Inductor failure risk response structure, high-reliability inductor and failure risk warning method

Abstract

The invention discloses an inductor failure risk response structure, a high-reliability inductor and a failure risk warning method, the inductor failure risk response structure is specifically a core-shell composite functional phase, and the functional phase takes metastable austenite microspheres as a core and borosilicate glass with density gradient as a shell. The austenite nucleus can generate martensite phase transformation under the triggering of mechanical stress to cause regular drift of the magnetic conductivity of the magnetic core, and the regular drift is used as an early warning electric signal; and the glass shell is softened and flows when being overheated, so that self-repairing of the microcracks is realized. Through the centrifugal forming technology, the functional phase can form gradient distribution with the concentration gradually decreased from inside to outside in the magnetic core, and therefore the intelligent response capacity is accurately located in a high-risk area. The manufactured high-reliability inductor has endogenous sensing, early warning and self-repairing capabilities on mechanical overload and overheating risks, and the reliability of the high-reliability inductor under severe working conditions is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of high-reliability inductor manufacturing technology, and more specifically, to an inductor failure risk response structure, a high-reliability inductor, and a failure risk warning method. Background Technology

[0002] As a fundamental passive component in electronic circuits, inductors undertake key functions such as filtering, energy storage, energy conversion, and electromagnetic interference suppression. With the development of electronic devices towards higher frequencies, smaller sizes, higher power densities, and higher reliability, especially in high-end applications such as artificial intelligence servers, electric drive systems for new energy vehicles, and 5G communication base stations, more stringent requirements are being placed on the operating frequency, saturation current, conversion efficiency, and long-term operational stability of inductors.

[0003] Traditional high-frequency power inductors typically use nickel-zinc-copper ferrite as the core material, which can maintain low losses at high frequencies through adjustments to composition and manufacturing processes. However, under harsh conditions such as continuous power surges, mechanical vibrations, or localized overheating, traditional homogeneous ferrite cores are prone to developing microcracks, leading to magnetic circuit performance degradation, inductance attenuation, and even short circuits due to insulation failure. More importantly, as completely passive components, these cores cannot provide early warnings of internal damage or progressive performance degradation; the system can only respond after a fault occurs, posing significant safety hazards in high-reliability applications.

[0004] To improve reliability, existing technologies mainly improve mechanical strength and thermal management through integrated molding processes or enhanced heat dissipation structures. These methods are passive protections; while they can delay failure, they do not change the inherently unpredictable nature of failure. Some solutions attempt to monitor parameters such as temperature and current using external sensors, but this increases system complexity and cost, and the monitoring is relatively slow, making it difficult to achieve true early warning.

[0005] In view of this, the present invention proposes an inductor failure risk response structure, a high-reliability inductor, and a failure risk warning method. The inductor failure risk response structure realizes the integrated function of early warning and repair through the intrinsic intelligence of the core-shell functional phase material and the gradient control of the centrifugation process. Under the premise of ensuring the basic electromagnetic performance, the active response mechanism improves the reliability of the inductor. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides an inductor failure risk response structure, a high-reliability inductor, and a failure risk warning method. In the technical solution of this invention, the inductor failure risk response structure is specifically a core-shell composite functional phase, comprising:

[0007] The core consists of metastable austenitic microspheres made of Fe-Ni-C alloys, with a particle size of 3-8 μm.

[0008] The gradient shell is a borosilicate glass layer covering the surface of the metastable austenitic microspheres. This glass layer has a gradient structure with a continuously decreasing density from the inside to the outside, and its softening point is 120-140℃.

[0009] The gradient shell has a total thickness of 0.5-2.0 μm, with the internal dense portion accounting for 30%-70% of the total thickness. The metastable austenitic microspheres are configured to undergo martensitic phase transformation when the mechanical stress reaches a critical threshold.

[0010] The gradient structure is formed by gradually increasing the pH value from 4 to 9-10 in the sol-gel coating process to control the hydrolysis-condensation reaction rate. Specifically, a low catalytic rate is used to form a dense inner layer in the early stage of coating, and the catalytic rate is increased in the later stage of coating to form a loose outer layer.

