TLVR high magnetic conductive inductor post material and preparation method thereof
By constructing a Na-Fe-Ni multi-element synergistic soft magnetic system, combined with a low-melting-point glass phase and a composite insulating coating agent, the problem of the inability to simultaneously achieve high permeability and high-frequency loss in the core material of TLVR inductors was solved. This achieved synergistic optimization of high permeability and low loss, improving the material's performance consistency and large-scale production capability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUACUI PIM MICRO INDUCTANCE ELECTRONIC(JIANGSU) CO LTD
- Filing Date
- 2026-05-28
- Publication Date
- 2026-07-31
AI Technical Summary
Existing TLVR inductor core materials suffer from a tradeoff between permeability and high-frequency loss, poor molding precision, and easy deformation during sintering, resulting in low mass production yield.
A multi-component synergistic soft magnetic system was constructed by using Na-Fe-Ni series high permeability sintered soft magnetic materials, combined with low melting point sintering aids, composite insulating coating agents and trace modifying elements. A high-resistivity insulating interface was constructed through low-temperature densification sintering and composite insulating coating agents to improve the synergistic unity of permeability and high-frequency loss.
It achieves synergistic optimization of high permeability and low loss, improves the material's performance consistency and adaptability to large-scale production, and reduces hot spot temperature and heat accumulation under high-frequency operating conditions.
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Abstract
Description
Technical Field
[0001] This application relates to the field of electronic component materials and manufacturing, and in particular to a high magnetic conductivity core material for TLVR and its preparation method. Background Technology
[0002] The rapid development of AI computing power, data centers, and the new energy vehicle industry has placed stringent performance requirements on TLVR inductors in power supply systems, demanding high inductance, low DCR, high saturation current, low high-frequency loss, and miniaturization. As the core component of the inductor, the performance of the magnetic core directly determines the overall performance of the component.
[0003] Existing TLVR inductors mostly use integrated ferrite cores or single-permeability split cores, which have significant technical defects: permeability and high-frequency loss cannot be balanced, and the magnetic circuit design is not reasonable enough; the split cores have poor molding precision, and deformation and magnetic performance decay are easy to occur during sintering and hot pressing, resulting in low mass production yield.
[0004] Currently, there is no effective solution in the industry to achieve synergistic optimization of permeability ≥100 and low high-frequency loss. The performance limitations of the core magnetic column have become a core bottleneck restricting the upgrade of TLVR inductors. Based on this, developing a core magnetic column material and manufacturing process for TLVR inductors that combines high permeability, low loss, high dimensional accuracy, good performance consistency, and is suitable for mass production has become a technical challenge that urgently needs to be solved in this field. Summary of the Invention
[0005] To improve the high permeability of high magnetic permeability core materials while taking into account low high-frequency loss, this application provides a high magnetic permeability inductive core material for TLVR and its preparation method.
[0006] Firstly, this application provides a high magnetic conductivity central pillar material, which adopts the following technical solution: A high magnetic conductivity core material, wherein the core material is a Na-Fe-Ni system high magnetic conductivity sintered soft magnetic material, comprising the following components by mass percentage: sintering aid 4-6wt%, composite insulating coating agent 2-4wt%, binder 1-2wt%, trace modifying elements ≤1wt%, and the balance being Fe-Ni alloy powder and unavoidable impurities.
[0007] By adopting the above technical solution, a Na-Fe-Ni multi-element synergistic soft magnetic material system is constructed. Fe-Ni alloy is used as a high permeability matrix, and low-melting-point sintering aids are used to achieve low-temperature densification sintering. Composite insulating coating agent is used to construct a high-resistance insulating interface to suppress high-frequency eddy current loss. Binder ensures the green forming strength, and trace modifiers regulate grain growth. This solves the technical problems of the traditional TLVR inductor core permeability and high-frequency loss being unable to be balanced, low sintering density, and poor performance consistency, and achieves a synergistic unity of high permeability and low loss.
[0008] Preferably, the Fe-Ni alloy powder has a nickel content of 46-50 wt%, a powder particle size D50 of 8-12 μm, an oxygen content of ≤300 ppm, and a saturation magnetic flux density of ≥1.5 T.
[0009] By adopting the above technical solutions, the composition, particle size and purity of the Fe-Ni alloy are limited. The nickel content ensures the stability of the alloy's intrinsic soft magnetic properties, the appropriate particle size improves the powder packing density and sintering uniformity, the low oxygen content avoids grain boundary oxidation and deterioration of magnetic properties, and the high saturation magnetic flux density provides a high inductance basis for magnetism, further improving the material's high permeability and low coercivity performance.
