purity is at least industrial pure.

3. The preparation method according to claim 1, characterized in that The particle size of the alloy powder ranges from 50 microns to 300 microns.

4. The preparation method according to claim 3, characterized in that The particle size of the alloy powder ranges from 100 to 150 microns.

5. The preparation method according to claim 1, characterized in that The nitrogen-rich compound has a rich -NH3 group in its chemical structure and can be pyrolyzed at 100-400°C to release NH3; the nitrogen-rich compound is selected from one or more of urea, melamine, dicyandiamide, ammonium bicarbonate, and amino acids, and has a purity of industrial purity or above.

6. The preparation method according to claim 1, characterized in that The mass ratio of the alloy powder to the nitrogen-rich compound is 8 to 10:

1.

7. The preparation method according to claim 1, characterized in that The step 3) is specifically as follows: placing the mixture into an inert atmosphere furnace or a heating device capable of providing inert atmosphere protection, and performing nitriding treatment at 450-600° C. under the condition that the initial pressure of the inert atmosphere is greater than or equal to 0.1 MPa. After reaching the target temperature, the nitriding process time is 20 minutes to 3 hours.

8. The preparation method according to claim 1, characterized in that During the nitriding treatment at 450-600° C., no flowing nitrogen source gas or hydrogen gas flow is provided.

9. A face-change rare earth alloy nitride soft magnetic material prepared by the method according to any one of claims 1 to 8.

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