[0011] Furthermore, in the technical solution of the present invention, the martensitic phase transformation can cause a regular drift of 3% to 8% in the permeability of the magnetic core containing the functional phase.

[0012] A magnetic core comprising a matrix phase and the aforementioned core-shell composite functional phase dispersed in the matrix phase.

[0013] Furthermore, in the technical solution of this invention, the raw materials of the magnetic core include, by mass percentage:

[0014] Nickel-zinc-copper ferrite powder: 80%–90%;

[0015] Bismuth oxide 1.0%–2.0%;

[0016] Vanadium pentoxide 0.5%–1.0%;

[0017] Core-shell composite functional phases: 10%–20%;

[0018] Nano-alumina 0.5%–1.0%.

[0019] Furthermore, in the technical solution of the present invention, the core-shell composite functional phase is distributed in a gradient in the magnetic core, specifically: from the central region of the magnetic core to the outer surface region, the volume concentration of the core-shell composite functional phase decreases continuously from 15%-20% to 5%-10%.

[0020] Furthermore, in the technical solution of this invention, the gradient distribution is achieved through a centrifugal forming process, which includes:

[0021] The matrix phase and the core-shell composite functional phase are mixed in a certain proportion, and then ball-milled with deionized water, dispersant and binder to form a uniform slurry with a total solids content of 50%-60%.

[0022] The slurry is injected into a cylindrical stainless steel mold and rotated for 5-15 minutes under an acceleration of 500G-1000G to form a wet blank with a gradient distribution.

[0023] The wet blank is sequentially aged, dried, debinded, and sintered to obtain the magnetic core.

[0024] Furthermore, in the technical solution of the present invention, the sintering step is carried out under a nitrogen protective atmosphere and includes: firstly, holding at 550°C for 0.5-1.5 hours, and then raising the temperature to 900-950°C and holding for 15-30 minutes.

[0025] A high-reliability inductor includes the aforementioned magnetic core and a winding wound on the magnetic core.

[0026] A method for warning of failure risk of a high-reliability inductor, using the aforementioned high-reliability inductor, includes the following steps:

[0027] Real-time monitoring of the inductance or permeability parameters of high-reliability inductors;

[0028] When a regular drift in inductance or permeability is detected, it is determined that the metastable austenitic microspheres in the magnetic core have undergone martensitic phase transformation, and an early warning signal characterizing mechanical stress overload is generated.

[0029] Furthermore, in the technical solution of the present invention, the range of regular drift is 3% to 8%.

[0030] Effective gain

[0031] In the technical solution of this invention, a core-shell composite functional phase with a gradient shell structure is designed and prepared, which uses metastable Fe-Ni-C austenitic alloy microspheres as the core and coats the surface of the microspheres with a borosilicate glass shell with a density gradient. This phase is used as the core unit to realize the inductor failure risk response.

[0032] When the mechanical stress on the magnetic core reaches a preset critical threshold, the austenite core undergoes a martensitic phase transformation. This transformation causes a regular drift of 3% to 8% in the permeability of the entire core. This change in magnetic properties can serve as an electrical signal detectable by a circuit, thus providing an early warning of potential mechanical overload or structural damage. When the temperature of a localized area of ​​the core rises due to abnormal conditions, the glass shell softens and becomes fluid, filling and healing microcracks that have formed nearby. This restores the mechanical integrity and structural density of the cracked area, helps eliminate potential conductive paths formed by cracks, and maintains the electrical insulation performance of the area. Simultaneously, the relatively loose outer shell of this gradient core-shell structure can sacrifice reactions during subsequent core sintering, increasing the green density while protecting the metastable austenite core from damage at high temperatures, ensuring the reliability of its phase transformation warning function.

[0033] Furthermore, by using a centrifugal forming process, the density difference between the core-shell functional phase and the matrix ferrite powder is utilized. Under the drive of a strong centrifugal force field, the functional phase forms a continuous concentration gradient distribution in the radial direction within the core green blank. This concentrates the functional phase in the area where the magnetic field and mechanical stress are more concentrated inside the core, thereby improving the efficiency of local early warning and repair.

