High-frequency ultralow-loss iron-nickel alloy powder and preparation process thereof

Abstract

The invention relates to high-frequency ultralow-loss iron-nickel alloy powder and a preparation method thereof.The powder comprises a powder core composed of iron-nickel alloy, the core comprises, by weight, 75.5%-77.5% of nickel, 4.5%-6.5% of molybdenum, 2%-3% of lanthanum and titanium, the mass ratio of lanthanum to titanium is 2: 1, and the balance is iron and inevitable impurities; the surface of the powder core is coated with an insulating metal oxide layer with the average thickness of 3 nm to 10 nm. The soft magnetic material prepared from the high-frequency ultralow-loss iron-nickel alloy powder has excellent high-frequency magnetic conductivity and low power loss, the high-frequency magnetic conductivity'under 50 MHz is 38-49, the power loss under 100 KHz / 100 mT is 260-281 mW / cm < 3 >, and high magnetic conductivity and power loss are still achieved under the high-frequency condition.

Description

Technical Field

[0001] This invention belongs to the field of magnetic materials technology, specifically relating to a high-frequency ultra-low loss iron-nickel alloy powder and its preparation process. Background Technology

[0002] With the rapid development of power electronics technology, especially the rise of emerging fields such as 5G communication, new energy vehicles, server power supplies, and wireless charging, electronic devices and power conversion systems are developing towards higher frequencies, smaller sizes, higher efficiency, and higher power densities. These trends place extremely stringent requirements on soft magnetic materials in core magnetic components (such as inductors and transformers). Under high-frequency operating conditions (typically above 100kHz, or even several MHz to hundreds of MHz), traditional soft magnetic materials face enormous challenges.

[0003] Among numerous metallic magnetic powder core materials, iron-nickel alloys, especially permalloy, have attracted considerable attention due to their extremely high permeability, extremely low coercivity, and magnetostriction coefficient. However, in high-frequency applications, the significant skin effect of existing iron-nickel alloy soft magnetic materials makes eddy current loss a key factor affecting their performance. Furthermore, the content of impurity elements is difficult to control effectively during the preparation of existing iron-nickel alloy powders, impacting their electrical properties. In addition, current coating processes are not perfect, resulting in low powder resistivity, which further exacerbates the eddy current loss problem and fails to meet the high-performance requirements of soft magnetic materials in high-frequency applications. Therefore, there is an urgent need to develop a high-frequency, ultra-low-loss iron-nickel alloy powder product to meet market demands and drive industry development. Summary of the Invention

[0004] This invention provides a high-frequency, ultra-low-loss iron-nickel alloy powder and its preparation process, addressing the problem of high eddy current loss in current high-frequency applications of iron-nickel alloy soft magnetic materials. The soft magnetic material made from the high-frequency, ultra-low-loss iron-nickel alloy powder prepared by this invention exhibits excellent high-frequency permeability and low power loss, with a high-frequency permeability µ′ of 38–49 at 50 MHz and a power loss of 260–281 mW / cm³ at 100 kHz / 100 mT, achieving high permeability and low power loss even at high frequencies.

[0005] In a first aspect, the present invention relates to a high-frequency ultra-low loss iron-nickel alloy powder, the powder comprising: a powder core composed of an iron-nickel alloy, the composition of the core by weight percentage being: nickel: 75.5%–77.5%, molybdenum: 4.5%–6.5%, lanthanum: 2%–3%, and titanium, wherein the mass ratio of lanthanum to titanium is 2:1, and the balance being iron and unavoidable impurities; the surface of the powder core is coated with an insulating metal oxide layer with an average thickness of 3 nm to 10 nm; the insulating metal oxide layer comprises NiZn ferrite powder and non-magnetic powders Al2O3, MgO, and Nb2O5, wherein the mass ratio of NiZn ferrite powder to Al2O3, MgO, and Nb2O5 is 15–20:3:1–2:4–5.

[0006] Preferably, the powder contains three particle sizes, with a mass ratio of 150 mesh: 250 mesh: 400 mesh of 1-2: 4-5: 1-3.

[0007] Preferably, the total content of unavoidable impurity elements carbon, sulfur, oxygen, and nitrogen in the powder core is less than 500 ppm.

