Nanocrystalline alloys with high permeability at both high and low frequencies, nanocrystalline magnetic rings and their preparation methods

Abstract

This invention provides a nanocrystalline alloy with high permeability at both high and low frequencies, a nanocrystalline magnetic ring, and a method for preparing the same, belonging to the field of magnetic material preparation technology. The chemical formula of the nanocrystalline alloy is: Fe (100‑x‑y‑z‑a‑b‑c) Si x B y Nb z Cu a Ni b M c； Wherein, 8≤x≤13, 8≤y≤10, 0≤z≤1, 0≤a≤2, 0.5≤b≤5, 0.5≤c≤3; M is Mo, Cr, or Co. The preparation method includes the following steps: the nanocrystalline alloy is made into a strip, and then wound into a magnetic core to be processed using an automatic winding machine; a stepped distributed heat treatment process is used to perform transverse magnetothermal treatment on the magnetic core to be processed, the stepped distributed heat treatment process including preheating under transverse magnetic conditions and vacuum heat treatment with segmented heating and holding; after rapid cooling by forced air, the magnetic core is removed from the furnace to obtain a nanocrystalline magnetic ring with high permeability at both high and low frequencies. The magnetic ring obtained by this invention has an effective permeability of over 45,000 at a frequency of 100kHz, and can also retain a permeability of over 120,000 at 1kHz-10kHz, and also has the characteristics of low loss, high Bs value, and high permeability.

Description

Technical Field

[0001] This invention belongs to the technical field of magnetic material preparation, and specifically relates to nanocrystalline alloys with both high frequency and low frequency high permeability, nanocrystalline magnetic rings, and their preparation methods. Background Technology

[0002] Amorphous and nanocrystalline soft magnetic alloys possess high permeability, low coercivity, and excellent high-frequency soft magnetic properties, earning them the title of "green electronic materials of the 21st century." In recent years, they have received widespread attention and research from academia and industry. With the rapid development of computer network technology, 5G communication, electric vehicles, photovoltaic new energy, and multimedia technology, electronic devices are required to be miniaturized, energy-efficient, and operate at higher frequencies. This places newer and higher demands on soft magnetic materials, requiring them to possess higher saturation magnetic induction, higher permeability, lower losses, and good high-frequency performance. With the development of modern industry, there is a desire for soft magnetic materials to have even higher permeability in higher frequency ranges, such as 10kHz to 100kHz. Existing technology fully utilizes the advantage of transverse magnetic field annealing, which can effectively reduce remanent magnetic induction. Vacuum transverse magnetic field annealing is used to improve the permeability of iron-based nanocrystalline alloy cores under high-frequency conditions: the effective permeability can reach approximately 150,000 at 1kHz, over 120,000 at 10kHz, and up to 35,000 at 100kHz.

[0003] Due to its advantages of low loss and high saturation compared to traditional magnetic powder core materials, iron-based nanocrystalline alloy soft magnetic materials have a huge market potential in energy storage inductors and common-mode inductors used in power devices such as new energy vehicles and server power supplies, especially in the fields of new energy vehicles and charging piles where they exhibit significant performance advantages. Currently, traditional nanocrystalline alloy magnetic rings mainly use Fe... 73.5 Nb3Cu1Si 13.5 The B9 formula is crystallized and annealed. This magnetic ring has high permeability, but it has always been impossible to achieve a permeability of over 40,000 at the high frequency of 100KHz, while simultaneously retaining a permeability of over 100,000 at the low frequency of 1KHz, which seriously affects the application fields of the product. Summary of the Invention

[0004] Therefore, the present invention aims to provide nanocrystalline alloys with high permeability at both high and low frequencies, nanocrystalline magnetic rings, and methods for preparing the same, in order to solve at least one technical problem in the prior art.

[0005] This invention is implemented as follows:

[0006] The first aspect of this invention provides a nanocrystalline alloy possessing both high-frequency and low-frequency high magnetic permeability, the chemical formula of which is: Fe (100-x-y-z-a-b-c) Si xB y Nb z Cu a Ni b M c； Wherein, 8 ≤ x ≤ 13, 8 ≤ y ≤ 10, 0 ≤ z<1, 0 ≤ a ≤ 2, 0.5 ≤ b ≤ 5, 0.5 ≤ c ≤ 3; M is Mo, Cr or Co.