[0034] Other features and advantages of the present invention will be set forth in the following description. Attached Figure Description

[0035] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0036] Figure 1 This is a flowchart illustrating the fabrication process of the high-reliability inductor of the present invention.

[0037] Figure 2 This is a schematic diagram of the inductor structure of the present invention.

[0038] It consists of 1 magnetic core, 2 windings, and 3 pins. Detailed Implementation

[0039] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] This invention proposes an inductor failure risk response structure, specifically a core-shell composite functional phase, comprising:

[0041] The core consists of metastable austenitic microspheres made of Fe-Ni-C alloys, with a particle size of 3-8 μm.

[0042] The gradient shell is a borosilicate glass layer covering the surface of the metastable austenitic microspheres. This glass layer has a gradient structure with a continuously decreasing density from the inside to the outside, and its softening point is 120-140℃.

[0043] The gradient shell has a total thickness of 0.5-2.0 μm, with the internal dense portion accounting for 30%-70% of the total thickness. The metastable austenitic microspheres are configured to undergo a martensitic phase transformation when the mechanical stress reaches a critical threshold. The martensitic phase transformation can cause a regular drift of 3% to 8% in the permeability of the magnetic core containing this functional phase.

[0044] In this embodiment, the core-shell composite functional phase is prepared through the following steps:

[0045] ① Weigh out metastable austenitic microspheres, add anhydrous ethanol at a ratio of 1:10, and disperse by ultrasonication to obtain an austenitic microsphere suspension.

[0046] ② Weigh TEOS, TBB, sodium nitrate, and calcium nitrate in a molar ratio of B2O3: SiO2: Na2O: CaO = 20: 65: 10: 5, dissolve them in 100 mL of anhydrous ethanol, and stir magnetically for 30 minutes to obtain a clear precursor mixture.

[0047] ③ Slowly add the precursor mixture to the austenitic microsphere suspension at a dropping rate of 1-2 mL / min.

[0048] ④ After the addition is complete, adjust and maintain the pH of the entire reaction system at 4.0 with hydrochloric acid. React for 3–4 hours in a 40°C water bath with stirring at 200–300 rpm. While maintaining the temperature and stirring, add ammonia water dropwise to the reaction system at a rate of 0.5 mL / min. Over 2–3 hours, slowly and uniformly raise the pH of the reaction system from 4.0 to 9.0–10.0. After reaching the target pH, continue the reaction for another 0.5 hours, then stop heating and stirring. Seal the reaction system and allow it to age at room temperature for 24 hours to allow the gel structure to fully age and stabilize.

[0049] ⑤ The aged product is centrifuged, washed, and vacuum-dried to obtain austenitic gradient glass powder with a dense inner layer, gradient transition, and loose outer layer structure.

[0050] The gradient drying process is as follows: 40℃, constant temperature for 4 hours, increase temperature to 60℃, constant temperature for 8 hours, then 80℃ again, constant temperature for 4 hours.

[0051] ⑥ The dried powder was subjected to low-temperature heat treatment as follows: The powder was placed under flowing argon gas and heated to 300°C at 2°C / min, held for 1 hour, then heated to 550°C at 1°C / min, held for 2 hours, cooled to 200°C at 1°C / min, and then cooled to room temperature in the furnace. The powder was then sieved to obtain the core-shell composite functional phase.

[0052] Understandably, hydrolysis is slow under acidic catalysis, and the condensation reaction tends to form a highly cross-linked, dense SiO2 network. Conversely, hydrolysis is rapid under alkaline catalysis, and the condensation products tend to generate more branched, loosely packed gel particles. By controlling the reaction time under acidic conditions, a dense inner layer with a thickness of approximately 0.15-1.4 μm is formed on the surface of the microspheres. As the pH increases, the newly deposited glass layer gradually becomes porous and loose, eventually forming a dense layer, a gradient transition layer, and a loose outer layer with a total thickness of 0.5-2 μm and a continuously decreasing density outwards. Subsequently, gradient drying is used to prevent the outer shell from cracking, and low-temperature heat treatment is used to amorphize the shell, forming a stable amorphous gradient shell.