[0008] Preferably, the NiZn ferrite powder is (Ni0.5Zn0.5)Fe2O4 powder.

[0009] In a second aspect, the present invention relates to the preparation process of the iron-nickel alloy powder, characterized in that the process includes the following steps: (1) smelting and atomization step: the metal raw materials conforming to the core composition of the powder are smelted under a protective atmosphere to form a uniform alloy melt, and the melt is superheated to a range of 150°C to 250°C above its liquidus temperature; subsequently, the alloy melt is atomized by a high-pressure gas atomization method, wherein the atomizing gas pressure is controlled between 5.0 MPa and 10.0 MPa, thereby obtaining the initial iron-nickel alloy powder; (2) Grading step: The initial iron-nickel alloy powder is finely graded and screened using an air classifier to obtain ultrafine spherical powder; (3) Coating step: NiZn ferrite powder and non-magnetic powders Al2O3, MgO and Nb2O5 powder are ball-milled in a stainless steel ball mill at a speed of 450-600 r / min to obtain nano-coated powder; the coated powder and the ultrafine spherical powder are ball-milled in a ball mill to obtain high-frequency ultra-low loss iron-nickel alloy powder.

[0010] Preferably, the atomizing gas is an inert gas, such as argon or nitrogen.

[0011] Preferably, the ball-to-material ratio in the ball mill insulation coating is 1.5 to 2.5:1, and the rotation speed is 350 to 400 r / min.

[0012] Thirdly, the present invention relates to a high-frequency ultra-low loss iron-nickel alloy soft magnetic material, which uses iron-nickel alloy powder or iron-nickel alloy powder obtained by the preparation method described above as raw material powder, presses the raw material powder into shape, and heat-treats it at 600℃~750℃ for 1.5~2h to obtain the high-frequency ultra-low loss iron-nickel alloy soft magnetic material.

[0013] Preferably, a high-frequency ultra-low loss iron-nickel alloy soft magnetic material is obtained after heat treatment at 650℃ for 1.8h.

[0014] The beneficial effects of this invention are as follows: By adjusting the proportions of nickel, molybdenum, lanthanum, and titanium in the iron-nickel alloy core and controlling impurities, optimizing the composition of the insulating coating layer, and optimizing the particle size ratio of the iron-nickel alloy, the skin effect can be effectively reduced, the resistivity can be maximized, and the microstructure can be stabilized most effectively. This fundamentally reduces eddy current loss and hysteresis loss, resulting in excellent high-frequency performance.

[0015] The preparation of iron-nickel alloys involves optimizing and controlling the ball milling insulation coating process to firmly "embed" or "weld" nano-coated powder onto the surface of iron-nickel alloy powder, forming a thin and dense coating layer, thus achieving the best balance between insulation performance and magnetic properties.

[0016] Specific heat treatment processes for soft magnetic materials can achieve the optimal balance between stress relief, performance recovery, and maintaining the integrity of the insulation layer, thereby obtaining the final ultra-low loss, high-performance soft magnetic material.

[0017] The soft magnetic material made from the high-frequency ultra-low loss iron-nickel alloy powder prepared by this invention has excellent high-frequency permeability and low power loss. The high-frequency permeability µ′ at 50MHz is 38-49, and the power loss at 100KHz / 100mT is 260-281mW / cm3, achieving high permeability and power loss even under high-frequency conditions. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the preparation process of a high-frequency ultra-low loss iron-nickel alloy powder disclosed in an embodiment of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In high-frequency applications, the significant skin effect of existing iron-nickel alloy soft magnetic materials makes eddy current loss a key factor affecting their performance. Furthermore, the preparation process of existing iron-nickel alloy powders makes it difficult to effectively control the content of impurity elements, and the current coating process is not perfect, resulting in low powder resistivity, which further exacerbates the eddy current loss problem and fails to meet the high-performance requirements of soft magnetic materials in high-frequency scenarios. Therefore, there is an urgent need to develop a high-frequency, ultra-low-loss iron-nickel alloy powder product to meet market demands and drive industry development.