[0010] Preferably, the sintering aid is a ternary low-melting-point glass phase of Na2O-Al2O3-SiO2, wherein the molar ratio of Na2O, Al2O3 and SiO2 is 1.6:1:(2.2-2.6), and the softening point is 650-700℃. By adopting the above technical solution, the optimal ratio of ternary glass and the range of softening temperature can be selected. During the sintering process, a uniform liquid phase can be formed to fill the grain boundary pores, promote the low-temperature densification of magnetic materials, and avoid abnormal grain growth and magnetic performance decay during high-temperature sintering. Together with the insulating coating layer, it can ensure the stability of the magnetic circuit structure.
[0011] Preferably, the composite insulating coating agent comprises silica composite powder and modified aluminum dihydrogen phosphate, and the coating layer thickness is 50-100 nm; the silica composite powder comprises silica and silicon carbide.
[0012] By adopting the above technical solution, an insulating system composed of inorganic core-shell powder and modified phosphate is constructed. Silicon carbide is introduced into the silica composite powder as the core, and the high thermal conductivity of silicon carbide is used to construct a thermally conductive path for the coating layer, so that the heat generated inside the magnetic core under high-frequency conditions can be dissipated quickly, reducing the hot spot temperature and reducing severe losses at high temperatures. Modified aluminum dihydrogen phosphate, as an inorganic binder, forms a continuous phosphate network during sintering, which complements the silica composite powder, further filling the microscopic defects of the coating layer, improving the insulation performance, and synergistically improving high-frequency loss and heat dissipation performance.
[0013] Preferably, the silica composite powder is prepared by the following method: Silicon carbide, ethanol, and deionized water were mixed, and a silane coupling agent was added. After ultrasonic dispersion, a silicon carbide dispersion was obtained. Tetraethyl orthosilicate was added to the silicon carbide dispersion, and then ammonia water was added. The mixture was heated and stirred. After reaction, the mixture was washed and dried to obtain a pre-made powder. The pre-made powder was added to anhydrous ethanol for dispersion, and then aniline methyltriethoxysilane was added to adjust the system to acidity. The mixture was heated and reacted. Finally, the mixture was washed and dried to obtain silicon dioxide composite powder.
[0014] By employing the above technical solution, the surface of silicon carbide is activated using a silane coupling agent, introducing organic reaction sites onto the surface of silicon carbide particles. Then, using tetraethyl orthosilicate as the silicon source and ammonia as the catalyst, a dense silica shell is generated on the surface of silicon carbide through in-situ hydrolysis and condensation via a sol-gel method, yielding a core-shell structured pre-formed powder. Subsequently, the pre-formed powder undergoes secondary surface modification using aniline methyltriethoxysilane, grafting amino groups onto the silica shell surface. The resulting silica composite powder not only provides an insulating coating for semiconductor silicon carbide, reducing the resistivity decrease caused by direct contact between silicon carbide and the Fe-Ni matrix, but also provides active reaction sites for subsequent chemical bonding with modified aluminum dihydrogen phosphate, further enhancing the interfacial bonding strength between the coating layer and the binder phase.
[0015] Preferably, the mass ratio of tetraethyl orthosilicate to silicon carbide is 1:(2.6-3.2).
[0016] By adopting the above technical solution, the silicon carbide content is preferably within the above range, so that the silicon carbide particles can be completely covered by a continuous and uniformly thick silicon dioxide insulating layer, so as to achieve a balance between thermal conductivity and insulation performance.
[0017] Preferably, the modified aluminum dihydrogen phosphate is prepared by the following method: Aluminum dihydrogen phosphate was mixed with water and the system was adjusted to acidity to obtain an aluminum dihydrogen phosphate dispersion. KH-560 was added to the aluminum dihydrogen phosphate dispersion, the mixture was heated and stirred to react, cooled after the reaction, and finally filtered to obtain modified aluminum dihydrogen phosphate.
[0018] By adopting the above technical solution, KH-560 hydrolyzes under acidic conditions in an aqueous phase to generate silanol groups, which undergo a condensation reaction with the aluminum dihydrogen phosphate molecular chain to form covalent bonds. The modified aluminum dihydrogen phosphate retains the ability to form a continuous phosphate glass insulating network during high-temperature sintering, and introduces reactive epoxy groups at the molecular ends, providing a structural basis for chemical cross-linking with amino groups on the surface of silica composite powder, thereby improving the density and overall strength of the coating layer.
[0019] Preferably, the mass ratio of aluminum dihydrogen phosphate to KH560 is 1:(0.03-0.13).
[0020] By adopting the above technical solution, and preferably within the above range the mass ratio of aluminum dihydrogen phosphate to KH-560, the prepared modified aluminum dihydrogen phosphate has sufficient epoxy group reactivity and good high-temperature calcination characteristics, which makes the subsequent insulating coating layer have good structural stability in the glue removal-sintering process.
[0021] Preferably, the mass ratio of the silica composite powder to the modified aluminum dihydrogen phosphate is 1:(0.7-0.9).
