Rare earth ion-doped soft magnetic alloy, soft magnetic composite material and method for manufacturing the same

Abstract

The application provides a rare earth ion doped soft magnetic alloy, a soft magnetic composite material and a preparation method thereof, the rare earth ion doped soft magnetic alloy is composed of Fe, Si, Al, N and Re, and Re is a rare earth element; wherein, in the rare earth ion doped soft magnetic alloy, the content of Fe is 82-85 wt%, the content of Si is 8-10 wt%, the content of Al is 3-5 wt%, the content of Re is 1-2 wt%, and the content of N is 0.25-0.65 wt%. The rare earth ion doped soft magnetic alloy of the application is mostly composed of FeSiAl grains, but there are appropriate easy surface Re-Fe-N compounds distributed between the FeSiAl grains. Based on such a structure, the rare earth ion doped soft magnetic alloy of the application has excellent electromagnetic characteristics and low loss under MHz working conditions.

Description

Technical Field

[0001] This invention relates to the field of magnetic materials, and more specifically, to a rare-earth ion-doped soft magnetic alloy, a soft magnetic composite material, and a method for preparing the same. Background Technology

[0002] Power inductors play a crucial role in energy coupling, transfer, and conversion in power and electronic devices. Their miniaturization and integration can improve equipment efficiency, reduce energy consumption, and decrease environmental pollution. In recent years, the practical application of third-generation wide-bandgap semiconductor materials, represented by GaN and SiC, has made it possible for electronic devices to achieve higher frequencies, miniaturization, and higher power outputs. This has also placed higher demands on soft magnetic materials in terms of high frequency, high saturation magnetic flux density, high permeability, and low loss. However, currently, there are no soft magnetic materials that can perfectly match third-generation wide-bandgap semiconductors, which has become a bottleneck restricting the high-frequency and integrated development of electronic information technology.

[0003] Currently, most inductors used in frequency bands above MHz employ ferrite as a soft magnetic material. Ferrite soft magnetic materials possess high resistivity and permeability, but their saturation magnetization is low (Bs < 0.5T), resulting in weak magnetic energy storage capacity, which is detrimental to miniaturization in electronic devices. In contrast, metallic soft magnetic materials, such as Fe, FeNi, FeSi, and FeSiAl, have higher saturation magnetization, which is beneficial for miniaturized electronic component design. However, due to their low resistivity, these materials exhibit very high eddy current losses under high-frequency application conditions, thus generally limiting their operation to frequency bands below 1MHz. Furthermore, amorphous and nanocrystalline magnetic powders, possessing both high saturation magnetization and relatively high resistivity, have become research hotspots in this field in recent years; however, difficulties in material forming and stringent stress-relief annealing conditions limit their application scope.

[0004] In the prior art, patent CN110047637A proposes a method for preparing rare-earth-iron-nitrogen composite magnetic materials, which produces Nd-Fe-N composite rare-earth materials and tests their electromagnetic absorption and shielding characteristics. However, this method results in excessively high rare-earth content, leading to low saturation magnetization of the material. Patent document CN110047637A points out that rare-earth ion doping can improve the high-frequency characteristics of soft magnetic metallic materials, especially by forming easily surface-type rare-earth iron-based intermetallic compounds Re2Fe. 17 This compound exhibits a very high cutoff frequency, allowing for use at GHz levels. Furthermore, nitriding this compound can increase the material's electrical resistance and reduce eddy current losses. However, Re₂Fe 17 Compounds and Re2Fe 17Although nitride products exhibit good loss characteristics at GHz conditions, their low permeability and saturation magnetization limit their application at MHz conditions, resulting in significant losses.

[0005] Patents CN109982791A, CN100513015C, CN1093311C, CN1286602C, and CN1022520C all propose methods for preparing novel rare-earth-iron-nitrogen materials, producing materials such as Sm-Fe-N and Nd-Fe-N. However, due to differences in alloy composition and microstructure, these materials exhibit excellent permanent magnet properties but insufficient soft magnetic properties, making them unsuitable for use as soft magnetic materials in inductors and electrical appliances.

[0006] J. Magn. Magn. Mater., 2017, 424(15):39-43 discloses a method for preparing Ce2Fe 17 N 3-δ The method for preparing the compound was used, and the high-frequency (GHz) absorption characteristics of the material were tested. However, the material prepared by this method is mainly used at ultra-high frequencies of GHz, and its saturation magnetization and permeability are low at MHz, resulting in high losses.

[0007] The master's thesis from Zhejiang University, "Preparation of FeSi, FeSiAl, and FeSiCr Soft Magnetic Composites by Surface Nitriding / Oxidation" (Zhao Jing, 2018), points out that surface nitriding / oxidation of magnetic powder can increase its resistivity, thereby reducing eddy current losses. However, while this thesis indicates that surface nitriding / oxidation of magnetic powder can improve resistivity and reduce eddy current losses, due to the highly stable chemical properties of nitrogen (N2), conventional FeSi, FeSiAl, and FeSiCr rarely react fully with N2. Therefore, the N content in the alloys is relatively low, and its effect on reducing eddy current losses remains insufficient.

[0008] In summary, existing soft magnetic materials cannot simultaneously achieve both high electromagnetic properties and low loss under MHz, high-current operating conditions. Therefore, it is necessary to provide a soft magnetic material to improve upon these issues. Summary of the Invention

[0009] The main objective of this invention is to provide a rare-earth ion-doped soft magnetic alloy, a soft magnetic composite material, and a method for preparing the same, in order to solve the problem that existing soft magnetic materials cannot simultaneously achieve high electromagnetic properties and low loss under MHz and high current operating conditions.

[0010] To achieve the above objectives, according to one aspect of the present invention, a rare-earth ion-doped soft magnetic alloy is provided, which is composed of Fe, Si, Al, N and Re, wherein Re is a rare earth element; wherein, in the rare-earth ion-doped soft magnetic alloy, the content of Fe is 82-85 wt%, the content of Si is 8-10 wt%, the content of Al is 3-5 wt%, the content of Re is 1-2 wt%, and the content of N is 0.25-0.65 wt%.