[0022] To address the aforementioned technical problems, embodiments of the present invention provide a high-frequency ultra-low loss iron-nickel alloy powder, which comprises: a powder core composed of an iron-nickel alloy, wherein the components of the core, by weight percentage, are: nickel: 75.5%–77.5%, molybdenum: 4.5%–6.5%, and also contain lanthanum: 2%–3% and titanium, wherein the mass ratio of lanthanum to titanium is 2:1, and the balance is iron and unavoidable impurities; The surface of the powder core is coated with an insulating metal oxide layer with an average thickness of 3 nm to 10 nm; the insulating metal oxide layer includes NiZn ferrite powder and non-magnetic powders Al2O3, MgO and Nb2O5, and the mass ratio of NiZn ferrite powder to Al2O3, MgO and Nb2O5 is 15 to 20: 3: 1 to 2: 4 to 5.

[0023] The powder contains three particle sizes, with a mass ratio of 150 mesh: 250 mesh: 400 mesh of 1-2: 4-5: 1-3.

[0024] In one embodiment, the total content of unavoidable impurity elements carbon, sulfur, oxygen, and nitrogen in the powder core is less than 500 ppm.

[0025] In one embodiment, the NiZn ferrite powder is (Ni0.5Zn0.5)Fe2O4 powder.

[0026] Nickel content in the powder core is 75.5%–77.5%. In iron-nickel alloys, the nickel content has a significant impact on magnetic properties. This ratio ensures that the alloy has good permeability and other key magnetic properties, providing good basic magnetic characteristics for high-frequency applications.

[0027] Molybdenum: 4.5%–6.5%. Adding 4.5%–6.5% molybdenum can effectively improve the resistivity of the powder core. When molybdenum enters the alloy lattice, it hinders electron movement, thereby increasing resistance and reducing eddy current losses, which is crucial for performance improvement in high-frequency applications. The addition of molybdenum can broaden the range of compositions that yield excellent soft magnetic properties, reduce sensitivity to the nickel-iron ratio, and improve process stability. Molybdenum can also effectively suppress the formation of the ordered Ni3Fe phase during heat treatment, thus maintaining the material's high permeability and low coercivity.

[0028] Lanthanum: 2%–3%, with a lanthanum to titanium mass ratio of 2:1. As a rare earth element, lanthanum adsorbs at grain boundaries, hindering grain growth and refining the grains. Titanium, on the other hand, forms stable compounds with impurities in the alloy, reducing their promoting effect on grain boundary migration. When lanthanum and titanium coexist in a 2:1 mass ratio, they do not function independently at grain boundaries, but rather form complex precipitates with specific structures. Compared to single Ti-based or La-based precipitates, these precipitates exert a stronger effect on pinning grain boundaries and inhibiting grain growth. More importantly, these complex precipitates introduce numerous phase interfaces and lattice defects at grain boundaries, creating strong electron scattering centers. This synergistic effect achieves an optimized golden ratio, maximizing resistivity while effectively stabilizing the microstructure, thereby fundamentally reducing eddy current and hysteresis losses.

[0029] The total content of impurity elements carbon, sulfur, oxygen, and nitrogen is less than 500 ppm. These impurity elements can form defects or second phases in the alloy, interfering with the movement of electrons and magnetic domains, and reducing the electrical and magnetic properties of the alloy. Low impurity content ensures that iron-nickel alloy powder has good basic properties.

[0030] The surface of the powder core is coated with an insulating metal oxide layer with an average thickness of 3 nm to 10 nm. The average thickness of the insulating metal oxide layer is controlled within the range of 3 nm to 10 nm because if the thickness is too thin, it is difficult to form a continuous and effective insulating layer, which cannot effectively block current and thus fails to reduce eddy current losses; while if the thickness is too thick, it will increase the distance between the powder particles, affecting the transmission of magnetic flux and reducing magnetic permeability. This thickness range can ensure good insulation while minimizing the negative impact on magnetic properties.