[0022] By adopting the above technical solution, silica composite powder serves as the main skeleton material of the coating layer, providing basic insulation and thermal conductivity. Modified aluminum dihydrogen phosphate serves as a binder phase and chemical crosslinking node, filling the gaps between silica particles and forming a continuous phosphate network after curing. Preferably, the mass ratio between silica composite powder and modified aluminum dihydrogen phosphate is within the above range. The amino groups on the surface of silica composite powder and the epoxy groups on modified aluminum dihydrogen phosphate can achieve a ring-opening crosslinking reaction to form a dense insulating layer, further synergistically improving the high magnetic permeability and low high-frequency loss performance of the central column material.
[0023] Secondly, this application provides a method for preparing a high magnetic conductivity induction core material for TLVR, employing the following technical solution: A method for preparing a high magnetic conductivity induction core material for TLVR includes the following steps: S1. Powder preparation: The Fe-Ni alloy is vacuum melted, atomized with inert gas to form powder, sieved and vacuum dried to obtain alloy powder. Then, the alloy powder is coated with a composite insulating agent, dispersed evenly and dried. Finally, sintering aids and binders are added and mixed thoroughly to obtain uniform modified powder. S2. Green body forming: The modified powder is pre-pressed to degas the air, and then cold isostatic pressing is used to form a type I central column green body; S3. Debinding process: The green blank is debinded and the binder is removed under a protective atmosphere, and then sintered to obtain the central core blank. S4. Precision machining: Grind the sintered central core to obtain the central core material; assemble the I-type central core, U-type outer core and coil to form a complete magnetic circuit structure, and then co-fire the assembled components to obtain the TLVR high magnetic conductivity central core material.
[0024] In summary, this application includes at least one of the following beneficial technical effects: A Na-Fe-Ni multi-component synergistic soft magnetic system was constructed, with Fe-Ni alloy as the high magnetic permeability matrix, combined with low melting point glass phase sintering aid, composite insulating coating agent and trace modifiers. The synergistic effect of the proportions of each component improved the problems of difficulty in achieving both magnetic permeability and high frequency loss, low sintering density and poor performance consistency. The composite insulating coating agent uses a core-shell structure powder with silicon carbide as the core and silicon dioxide as the shell. The high thermal conductivity of silicon carbide is used to build a heat dissipation path, and the silicon dioxide shell provides insulation. In conjunction with modified aluminum dihydrogen phosphate to fill the defects of the coating layer, a continuous phosphate network is formed, which reduces the hot spot temperature of the magnetic core under high frequency conditions and achieves synergistic optimization of high frequency loss and heat dissipation performance. The surface of the silica composite powder is modified with aniline methyltriethoxysilane to introduce aromatic amino groups, and the modified aluminum dihydrogen phosphate is silanized with KH-560 to introduce epoxy groups. During the coating process, the two undergo a ring-opening cross-linking reaction to form a covalently bonded organic-inorganic hybrid insulating layer, which upgrades the traditional physical coating to a chemical bonded network, significantly enhancing the interfacial bonding strength and density of the coating layer, and preventing the coating layer from cracking and falling off during the pressing and sintering process. Detailed Implementation
[0025] The present application will be further described in detail below with reference to the embodiments: Raw material description: All raw materials in the examples are commercially available; the trace modifiers are chromium and molybdenum mixed in a mass ratio of 1:1; the binder is a thermosetting phenolic resin. Example 1
[0026] Preparation of silica composite powder: 21.67 g of 5 μm silicon carbide, 800 g of anhydrous ethanol, and 400 g of deionized water were mixed, and 2 g of silane coupling agent KH-550 (CAS No.: 919-30-2) was added. The mixture was ultrasonically dispersed for 30 min to obtain a silicon carbide dispersion. 8.33 g of tetraethyl orthosilicate (CAS No.: 78-10-4) was added to the silicon carbide dispersion, followed by 5 g of ammonia. The mixture was heated to 60 °C and stirred at 600 rpm for 2 h. After the reaction, the mixture was allowed to stand for 1 h, and then repeatedly washed with anhydrous ethanol and deionized water to remove residual silane coupling agent. The mixture was dried at 80 °C for 18 h to obtain a pre-prepared powder. The pre-prepared powder was magnetically dispersed in 300 g of anhydrous ethanol, and then 8 g of anilinemethyltriethoxysilane (CAS No.: The system was prepared by adjusting the pH to 4 with anhydrous formic acid, reacting at 40°C for 2 hours, washing with anhydrous ethanol, and drying at 60°C for 12 hours to obtain silica composite powder.
[0027] Preparation of modified aluminum dihydrogen phosphate: 20g of aluminum dihydrogen phosphate (CAS No.: 13530-50-2) was mixed with 300g of deionized water, and the pH of the system was adjusted to 3 using glacial acetic acid to obtain an aluminum dihydrogen phosphate dispersion. 0.6g of KH-560 (CAS No.: 2530-83-8) was added to the aluminum dihydrogen phosphate dispersion, the temperature was raised to 40℃, and the mixture was stirred for 3h. After the reaction, the heating was stopped, and the mixture was allowed to cool naturally to 25℃. After standing for 40min, impurities were removed by filtration to obtain modified aluminum dihydrogen phosphate.
