Rare earth alloy nitride composite soft magnetic material and preparation method thereof

Abstract

The invention discloses a rare earth alloy nitride composite soft magnetic material and a preparation method thereof, and belongs to the field of metal soft magnetic materials. The material comprises an alloy nitride and a coating layer which is positioned on the surface of the alloy nitride and coats the alloy nitride, wherein the composition of the alloy nitride is Ce2 (FexCo1-x) 17N3-delta, the composition of the coating layer is Fe4N, the rare earth alloy nitride composite material is expressed as Ce2 (FexCo1-x) 17N3-delta-coated Fe4N, x is the atomic ratio of Fe, and delta is a nitrogen deficiency coefficient. A nitrogen-rich compound is adopted for carrying out in-situ nitridation on a Ce2 (FexCo1-x) 17 material, Ce2 (FexCo1-x) 17N3-delta can be generated, a coating layer mainly comprising Fe4N can be formed on the surface of the Ce2 (FexCo1-x) 17N3-delta, and the composite material is obtained. Compared with Ce2 (FexCo1-x) 17, the composite material has the advantages that the eddy-current loss is obviously reduced while the high-frequency magnetism is improved.

Description

Technical Field

[0001] The present invention relates to a rare earth alloy nitride composite soft magnetic material and a preparation method thereof, in particular to the field of metallic soft magnetic materials. Background Art

[0002] Metal soft magnetic composite materials are one of the key basic materials that are indispensable in the field of power electronics. With the rapid development of communication technology and new energy industries, high frequency, high efficiency and low power consumption requirements have been put forward for various power electronic components. The performance of traditional soft magnetic materials is limited by high-frequency resonance, and the magnetic permeability is difficult to maintain and the residual loss increases sharply. Some rare earth transition metal alloys RE2Me 17 (RE is a rare earth element, Me is Fe or Co) has the characteristic of multiple easy magnetization axes in the same plane. This easy plane characteristic can break through the limitations of high-frequency magnetic resonance and has high complex magnetic permeability and resonance frequency in the MHz band.

[0003] CN108777931A discloses a high magnetic permeability electromagnetic wave absorbing material, which is characterized in that the electromagnetic wave absorbing material is composed of a thin sheet of iron-based nanocrystalline alloy and Ce2Fe 17 N3, of which Ce2Fe 17 N3 accounts for 15% to 50% of the weight of the mixed powder, and the particle size is less than 5 microns. The invention uses a gas atomization device to prepare spherical amorphous powder, and uses smelting Ce-Fe alloy ingots, rapid quenching strips and high temperature and high pressure nitriding to obtain Ce2Fe 17 N3, with a nitriding temperature of 400-500°C, a holding time of 1-2 hours, and a nitriding pressure of 0.7-1 MPa. The mixed powder is then mixed with silicone rubber to form a viscous fluid slurry, which is then fabricated using a tape casting process to form a polymer composite electromagnetic wave absorbing membrane. This composite material is primarily composed of a two-phase metal and an intermetallic compound, and is designed to improve the resulting material's electromagnetic wave absorption performance in the GHz frequency range.

[0004] CN101880817A discloses a planar 2:17 rare earth-3d transition metal intermetallic compound electromagnetic wave absorbing material, the general formula of which is R2(Co 1-x Fe x ) 17In the general formula, R is Nd or Ce, and when R is Nd, 0≤x≤1; when R is Ce, 0.6≤x≤0.8. The preparation method comprises smelting rare earth elements, iron, and cobalt into an alloy, homogenizing it at high temperature, and then quenching it. The alloy is then crushed and ground into fine particles, followed by ball milling to obtain a metal powder. The composite material is prepared by placing the aforementioned materials into an uncured binder material, thoroughly mixing them, and then placing them into a mold made of a non-magnetic material. The mold is then placed in a magnetic field. The binder material is a polymer material such as resin, paraffin, polyethylene, or polypropylene. This intermetallic compound material is primarily composed of metal elements, and its purpose is to improve the electromagnetic wave absorption performance of the resulting alloy in the GHz frequency range.