[0007] A second aspect of the present invention provides a method for preparing the above-mentioned nanocrystalline magnetic ring with both high frequency and low frequency high permeability, comprising the following steps:

[0008] The above-mentioned nanocrystalline alloy is made into a strip, and then wound into a magnetic core to be processed using an automatic winding machine;

[0009] A stepped distributed heat treatment process was used to perform transverse magnetization heat treatment on the magnetic core to be treated.

[0010] After rapid cooling by blast air, the nanocrystalline magnetic ring with high permeability at both high and low frequencies is obtained.

[0011] The stepped distributed heat treatment process includes preheating under transverse magnetic conditions and vacuum heat treatment with segmented heating and holding.

[0012] Furthermore, the stepped distributed heat treatment process specifically includes:

[0013] The magnetic core to be processed is placed in a heat treatment furnace, a transverse magnetic field is applied, and the temperature is heated to the first set temperature, followed by heat preservation and preheating treatment.

[0014] The preheated magnetic core is placed in a vacuum horizontal furnace, first heated to the first set temperature and held; then heated to the second set temperature and held; and finally heated to the third set temperature and held.

[0015] Furthermore, the first set temperature is 410~430℃, and the preheating treatment is maintained at this temperature for 25~35 minutes;

[0016] In a vacuum horizontal furnace, the magnetic core is held at a first set temperature of 410~430℃ for 25~35 minutes;

[0017] The second set temperature is set to 470~490℃ and held for 55~65 minutes;

[0018] The third set temperature is set to 550~570℃ and held for 85~95 minutes;

[0019] The transverse magnetic field strength in the stepped distributed heat treatment process is set to 100~150mT.

[0020] Furthermore, a transverse magnetic field with an intensity of 100~150mT is maintained during the rapid cooling process.

[0021] Furthermore, the method for fabricating the nanocrystalline alloy into a strip comprises the following steps:

[0022] Prepare the raw materials for Fe-Si-B-Nb-Cu-Ni-M alloy according to the weight ratio after chemical formula conversion, add the raw materials to the medium frequency induction furnace, and heat to 1600~1680℃ for melting;

[0023] After smelting, slag is removed and the alloy is molded to produce a nanocrystalline alloy.

[0024] Nanocrystalline alloys are sprayed using a constant pressure stripping device to produce strips with a thickness of 14~16μm.

[0025] Furthermore, B uses a boron-iron master alloy, while all other raw materials are single-element materials.

[0026] Furthermore, the fill factor of the magnetic core to be processed is set to 0.75~0.8.

[0027] The third aspect of the present invention provides a nanocrystalline magnetic ring with high permeability at both high and low frequencies, obtained by the above method. The permeability of the nanocrystalline magnetic ring is not less than 45,000 at a high frequency of 100 kHz, and the permeability of the nanocrystalline alloy is not less than 120,000 at a low frequency below 10 kHz.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. This invention proposes a high-permeability amorphous nanocrystalline alloy by using innovative amorphous alloy composition and alloy preparation method. After heat treatment of the amorphous alloy, the resulting nanocrystalline alloy has both high permeability at high and low frequencies, and features low loss, high Bs value, and high permeability.

[0030] 2. The present invention adds Ni element to the alloy, which purifies the alloy melt and increases the fluidity of the molten steel. This allows for better control of the strip thickness and density during the strip spraying process, and improves the filling coefficient of the magnetic ring, thereby increasing the magnetic permeability of the magnetic ring.

[0031] 3. In the preparation of the magnetic ring, the present invention adopts a step-by-step segmented heating heat treatment after transverse magnetic preheating. This ensures that the magnetic domains generated in the initial stage of heat treatment are deflected in one direction and form copper clusters, so that the characteristics of copper clusters are retained during subsequent heat treatment crystallization, thereby optimizing the magnetic permeability. Attached Figure Description

[0032] Figure 1 This is a physical image of the nanocrystalline magnetic ring prepared according to the present invention;

[0033] Figure 2 This is a hysteresis loop diagram of Embodiment 1 of the present invention;

[0034] Figure 3 This is a magnetization hysteresis loop diagram of Embodiment 1 of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] A nanocrystalline alloy possessing both high-frequency and low-frequency high magnetic permeability, its chemical formula is: Fe (100-x-y-z-a-b-c) Si x B y Nb z Cu a Ni b M c；

[0037] Wherein, 8 ≤ x ≤ 13, 8 ≤ y ≤ 10, 0 ≤ z<1, 0 ≤ a ≤ 2, 0.5 ≤ b ≤5, 0.5 ≤ c ≤ 3; M is Mo, Cr or Co.