[0028] Preparation of composite insulating coating agent: The silica composite powder prepared above was weighed and mixed with modified aluminum dihydrogen phosphate at a mass ratio of 1:0.7. The silica composite powder was mixed with anhydrous ethanol at a mass ratio of 1:1. The mixture was magnetically stirred at 500 rpm for 20 minutes at 25°C to form a uniform suspension. Then, the modified aluminum dihydrogen phosphate was added to the suspension and stirred for another 40 minutes to finally obtain the composite insulating coating agent.
[0029] Preparation of high magnetic conductivity core material for TLVR: Prepare the raw materials according to the following mass percentages: 4wt% sintering aid, 2wt% composite insulating coating agent, 1wt% binder, 0.1wt% trace modifying elements, and the balance being Fe-Ni alloy powder; The Fe-Ni alloy powder has a nickel content of 46wt%, a particle size D50 of 8μm, an oxygen content of 300ppm, and a saturation magnetic flux density of 1.5T. The sintering aid is a ternary low-melting-point glass phase of Na2O-Al2O3-SiO2, in which the molar ratio of Na2O, Al2O3 and SiO2 is 1.6:1:2.2, and the softening point is 650℃. S1. Powder preparation: The Fe-Ni alloy was vacuum melted and powdered by inert gas atomization. After sieving, alloy powder with a particle size of 8μm was obtained and vacuum dried. Then, the alloy powder was coated with a composite insulating agent, dispersed evenly, dried, and then sintering aid and binder were added and mixed thoroughly to obtain a uniform modified powder. S2. Green body forming: The modified powder is loaded into the mold for pre-pressing and degassing, and then cold isostatic pressing is used to form a type I green column. S3. Debinding treatment: The green blank is pre-fired at low temperature under a protective atmosphere to completely remove the binder. Then, it is sintered in a segmented heating atmosphere to obtain a high permeability central core. The main and auxiliary coils are fixed and shaped. Then, the I-shaped central core, U-shaped outer core and coil are precisely assembled to form a complete magnetic circuit structure. Finally, the whole assembly is co-fired under ultra-high pressure to obtain TLVR high permeability inductive central core material. Example 2
[0030] Preparation of silica composite powder: 22.86 g of 5 μm silicon carbide, 800 g of anhydrous ethanol, and 400 g of deionized water were mixed, and 2 g of silane coupling agent KH-550 was added. The mixture was ultrasonically dispersed for 30 min to obtain a silicon carbide dispersion. 7.14 g of tetraethyl orthosilicate was added to the silicon carbide dispersion, followed by 5 g of ammonia. The mixture was heated to 60 °C and stirred at 600 rpm for 2 h. After the reaction, the mixture was allowed to stand for 1 h. Then, it was repeatedly washed with anhydrous ethanol and deionized water to remove residual silane coupling agent. The mixture was dried at 80 °C for 18 h to obtain a pre-formulated powder. The pre-formulated powder was magnetically dispersed in 300 g of anhydrous ethanol, and then 8 g of aniline methyltriethoxysilane was added. The pH of the system was adjusted to 4 using anhydrous formic acid, and the mixture was reacted at 40 °C for 2 h. Finally, the mixture was washed with anhydrous ethanol and dried at 60 °C for 12 h to obtain a silica composite powder.
[0031] Preparation of modified aluminum dihydrogen phosphate: 20g of aluminum dihydrogen phosphate was mixed with 300g of deionized water, and the pH of the system was adjusted to 3 using glacial acetic acid to obtain an aluminum dihydrogen phosphate dispersion. 2.6g of KH-560 was added to the aluminum dihydrogen phosphate dispersion, the temperature was raised to 40℃, and the mixture was stirred for 3h. After the reaction, the heating was stopped, and the mixture was allowed to cool naturally to 25℃. After standing for 40min, the mixture was filtered to remove impurities to obtain modified aluminum dihydrogen phosphate.
[0032] Preparation of composite insulating coating agent: The silica composite powder prepared above was weighed and mixed with modified aluminum dihydrogen phosphate at a mass ratio of 1:0.9. The silica composite powder was mixed with anhydrous ethanol at a mass ratio of 1:1. The mixture was magnetically stirred at 500 rpm for 20 minutes at 25°C to form a uniform suspension. Then, the modified aluminum dihydrogen phosphate was added to the suspension and stirred for another 40 minutes to obtain the composite insulating coating agent.