[0031] The insulating metal oxide layer comprises NiZn ferrite powder and non-magnetic powders Al2O3, MgO, and Nb2O5, wherein the mass ratio of NiZn ferrite powder to Al2O3, MgO, and Nb2O5 is 15–20:3:1–2:4–5. Using (Ni0.5Zn0.5)Fe2O4 as the NiZn ferrite powder not only provides extremely high resistivity, effectively blocking eddy currents between particles, but also, being a soft magnetic material itself, can participate in the magnetization process, reducing the magnetic dilution effect caused by introducing too much pure non-magnetic material. This helps maintain a high permeability of the magnetic core. (Ni0.5Zn0.5)Fe2O4 possesses excellent high-frequency magnetic properties and insulation characteristics, effectively improving the magnetic properties and insulation effect of the cladding layer. Al₂O₃ possesses high resistivity and chemical stability, enhancing the insulation performance and stability of the coating layer. Nanoscale Al₂O₃ particles fill the gaps between NiZn ferrite particles and adhere to the surface of the iron-nickel core, acting as both "secondary insulation" and "structural reinforcement." MgO can regulate the crystal structure of the coating layer, improving its bonding with the powder core. MgO is also an effective sintering aid; during subsequent heat treatment, it can lower the interfacial reaction temperature, promoting a stronger interfacial bond between high-melting-point oxides such as Al₂O₃ and Nb₂O₅ and the NiZn ferrite and iron-nickel matrix, thus improving the adhesion and mechanical strength of the insulation layer. At high temperatures, Nb₂O₅ can promote the formation of a glassy or amorphous phase at the interface. This amorphous layer can "bond" other oxide particles, forming a completely dense, non-porous composite insulation layer, improving the density and wear resistance of the coating layer. The components are combined in a mass ratio of 15–20:3:1–2:4–5, resulting in a synergistic structure at the nanoscale: ferrite as the main body, Al2O3 as the framework, MgO as an auxiliary agent, and Nb2O5 forming a continuous interface phase. This structure makes the resistivity of the insulating layer much higher than that of any single component and exhibits excellent stability in subsequent processes. This allows the insulating metal oxide layer to exert optimal synergistic insulation and magnetic properties at high frequencies, reducing eddy current losses.

[0032] Powder particle size ratio: 150 mesh: 250 mesh: 400 mesh mass ratio of 1-2: 4-5: 1-3. Controlling the proportion of different particle sizes within this range is not merely a simple physical mixing process, but a key characteristic directly affecting the final magnetic core performance. Because the combination of powders of different sizes increases the powder packing density and reduces voids, the structure of the pressed soft magnetic material is more compact. In this dense stacked structure, due to the effective isolation of the particles by the insulating layer, eddy currents at high frequencies are firmly confined within each particle and mainly distributed on the particle surface, preventing the formation of large loops across particles, thus effectively suppressing macroscopic losses caused by the skin effect.

[0033] like Figure 1 As shown, the preparation process of the iron-nickel alloy powder of the present invention includes the following steps: (1) Melting and atomization step: the metal raw materials that conform to the core composition of the powder are melted under a protective atmosphere to form a uniform alloy melt, and the melt is superheated to a range of 150°C to 250°C above its liquidus temperature; then, the alloy melt is atomized by high pressure gas atomization method, wherein the atomizing gas pressure is controlled between 5.0 MPa and 10.0 MPa, thereby obtaining the initial iron-nickel alloy powder; (2) Grading step: The initial iron-nickel alloy powder is finely graded and screened using an air classifier to obtain ultrafine spherical powder; (3) Coating step: NiZn ferrite powder and non-magnetic powders Al2O3, MgO and Nb2O5 powder are ball-milled in a stainless steel ball mill at a speed of 450-600 r / min to obtain nano-coated powder; the coated powder and the ultrafine spherical powder are ball-milled in a ball mill to obtain high-frequency ultra-low loss iron-nickel alloy powder.

[0034] In one embodiment, the atomizing gas is an inert gas, argon or nitrogen.

[0035] In one embodiment, the ball-to-material ratio in the ball mill insulation coating is 1.5 to 2.5:1, and the rotation speed is 350 to 400 r / min.