[0038] The addition of Ni element in this invention can effectively reduce the residual magnetic flux density and magnetostriction coefficient of the magnetic core, thereby reducing high-frequency loss and increasing high-frequency permeability.

[0039] This invention reduces the Nb content, changing it from the traditional 3% to below 1%, which can better improve the fluidity of the molten steel in the strip. The reason is that Nb has the highest melting point, and reducing the proportion can achieve more uniform melting and better molten steel fluidity, thereby increasing the toughness of the strip. Increased strip toughness allows for thinner strips to be sprayed during the process. The thinner the strip, the lower the high-frequency loss and the higher the high-frequency permeability.

[0040] A method for preparing nanocrystalline magnetic rings with both high frequency and low frequency high permeability includes the following steps:

[0041] S1, Fe nanocrystalline alloy (100-x-y-z-a-b-c) Si x B y Nb z Cu a Ni b M c The material is made into a strip, and then wound into a magnetic core to be processed using an automatic winding machine;

[0042] (1) Prepare Fe-Si-B-Nb-Cu-Ni-M alloy raw materials according to the weight ratio after chemical formula conversion, add the raw materials to the medium frequency induction furnace, and heat to 1600~1680℃ for smelting; among them, B is a boron iron master alloy, and the rest of the raw materials are all single materials.

[0043] (2) After smelting, slag is removed and the alloy is molded into nanocrystalline alloy;

[0044] (3) The nanocrystalline alloy is sprayed with a constant pressure strip machine to produce a strip with a thickness of 14~16μm, and then cut into different width specifications by a copper roller precision roll shearing machine.

[0045] (4) Use an automatic winding machine to wind the magnetic core. When winding the magnetic core, adjust the appropriate tension of the strip. The strip should not be pulled too tight when winding the magnetic core. The filling coefficient should be controlled at 0.75~0.8.

[0046] S2. A stepped distributed heat treatment process is used to perform transverse magnetic heat treatment on the magnetic core to be treated.

[0047] (1) Place the magnetic core to be treated in a heat treatment furnace, apply a transverse magnetic field of 100~150mT, and heat it to the first set temperature of 410~430℃ simultaneously, and keep it warm for 25~35min.

[0048] During the heat treatment process, copper clusters will begin to form in the amorphous nanocrystalline ribbon. As copper atoms begin to crystallize, a transverse magnetic field is applied to ensure that the magnetic domains generated at the beginning are deflected in one direction. In this step, heating can be done in stages or directly from the initial temperature to the target temperature.

[0049] (2) Place the preheated magnetic core in a vacuum horizontal furnace, first heat it to the first set temperature of 410~430℃ and hold it for 25~35min; then heat it to the second set temperature of 470~490℃ and hold it for 55~65min; then heat it to the third set temperature of 550~570℃ and hold it for 85~95min; the following embodiments of the present invention use a mechanical pump type vacuum horizontal furnace, and the vacuum degree requirement is that the display scale is below -0.1MPa to meet the requirements;

[0050] In a vacuum horizontal furnace, the magnetic core undergoes complete crystallization annealing to form a 10-20 nanometer nanocrystalline structure. Since the magnetic domains are already in one direction and good copper clusters have been formed in the early stage, the above characteristics can be retained after vacuum horizontal furnace annealing, thereby obtaining better magnetic permeability.

[0051] S3. After rapid cooling by forced air, the product is removed from the furnace.

[0052] After the magnetic core has undergone heat treatment and heat preservation, it is cooled rapidly by blowing air with a blower. At the same time, a constant transverse magnetic field of 100~150mT is maintained during the cooling process to obtain a nanocrystalline magnetic ring with both high frequency and low frequency high permeability.

[0053] The nanocrystalline magnetic rings prepared by the above method have a permeability of not less than 45,000 at a high frequency of 100kHz and a permeability of not less than 120,000 at a low frequency below 10kHz.