[0033] Preparation of high magnetic conductivity core material for TLVR: The raw materials are prepared according to the following mass percentages: sintering aid 6wt%, composite insulating coating agent 4wt%, binder 2wt%, trace modifying elements 1wt%, and the balance is Fe-Ni alloy powder; wherein the Fe-Ni alloy powder has a nickel content of 50wt%, a particle size D50 of 12μm, an oxygen content of 150ppm, and a saturation magnetic flux density of 1.5T; the sintering aid is a ternary low-melting-point glass phase of Na2O-Al2O3-SiO2, wherein the molar ratio between Na2O, Al2O3 and SiO2 is 1.6:1:2.6, and the softening point is 700℃; S1. Powder preparation: The Fe-Ni alloy was vacuum melted and powdered by inert gas atomization. After sieving, alloy powder with a particle size of 8μm was obtained and vacuum dried. Then, the alloy powder was coated with a composite insulating agent, dispersed evenly, dried, and then sintering aid and binder were added and mixed thoroughly to obtain a uniform modified powder. S2. Green body forming: The modified powder is loaded into the mold for pre-pressing and degassing, and then cold isostatic pressing is used to form a type I green column. S3. Debinding treatment: The green blank is pre-fired at low temperature under a protective atmosphere to completely remove the binder. Then, it is sintered in a segmented heating atmosphere to obtain a high permeability central core. The main and auxiliary coils are fixed and shaped. Then, the I-shaped central core, U-shaped outer core and coil are precisely assembled to form a complete magnetic circuit structure. Finally, the whole assembly is co-fired under ultra-high pressure to obtain TLVR high permeability inductive central core material. Example 3
[0034] Preparation of silica composite powder: 22.31 g of 5 μm silicon carbide, 800 g of anhydrous ethanol, and 400 g of deionized water were mixed, and 2 g of silane coupling agent KH-550 was added. The mixture was ultrasonically dispersed for 30 min to obtain a silicon carbide dispersion. 7.69 g of tetraethyl orthosilicate was added to the silicon carbide dispersion, followed by 5 g of ammonia. The mixture was heated to 60 °C and stirred at 600 rpm for 2 h. After the reaction, the mixture was allowed to stand for 1 h. Then, it was repeatedly washed with anhydrous ethanol and deionized water to remove residual silane coupling agent. The mixture was dried at 80 °C for 18 h to obtain a pre-formulated powder. The pre-formulated powder was magnetically dispersed in 300 g of anhydrous ethanol, and then 8 g of aniline methyltriethoxysilane was added. The pH of the system was adjusted to 4 using anhydrous formic acid, and the mixture was reacted at 40 °C for 2 h. Finally, the mixture was washed with anhydrous ethanol and dried at 60 °C for 12 h to obtain a silica composite powder.
[0035] Preparation of modified aluminum dihydrogen phosphate: 20g of aluminum dihydrogen phosphate was mixed with 300g of deionized water, and the pH of the system was adjusted to 3 using glacial acetic acid to obtain an aluminum dihydrogen phosphate dispersion. 1.6g of KH-560 was added to the aluminum dihydrogen phosphate dispersion, the temperature was raised to 40℃, and the reaction was stirred for 3h. After the reaction, the heating was stopped, and the mixture was allowed to cool naturally to 25℃. After standing for 40min, the mixture was filtered to remove impurities to obtain modified aluminum dihydrogen phosphate.
[0036] Preparation of composite insulating coating agent: The silica composite powder prepared above was weighed and mixed with modified aluminum dihydrogen phosphate at a mass ratio of 1:0.8. The silica composite powder was mixed with anhydrous ethanol at a mass ratio of 1:1. The mixture was magnetically stirred at 500 rpm for 20 minutes at 25°C to form a uniform suspension. Then, the modified aluminum dihydrogen phosphate was added to the suspension and stirred for another 40 minutes to obtain the composite insulating coating agent.