[0005] CN101699577A discloses a Nd2(CoFe) 17 Intermetallic compound high-frequency soft magnetic materials are prepared by melting neodymium, cobalt, and iron into ingots according to the material ratio, then heating the ingots and homogenizing them thoroughly. Alternatively, transition metals such as neodymium, cobalt, and iron are melted into ingots according to the material ratio, then melt-quenched into thin ribbons. The homogenized ingots or thin ribbons produced by melt-quenching are then crushed and ground into a powder of 5 microns or less. The composite material is prepared by placing the aforementioned materials into an uncured binder material, thoroughly mixing them, and then placing them into a mold made of a non-magnetic material. The mold is then exposed to a magnetic field. The binder material is a polymer material such as resin, paraffin wax, polyethylene, or polypropylene. This intermetallic compound material is primarily composed of metallic elements and is intended to improve the electromagnetic wave absorption properties of the resulting alloy in the GHz frequency range.

[0006] The above three patents show that the application of rare earth intermetallic compound materials is reflected in the GHz band absorption, but not in the electromagnetic conversion application in the MHz range. 17 Three interstitial N atoms can also be introduced into the unit cell to form rare earth alloy nitrides, further regulating high-frequency magnetism.

[0007] CN 113871124 A discloses a method for preparing high-performance samarium iron nitrogen permanent magnetic material with high nitriding efficiency, wherein the method comprises: 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, a high-speed high-purity nitrogen gas flow (10-30 m / s) is continuously filled from the bottom of the tower vacuum nitriding furnace for 10-30 hours. The method for preparing high-performance samarium iron nitrogen permanent magnet material with high nitriding efficiency provided by the present invention is to flush the Sm2Fe 17 Alloy powder, making Sm2Fe 17The 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.

[0008] CN 115537711 A discloses a method for increasing the nitriding rate of samarium iron nitrogen permanent magnet materials. The method comprises: first, mixing an active metal (nickel, cobalt, copper, or zinc) salt and an initiator to prepare an active component solution; then, mixing the active component solution with a carbon carrier, solidifying (3-4 hours), and calcining (1.5-3 hours) to prepare a nitriding catalyst; then, mixing the nitriding catalyst with a samarium iron alloy and heating in a nitrogen-containing atmosphere for 3-10 hours to obtain a solid mixture; and finally, separating the solid mixture to obtain the samarium iron nitrogen permanent magnet material. This method utilizes a catalyst mixing method to carry out the nitriding process, and its purpose is to increase the nitrogen content and nitriding efficiency of the resulting alloy.

[0009] The above two patents show that, on the one hand, in order to improve the nitriding efficiency, high-pressure flowing N2 gas must be used, and the nitriding process takes 10-30 hours; or additional catalysts or reducing agents must be used, and the nitriding process takes 3-30 hours. This increases the overall process complexity and increases the material and equipment costs of the overall process. At the same time, the nitriding efficiency needs to be further improved.

[0010] In addition, due to the low intrinsic resistivity of metallic soft magnetic materials, their high-frequency applications are also limited by eddy current losses. Therefore, it is usually necessary to perform an insulating coating treatment on the surface of the soft magnetic powder matrix to increase the resistivity of the composite material and reduce eddy current losses. CN 115475935 A discloses a method for preparing an iron-based soft magnetic composite powder and an iron-based soft magnetic composite powder. The method is as follows: first, a phosphoric acid solution is used to in-situ generate a phosphate protective layer on the surface of the iron-based powder, and then a mixture of potassium permanganate and phosphoric acid is used to continue the reaction, thereby obtaining an insulating protective layer with a gradient distribution of phosphate and oxide content along the thickness direction. The method uses a liquid phase method to implement the coating process, the purpose of which is to improve the insulation performance of the resulting alloy powder.

[0011] CN 114050043 A discloses a method for preparing an oxide-coated iron-silicon-cadmium soft magnetic composite material. The method comprises: (1) pre-treating an iron-silicon-cadmium metal alloy powder to obtain a metal powder; (2) sequentially mixing the metal powder with a magnesium acetate solution and performing a heat decomposition treatment to obtain a semi-finished metal powder; and (3) sequentially mixing the semi-finished metal powder with an organic binder and drying the mixture to obtain an oxide-coated iron-silicon-cadmium soft magnetic composite material. This method employs a liquid phase coating process to improve the insulation properties of the resulting alloy powder.