[0036] Melting and atomization steps: Metal raw materials conforming to the powder core composition are melted under a protective atmosphere to form a homogeneous alloy melt. The melt is then superheated to 150°C to 250°C above its liquidus temperature. The alloy melt is atomized using a high-pressure gas (inert gas argon or nitrogen), with the atomizing gas pressure controlled between 5.0 MPa and 10.0 MPa. Superheating the melt to 150°C to 250°C above its liquidus temperature reduces its viscosity, making it easier to break into fine droplets during atomization, thus obtaining powder with uniform particle size. Controlling the atomizing gas pressure between 5.0 MPa and 10.0 MPa ensures that the powder is not too fine and easily oxidized, while too low a pressure results in larger particle sizes. This pressure range guarantees the acquisition of initial iron-nickel alloy powder with a suitable particle size.

[0037] Grading Steps: An air classifier is used to finely classify and screen the initial iron-nickel alloy powder to obtain ultrafine spherical powder. The air classifier is used to finely classify and screen the initial iron-nickel alloy powder to obtain ultrafine spherical powder because the small particle size of ultrafine powder reduces the skin depth, thereby reducing eddy current losses at high frequencies. The spherical structure is also beneficial for powder accumulation and subsequent pressing and forming.

[0038] Coating Steps: NiZn ferrite powder and non-magnetic powders Al2O3, MgO, and Nb2O5 are ball-milled in a stainless steel ball mill at a speed of 450–600 r / min to obtain nanoscale coated powder. The coated powder is then ball-milled with ultrafine spherical powder in a ball mill jar for insulating coating (ball-to-powder ratio of 1.5–2.5:1, speed of 350–400 r / min). The ball-milling of the coated powder to the nanoscale is to ensure a more uniform coating on the powder core surface, forming a continuous insulating layer. During the insulating ball-milling process, the ball-to-powder ratio is controlled at 1.5–2.5:1, and the speed is 350–400 r / min. This step is not a simple mixing process, but rather a "mechanical-chemical coating" or "mechanical fusion" process. The low rotational speed and suitable ball-to-powder ratio provide just the right amount of mechanical energy, sufficient to firmly "embed" or "weld" the nano-coated powder to the surface of the iron-nickel alloy powder, forming a thin and dense coating layer, but not enough to cause severe plastic deformation or breakage of the alloy powder itself. The thickness of the coating layer obtained in this way can be precisely controlled between 3 nm and 10 nm, achieving the best balance between insulation and magnetic properties.

[0039] This invention discloses a high-frequency ultra-low loss iron-nickel alloy soft magnetic material, which uses iron-nickel alloy powder or iron-nickel alloy powder obtained by the preparation method described above as raw material powder. The raw material powder is pressed into shape and then heat-treated at 600℃~750℃ for 1.5~2h to obtain the high-frequency ultra-low loss iron-nickel alloy soft magnetic material.

[0040] In one embodiment, a high-frequency ultra-low loss iron-nickel alloy soft magnetic material is obtained after heat treatment at 650°C for 1.8 hours.

[0041] The soft magnetic material is prepared using the aforementioned iron-nickel alloy powder as the raw material. The raw material powder is pressed into shape and then heat-treated at 600℃~750℃ for 1.5~2h (preferably 650℃ for 1.8h) to obtain a high-frequency ultra-low loss iron-nickel alloy soft magnetic material. The heat treatment at 600℃~750℃ for 1.5~2h after pressing the raw material powder eliminates the internal stress generated during the pressing process, making it easier for the magnetic domain walls to move, thereby restoring and improving the soft magnetic properties of the material (such as permeability) and reducing hysteresis loss. It also promotes limited interfacial reactions and diffusion between the insulating layer and the matrix, as well as between the components of the insulating layer, forming a stronger and denser interfacial bond, further improving the stability and insulation effect of the insulating layer. If the temperature is too low, stress elimination will be insufficient; if the temperature is too high, it may lead to damage to the insulating layer, metallurgical bonding between particles, and excessive growth of alloy grains, which will drastically increase eddy current losses. The 600℃~750℃ range determined in this invention, particularly the preferred process conditions of 650℃ and 1.8h, represents the optimal balance between stress relief, performance recovery, and maintaining the integrity of the insulation layer, thereby obtaining the final ultra-low loss high-performance soft magnetic material. The soft magnetic material made from the high-frequency ultra-low loss iron-nickel alloy powder prepared by this invention exhibits excellent high-frequency permeability and low power loss. The high-frequency permeability µ′ at 50MHz is 38~49, and the power loss at 100KHz / 100mT is 260~281mW / cm3, achieving high permeability and power loss even under high-frequency conditions.