[0011] Furthermore, the rare earth element is one or more of Ce, La, Sm, Nd, Pr, or Ho.

[0012] Furthermore, the average particle size of the rare earth ion-doped soft magnetic alloy is 5–50 μm.

[0013] To achieve the above objectives, according to one aspect of the present invention, a method for preparing the above-mentioned rare-earth ion-doped soft magnetic alloy is provided. The method includes the following steps: mixing and melting iron, iron-silicon alloy, aluminum, and rare-earth metals under an inert gas atmosphere to form a melt; subjecting the melt to atomization powdering, heat treatment, and nitriding treatment in sequence to form a rare-earth ion-doped soft magnetic alloy; wherein the rare-earth ion-doped soft magnetic alloy is composed of Fe, Si, Al, N, and Re, with Re being a rare-earth element; in the rare-earth ion-doped soft magnetic alloy, the content of Fe is 82-85 wt%, the content of Si is 8-10 wt%, the content of Al is 3-5 wt%, the content of Re is 1-2 wt%, and the content of N is 0.25-0.65 wt%.

[0014] Furthermore, during the nitriding process, nitrogen gas is introduced into the system for nitriding treatment; preferably, during the nitriding process, the treatment temperature is 450-550℃ and the treatment time is 4-6h; preferably, during the nitriding process, the nitrogen pressure is 0.1-0.2MPa.

[0015] Furthermore, during the smelting process, the smelting temperature is 1800–2000℃ and the smelting time is 0.5–5h; preferably, during the heat treatment process, the treatment temperature is 900–1000℃ and the treatment time is 2–3h; preferably, a gas atomization device is used for atomization powder production; more preferably, in the gas atomization device, the atomizing gas is an inert gas with a gas pressure of 0.1–1.0MPa.

[0016] According to another aspect of the present invention, a soft magnetic composite material is provided, comprising: a rare earth ion-doped soft magnetic alloy core layer; a phosphating layer covering the outer surface of the rare earth ion-doped soft magnetic alloy core layer; a glass layer covering the outer surface of the phosphating layer away from the rare earth ion-doped soft magnetic alloy core layer; and a lubricating layer covering the outer surface of the glass layer away from the rare earth ion-doped soft magnetic alloy core layer, wherein the lubricating layer is coupled to the surface of the glass layer by a coupling agent; wherein the material of the rare earth ion-doped soft magnetic alloy core layer is the aforementioned rare earth ion-doped soft magnetic alloy, the material of the phosphating layer is iron phosphate and / or aluminum phosphate, the material of the glass layer is one or more of silicon dioxide, sodium pyrophosphate, or sodium silicate, and the material of the lubricating layer is a lubricant.

[0017] Further, the coupling agent is selected from one or more of silane coupling agents, titanate coupling agents, or aluminate coupling agents; preferably, the lubricant is selected from one or more of zinc stearate, calcium stearate, or magnesium stearate; preferably, the average particle size of the soft magnetic composite material is 10-40 μm; preferably, the thickness of the phosphating layer is 10-50 nm, the thickness of the glass layer is 10-50 nm, and the thickness of the lubricating layer is 10-50 nm.

[0018] According to another aspect of the present invention, a method for preparing the above-mentioned soft magnetic composite material is provided. The method includes the following steps: providing a rare earth ion-doped soft magnetic alloy core layer, and coating the outer surface of the rare earth ion-doped soft magnetic alloy core layer with a phosphating layer; coating the outer surface of the phosphating layer away from the rare earth ion-doped soft magnetic alloy core layer with a glass layer; and coupling a lubricating layer onto the outer surface of the glass layer away from the rare earth ion-doped soft magnetic alloy core layer using a coupling agent, thereby forming a soft magnetic composite material; wherein the material of the rare earth ion-doped soft magnetic alloy core layer is the above-mentioned rare earth ion-doped soft magnetic alloy, the material of the phosphating layer is iron phosphate and / or aluminum phosphate, the material of the glass layer is one or more of silicon dioxide, sodium pyrophosphate, or sodium silicate, and the material of the lubricating layer is a lubricant.

[0019] Further, the preparation method includes: in a vacuum environment, mixing a first dispersion containing a soft magnetic alloy core layer doped with rare earth ions with phosphoric acid, and performing a first stirring, so that the phosphoric acid reacts with the material in the surface region of the soft magnetic alloy core layer doped with rare earth ions to coat its outer surface and form a phosphate layer, to obtain intermediate material A; the material of the phosphate layer includes iron phosphate and aluminum phosphate; under pH 6.0 to 8.0 conditions, performing a second stirring, mixing a second dispersion containing intermediate material A, ethyl silicate, sodium pyrophosphate and sodium silicate, so as to react on the outer surface of the soft magnetic alloy core layer away from the rare earth ion doped phosphate layer and form a glass layer, to obtain intermediate material B; the glass layer includes silicon dioxide, sodium pyrophosphate and sodium silicate; performing a third stirring, mixing a third dispersion containing intermediate material B and a coupling agent, so as to connect the coupling agent on the outer surface of the soft magnetic alloy core layer away from the rare earth ion doped glass layer, to obtain intermediate material C; mixing intermediate material C and a lubricant, and performing a fourth stirring, so that the lubricant is coupled and coated on the surface of the glass layer by the coupling agent to form a lubricating layer, thereby forming a soft magnetic composite material.

[0020] Further, the amount of phosphoric acid used is 0.5-1% of the weight of the rare earth ion-doped soft magnetic alloy core layer; preferably, the amount of ethyl silicate used is 0.5-1% of the weight of the rare earth ion-doped soft magnetic alloy core layer, the amount of sodium pyrophosphate used is 0.2-0.5% of the weight of the rare earth ion-doped soft magnetic alloy core layer, and the amount of sodium silicate used is 0.5-1% of the weight of the rare earth ion-doped soft magnetic alloy core layer; preferably, the amount of coupling agent used is 0.5-1.0% of the weight of the rare earth ion-doped soft magnetic alloy core layer; preferably, the amount of lubricant used is 0.1-1% of the weight of the rare earth ion-doped soft magnetic alloy core layer.