[0012] For easy-to-surface rare earth soft magnetic materials, the rare earth in the structure is extremely easy to oxidize. Using traditional liquid phase chemical methods or corrosive liquid phase methods to coat 100μm-level easy-to-surface rare earth soft magnetic powder materials, due to their large surface area, it is difficult to ensure their composition stability. Therefore, there is a lack of effective methods to increase their bulk resistance or one-time insulation coating. Summary of the Invention

[0013] In view of this, the present invention has adopted a rare earth alloy nitride composite soft magnetic material and its preparation method. First, 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 into Ce2 (Fe x Co 1-x ) 17 The process of N penetration into Ce2(Fe x Co 1-x ) 17 The efficiency of the lattice is improved, and its resonant frequency and high complex permeability in the MHz range are increased; at the same time, the present invention can form an in-situ coating structure on the surface of the soft magnetic powder, which can effectively increase the resistivity of the composite material to reduce eddy current loss. Secondly, compared with the traditional flowing atmosphere reduction method, the nitriding process of the present invention does not require the use of high-pressure flowing gas throughout the process, thus avoiding the problems of gas safety and exhaust gas treatment; on the other hand, the nitriding process of the present invention does not require additional catalysts or reducing agents; thus, the overall process complexity is reduced, making the process simpler and cheaper.

[0014] The present invention achieves the above-mentioned purpose through the following technical solutions.

[0015] On the one hand, the present invention provides a rare earth alloy nitride composite soft magnetic material, which comprises an alloy nitride and a coating layer located on the surface of the alloy nitride and coating the alloy nitride; wherein the composition of the alloy nitride is Ce2(Fe x Co 1-x ) 17 N 3-δ The coating layer is composed of Fe4N, and the rare earth alloy nitride composite soft magnetic material is represented by Ce2(Fe x Co 1-x ) 17 N 3-δ @Fe4N;

[0016] Wherein, x is the atomic ratio of Fe in the structure, 0.6≤x<1;

[0017] Among them, δ is the nitrogen deficiency coefficient in the structure, 1≤δ≤2.5.

[0018] Preferably, the coating layer has a thickness of 0.1-2 μm.

[0019] On the other hand, the present invention also provides a method for preparing the rare earth alloy nitride composite soft magnetic material, which comprises the following steps:

[0020] 1) Crushing and sieving the rare earth alloy material to obtain uniform alloy powder;

[0021] 2) mixing the alloy powder with a nitrogen-rich compound to obtain a mixture;

[0022] 3) subjecting the mixture to nitriding treatment to obtain the rare earth alloy nitride composite soft magnetic material having an alloy nitride and a coating layer.

[0023] According to a preferred embodiment of the present invention, the chemical composition of the rare earth alloy material is Ce2(Fe x Co 1-x ) 17 , where x is the Fe atomic ratio, 0.6≤x<1, and the raw material purity is at least industrial pure.

[0024] According to a preferred embodiment of the present invention, the particle size of the alloy powder ranges from 75 microns to 150 microns.

[0025] 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, ammonium bicarbonate, and amino acids, and has a purity of at least industrial purity.

[0026] According to a preferred embodiment of the present invention, the mass ratio of the alloy powder to the nitrogen-rich compound is 3 to 8:1.

[0027] 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 550-650° C. under the condition that the initial nitrogen pressure is greater than or equal to 0.1 MPa. After reaching the target temperature, the nitriding process time is 1-3 hours.

[0028] According to a preferred embodiment of the present invention, during the nitriding treatment at 550-650° C., no flowing nitrogen source gas or hydrogen gas flow is provided.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The preparation process of the present invention is simple and feasible. After reaching the nitriding treatment temperature, the nitriding depth is not less than 75 microns in a short time. The required Ce2(Fe x Co 1-x ) 17 The powder particle size can be selected from 75 to 150 microns, which significantly improves the nitriding efficiency; it can quickly form Ce2(Fex Co 1-x ) 17 N 3-δ Intermediate compound, increases system resistance.