[0053] In this embodiment, the metastable austenitic Fe-Ni-C microspheres have a diameter of 3-8 μm and are selected from Shandong Jinwei Nano.

[0054] In this embodiment, the chemical raw materials used, including tetraethyl orthosilicate (TEOS), tributyl borate (TBB), sodium nitrate, calcium nitrate, and anhydrous ethanol, are all commercially available analytical grade reagents.

[0055] A magnetic core comprising a matrix phase and the aforementioned core-shell composite functional phase dispersed in the matrix phase.

[0056] Furthermore, the raw materials of the magnetic core, by mass percentage, include:

[0057] Nickel-zinc-copper ferrite powder: 80%–90%;

[0058] Bismuth oxide 1.0%–2.0%;

[0059] Vanadium pentoxide 0.5%–1.0%;

[0060] Core-shell composite functional phases: 10%–20%;

[0061] Nano-alumina 0.5%–1.0%.

[0062] Furthermore, the core-shell composite functional phase exhibits a gradient distribution within the magnetic core, with its volume concentration decreasing continuously from 15%–20% to 5%–10% from the central region to the outer surface region of the core.

[0063] Among them, the nickel-zinc-copper ferrite powder has a particle size of 0.5-2.0 μm and a specific surface area of ​​2-6 m². 2 / g, in this embodiment, the nickel-zinc-copper ferrite powder is selected from Hengdian Dongci, and the model is Ni-Zn-Cu ferrite;

[0064] Bismuth oxide was selected from Ningxia Juntao New Material Technology Co., Ltd., model JTM-BO3-30B; vanadium pentoxide was selected from Wuhan Kanos Technology Co., Ltd., model industrial grade, purity 99%.

[0065] In this embodiment, the gradient distribution is achieved through a centrifugal forming process, which includes:

[0066] ① After mixing the matrix phase and the core-shell composite functional phase in a certain proportion, the mixture is ball-milled with deionized water, dispersant and binder to form a uniform slurry with a total solids content of 50%-60%.

[0067] The dispersant is BYK-154 and the binder is polyvinyl alcohol, both of which are commercially available industrial-grade reagents. The amount of dispersant added is 0.5%-1.5% of the total mass of the dry powder, and the amount of binder added is 3.0%-4.0% of the total mass of the dry powder.

[0068] ② Inject the slurry into a cylindrical stainless steel mold and rotate it for 5-15 minutes under an acceleration of 500G-1000G to form a wet blank with a gradient distribution.

[0069] It should be added that, in other embodiments, the wet blank is cold isostatically pressed at 3-10 MPa for 5-10 minutes before subsequent heat treatment forming process.

[0070] ③ Place the wet blank in an air atmosphere furnace and heat it to 500℃ at a rate of 0.5℃ / min, and keep it at that temperature for a sufficient time to remove the organic binder.

[0071] ④ Switch to a nitrogen atmosphere and heat to 550℃ at a rate of 5℃ / min, holding for 1 hour. This promotes the full flow of the loose outer phase of the core-shell composite functional group, heals the micropores caused by debinding, and allows for initial bonding with the matrix.

[0072] ⑤ Under nitrogen protection, the temperature is increased to the target sintering temperature of 950℃ at a relatively rapid rate of 10℃ / min, and held for 15-30 minutes. The liquid phase formed by Bi2O3 is used to achieve rapid densification of the ferrite matrix, and the ultra-short holding time greatly reduces the thermal exposure of the austenite core, inhibiting its decomposition or phase transformation.

[0073] ⑥ After sintering, the temperature is controlled to be cooled to 800℃ at a rate of 2℃ / min, and then cooled with the furnace to eliminate thermal stress.

[0074] ⑦ Perform grinding as required to obtain a highly reliable magnetic core.

[0075] Another aspect of this invention proposes a highly reliable inductor; please refer to [link to relevant documentation]. Figure 2 This includes the aforementioned magnetic core 1 and the winding 2 wound on the magnetic core.

[0076] Specifically, a high-reliability inductor is produced by winding wires on the aforementioned magnetic core to form a winding, and then soldering and encapsulating it via pin 3.