[0021] Furthermore, the processing temperature of the first stirring, the second stirring, the third stirring and the fourth stirring are each independently selected from 50 to 100°C, and the processing time is each independently 1 to 5 hours.

[0022] According to another aspect of the present invention, an application of the above-described soft magnetic composite material in an inductor device for the MHz frequency band is provided.

[0023] The rare-earth ion-doped soft magnetic alloy of this invention is predominantly composed of FeSiAl grains, but a small amount of easily distributed Re-Fe-N compounds are dispersed between the FeSiAl grains. This structure contributes to the excellent electromagnetic properties and low losses of the rare-earth ion-doped soft magnetic alloy even when applied to MHz operating conditions. Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0025] As described in the background section, existing soft magnetic materials cannot simultaneously achieve both high electromagnetic properties and low loss under MHz, high current operating conditions.

[0026] To address this problem, the present invention provides a rare-earth ion-doped soft magnetic alloy, which is composed of Fe, Si, Al, N and Re, where Re is a rare earth element; wherein, in the rare-earth ion-doped soft magnetic alloy, the content of Fe is 82-85 wt%, the content of Si is 8-10 wt%, the content of Al is 3-5 wt%, the content of Re is 1-2 wt%, and the content of N is 0.25-0.65 wt%.

[0027] This invention controls the weight content of Fe, Si, Al, N, and Re within the aforementioned ranges. On one hand, the property of rare earth elements to more easily adsorb N allows for the formation of easily oriented Re-Fe-N compounds within the soft magnetic alloy. In the soft magnetic alloy structure of this invention, the interior is mostly composed of FeSiAl grains, with a small amount of easily oriented Re-Fe-N compounds dispersed between the FeSiAl grains. These easily oriented Re-Fe-N compounds, as high resistivity materials, discontinuous the low resistivity of FeSiAl, thereby increasing the resistivity of the soft magnetic alloy and effectively reducing eddy current losses. On the other hand, avoiding the formation of excessive Re-Fe-N compounds effectively prevents the reduction of saturation magnetization and permeability, thus enabling the material of this invention to possess excellent electromagnetic properties and low losses even under MHz operating conditions. Specifically, in subsequent applications, it can achieve higher compatibility with third-generation wide-bandgap semiconductors, making it more suitable for the miniaturization, high-frequency operation, and high-power requirements of inductor devices.

[0028] To further balance the electromagnetic properties and losses of the material under MHz operating conditions, rare earth elements are preferably one or more of Ce, La, Sm, Nd, Pr or Ho.

[0029] In a preferred embodiment, the rare-earth ion-doped soft magnetic alloy has an average particle size of 5–50 μm. Based on this, the particle size is more suitable for applications under MHz operating conditions, exhibiting excellent electromagnetic properties and low losses. It is better suited to the miniaturization, high-frequency operation, and high-power requirements of inductor devices.

[0030] In a preferred embodiment, the rare-earth ion-doped soft magnetic alloy contains 83 wt% Fe, 9.45 wt% Si, 5 wt% Al, 2 wt% Re, and 0.55 wt% N; or, the rare-earth ion-doped soft magnetic alloy contains 85 wt% Fe, 9.5 wt% Si, 3 wt% Al, 2 wt% Re, and 0.50 wt% N; or, the rare-earth ion-doped soft magnetic alloy contains 85 wt% Fe, 8.75 wt% Si, 5 wt% Al, 1 wt% Re, and 0.25 wt% N; or, the rare-earth ion-doped soft magnetic alloy contains 85 wt% Fe, 9.45 wt% Si, 5 wt% Al, 1 wt% Re, and 0.25 wt% N. The rare earth ion-doped soft magnetic alloy contains 7.47 wt% Fe, 5 wt% Al, 2 wt% Re, and 0.53 wt% N; or, the rare earth ion-doped soft magnetic alloy contains 83 wt% Fe, 8.47 wt% Si, 6 wt% Al, 2 wt% Re, and 0.53 wt% N; or, the rare earth ion-doped soft magnetic alloy contains 83 wt% Fe, 9.39 wt% Si, 5 wt% Al, 2 wt% Re, and 0.61 wt% N; or, the rare earth ion-doped soft magnetic alloy contains 83 wt% Fe, 10 wt% Si, 5 wt% Al, 2 wt% Re, and 0.25 wt% N.

[0031] The present invention also provides a method for preparing the aforementioned rare-earth ion-doped soft magnetic alloy. The preparation method includes the following steps: under an inert gas atmosphere, iron, iron-silicon alloy, aluminum and rare earth metals are mixed and smelted to form a melt; the melt is then subjected to atomization powdering, heat treatment and nitriding treatment in sequence to form a rare-earth ion-doped soft magnetic alloy; wherein the rare-earth ion-doped soft magnetic alloy is composed of Fe, Si, Al, N and Re, and Re is a rare earth element; in the rare-earth ion-doped soft magnetic alloy, the content of Fe is 82-85 wt%, the content of Si is 8-10 wt%, the content of Al is 3-5 wt%, the content of Re is 1-2 wt%, and the content of N is 0.25-0.65 wt%.