[0031] (2) The preparation process of the present invention can realize synchronous (one-step) coating, that is, forming Ce2(Fe x Co 1-x ) 17 N 3-δ The same process of intermediate compounds, in Ce2(Fe x Co 1-x ) 17 N 3-δ A layer of iron-based coating is formed on the surface, which is better than Ce2(Fe x Co 1-x ) 17 Can significantly reduce magnetic losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 These are the X-ray diffraction spectra of the material of Example 1 of the present invention before and after nitridation, where (a) is before nitridation and (b) is after nitridation.

[0033] 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.

[0034] 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.

[0035] Figure 4 The relationship between complex magnetic permeability and frequency is obtained from the test of the composite material ring of Example 1 of the present invention.

[0036] Figure 5 The loss-frequency relationship diagram obtained from the composite material ring test of Example 1 of the present invention, wherein (a) is before nitriding; (b) is after nitriding.

[0037] Figure 6 These are the X-ray diffraction spectra of the material of Example 2 of the present invention before and after nitridation, where (a) is before nitridation and (b) is after nitridation.

[0038] Figure 7 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.

[0039] Figure 8 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.

[0040] Figure 9 The relationship between complex magnetic permeability and frequency is obtained from the test of the composite material ring of Example 2 of the present invention.

[0041] Figure 10 The loss-frequency relationship diagram obtained from the composite material ring test of Example 2 of the present invention, wherein (a) is before nitriding; (b) is after nitriding. DETAILED DESCRIPTION

[0042] 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.

[0043] The present invention provides a rare earth alloy nitride composite soft magnetic material. The present invention found that by pyrolysis of nitrogen-rich compounds NH3 to solid-dissolve N into Ce2 (Fe x Co 1-x ) 17 The alloy has a high local NH3 partial pressure, which improves the nitriding efficiency and nitriding depth, and can obtain an alloy nitride (rare earth alloy intermediate nitride material) with a primary nitriding depth of not less than 75 microns. At the same time, an Fe4N coating layer is formed on the surface of the alloy nitride, which can not only improve the domain wall displacement and natural resonance frequency of the alloy nitride on the basis of having a good composite magnetic permeability in the MHz range, but also reduce the loss, thereby obtaining a rare earth alloy nitride composite soft magnetic material with better performance.

[0044] The rare earth alloy nitride composite soft magnetic material comprises an alloy nitride and a coating layer located on the surface of the alloy nitride and coating the alloy nitride; wherein the composition of the alloy nitride is Ce2(Fe x Co 1-x ) 17 N 3-δ The coating layer is composed of Fe4N, and the rare earth alloy nitride composite soft magnetic material can be expressed as Ce2(Fe x Co 1-x ) 17 N 3-δ @Fe4N. It may contain unavoidable impurities. Wherein, x is the mass ratio of Fe in the structure, 0.6≤x<1, preferably 0.6<x<0.9, more preferably, 0.7<x<0.9, further preferably 0.7<x≤0.8, for example, x is 0.8;

[0045] Wherein, δ is the nitrogen deficiency coefficient in the structure, 1≤δ≤2.5, preferably 1≤δ≤2, more preferably, 1≤δ≤1.5, further preferably 1≤δ≤1.2, for example, δ is 1;

[0046] According to a specific embodiment of the present invention, the chemical composition of the alloy nitride is RE2(Fe x Co 1-x ) 17 N2.

[0047] The method for preparing a rare earth alloy intermediate nitride composite soft magnetic material of the present invention comprises the following steps: (1) preparing rare earth alloy material powder; (2) mixing the powder; and (3) nitriding. After the nitriding step, the rare earth alloy nitride composite soft magnetic material is obtained. If further consideration is given to the subsequent application of the material, the composite material can be pressed into a ring in step (4).

[0048] Each step is described in detail below. It should be noted that the following specific steps are only for the purpose of illustrating the present invention and should not be construed as limiting the scope of the present invention. A person skilled in the art would be able to make various modifications and improvements without departing from the scope of the present invention, and these modifications and improvements are all within the scope of protection of the present invention.