[0042] The embodiments of the present invention are described in detail below. The high-frequency ultra-low loss iron-nickel alloy powder used in the embodiments is as follows, and the powder comprises: A powder core made of an iron-nickel alloy, wherein the composition of the core by weight percentage is: nickel: 75.5% to 77.5%, molybdenum: 4.5% to 6.5%, and also contains lanthanum: 2% to 3% and titanium, wherein the mass ratio of lanthanum to titanium is 2:1, and the balance is iron and unavoidable impurities; The surface of the powder core is coated with an insulating metal oxide layer with an average thickness of 3 nm to 10 nm; the insulating metal oxide layer includes NiZn ferrite powder and non-magnetic powders Al2O3, MgO and Nb2O5, and the mass ratio of NiZn ferrite powder to Al2O3, MgO and Nb2O5 is 15 to 20: 3: 1 to 2: 4 to 5.

[0043] The powder has a particle size ratio of 150 mesh: 250 mesh: 400 mesh in mass of 1-2: 4-5: 1-3.

[0044] The total content of unavoidable impurity elements carbon, sulfur, oxygen, and nitrogen in the powder core is less than 500 ppm.

[0045] The NiZn ferrite powder is (Ni0.5Zn0.5)Fe2O4 powder.

[0046] The preparation process of the iron-nickel alloy powder in this example includes the following steps: (1) Melting and atomization steps: The metal raw materials that conform to the core composition of the powder are melted under a protective atmosphere to form a uniform alloy melt, and the melt is superheated to a range of 150°C to 250°C above its liquidus temperature; then, the alloy melt is atomized by high-pressure gas atomization, wherein the atomizing gas pressure is controlled between 5.0 MPa and 10.0 MPa, thereby obtaining the initial iron-nickel alloy powder; (2) Grading step: The initial iron-nickel alloy powder is finely graded and screened using an air classifier to obtain ultrafine spherical powder; (3) Coating step: NiZn ferrite powder and non-magnetic powders Al2O3, MgO and Nb2O5 powder are ball-milled in a stainless steel ball mill at a speed of 450-600 r / min to obtain nano-coated powder; the coated powder and the ultrafine spherical powder are ball-milled in a ball mill to obtain high-frequency ultra-low loss iron-nickel alloy powder.

[0047] The atomizing gas is an inert gas, such as argon or nitrogen.

[0048] The ball milling insulation coating has a ball-to-material ratio of 1.5 to 2.5:1 and a rotation speed of 350 to 400 r / min.

[0049] This embodiment describes the preparation of a high-frequency ultra-low loss iron-nickel alloy soft magnetic material. Iron-nickel alloy powder or iron-nickel alloy powder obtained by the aforementioned preparation method is used as the raw material. The raw material powder is pressed into shape and then heat-treated at 600℃~750℃ for 1.5~2h to obtain the high-frequency ultra-low loss iron-nickel alloy soft magnetic material.

[0050] The composition of the high-frequency ultra-low loss iron-nickel alloy powder of Examples 1-5 and Comparative Examples 1-2 of this invention is shown in Table 1.

[0051] Table 1: Composition of iron-nickel alloy powders in Examples 1-4 and Comparative Examples 1-5

[0052] The process parameters used in the preparation methods of Examples 1-4 and Comparative Examples 6-7 of this invention are shown in Table 2.

[0053] Table 2: Process parameters used in the preparation methods of Examples 1-5 and Comparative Examples 6-7

[0054] The preparation process parameters for Comparative Examples 1 to 5 are the same as those for Example 1, as detailed in Table 1.

[0055] The iron-nickel alloy powders of Comparative Examples 6 and 7 have the same composition as those of Example 3, and the preparation process parameters are shown in Table 2.

[0056] The high-frequency ultra-low loss iron-nickel alloy soft magnetic materials of the above-mentioned examples and comparative examples were measured for their high-frequency permeability µ′ and power loss (100KHz / 100mT) at 50MHz. The results are shown in Table 3.