[0032] Based on the reasons stated above, this invention, through the aforementioned preparation method, achieves several advantages. Firstly, the property of rare earth elements readily adsorbing nitrogen (N) allows for the formation of easily distributed Re-Fe-N compounds within the soft magnetic alloy. In the soft magnetic alloy structure of this invention, the majority of the interior is composed of FeSiAl grains, with a small amount of easily distributed Re-Fe-N compounds dispersed between the FeSiAl grains. These easily distributed Re-Fe-N compounds, being high resistivity materials, disrupt the low resistivity of FeSiAl, thereby increasing the resistivity of the soft magnetic alloy and effectively reducing eddy current losses. Secondly, the formation of excessive Re-Fe-N compounds avoids the problem of reduced saturation magnetization and permeability, thus enabling the material of this invention to possess excellent electromagnetic properties and low losses even under MHz operating conditions. Specifically, in subsequent applications, it exhibits higher compatibility with third-generation wide-bandgap semiconductors, making it more suitable for the miniaturization, high-frequency operation, and high-power requirements of inductor devices. Furthermore, the raw materials selected for this invention, such as iron, iron-silicon alloys, and aluminum, are more readily available, lower in cost, and the preparation process is simpler and easier to operate.

[0033] Preferably, during the nitriding process, N2 is introduced into the system for nitriding. This makes the nitriding process more convenient and easier to control, thus allowing for better control of the formation of easily distributed Re-Fe-N compounds, resulting in improved electromagnetic properties while reducing eddy current losses. Preferably, the nitriding temperature is 450–550°C, the treatment time is 4–6 hours, and the nitrogen pressure is 0.1–0.2 MPa. This allows the easily distributed Re-Fe-N compounds to be more uniformly dispersed between FeSiAl grains, further balancing the electromagnetic properties and losses of the material under MHz operating conditions. If the treatment temperature is below 450°C, the magnetic powder nitriding is incomplete, and the nitrogen content is too low, leading to increased eddy current losses. If the treatment temperature is above 550°C, the formed easily distributed rare earth-iron-nitride compounds are easily decomposed, generating other compounds, which also increases eddy current losses.

[0034] In a preferred embodiment, during the smelting process, the smelting temperature is 1800–2000°C, and the smelting time is 0.5–5 hours. During the heat treatment process, the treatment temperature is 900–1000°C, and the treatment time is 2–3 hours. Based on this, the material exhibits better structural properties, superior electromagnetic characteristics, and lower losses.

[0035] Preferably, a gas atomization device is used for atomization powder preparation; more preferably, in the gas atomization device, the atomizing gas is an inert gas with a pressure of 0.1–1.0 MPa. Based on this, the particle size of the material is more suitable for application under MHz operating conditions, and under these conditions, it possesses excellent electromagnetic properties and low losses. It is more suitable for the miniaturization, high-frequency operation, and high-power requirements of inductor devices.

[0036] The present invention also provides a soft magnetic composite material, comprising: a rare earth ion-doped soft magnetic alloy core layer; a phosphating layer coated on the outer surface of the rare earth ion-doped soft magnetic alloy core layer; a glass layer coated on the outer surface of the phosphating layer away from the rare earth ion-doped soft magnetic alloy core layer; and a lubricating layer coated on the outer surface of the glass layer away from the rare earth ion-doped soft magnetic alloy core layer; wherein the lubricating layer is coupled to the surface of the glass layer by a coupling agent; wherein the material of the rare earth ion-doped soft magnetic alloy core layer is the aforementioned rare earth ion-doped soft magnetic alloy, the material of the phosphating layer is iron phosphate and / or aluminum phosphate, the material of the glass layer is one or more of silicon dioxide, sodium pyrophosphate, or sodium silicate, and the material of the lubricating layer is a lubricant.

[0037] For the reasons stated above, the rare-earth ion-doped soft magnetic alloy of this invention is mostly composed of FeSiAl grains, but a small amount of easily distributed Re-Fe-N compounds are dispersed between the FeSiAl grains. This structure enables the rare-earth ion-doped soft magnetic alloy of this invention to possess excellent electromagnetic properties and low losses even under MHz operating conditions.

[0038] Based on this, the present invention uses the aforementioned alloy as the core layer, and further coats the surface of the alloy core layer with a phosphating layer, a glass layer, a coupling layer, and a lubricating layer in sequence, forming a soft magnetic composite material structure with multiple coating films. This further improves the insulation and pressing properties of the composite material, and the improved insulation properties can further reduce the eddy current losses between rare earth ion-doped soft magnetic alloys. Specifically, the phosphating layer and the glass layer work together to further improve the insulation properties of the material, the lubricating layer can further improve the pressing properties of the material, and the intermediate coupling layer, as a transitional connecting layer between the inorganic material (glass layer) and the organic material (lubricating layer), can further balance the insulation and pressing properties of the material.

[0039] Therefore, when rare earth ion-doped soft magnetic alloys are used synergistically based on this composite material, it has better electromagnetic properties and lower losses. As a result, it can be better matched with third-generation wide bandgap semiconductors in subsequent applications, making it more suitable for the miniaturization, high frequency and high power requirements of inductor devices.

[0040] To further balance the beneficial electromagnetic properties and low loss performance of the material, and to further improve the pressing characteristics of the material, preferably, the average particle size of the soft magnetic composite material is 10-40 μm; preferably, the thickness of the phosphating layer is 10-50 nm, the thickness of the glass layer is 10-50 nm, the thickness of the coupling layer is 10-50 nm, and the thickness of the lubricating layer is 10-50 nm.

[0041] The present invention also provides a method for preparing the above-mentioned soft magnetic composite material, the method comprising the following steps: providing a rare earth ion-doped soft magnetic alloy core layer; coating a phosphating layer on the outer surface of the rare earth ion-doped soft magnetic alloy core layer; coating a glass layer on the outer surface of the phosphating layer away from the rare earth ion-doped soft magnetic alloy core layer; coating a lubricating layer on the outer surface of the glass layer away from the rare earth ion-doped soft magnetic alloy core layer using a coupling agent; and coating a lubricating layer on the outer surface of the coupling layer away from the rare earth ion-doped soft magnetic alloy core layer, thereby forming a soft magnetic composite material; wherein, the material of the rare earth ion-doped soft magnetic alloy core layer is the above-mentioned rare earth ion-doped soft magnetic alloy, the material of the phosphating layer is iron phosphate and / or aluminum phosphate, the material of the glass layer is one or more of silicon dioxide, sodium pyrophosphate, or sodium silicate, and the material of the lubricating layer is a lubricant.