[0049] Step (1) Preparation of rare earth alloy material powder:

[0050] Ce, Fe and Co metals were weighed according to the weight ratio of 2:17x:17 (1-x) molar ratio, and a master alloy was obtained by using a melting furnace, and Ce2 (Fe x Co 1-x ) 17 Master alloy. Ce2(Fe x Co 1-x ) 17 The master alloy is crushed and sieved to obtain alloy powder.

[0051] RE2Fe 17 The master alloy crushing and screening interval is selected from 50 to 200 microns, preferably 75 to 150 microns.

[0052] 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.

[0053] When using the medium frequency casting method, a copper mold of Φ50mm*50mm can be used, and a quartz crucible can be used. In certain embodiments, the co-medium frequency casting method may include the following steps: Ce, Fe and Co metals are weighed according to a weight ratio calculated by measuring the molar ratio of 2:17x:17(1-x), and placed in a crucible, the coil power is increased, the alloy mixture begins to melt and is continuously mixed to obtain a master alloy; the cut master alloy is placed in a vacuum furnace for annealing at 1000℃ for 10 days; after the annealing process, Ce2(Fe x Co 1-x ) 17 The master alloy is quenched and Ce2(Fe x Co 1-x ) 17 alloy.

[0054] In the present invention, Ce2(Fe x Co 1-x ) 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.

[0055] Step (2) powder mixing step:

[0056] In the present invention, the nitrogen-rich compound may be a compound containing an -NH3 functional group that can be pyrolyzed at 100-200°C to release NH3. Preferably, the nitrogen-rich compound is selected from one or more of urea, ammonium bicarbonate, and an amino acid. More preferably, the nitrogen-rich compound is selected from one of urea, ammonium bicarbonate, and an amino acid. According to one embodiment of the present invention, the nitrogen-rich compound is urea.

[0057] The mass ratio of the nitrogen-rich compound to the alloy powder is 3 to 8:1, preferably 5 to 8:1, more preferably 6 to 8:1, and even more preferably 7 to 8:1.

[0058] Step (3) Nitriding treatment step:

[0059] The precursor is subjected to nitriding treatment to obtain the rare earth alloy nitride composite soft magnetic material.

[0060] Specifically, the mixture is placed in a heating device capable of providing inert atmosphere protection, and nitriding treatment is performed at 550-650° C. for 1-3 hours under the condition that the initial inert gas pressure is greater than or equal to 0.1 MPa.

[0061] During the nitriding treatment at 550-650° C., no flowing nitrogen source gas (such as N 2 , NH 3 , etc.) or hydrogen gas flow is provided.

[0062] 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 Ce2 (Fe x Co 1-x ) 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 Ce2 (Fe x Co 1-x ) 17Compared 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.

[0063] In the present invention, the inert atmosphere can be an initial 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.

[0064] The annealing temperature may be 550 to 650° C., preferably 550 to 600° C., more preferably 550 to 580° C. The annealing time may be 1 to 3 hours, preferably 1.5 to 3 hours, more preferably 2 to 2.5 hours.

[0065] The inventors of this application believe that Ce2(Fe x Co 1-x ) 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.

[0066] Step (4) Pressing into a ring:

[0067] The resulting nitrided material powder is mixed with polyurethane (30-35 at.% by volume) and stirred with a solvent (e.g., acetone) under ultrasonication. Finally, the resulting mixture is placed in a ring mold with an outer diameter of 12 mm and an inner diameter of 6 mm and molded at 90°C and a pressure of 300 MPa for 10 minutes to produce a composite test ring. The ring's magnetic spectrum is then measured from 1 to 1000 MHz.

[0068] Some of the test methods in the following examples and comparative examples are described as follows:

[0069] Electron probe image: Using JXA-IHP200F Hyper probe.

[0070] XRD pattern: Bruker D8 Advance was used.

[0071] Room temperature static magnetic properties diagram: using Quantum Design VersaLab.

[0072] High-frequency magnetic parameter diagram: using Agilent E4991A.

[0073] Example 1

[0074] The alloy nitride (rare earth alloy intermediate nitride material) of this embodiment is Ce2(Fe 0.8 Co 0.2 ) 17 N2, that is, x=0.8, δ=1.