[0037] Preparation of high magnetic conductivity core material for TLVR: The raw materials are prepared according to the following mass percentages: 5wt% sintering aid, 3wt% composite insulating coating agent, 1.5wt% binder, 0.5wt% trace modifying elements, and the balance being Fe-Ni alloy powder; wherein the Fe-Ni alloy powder has a nickel content of 48wt%, a particle size D50 of 10μm, an oxygen content of 250ppm, and a saturation magnetic flux density of 1.5T; the sintering aid is a ternary low-melting-point glass phase of Na2O-Al2O3-SiO2, wherein the molar ratio between Na2O, Al2O3 and SiO2 is 1.6:1:2.4, and the softening point is 675℃; S1. Powder preparation: The Fe-Ni alloy was vacuum melted and powdered by inert gas atomization. After sieving, alloy powder with a particle size of 8μm was obtained and vacuum dried. Then, the alloy powder was coated with a composite insulating agent, dispersed evenly, dried, and then sintering aid and binder were added and mixed thoroughly to obtain a uniform modified powder. S2. Green body forming: The modified powder is loaded into the mold for pre-pressing and degassing, and then cold isostatic pressing is used to form a type I green column. S3. Debinding treatment: The green blank is pre-fired at low temperature under a protective atmosphere to completely remove the binder. Then, it is sintered in a segmented heating atmosphere to obtain a high permeability central core. The main and auxiliary coils are fixed and shaped. Then, the I-shaped central core, U-shaped outer core and coil are precisely assembled to form a complete magnetic circuit structure. Finally, the whole assembly is co-fired under ultra-high pressure to obtain TLVR high permeability inductive central core material. Example 4
[0038] Example 4 is based on Example 3. The difference between Example 4 and Example 3 is that in Example 4, when preparing the silica composite powder, 9.68g of tetraethyl orthosilicate and 20.32g of silicon carbide were used. Example 5
[0039] Example 5 is based on Example 3. The difference between Example 5 and Example 3 is that in Example 5, when preparing the silica composite powder, 6.38g of tetraethyl orthosilicate and 23.62g of silicon carbide were used. Example 6
[0040] Example 6 is based on Example 3. The difference between Example 6 and Example 3 is that in Example 6, silicon carbide was not activated using KH-550 when preparing silicon dioxide composite powder. Example 7
[0041] Example 7 is based on Example 3. The difference between Example 7 and Example 3 is that in Example 7, the pre-prepared powder was not treated with aniline triethoxysilane when preparing the silica composite powder. Example 8
[0042] Example 8 is based on Example 3. The difference between Example 8 and Example 3 is that in Example 8, 0.2g of KH560 was used in the preparation of modified aluminum dihydrogen phosphate. Example 9
[0043] Example 9 is based on Example 3. The difference between Example 9 and Example 3 is that in Example 9, 3.4g of KH560 was used in the preparation of modified aluminum dihydrogen phosphate. Example 10
[0044] Example 10 is based on Example 3. The difference between Example 10 and Example 3 is that in Example 10, the mass ratio between silica composite powder and modified aluminum dihydrogen phosphate is 1:0.5 when preparing the composite insulating coating agent. Example 11
[0045] Example 11 is based on Example 3. The difference between Example 11 and Example 3 is that in Example 11, the mass ratio between silica composite powder and modified aluminum dihydrogen phosphate is 1:1.1 when preparing the composite insulating coating agent. Example 12
[0046] Example 12 is based on Example 3. The difference between Example 12 and Example 3 is that in Example 12, when preparing the composite insulating coating agent, the silica composite powder is replaced with ordinary nano silica. Example 13
[0047] Example 13 is based on Example 3. The difference between Example 13 and Example 3 is that in Example 13, the modified aluminum dihydrogen phosphate is replaced with ordinary aluminum dihydrogen phosphate when preparing the composite insulating coating agent. Example 14
[0048] Example 14 is based on Example 3. The difference between Example 14 and Example 3 is that the nickel content of the Fe-Ni alloy powder in Example 14 is 40wt%. Example 15
[0049] Example 15 is based on Example 3. The difference between Example 15 and Example 3 is that the nickel content of the Fe-Ni alloy powder in Example 15 is 56 wt%. Example 16
[0050] Example 16 is based on Example 3. The difference between Example 16 and Example 3 is that the molar ratio of Na2O, Al2O3 and SiO2 in the sintering aid of Example 16 is 1.6:1:1.9. Example 17
[0051] Example 17 is based on Example 3. The difference between Example 17 and Example 3 is that the molar ratio of Na2O, Al2O3 and SiO2 in the sintering aid of Example 17 is 1.6:1:2.9.
[0052] Comparative Example 1 Comparative Example 1 is based on Example 3, but no trace amounts of modifying elements were added in Comparative Example 1.
[0053] Comparative Example 2 Comparative Example 2 is based on Example 3, and the sintering aid in Comparative Example 2 is a Bi2O3-B2O3 binary glass phase.
[0054] Comparative Example 3 Comparative Example 3 is based on Example 3, except that the composite insulating coating agent is replaced with an equal amount of nano-silica.
[0055] Performance testing The following performance tests were performed on the samples of Examples 1-17 and Comparative Examples 1-3: (1) Initial permeability Using GB / T 13012-2008 as the testing reference, the initial magnetic permeability of the samples was tested. Each sample was tested 3 times, and the average value was taken. The test results were recorded in Table 1.
[0056] (2) High-frequency loss Using GB / T 3658-2022 as the testing reference, the high-frequency loss value of the samples was tested. Each sample was tested 3 times, and the average value was taken. The test results were filled in Table 1.
[0057] (3) Volume resistivity test Using GB / T 5167-2018 as the testing reference, the volume resistivity of the samples was tested. Each sample was tested 3 times, and the average value was taken. The test results were recorded in Table 1.
[0058] (4) DC magnetic properties Using GB / T 13012-2008 as the testing reference, the DC magnetic properties of the samples were tested. Each sample was tested 3 times, and the average value was taken. The test results were recorded in Table 1.