[0042] Based on the aforementioned phase-related reasons, this invention uses the aforementioned alloy as the core layer, and further coats the surface of the alloy core layer with a phosphating layer, a glass layer, a coupling layer, and a lubricating layer in sequence, forming a soft magnetic composite material structure with multi-layer coating films. This further improves the insulation and pressing characteristics of the composite material, and the improved insulation characteristics can further reduce the eddy current loss of the material. Therefore, the composite material based on this structure has better electromagnetic characteristics and lower losses, thus enabling it to have a higher compatibility with third-generation wide-bandgap semiconductors in subsequent applications, making it more suitable for the miniaturization, high-frequency operation, and high-power requirements of inductor devices.

[0043] In a preferred embodiment, the preparation method includes: mixing a first dispersion containing a rare-earth ion-doped soft magnetic alloy core layer with phosphoric acid under vacuum, and performing a first stirring to react the phosphoric acid with the material in the surface region of the rare-earth ion-doped soft magnetic alloy core layer to coat it with a phosphate layer on its outer surface, obtaining intermediate material A; the material of the phosphate layer includes iron phosphate and aluminum phosphate; under pH 6.0-8.0 conditions, performing a second stirring on a second dispersion containing intermediate material A, ethyl silicate, sodium pyrophosphate, and sodium silicate to react on the outer surface of the phosphate layer away from the rare-earth ion-doped soft magnetic alloy core layer and form a glass layer, obtaining intermediate material B; the glass layer includes silicon dioxide, sodium pyrophosphate, and sodium silicate; performing a third stirring on a third dispersion containing intermediate material B and a coupling agent to connect the coupling agent on the outer surface of the glass layer away from the rare-earth ion-doped soft magnetic alloy core layer, obtaining intermediate material C; mixing intermediate material C with a lubricant and performing a fourth stirring to coat the lubricant onto the surface of the glass layer through the coupling agent to form a lubricating layer, thereby forming a soft magnetic composite material.

[0044] Based on this operation, the phosphating layer and glass layer work together to further improve the insulation properties of the material, the lubricating layer further improves the pressing properties, and the intermediate coupling layer, as a transitional connecting layer between the inorganic material (glass layer) and the organic material (lubricating layer), further balances the insulation and pressing properties of the material. Subsequently, when rare-earth ion-doped soft magnetic alloys are used synergistically, they exhibit better electromagnetic properties and lower losses. This results in higher compatibility with third-generation wide-bandgap semiconductors in subsequent applications, making them more suitable for the miniaturization, high-frequency operation, and high-power requirements of inductor devices.

[0045] In a preferred embodiment, during the fourth stirring process of mixing intermediate material C and lubricant, silicone resin can be added to the system. This can further improve the insulation properties of the composite material and also help to further improve the molding properties of the material. Preferably, the amount of silicone resin used is 0.5% to 1% of the weight of the rare earth ion-doped soft magnetic alloy core layer.

[0046] In a preferred embodiment, the intermediate material obtained in each step can be heated to 80°C to dry the material before being added to the next preparation step. Based on this, the aforementioned excellent structural properties of the material are further improved.

[0047] In one optional embodiment, the material after the fourth stirring can be cooled to room temperature, then the material can be broken up by a crusher and sieved through a 300-400 mesh sieve to obtain a soft magnetic composite material.

[0048] Preferably, the amount of phosphoric acid used is 0.5% to 1% of the weight of the rare-earth ion-doped soft magnetic alloy core layer. If the amount of phosphoric acid is less than 0.5%, the passivation effect of the magnetic powder will be slightly worse, thereby reducing the resistivity of the material and leading to a slight increase in high-frequency eddy current losses. If the amount of phosphoric acid is more than 1%, it will cause the magnetic powder to react with excess phosphoric acid, thereby reducing the saturation magnetization of the material.

[0049] Preferably, the amount of ethyl silicate is 0.5-1% of the weight of the rare-earth ion-doped soft magnetic alloy core layer, the amount of sodium pyrophosphate is 0.2-0.5% of the weight of the rare-earth ion-doped soft magnetic alloy core layer, and the amount of sodium silicate is 0.5-1% of the weight of the rare-earth ion-doped soft magnetic alloy core layer. If the amounts of ethyl silicate, sodium pyrophosphate, and sodium silicate are lower than the above ranges, the thickness of the glass layer will be thinner, failing to achieve a good insulating effect. If the amounts are higher than the above ranges, it will result in an excessive amount of non-magnetic material, reducing the soft magnetic properties of the magnetic powder.

[0050] Preferably, the amount of silane coupling agent used is 0.5% to 1.0% of the weight of the rare-earth ion-doped soft magnetic alloy core layer. Based on this, the connection between the glass layer and the lubricating layer is better, and the structural properties of the material are more stable. More preferably, the silane coupling agent is selected from one or more of silane coupling agents, titanate coupling agents, or aluminate coupling agents.

[0051] To further improve the compression molding properties of the material, the amount of lubricant used is preferably 0.1% to 1% of the weight of the rare earth ion-doped soft magnetic alloy core layer. More preferably, the lubricant is selected from one or more of zinc stearate, calcium stearate, or magnesium stearate.

[0052] In a preferred embodiment, during the first stirring process, the processing temperature is 50–100°C, and the processing time is 1–5 hours. This results in a more stable and denser phosphating layer formation. In a preferred embodiment, during the second stirring process, the processing temperature is 50–100°C, and the processing time is 1–5 hours. This allows the glass layer to more smoothly coat the phosphating layer, further improving the insulation of the core layer. In a preferred embodiment, during the third stirring process, the processing temperature is 50–100°C, and the processing time is 1–5 hours. During the fourth stirring process, the processing temperature is 50–100°C, and the processing time is 1–5 hours. This allows the lubricating layer to more smoothly coat the glass layer, further improving the material's insulation and molding properties.