[0075] The preparation method of the rare earth alloy intermediate nitride material is as follows:

[0076] According to the molar ratio of Ce, Fe and Co metals, the corresponding amount of metals was poured into a medium frequency induction furnace to obtain a master alloy; and then annealed at 1000 ° C in a vacuum furnace for 10 days to obtain Ce2 (Fe 0.8 Co 0.2 ) 17 Master alloy; Ce2(Fe 0.8 Co 0.2 ) 17 The master alloy is crushed and screened to select Ce2(Fe 0.8 Co 0.2 ) 17 Powder material 1g;

[0077] 8 g of urea was mixed thoroughly with the alloy powder to obtain a mixture; the mixture was placed in an inert atmosphere annealing device, and an initial N2 atmosphere of 0.1 MPa was provided; and annealing was performed at 575°C for 120 minutes to obtain Ce2(Fe 0.8 Co 0.2 ) 17 N2 material.

[0078] 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 , high frequency magnetic energy can be seen Figure 4 , loss performance see Figure 5 .

[0079] Depend on Figure 1 It can be seen that the material obtained in Example 1 is Ce2Fe 17 N3 phase (XRD-Cobalt target), in accordance with standard card PDF#97-065-8561.

[0080] Depend on Figure 2 It can be seen that the Ce2(Fe 0.8 Co 0.2 ) 17 The static magnetic properties of N2 powder material at room temperature reach 140emu / g.

[0081] Depend on Figure 3It can be seen that the Ce2(Fe 0.8 Co 0.2 ) 17 For N2 bulk material, under the same nitriding conditions, the nitriding depth is not less than 75μm, and a layer of nitride structure is formed on the surface.

[0082] Depend on Figure 4 It can be seen that the composite material ring obtained in Example 1 has a theoretical domain wall displacement resonance frequency of 103.5 MHz and a domain wall spin resonance frequency of 316.2 MHz according to magnetic spectrum simulation.

[0083] Depend on Figure 5 It can be seen that the composite material ring obtained in Example 1 is better than the unnitrided Ce2(Fe 0.8 Co 0.2 ) 17 Materials, Ce2(Fe 0.8 Co 0.2 ) 17 The total loss of N2, especially the eddy current loss, is significantly reduced.

[0084] Example 2

[0085] The rare earth alloy intermediate nitride material of this embodiment is Ce2(Fe 0.6 Co 0.4 ) 17 N 1.5 , that is, x=0.6, δ=1.5.

[0086] The preparation method of the easy-surface rare earth alloy intermediate nitride soft magnetic material is as follows:

[0087] 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, Ce2(Fe 0.6 Co 0.4 ) 17 Master alloy; Ce2Fe 17 The master alloy is crushed and screened, and Ce2(Fe 0.6 Co 0.4 ) 17 Powder material 1g;

[0088] Take 7.5g 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 570℃ for 120 minutes to obtain Ce2(Fe 0.6 Co 0.4 ) 17 N 1.5 Material.

[0089] X-ray diffraction spectra before and after nitriding are shown in Figure 6 , room temperature static magnetic properties can be seen Figure 7 , the electron probe scanning nitriding cross-section of the bulk material under the same nitriding conditions is shown in Figure 8 , high frequency magnetic energy can be seen Figure 9 , loss performance see Figure 10 .

[0090] Depend on Figure 6 It can be seen that the material obtained in Example 2 is Ce2Fe 17 N3 phase (XRD-Cobalt target), in accordance with standard card PDF#97-065-8561.

[0091] Depend on Figure 7 It can be seen that the Ce2(Fe 0.6 Co 0.4 ) 17 N 1.5 The static magnetic properties of powder material at room temperature reach 121emu / g.

[0092] Depend on Figure 8 It can be seen that the Ce2(Fe 0.6 Co 0.4 ) 17 N 1.5 For bulk materials, under the same nitriding conditions, the nitriding depth is greater than or equal to 75μm, and a layer of nitride structure is formed on the surface.

[0093] Depend on Figure 9 It can be seen that, according to the magnetic spectrum simulation, the theoretical domain wall displacement resonance frequency of the composite material ring of Example 2 is 113.6 MHz, and the domain wall spin resonance frequency is 206.9 MHz.