[0077] This invention also proposes a method for warning of failure risk of a high-reliability inductor, which uses the above-mentioned high-reliability inductor to monitor the inductance value or permeability parameter of the high-reliability inductor in real time.

[0078] When a regular drift of 3% to 8% in inductance or permeability is detected, it is determined that the metastable austenitic microspheres in the magnetic core have undergone martensitic phase transformation, and an early warning signal characterizing mechanical stress overload is generated.

[0079] To further understand the present invention, the high-reliability inductor provided by the present invention will be described below with reference to embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0080] Example 1

[0081] Preparation of core-shell composite functional phases:

[0082] ① Weigh 50g of metastable austenitic microspheres, add anhydrous ethanol at a mass ratio of 1:10, and disperse by ultrasonication to obtain a metastable austenitic microsphere suspension.

[0083] ② Weigh TEOS, TBB, sodium nitrate, and calcium nitrate in a molar ratio of B2O3: SiO2: Na2O: CaO = 20: 65: 10: 5, dissolve them in 100 mL of anhydrous ethanol, and stir magnetically for 30 minutes to obtain a clear precursor mixture.

[0084] ③ Slowly add the precursor mixture to the austenitic microsphere suspension at a dropping rate of 1 mL / min.

[0085] ④ After the addition is complete, adjust and maintain the pH of the entire reaction system at 4.0 with hydrochloric acid. React for 4 hours in a 40℃ water bath with stirring at 200 rpm. While maintaining the temperature and stirring, add ammonia water dropwise to the reaction system at a rate of 0.5 mL / min. Within 2 hours, raise the pH of the reaction system uniformly from 4.0 to 9.0. After reaching the target pH, continue the reaction for another 0.5 hours, then stop heating and stirring. Seal the reaction system and allow it to age at room temperature for 24 hours.

[0086] ⑤ The aged product is centrifuged, washed, and vacuum-dried to obtain austenitic gradient glass powder with a dense inner layer, gradient transition, and loose outer layer structure.

[0087] The gradient drying process is as follows: 40℃, constant temperature for 4 hours, increase temperature to 60℃, constant temperature for 8 hours, then 80℃ again, constant temperature for 4 hours.

[0088] ⑥ The dried powder was subjected to low-temperature heat treatment as follows: The powder was placed under flowing argon gas and heated to 300°C at 2°C / min, held for 1 hour, then heated to 550°C at 1°C / min, held for 2 hours, cooled to 200°C at 1°C / min, and then cooled to room temperature in the furnace. The powder was then sieved to obtain the core-shell composite functional phase.

[0089] Example 2

[0090] Core fabrication:

[0091] ① Mix 80g of nickel-zinc-copper ferrite powder, 1g of bismuth oxide, 0.5g of vanadium pentoxide, 10g of the core-shell composite functional phase prepared in Example 1, and 0.5g of nano-alumina. Then, ball mill the mixture with 200ml of deionized water, 0.5g of BYK-154, and 3g of polyvinyl alcohol to form a uniform slurry with a total solids content of 50%.

[0092] ② Inject the slurry into a cylindrical stainless steel mold and rotate it for 10 minutes under an acceleration of 500G to form a wet blank with a gradient distribution. Then, cold isostatically press the wet blank at 3MPa for 5 minutes.

[0093] ③ Place the wet blank in an air atmosphere furnace and heat it to 500℃ at a rate of 0.5℃ / min.

[0094] ④ Switch to a nitrogen atmosphere, raise the temperature to 550℃ at 5℃ / min, and hold for 1 hour.

[0095] ⑤ Under nitrogen protection, the temperature is increased to the target sintering temperature of 950℃ at a relatively rapid rate of 10℃ / min, and held for 15 minutes.

[0096] ⑥ After sintering, the temperature is controlled to be cooled to 800℃ at a rate of 2℃ / min, and then cooled with the furnace.

[0097] ⑦ Perform grinding as required to obtain a highly reliable magnetic core.