[0053] This invention also provides an application of the aforementioned soft magnetic composite material in inductor devices used in frequency bands above MHz. Based on the reasons stated above, it exhibits superior electromagnetic characteristics and lower losses, thus enabling it to achieve higher compatibility with third-generation wide-bandgap semiconductors in subsequent applications, making it more suitable for the miniaturization, high-frequency operation, and high-power requirements of inductor devices.

[0054] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0055] Example 1

[0056] Preparation of rare earth ion-doped soft magnetic alloys

[0057] (1) First, prepare the following initial materials: iron, iron-silicon alloy, aluminum metal and rare earth metal cerium.

[0058] (2) Iron, iron-silicon alloy, aluminum and rare earth metal cerium are smelted under Ar gas protection to form a melt; the smelting temperature is 1900℃ and the smelting time is 3h.

[0059] (3) The melt is atomized into powder in an Ar gas environment by passing it through a gas atomization device; the atomizing gas pressure is 0.5 MPa.

[0060] (4) The atomized powder was heat-treated at 900℃ in an Ar atmosphere for 2 hours.

[0061] (5) Reduce the treatment temperature to 450℃, then extract the Ar gas and fill it with N2 for 4 hours of nitriding treatment; during the treatment process, always maintain the nitrogen pressure at 0.1MPa.

[0062] (6) Cool the powder to room temperature to obtain a rare earth ion-doped soft magnetic alloy. In the rare earth ion-doped soft magnetic alloy, the content of Fe is 83wt%, the content of Si is 9.45wt%, the content of Al is 5wt%, the content of Ce is 2wt%, and the content of N is 0.55wt%.

[0063] Preparation of soft magnetic composite materials

[0064] (7) The above-mentioned rare earth ion doped soft magnetic alloy is immersed in alcohol, and then 0.5% of the weight of the rare earth ion doped soft magnetic alloy of phosphoric acid is added to the alcohol. The mixture is stirred in a vacuum environment for 1 hour, and then heated to 80°C to dry, to obtain intermediate material A.

[0065] (8) Disperse 0.5% by weight of ethyl silicate, 0.2% by weight of sodium pyrophosphate and 0.5% by weight of rare earth ion doped soft magnetic alloy with alcohol, pour it into the above intermediate material A to make it into a slurry, and then stir at high speed for 1 hour. During the stirring process, add ammonia water to the slurry to make the pH value of the slurry close to 8.0, and then heat it to 80°C to dry it to obtain intermediate material B.

[0066] (9) Dilute 0.5% by weight of KH550 silane coupling agent of rare earth ion doped soft magnetic alloy with alcohol, add it to the above intermediate material B and stir for 1 hour, and then dry at 80°C.

[0067] (10) Add 0.1% of the weight of the rare earth ion-doped soft magnetic alloy zinc stearate, stir at 80 degrees for 30 minutes, then add 1% of the weight of the rare earth ion-doped soft magnetic alloy silicone resin, and continue stirring for 1 hour.

[0068] (11) Cool the material processed in step (10) to room temperature, then break the material apart with a crusher and sieve it through a 300-mesh sieve to obtain a soft magnetic composite material.

[0069] The material was molded under a pressure of 1600 MPa to obtain a ring sample with an outer diameter of 20 mm, an inner diameter of 10 mm, and a height of 5 mm.

[0070] Example 2

[0071] The only difference from Example 1 is that in the rare earth ion-doped soft magnetic alloy, the content of Fe is 85 wt%, the content of Si is 9.5 wt%, the content of Al is 3 wt%, the content of Ce is 2 wt%, and the content of N is 0.50 wt%.

[0072] Example 3

[0073] The only difference from Example 1 is that in the rare earth ion-doped soft magnetic alloy, the content of Fe is 85 wt%, the content of Si is 8.75 wt%, the content of Al is 5 wt%, the content of Ce is 1 wt%, and the content of N is 0.25 wt%.

[0074] Example 4

[0075] The only difference from Example 1 is that in the rare earth ion-doped soft magnetic alloy, the content of Fe is 85 wt%, the content of Si is 7.47 wt%, the content of Al is 5 wt%, the content of Ce is 2 wt%, and the content of N is 0.53 wt%.

[0076] Example 5

[0077] The only difference from Example 1 is that in the rare earth ion-doped soft magnetic alloy, the content of Fe is 83 wt%, the content of Si is 8.47 wt%, the content of Al is 6 wt%, the content of Ce is 2 wt%, and the content of N is 0.53 wt%.

[0078] Example 6

[0079] The only difference from Example 1 is that in step (5), the nitriding treatment temperature is 550°C and the time is 6 hours.

[0080] In the rare earth ion-doped soft magnetic alloy, the content of Fe is 83 wt%, the content of Si is 9.39 wt%, the content of Al is 5 wt%, the content of Ce is 2 wt%, and the content of N is 0.61 wt%.

[0081] Example 7

[0082] The only difference from Example 1 is that in step (7), the amount of phosphoric acid added is 1 wt%.

[0083] Example 8

[0084] The only difference from Example 1 is that in step (8), the amount of ethyl silicate is 1 wt%, sodium pyrophosphate is 0.5 wt%, and sodium silicate is 1 wt%.

[0085] Example 9

[0086] The only difference from Example 1 is that in step (5), the nitriding treatment temperature is 380°C.

[0087] A rare earth ion-doped soft magnetic alloy was obtained, in which the content of Fe was 83 wt%, the content of Si was 10 wt%, the content of Al was 5 wt%, the content of Ce was 2 wt%, and the content of N was 0.25 wt%.

[0088] Example 10

[0089] The only difference from Example 1 is that in step (9), the amount of coupling agent used is 1 wt%.

[0090] Example 11

[0091] The only difference from Example 1 is that in step (10), the amount of lubricant used is 1 wt%.