[0054] Example 1

[0055] A method for preparing nanocrystalline magnetic rings with both high frequency and low frequency high permeability includes the following steps:

[0056] S1. Prepare Fe according to the weight ratio after chemical formula conversion. 73.6 Si 10 B9Nb 0.9 Cu1Ni3Mo 2.5 The alloy raw materials are added to a medium-frequency induction furnace and smelted at 1650℃ for about 3 hours. B is a boron-iron master alloy, and the remaining raw materials are all elemental materials. After smelting, the slag is removed and the alloy is molded into a nanocrystalline alloy. The nanocrystalline alloy is then sprayed into a 14μm thick strip using a constant pressure strip machine, and then cut into different widths using a copper roller precision roll shearing machine. The magnetic core is then wound into an automatic winding machine. When winding the magnetic core, the appropriate tension of the strip is adjusted. The strip should not be pulled too tight when winding the magnetic core, and the filling factor is set to 0.78.

[0057] S2. Place the magnetic core to be treated in a heat treatment furnace, apply a 100T transverse magnetic field, and heat synchronously. Raise the temperature to 420℃ within 30 minutes and hold for 30 minutes for preheating. Place the preheated magnetic core in a vacuum horizontal furnace, raise the temperature to 420℃ within 60 minutes and hold for 30 minutes. Then raise the temperature to 480℃ within 60 minutes and hold for 60 minutes. Finally, raise the temperature to 560℃ within 60 minutes and hold for 90 minutes.

[0058] S3. After rapid cooling by forced air, the product is removed from the furnace.

[0059] After heat treatment and heat preservation, the magnetic core is rapidly cooled using a blower while maintaining a constant 100mT transverse magnetic field during the cooling process. This results in a nanocrystalline magnetic ring with high permeability at both high and low frequencies. The ring dimensions are OD*ID*HT = 30*20*10mm. Figure 1 As shown.

[0060] The measured inductance values ​​of the nanocrystalline magnetic rings prepared in this embodiment are AL=90μH@1KHz; AL=80μH@10KHz; AL=30μH@100KHz. Based on the permeability μe=Ae*Le*1000 / N²*0.4π*Ae, where Le is the magnetic path length of the magnetic ring, N is the fill factor, and Ae is the magnetic cross-sectional area of ​​the magnetic ring, we can calculate: μe=144000@1KHz; μe=128000@10KHz; μe=48000@100KHz.

[0061] The hysteresis loop and magnetization curve of the nanocrystalline magnetic ring prepared in Example 1 were measured using a hysteresis loop and magnetization curve measuring instrument. The results are referenced. Figure 2 and Figure 3 As can be seen from the test data and the diagram, the initial permeability of the product can reach 103K, the remanence Br is only 60mT, and the coercivity Hc=0.43A / m. The magnetic core made using this process has extremely low remanence and very low coercivity; and it also retains a permeability of over 100,000.

[0062] Example 2

[0063] In this embodiment, a nanocrystalline magnetic ring with high permeability at both high and low frequencies was prepared. The thickness of the strip was 16 μm, and the remaining parameters, conditions, and steps were the same as in Example 1.

[0064] The measured inductance values ​​of the nanocrystalline magnetic rings prepared in this embodiment are AL=95μH@1KHz; AL=75μH@10KHz; AL=28.5μH@100KHz. Based on the permeability μe=Ae*Le*1000 / N²*0.4π*Ae, where Le is the magnetic path length of the magnetic ring, N is the fill factor, and Ae is the magnetic cross-sectional area of ​​the magnetic ring, we can calculate: μe=152000@1KHz; μe=120000@10KHz; μe=45600@100KHz.

[0065] Example 3

[0066] In this embodiment, a nanocrystalline magnetic ring with both high frequency and low frequency high permeability was prepared. The transverse magnetic field strength applied during the heat treatment process and cooling process was 150 mT. The other parameters, conditions and steps were the same as in Example 1.

[0067] The measured inductance values ​​of the nanocrystalline magnetic rings prepared in this embodiment are AL=90μH@1KHz; AL=80μH@10KHz; AL=30μH@100KHz. Based on μe=Ae*Le*1000 / N²*0.4π*Ae, where Le is the magnetic circuit length of the magnetic ring, N is the fill factor, and Ae is the magnetic cross-sectional area of ​​the magnetic ring, we can calculate: μe=141000@1KHz; μe=131000@10KHz; μe=49700@100KHz.