[0098] Example 3

[0099] Core fabrication:

[0100] ① Mix 90g of nickel-zinc-copper ferrite powder, 2g of bismuth oxide, 1g of vanadium pentoxide, 20g of the core-shell composite functional phase prepared in Example 1 and 1g of nano-alumina, and then ball-mill and mix with 200ml of deionized water, 1g of BYK-154 and 5g of polyvinyl alcohol to form a uniform slurry with a total solids content of 60%.

[0101] ② Inject the slurry into a cylindrical stainless steel mold and rotate it for 5 minutes under an acceleration of 1000G to form a wet blank with a gradient distribution. Then, cold isostatically press the wet blank at 10MPa for 5 minutes.

[0102] ③ Place the wet blank in an air atmosphere furnace and heat it to 500℃ at a rate of 0.5℃ / min.

[0103] ④ Switch to a nitrogen atmosphere, raise the temperature to 550℃ at 5℃ / min, and hold for 1 hour.

[0104] ⑤ Under nitrogen protection, the temperature is increased to the target sintering temperature of 950℃ at a relatively rapid rate of 10℃ / min, and held for 30 minutes.

[0105] ⑥ After sintering, the temperature is controlled to be cooled to 800℃ at a rate of 2℃ / min, and then cooled with the furnace.

[0106] ⑦ Perform grinding as required to obtain a highly reliable magnetic core.

[0107] Comparative Example 1

[0108] Commercially available magnetic cores are selected from Feici, model 4A11 nickel-zinc ferrite series.

[0109] Comparative Example 2

[0110] ① Mix 90g of nickel-zinc-copper ferrite powder, 2g of bismuth oxide, 1g of vanadium pentoxide, 15g of metastable austenitic microspheres, 5g of borosilicate glass powder and 1g of nano alumina, and then ball-mill with 200ml of deionized water, 1g of BYK-154 and 5g of polyvinyl alcohol to form a uniform slurry with a total solids content of 60%.

[0111] ② Inject the slurry into a cylindrical stainless steel mold and rotate it for 5 minutes under an acceleration of 1000G to form a wet blank with a gradient distribution. Then, cold isostatically press the wet blank at 10MPa for 5 minutes.

[0112] ③ Place the wet blank in an air atmosphere furnace and heat it to 500℃ at a rate of 0.5℃ / min.

[0113] ④ Switch to a nitrogen atmosphere, raise the temperature to 550℃ at 5℃ / min, and hold for 1 hour.

[0114] ⑤ Under nitrogen protection, the temperature is increased to the target sintering temperature of 950℃ at a relatively rapid rate of 10℃ / min, and held for 30 minutes.

[0115] ⑥ After sintering, the temperature is controlled to be cooled to 800℃ at a rate of 2℃ / min, and then cooled with the furnace.

[0116] ⑦ Perform grinding as required to obtain the magnetic core.

[0117] Comparative Example 3

[0118] ① Weigh 50g of metastable austenitic microspheres, add anhydrous ethanol at a mass ratio of 1:10, and disperse by ultrasonication to obtain a metastable austenitic microsphere suspension.

[0119] ② Weigh TEOS, TBB, sodium nitrate, and calcium nitrate in a molar ratio of B2O3: SiO2: Na2O: CaO = 20: 65: 10: 5, dissolve them in 100 mL of anhydrous ethanol, and stir magnetically for 30 minutes to obtain a clear precursor mixture.

[0120] ③ Slowly add the precursor mixture to the austenitic microsphere suspension at a dropping rate of 1 mL / min.

[0121] ④ After the addition is complete, adjust and maintain the pH of the entire reaction system at 4.0 with hydrochloric acid. After reacting for 6.5 hours in a 40°C water bath with stirring at 200 rpm, stop heating and stirring. Seal the reaction system and let it stand at room temperature for 24 hours to age.

[0122] ⑤ The aged product is centrifuged, washed, and subjected to gradient vacuum drying to obtain austenitic glass powder.

[0123] The gradient drying process is as follows: 40℃, constant temperature for 4 hours, increase temperature to 60℃, constant temperature for 8 hours, then 80℃ again, constant temperature for 4 hours.