[0092] Comparative Example 1

[0093] (1) First, prepare the following initial materials: iron, iron-silicon alloy, and aluminum.

[0094] (2) Iron, iron-silicon alloy and aluminum are fed into the feed. By adjusting the proportions, the weight ratios of Fe, Si and Al in the feed are 85wt%, 10wt% and 5wt%, respectively. Then, the feed is smelted under Ar gas protection to form a melt. The smelting temperature is 1900℃ and the smelting time is 3h.

[0095] (3) The melt is atomized into powder in an Ar gas environment using a gas atomization device; the atomizing gas pressure is 0.5 MPa;

[0096] (4) The atomized powder was heat-treated at 900℃ in an Ar atmosphere for 2 hours to obtain FeSiAl alloy powder.

[0097] The prepared FeSiAl powder was sieved through a 300-mesh sieve and molded under a pressure of 1600 MPa to obtain a ring sample with an outer diameter of 20 mm, an inner diameter of 10 mm, and a height of 5 mm.

[0098] Comparative Example 2

[0099] The only difference from Example 1 is that in the rare earth ion-doped soft magnetic alloy, the content of Fe is 80 wt%, the content of Si is 15 wt%, the content of Al is 4.5 wt%, the content of Ce is 0.5 wt%, and the content of N is 0.12 wt%.

[0100] Comparative Example 3

[0101] The only difference from Example 1 is that in the rare earth ion-doped soft magnetic alloy, the content of Fe is 90 wt%, the content of Si is 5 wt%, the content of Al is 1 wt%, the content of Ce is 4 wt%, and the content of N is 1.0 wt%.

[0102] Performance testing:

[0103] The composite materials of the above embodiments and comparative examples were tested under conditions of 1 MHz and 50 mT, and the performance results are shown in Table 1 below:

[0104] Table 1

[0105] Saturation magnetization magnetic permeability loss Soft magnetic composite material in Example 1 0.79T 70 <![CDATA[1750mW / cm 3 ]]> Soft magnetic composite material in Example 2 0.82T 75 <![CDATA[1920mW / cm 3 ]]> Soft magnetic composite material in Example 3 0.83T 75 <![CDATA[2010mW / cm 3 ]]> Soft magnetic composite material in Example 4 0.82T 77 <![CDATA[2060mW / cm 3 ]]> Soft magnetic composite material in Example 5 0.75T 58 <![CDATA[1730mW / cm 3 ]]> Soft magnetic composite material in Example 6 0.78T 69 <![CDATA[1710mW / cm 3 ]]> Soft magnetic composite material in Example 7 0.77T 66 <![CDATA[1670mW / cm 3 ]]> Soft magnetic composite material in Example 8 0.77T 63 <![CDATA[1710mW / cm 3 ]]> Soft magnetic composite material in Example 9 0.79T 71 <![CDATA[2150mW / cm 3 ]]> Soft magnetic composite material in Example 10 0.78T 69 <![CDATA[1735mW / cm 3 ]]> Soft magnetic composite material in Example 11 0.79T 69 <![CDATA[1720mW / cm 3 ]]> Soft magnetic composite material in Comparative Example 1 0.80T 69 <![CDATA[2406mW / cm 3 ]]> Soft magnetic composite material in Comparative Example 2 0.68T 55 <![CDATA[2312mW / cm 3 ]]> Soft magnetic composite material in Comparative Example 3 0.82T 71 <![CDATA[4012mW / cm 3 ]]>

[0106] Comparing Examples 1, 6, 10, 11, and Comparative Example 1, it can be seen that the saturation magnetization and permeability of Examples 1, 6, 10, and 11 are basically the same as those of Comparative Example 1, but the loss in Comparative Example 1 increases significantly. Comparing Examples 1 to 11 and Comparative Example 2, it can be seen that the saturation magnetization and permeability of Comparative Example 2 are significantly reduced, and the loss also increases significantly. Comparing Examples 2, 3, 4, and Comparative Example 3, it can be seen that the saturation magnetization and permeability of Examples 2, 3, and 4 are basically the same as those of Comparative Example 3, but the loss in Comparative Example 3 increases significantly.

[0107] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rare-earth ion-doped soft magnetic alloy, characterized in that, The rare earth ion-doped soft magnetic alloy is composed of Fe, Si, Al, N and Re, where Re is a rare earth element. In the rare earth ion-doped soft magnetic alloy, the Fe content is 82-85 wt%, the Si content is 8-10 wt%, the Al content is 3-5 wt%, the Re content is 1-2 wt%, and the N content is 0.25-0.65 wt%; the rare earth element is one or more of Ce, La, Sm, Nd, and Pr. The preparation method of the rare earth ion-doped soft magnetic alloy includes the following steps: In an inert gas atmosphere, iron, iron-silicon alloy, aluminum and rare earth metals are mixed and smelted to form a melt; the melt is then subjected to atomization powdering, heat treatment and nitriding treatment in sequence to form the rare earth ion-doped soft magnetic alloy.

2. The rare-earth ion-doped soft magnetic alloy according to claim 1, characterized in that, The average particle size of the rare earth ion-doped soft magnetic alloy is 5~50 μm.

3. A method for preparing a rare-earth ion-doped soft magnetic alloy as described in claim 1 or 2, characterized in that, The preparation method includes the following steps: In an inert gas atmosphere, iron, iron-silicon alloys, aluminum and rare earth metals are mixed and smelted to form a melt; The melt is subjected to atomization powdering, heat treatment and nitriding treatment in sequence to form the rare earth ion doped soft magnetic alloy; The rare earth ion-doped soft magnetic alloy is composed of Fe, Si, Al, N and Re, where Re is a rare earth element; in the rare earth ion-doped soft magnetic alloy, the content of Fe is 82~85wt%, the content of Si is 8~10wt%, the content of Al is 3~5wt%, the content of Re is 1~2wt%, and the content of N is 0.25~0.65wt%.

4. The preparation method according to claim 3, characterized in that, During the nitriding process, nitrogen gas is introduced into the system to carry out the nitriding treatment.