[0059] Table 1 Performance test results of Examples 1-17 and Comparative Examples 1-3
[0060] As shown in Table 1, the initial permeability of Examples 1-3 is 101 or higher, and the high-frequency loss is 272 mW / cm. 3 The volume resistivity is 1.5 × 10⁻⁶ and below. 9 With Ω·cm and above, and coercivity of 13.2 and below, the high magnetic permeability of the TLVR high magnetic conductivity inductive column material prepared in this application indicates that it has good high magnetic permeability and low high-frequency loss.
[0061] In Examples 4 and 5, the mass ratio of tetraethyl orthosilicate to silicon carbide during the preparation of silica composite powder was not within the range specified in this application. When silicon carbide was insufficient, excess tetraethyl orthosilicate would increase the thickness of the shell, which, while improving the integrity of the coating, diluted the volume fraction of the thermally conductive silicon carbide phase, leading to heat accumulation and increased losses under high-frequency operating conditions, and affecting the magnetic permeability. When silicon carbide was excessive, the silica shell was too thin, and some silicon carbide surfaces were not fully coated, resulting in exposed areas that directly contacted the Fe-Ni matrix, forming local conductive channels and degrading performance.
[0062] In Example 6, when preparing the silica composite powder, the silicon carbide was not activated using KH-550. The unactivated silicon carbide surface had no reaction sites, and the silica and silicon carbide were only physically adsorbed, resulting in poor bonding performance. During the subsequent preparation process, some of the silica shell detached, exposing the silicon carbide and causing a decrease in performance.
[0063] In Example 7, when preparing silica composite powder, the pre-powder was not treated with aniline triethoxysilane. The surface of the untreated pre-powder lacked aromatic amino groups, making it difficult to undergo ring-opening crosslinking reaction with the epoxy groups of modified aluminum dihydrogen phosphate. The silica and phosphate only had hydrogen bonding. During the subsequent cold isostatic pressing and sintering process, cracks were generated at the interface, resulting in decreased stability and performance.
[0064] In Examples 8 and 9, the mass ratio of KH-560 to aluminum dihydrogen phosphate during the preparation of modified aluminum dihydrogen phosphate was not within the range specified in this application. When KH-560 was insufficient, the number of epoxy groups introduced on the surface of aluminum dihydrogen phosphate was insufficient. When compounded with amino dioxide composite powder, the crosslinking density was low, making it difficult to form a continuous and dense chemical crosslinking network. The cohesion of the coating layer was insufficient, and the performance was degraded. When KH-560 was excessive, the excess silane coupling agent self-condensed in the reaction system, generating free oligomers. These oligomers decomposed during subsequent sintering, producing pores and affecting the density and stability of the system.
[0065] In Examples 10 and 11, the mass ratio between silica composite powder and modified aluminum dihydrogen phosphate was outside the range specified in this application during the preparation of the composite insulating coating. When the modified aluminum dihydrogen phosphate was insufficient, the phosphate content as the binder phase was insufficient, making it difficult to fully fill the gaps between silica particles, resulting in voids in the coating layer and a decrease in performance. When the modified aluminum dihydrogen phosphate was excessive, an excessively thick non-magnetic grain boundary layer was formed after sintering, leading to a decrease in magnetic permeability and affecting stability.
[0066] The composite insulating coating agent in Example 12 uses ordinary nano-silica. Ordinary nano-silica does not have a silicon carbide high thermal conductivity core, and the heat from the magnetism is difficult to be effectively dissipated under high frequency conditions, resulting in excessively high internal hot spot temperatures and excessive losses.
[0067] The composite insulating coating agent in Example 13 uses ordinary aluminum dihydrogen phosphate. Ordinary aluminum dihydrogen phosphate does not contain oxygen-containing groups and can only form hydrogen bonds with the silica composite powder, making it difficult to form chemical bonds. During the pressing and sintering process, the coating layer cracks due to shrinkage stress, resulting in a decrease in performance.
[0068] The nickel content in the Fe-Ni alloy powders of Examples 14 and 15 is not within the range specified in this application. When the nickel content is insufficient, the alloy composition deviates from the high permeability range, the magnetocrystalline anisotropy constant increases, and the performance decreases. When the nickel content is excessive, the permeability stability decreases and the high-frequency loss increases.
[0069] In Examples 16 and 17, the molar ratios of Na2O, Al2O3, and SiO2 in the sintering aids are not within the range specified in this application. When there is insufficient silicon dioxide, the softening point is too low, resulting in an excess of liquid phase during sintering. When there is an excess of silicon dioxide, the softening point is too high, resulting in insufficient liquid phase filling, increased grain boundary porosity, and decreased density. Therefore, the performance of Examples 16 and 17 is reduced.
[0070] In Comparative Example 1, no trace elements were added. During the ternary glass phase liquid phase sintering process, the grain boundaries were difficult to constrain, and the grains grew irregularly and abnormally, resulting in a decrease in performance.