[0094] Depend on Figure 10 It can be seen that the composite material ring obtained in Example 2 is better than the unnitrided Ce2(Fe 0.6 Co 0.4 ) 17 Materials, Ce2(Fe 0.6 Co 0.4 ) 17 The total loss of N2, especially the eddy current loss, is significantly reduced.

[0095] Examples 3-7

[0096] Examples 3-7 use the same raw materials and preparation methods as Example 2, and differ from Example 2 in that x, δ, annealing temperature, annealing time, and urea amount are different. The static magnetic properties and composite surface resistance of the materials obtained by nitriding in Examples 3-7 at room temperature are shown in the Ms column of Table 1. Comparative Examples 1-5 use a traditional 0.5 MPa N2 atmosphere nitriding method (the specific nitriding process is: at the temperature set in each comparative example in Table 2, a flowing nitrogen-based gas flow is introduced according to the gas flow rate in Table 2, and the nitriding process continues for the set time). The static magnetic properties of the materials obtained by nitriding at room temperature and the surface resistance of their composite materials are shown in the column of Table 2.

[0097] Table 1 Performance data of materials in other embodiments

[0098]

[0099] Table 2 Performance data list of materials in comparative examples 1-5

[0100]

[0101] As can be seen from Table 1 above, the nitriding condition window provided by the present invention can be used to adjust Ce2(Fe x Co 1-x ) 17 N 3-δ A higher nitrogen content and Ms are obtained, and a higher surface resistance value of the composite material is obtained by adjusting the coating layer. As can be seen from Table 2, the traditional large flow N2 gas nitriding method requires a longer time and a higher initial gas pressure to adjust the Ce2Fe 17 N 3-δ The nitrogen content and Ms are low, so the nitriding efficiency is low, and an adjustable coating structure or coating layer cannot be obtained to significantly improve the surface resistance of the composite material.

[0102] 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 rare earth alloy nitride composite soft magnetic material, characterized in that: The alloy nitride comprises an alloy nitride and a coating layer located on the surface of the alloy nitride and coating the alloy nitride; wherein the composition of the alloy nitride is Ce2(Fe x Co 1-x ) 17 N 3-δ The coating layer is composed of Fe4N, and the rare earth alloy nitride composite soft magnetic material is represented by Ce2(Fe x Co 1-x ) 17 N 3-δ @Fe4N; Wherein, x is the atomic ratio of Fe in the structure, 0.6≤x<1; Among them, δ is the nitrogen deficiency coefficient in the structure, 1≤δ≤2.

5.

2. The rare earth alloy nitride composite soft magnetic material according to claim 1, characterized in that: The coating layer has a thickness of 0.1-2 μm.

3. A method for preparing the rare earth alloy nitride composite soft magnetic material according to claim 1 or 2, characterized in that: The following steps are involved: 1) Crushing and sieving the rare earth alloy material to obtain uniform alloy powder; 2) mixing the alloy powder with a nitrogen-rich compound to obtain a mixture; 3) subjecting the mixture to nitriding treatment to obtain the rare earth alloy nitride composite soft magnetic material having an alloy nitride and a coating layer.

4. The preparation method according to claim 3, characterized in that The chemical composition of the rare earth alloy material is Ce2(Fe x Co 1-x ) 17 , where x is the Fe atomic ratio, 0.6≤x<1, and the raw material purity is at least industrial pure.

5. The preparation method according to claim 3, characterized in that The particle size of the alloy powder ranges from 75 microns to 150 microns.

6. The preparation method according to claim 3, 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, ammonium bicarbonate, and amino acids, and has a purity of at least industrial purity.

7. The preparation method according to claim 3, characterized in that The mass ratio of the alloy powder to the nitrogen-rich compound is 3 to 8:

1.

8. The preparation method according to claim 3, 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 550-650° C. under the condition that the initial nitrogen pressure is greater than or equal to 0.1 MPa. After reaching the target temperature, the nitriding process time is 1-3 hours.

9. The preparation method according to claim 8, characterized in that During the nitriding treatment at 550-650° C., no flowing nitrogen source gas or hydrogen gas flow is provided.

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