5. The preparation method according to claim 4, characterized in that, During the nitriding process, the treatment temperature is 450~550℃ and the treatment time is 4~6h.

6. The preparation method according to claim 4, characterized in that, During the nitriding process, the nitrogen pressure is 0.1~0.2MPa.

7. The preparation method according to claim 3, characterized in that, During the smelting process, the smelting temperature is 1800~2000℃ and the smelting time is 0.5~5h.

8. The preparation method according to claim 3, characterized in that, During the heat treatment process, the treatment temperature is 900~1000℃ and the treatment time is 2~3h.

9. The preparation method according to claim 3, characterized in that, A gas atomization device is used to perform the atomization powder production.

10. The preparation method according to claim 9, characterized in that, In the aforementioned gas atomizing device, the atomizing gas is an inert gas with a pressure of 0.1~1.0 MPa.

11. A soft magnetic composite material, characterized in that, The soft magnetic composite material includes: Rare earth ion-doped soft magnetic alloy core layer; A phosphating layer is applied to the outer surface of the rare-earth ion-doped soft magnetic alloy core layer. A glass layer is formed on the outer surface of the phosphating layer, away from the rare earth ion-doped soft magnetic alloy core layer. A lubricating layer is coated on the outer surface of the glass layer away from the rare earth ion-doped soft magnetic alloy core layer, and the lubricating layer is coupled to the surface of the glass layer by a coupling agent. Wherein, the material of the rare earth ion-doped soft magnetic alloy core layer is the rare earth ion-doped soft magnetic alloy as described in claim 1 or 2, the material of the phosphating layer is iron phosphate and / or aluminum phosphate, the material of the glass layer is one or more of silicon dioxide, sodium pyrophosphate or sodium silicate, and the material of the lubricating layer is a lubricant.

12. The soft magnetic composite material according to claim 11, characterized in that, The coupling agent is selected from one or more of silane coupling agents, titanate coupling agents, or aluminate coupling agents.

13. The soft magnetic composite material according to claim 11, characterized in that, The lubricant is selected from one or more of zinc stearate, calcium stearate, or magnesium stearate.

14. The soft magnetic composite material according to claim 11, characterized in that, The thickness of the phosphating layer is 10~50nm, the thickness of the glass layer is 10~50nm, and the thickness of the lubricating layer is 10~50nm.

15. A method for preparing a soft magnetic composite material according to any one of claims 11 to 14, characterized in that, The preparation method includes the following steps: A rare earth ion-doped soft magnetic alloy core layer is provided, and a phosphating layer is coated on the outer surface of the rare earth ion-doped soft magnetic alloy core layer. A glass layer is coated on the outer surface of the phosphating layer, away from the rare earth ion-doped soft magnetic alloy core layer; A lubricating layer is coupled and coated with a coupling agent on the outer surface of the glass layer away from the rare earth ion-doped soft magnetic alloy core layer, thereby forming the soft magnetic composite material. Wherein, the material of the rare earth ion-doped soft magnetic alloy core layer is the rare earth ion-doped soft magnetic alloy as described in claim 1 or 2, the material of the phosphating layer is iron phosphate and / or aluminum phosphate, the material of the glass layer is one or more of silicon dioxide, sodium pyrophosphate or sodium silicate, and the material of the lubricating layer is a lubricant.

16. The preparation method according to claim 15, characterized in that, The preparation method includes: In a vacuum environment, a first dispersion containing the rare earth ion-doped soft magnetic alloy core layer is mixed with phosphoric acid and stirred for the first time, so that the phosphoric acid reacts with the material in the surface region of the rare earth ion-doped soft magnetic alloy core layer to coat its outer surface and form the phosphating layer, thus obtaining intermediate material A; the material of the phosphating layer includes the iron phosphate and the aluminum phosphate. Under pH conditions of 6.0 to 8.0, a second dispersion containing the intermediate material A, the ethyl silicate, the sodium pyrophosphate, and the sodium silicate is subjected to a second stirring to react on the outer surface of the phosphating layer away from the rare earth ion-doped soft magnetic alloy core layer and form the glass layer, thereby obtaining intermediate material B; the glass layer contains the silicon dioxide, the sodium pyrophosphate, and the sodium silicate. The third dispersion containing the intermediate material B and the coupling agent is stirred for the third time to connect the coupling agent to the outer surface of the glass layer away from the rare earth ion-doped soft magnetic alloy core layer, thereby obtaining the intermediate material C. The intermediate material C and the lubricant are mixed and stirred for a fourth time, so that the lubricant is coupled and coated on the surface of the glass layer by the coupling agent to form the lubricating layer, thereby forming the soft magnetic composite material.

17. The preparation method according to claim 16, characterized in that, The amount of phosphoric acid used is 0.5 to 1% of the weight of the rare earth ion-doped soft magnetic alloy core layer.

18. The preparation method according to claim 16, characterized in that, The amount of ethyl silicate used is 0.5-1% of the weight of the rare earth ion-doped soft magnetic alloy core layer, the amount of sodium pyrophosphate used is 0.2-0.5% of the weight of the rare earth ion-doped soft magnetic alloy core layer, and the amount of sodium silicate used is 0.5-1% of the weight of the rare earth ion-doped soft magnetic alloy core layer.

19. The preparation method according to claim 16, characterized in that, The amount of the coupling agent is 0.5 to 1.0% of the weight of the rare earth ion-doped soft magnetic alloy core layer.

20. The preparation method according to claim 16, characterized in that, The amount of lubricant used is 0.1 to 1% of the weight of the rare earth ion-doped soft magnetic alloy core layer.

21. The preparation method according to claim 16, characterized in that, The processing temperature of the first stirring, the second stirring, the third stirring and the fourth stirring are each independently selected from 50~100℃, and the processing time of each is independently 1~5h.

22. The application of a soft magnetic composite material according to any one of claims 11 to 14 in an inductor device for the MHz band.