[0071] In Comparative Example 2, the sintering aid was replaced with a Bi2O3-B2O3 binary glass phase, which had poor interfacial wettability with the Fe-Ni alloy matrix, making it difficult to fill grain boundary pores during sintering, resulting in a decrease in performance.
[0072] Comparative Example 3 replaced the composite insulating coating agent with an equal amount of nano-silica. The silica powder alone lacked the high thermal conductivity core of silicon carbide, making it difficult to build a continuous thermal conductivity path inside the magnetic material. Furthermore, its poor dispersion performance led to severe agglomeration during sintering, affecting the overall stability of the system and causing a decline in performance.
[0073] This specific embodiment is merely an explanation of this application and is not intended to limit it. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification but must be determined according to the scope of the claims.
Claims
1. A high magnetic conductivity induction column material for TLVR, characterized in that: The central column material is a Na-Fe-Ni series high magnetic permeability sintered soft magnetic material, which includes the following components by mass percentage: sintering aid 4-6wt%, composite insulating coating agent 2-4wt%, binder 1-2wt%, trace modifying elements ≤1wt%, and the balance being Fe-Ni alloy powder and unavoidable impurities.
2. The TLVR high magnetic conductivity induction column material according to claim 1, characterized in that: The Fe-Ni alloy powder has a nickel content of 46-50 wt%, a powder particle size D50 of 8-12 μm, an oxygen content of ≤300 ppm, and a saturation magnetic flux density of ≥1.5 T.
3. The TLVR high magnetic conductivity induction column material according to claim 1, characterized in that: The sintering aid is a ternary low-melting-point glass phase of Na2O-Al2O3-SiO2, wherein the molar ratio of Na2O, Al2O3 and SiO2 is 1.6:1:(2.2-2.6), and the softening point is 650-700℃.
4. The TLVR high magnetic conductivity induction column material according to claim 1, characterized in that: The composite insulating coating agent comprises silica composite powder and modified aluminum dihydrogen phosphate, and the coating layer thickness is 50-100 nm; the silica composite powder comprises silica and silicon carbide.
5. The TLVR high magnetic conductivity induction column material according to claim 4, characterized in that: The silica composite powder is prepared by the following method: Silicon carbide, ethanol, and deionized water were mixed, and a silane coupling agent was added. After ultrasonic dispersion, a silicon carbide dispersion was obtained. Tetraethyl orthosilicate was added to the silicon carbide dispersion, and then ammonia water was added. The mixture was heated and stirred. After reaction, the mixture was washed and dried to obtain a pre-made powder. The pre-made powder was added to anhydrous ethanol for dispersion, and then aniline methyltriethoxysilane was added to adjust the system to acidity. The mixture was heated and reacted. Finally, the mixture was washed and dried to obtain silicon dioxide composite powder.
6. The TLVR high magnetic conductivity induction column material according to claim 5, characterized in that: The mass ratio of tetraethyl orthosilicate to silicon carbide is 1:(2.6-3.2).
7. The TLVR high magnetic conductivity induction column material according to claim 4, characterized in that: The modified aluminum dihydrogen phosphate was prepared by the following method: Aluminum dihydrogen phosphate was mixed with water and the system was adjusted to acidity to obtain an aluminum dihydrogen phosphate dispersion. KH-560 was added to the aluminum dihydrogen phosphate dispersion, the mixture was heated and stirred to react, cooled after the reaction, and finally filtered to obtain modified aluminum dihydrogen phosphate.
8. The TLVR high magnetic conductivity induction column material according to claim 7, characterized in that: The mass ratio of aluminum dihydrogen phosphate to KH560 is 1:(0.03-0.13).
9. A TLVR high magnetic conductivity induction column material according to claim 4, characterized in that, The mass ratio of the silica composite powder to the modified aluminum dihydrogen phosphate is 1:(0.7-0.9).
10. A method for preparing a high magnetic conductivity induction column material for TLVR as described in any one of claims 1-9, characterized in that: Includes the following steps: S1. Powder preparation: The Fe-Ni alloy is vacuum melted, atomized with inert gas to form powder, sieved and vacuum dried to obtain alloy powder. Then, the alloy powder is coated with a composite insulating agent, dispersed evenly and dried. Finally, sintering aids and binders are added and mixed thoroughly to obtain uniform modified powder. S2. Green body forming: The modified powder is pre-pressed to degas the air, and then cold isostatic pressing is used to form a type I central column green body; S3. Debinding process: The green blank is debinded and the binder is removed under a protective atmosphere, and then sintered to obtain the central core blank. S4. Precision machining: Grind the sintered central core to obtain the central core material; assemble the I-type central core, U-type outer core and coil to form a complete magnetic circuit structure, and then co-fire the assembled components to obtain the TLVR high magnetic conductivity central core material.