[0124] ⑥ The dried powder was subjected to low-temperature heat treatment as follows: The powder was placed under flowing argon gas and heated to 300°C at 2°C / min, held for 1 hour, then heated to 550°C at 1°C / min, held for 2 hours, cooled to 200°C at 1°C / min, and then cooled to room temperature in the furnace. The powder was then sieved to obtain the core-shell composite phase.

[0125] ⑦ Mix 90g of nickel-zinc-copper ferrite powder, 2g of bismuth oxide, 1g of vanadium pentoxide, 20g of the core-shell composite phase prepared in step ⑥, and 1g of nano-alumina. Then, ball mill and mix the mixture with 200ml of deionized water, 1g of BYK-154, and 5g of polyvinyl alcohol to form a uniform slurry with a total solids content of 60%.

[0126] ⑧ Inject the slurry into a cylindrical stainless steel mold and rotate it for 5 minutes at an acceleration of 1000G to form a wet blank with a gradient distribution. Apply a cold isostatic press of 10MPa to the wet blank for 5 minutes. Place the wet blank in an air atmosphere furnace and heat it to 500℃ at a rate of 0.5℃ / min. Switch to a nitrogen atmosphere and heat it to 550℃ at a rate of 5℃ / min, holding for 1 hour. Under nitrogen protection, heat it to the target sintering temperature of 950℃ at a relatively rapid rate of 10℃ / min and hold for 30 minutes. After sintering, cool it to 800℃ at a controlled rate of 2℃ / min, then allow it to cool in the furnace.

[0127] ⑨ Grind the material as required to obtain the magnetic core.

[0128] Test example:

[0129] The initial permeability of the magnetic cores in Example 3 and Comparative Examples 1-3 was tested according to the IEC 60401-1 standard, and the specific results are shown in Table 1.

[0130] The saturation magnetic flux density of the magnetic cores in Example 3 and Comparative Examples 1-3 was tested according to the IEC 60401-1 standard, and the specific results are shown in Table 1.

[0131] The power loss of the magnetic cores in Example 3 and Comparative Examples 1-3 was tested according to the IEC 62044-3 standard, and the specific results are shown in Table 1.

[0132] The bending strength of the magnetic cores in Example 3 and Comparative Examples 1-3 was tested according to ASTM C1161 standard, and the specific results are shown in Table 1.

[0133] Thermal cycling performance of the magnetic cores in Example 3 and Comparative Examples 1-3 was tested at 55℃-125℃ for 100 cycles. The specific results are shown in Table 1.

[0134] After assembling the magnetic cores from Example 3 and Comparative Examples 1-3 into inductors, a warning function test was conducted under specific stress, and an insulation resistance recovery rate test was conducted after overload. The specific results are shown in Table 1.

[0135] Table 1. Statistical Table of Parameters for Examples and Comparative Examples

[0136] In summary, this invention provides an inductor failure risk response structure, a high-reliability inductor, and a failure risk warning method. The inductor failure risk response structure is a core-shell composite functional phase with a gradient shell design. It uses metastable Fe-Ni-C austenitic alloy microspheres as the core, with a borosilicate glass shell covering the surface. The microstructure of this glass shell exhibits a gradient change from the inside out: the inner layer is dense to ensure protection of the core and its service life; the outer layer is relatively porous, designed to preferentially participate in the densification reaction during sintering, improving process performance.

[0137] The gradient shell was prepared using an improved sol-gel process, and the pH of the reaction system was programmed to be adjusted during the coating process. In the early stage of coating, acidic conditions were used to form a highly cross-linked and dense inner layer. Subsequently, the pH of the system was gradually increased to alkaline conditions, which caused the structure of the subsequently deposited glass layer to gradually become porous and loose, and finally formed an integrated gradient shell of dense inner layer, gradient transition and loose outer layer.

[0138] When the mechanical stress on the magnetic core reaches a preset critical threshold, the austenite nucleus will undergo a martensitic phase transformation. This phase transformation can cause a regular drift of 3% to 8% in the permeability of the entire magnetic core. This change in magnetic properties can serve as an electrical signal that can be detected by a circuit, thereby enabling early warning of potential mechanical overload or structural damage.