[0057] Table 3: Performance data of examples and comparative examples

[0058] As can be seen from Table 3, the soft magnetic material made of high-frequency ultra-low loss iron-nickel alloy powder prepared in this invention has excellent high-frequency permeability and low power loss. The high-frequency permeability µ′ at 50MHz is 38-49, and the power loss at 100KHz / 100mT is 260-281mW / cm3.

[0059] Compared to Example 1, Comparative Examples 1-5, after adjusting the composition of the iron-nickel alloy powder core, the particle size of the powder, and the thickness and composition of the coating layer, resulted in a weakening of the synergistic effect of the magnetic properties of each component and the coating layer with the core, a significant decrease in magnetic permeability, and an increase in power loss.

[0060] Compared to Example 3, Comparative Examples 6 and 7 adjusted the ball milling insulation coating speed for preparing iron-nickel alloy powder and the heat treatment temperature for preparing soft magnetic materials, resulting in the inability to form an effective coating layer, failing to achieve a balance between stress relief, performance recovery, and maintaining the integrity of the insulation layer, leading to a significant decrease in magnetic permeability and an increase in power loss.

[0061] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A high frequency ultra-low loss iron-nickel alloy powder, characterized by, The powder comprises: a powder core composed of an iron-nickel alloy, the components of the core being, in percentage by weight: nickel: 75.5% to 77.5%, molybdenum: 4.5% to 6.5%, further containing lanthanum: 2% to 3% and titanium, the mass ratio of lanthanum to titanium being 2:1, the balance being iron and unavoidable impurities; the surface of the powder core is coated with an insulating metal oxide layer having an average thickness of 3nm to 10nm; the insulating metal oxide layer comprises NiZn ferrite powder and non-magnetic powders Al2O3, MgO and Nb2O5, the mass ratio of the NiZn ferrite powder to Al2O3, MgO, Nb2O5 being 15-20:3:1-2:4-5; the powder comprises three particle sizes, the mass ratio of the particle sizes 150 mesh: 250 mesh: 400 mesh being 1-2:4-5:1-3.

2. The iron-nickel alloy powder according to claim 1, characterized by The total content of unavoidable impurity elements carbon, sulfur, oxygen and nitrogen in the powder core is less than 500ppm.

3. The iron-nickel alloy powder according to claim 1, characterized by The NiZn ferrite powder is (Ni 0.5 Zn 0.5 )Fe2O4 powder.

4. The process for producing a high-frequency ultra-low-loss Fe-Ni alloy powder according to any one of claims 1 to 3, characterized in that, The process comprises the following steps: (1) smelting and atomization step: smelt the metal raw materials meeting the components of the powder core in a protective atmosphere to form a uniform alloy melt, and superheat the melt to a range of 150℃ to 250℃ above the liquidus temperature of the melt; then, atomize the alloy melt using a high-pressure gas atomization method, wherein the atomizing gas pressure is controlled between 5.0MPa and 10.0MPa, thereby obtaining an initial iron-nickel alloy powder; (2) classification step: finely classify the initial iron-nickel alloy powder using an air classifier to screen out superfine spherical powder; (3) coating step: mill the NiZn ferrite powder and non-magnetic powders Al2O3, MgO and Nb2O5 powder in a stainless steel ball mill jar on a ball mill at a speed of 450-600r / min to obtain nanoscale coated powder; ball mill the coated powder and the superfine spherical powder in the ball mill jar to obtain high-frequency ultra-low-loss iron-nickel alloy powder.

5. The manufacturing process of claim 4, wherein, The atomizing gas is inert gas argon or nitrogen.

6. The manufacturing process of claim 4, wherein, The ball milling ratio in the ball milling insulation coating is 1.5-2.5:1, and the rotation speed is 350-400r / min.

7. A high frequency ultra-low loss iron-nickel alloy soft magnetic material, characterized by, The iron-nickel alloy powder of any one of claims 1-3 or obtained by the preparation method of any one of claims 4-6 is used as a raw powder, the raw powder is pressed into a shape, and a high-frequency ultra-low-loss iron-nickel alloy soft magnetic material is obtained after heat treatment at 600℃-750℃ for 1.5-2h.

8. The soft magnetic material of claim 7, wherein, A high-frequency ultra-low-loss iron-nickel alloy soft magnetic material is obtained after heat treatment at 650℃ for 1.8h.

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