[0139] When the temperature rises locally in the magnetic core due to abnormal conditions, the glass shell softens and becomes fluid, which can fill and heal microcracks that have emerged nearby, thereby restoring the mechanical integrity and structural density of the cracked area. This helps to eliminate potential conductive paths formed by cracks and maintain the electrical insulation performance of the area.

[0140] By utilizing the density difference between the core-shell functional phase and the matrix ferrite powder through centrifugal forming, a continuous concentration gradient distribution of the functional phase spontaneously forms radially within the core green body under the drive of a strong centrifugal force field. This means that the functional phase concentration continuously transitions from high-risk areas inside the core to low concentrations on the outside. This spatial distribution design precisely places limited intelligent response materials in the most needed locations, thereby significantly improving the sensitivity of early warning and the local efficiency of repair at the system level.

[0141] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. An inductor failure risk response structure, characterized in that, Specifically, it is a core-shell composite functional phase, including: The core is a metastable austenitic microsphere made of Fe-Ni-C alloy; The gradient shell is a borosilicate glass layer covering the surface of the metastable austenitic microspheres. This glass layer has a gradient structure with a continuously decreasing density from the inside to the outside, and its softening point is 120-140℃. The gradient shell has a total thickness of 0.5-2.0 μm, with the internal dense portion accounting for 30%-70% of the total thickness. The metastable austenitic microspheres are configured to undergo a martensitic phase transformation when the applied mechanical stress reaches a critical threshold.

2. The inductor failure risk response structure according to claim 1, characterized in that, The martensitic phase transformation can cause a regular drift of 3% to 8% in the permeability of the magnetic core containing the functional phase.

3. The inductor failure risk response structure according to claim 1, characterized in that, The gradient structure is formed by gradually increasing the pH value from 4 to 9-10 during the sol-gel coating process, thereby controlling the hydrolysis-condensation reaction rate.

4. A magnetic core, characterized in that, The magnetic core comprises a matrix phase and a core-shell composite functional phase as described in any one of claims 1-3 dispersed in the matrix phase, wherein the raw materials of the magnetic core comprise, by mass percentage: Nickel-zinc-copper ferrite powder: 80%–90%; Bismuth oxide 1.0%–2.0%; Vanadium pentoxide 0.5%–1.0%; Core-shell composite functional phases: 10%–20%; Nano-alumina 0.5%–1.0%.

5. The magnetic core according to claim 4, characterized in that, The core-shell composite functional phase is distributed in a gradient in the magnetic core, specifically: from the central region of the magnetic core to the outer surface region, the volume concentration of the core-shell composite functional phase decreases continuously from 15%-20% to 5%-10%.

6. The magnetic core according to claim 5, characterized in that, The gradient distribution is achieved through a centrifugal forming process, which includes: The matrix phase and the core-shell composite functional phase are mixed in a certain proportion, and then ball-milled with deionized water, dispersant and binder to form a uniform slurry with a total solids content of 50%-60%. The slurry is injected into a cylindrical stainless steel mold and rotated for 5-15 minutes under an acceleration of 500G-1000G to form a wet blank with a gradient distribution. The wet blank is subjected to aging, drying, debinding and sintering in sequence to obtain the magnetic core.

7. The magnetic core according to claim 6, characterized in that, The sintering step, under a nitrogen protective atmosphere, includes: first, holding at 550°C for 0.5-1.5 hours, then raising the temperature to 900-950°C and holding for 15-30 minutes.

8. A high-reliability inductor, characterized in that, It includes a magnetic core as described in any one of claims 3-7, and a winding wound on the magnetic core.

9. A method for warning of inductor failure risk, using the high-reliability inductor as described in claim 8, characterized in that, Includes the following steps: Real-time monitoring of the inductance or permeability parameters of the high-reliability inductor; When a regular drift in the inductance or permeability is detected, it is determined that the metastable austenitic microspheres in the magnetic core have undergone martensitic phase transformation, and an early warning signal characterizing mechanical stress overload is generated.

10. The inductor failure risk warning method according to claim 9, characterized in that, The range of the regular drift is 3% to 8%.

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