[0068] Example 4

[0069] A method for preparing nanocrystalline magnetic rings with both high frequency and low frequency high permeability includes the following steps:

[0070] S1. Prepare Fe according to the weight ratio after chemical formula conversion. 72 Si 13 B 10 Nb 0.5 Cu2Ni2Cr 0.5 The alloy raw materials are added to a medium-frequency induction furnace and smelted at 1600℃ for about 3 hours. B is a boron-iron master alloy, and the remaining raw materials are all elemental materials. After smelting, the slag is removed and the alloy is molded into a nanocrystalline alloy. The nanocrystalline alloy is sprayed into a 14μm thick strip using a constant pressure strip machine, and then cut into different widths using a copper roller precision roll shearing machine. The magnetic core is wound into an automatic winding machine. When winding the magnetic core, the appropriate tension of the strip is adjusted. The strip should not be pulled too tightly when winding the magnetic core, and the filling factor is set to 0.78.

[0071] S2. Place the magnetic core to be treated in a heat treatment furnace, apply a 100T transverse magnetic field, and heat synchronously. Raise the temperature to 410℃ within 30 minutes and hold for 35 minutes for preheating. Place the preheated magnetic core in a vacuum horizontal furnace, raise the temperature to 410℃ within 60 minutes and hold for 35 minutes. Then raise the temperature to 470℃ within 60 minutes and hold for 65 minutes. Finally, raise the temperature to 550℃ within 60 minutes and hold for 95 minutes.

[0072] S3. After the magnetic core has undergone heat treatment and heat preservation, it is cooled quickly by blowing air with a blower. At the same time, a constant 100mT transverse magnetic field is maintained during the cooling process to obtain a nanocrystalline magnetic ring with both high frequency and low frequency high permeability. The size of the magnetic ring is OD*ID*HT=30*20*10mm.

[0073] The measured inductance values ​​of the nanocrystalline magnetic rings prepared in this embodiment are AL=83.2μH@1KHz; AL=74μH@10KHz; AL=28.8μH@100KHz. Based on the permeability μe=Ae*Le*1000 / N²*0.4π*Ae, where Le is the magnetic path length of the magnetic ring, N is the fill factor, and Ae is the magnetic cross-sectional area of ​​the magnetic ring, we can calculate: μe=130000@1KHz; μe=115000@10KHz; μe=45000@100KHz.

[0074] Example 5

[0075] A method for preparing nanocrystalline magnetic rings with both high frequency and low frequency high permeability includes the following steps:

[0076] S1. Prepare Fe according to the weight ratio after chemical formula conversion. 75.4 Si8B8Nb 0.1 Cu 0.5 The Ni5Co3 alloy raw material was added to a medium-frequency induction furnace and smelted at 1670℃ for about 3 hours. Boron-iron master alloy (B) was used, while all other raw materials were elemental. After smelting, slag was removed, and the alloy was molded into nanocrystalline alloy. The nanocrystalline alloy was then sprayed using a constant pressure stripping machine to produce a 14μm thick strip. A copper roller precision shearing machine was used to cut the strip to different widths. An automatic winding machine was used to wind the strip into a magnetic core. During core winding, the strip tension was adjusted appropriately; the strip should not be pulled too tight, and the fill factor was set to 0.78.

[0077] S2. Place the magnetic core to be treated in a heat treatment furnace, apply a 100T transverse magnetic field, and heat synchronously. Raise the temperature to 430℃ within 30 minutes and hold for 25 minutes for preheating. Place the preheated magnetic core in a vacuum horizontal furnace, raise the temperature to 430℃ within 60 minutes and hold for 25 minutes. Then raise the temperature to 490℃ within 60 minutes and hold for 55 minutes. Finally, raise the temperature to 570℃ within 60 minutes and hold for 85 minutes.

[0078] S3. After the magnetic core has undergone heat treatment and heat preservation, it is cooled quickly by blowing air with a blower. At the same time, a constant 100mT transverse magnetic field is maintained during the cooling process to obtain a nanocrystalline magnetic ring with both high frequency and low frequency high permeability. The size of the magnetic ring is OD*ID*HT=30*20*10mm.

[0079] The measured inductance values ​​of the nanocrystalline magnetic rings prepared in this embodiment are AL=71μH@1KHz; AL=61μH@10KHz; AL=30.1μH@100KHz. Based on the permeability μe=Ae*Le*1000 / N²*0.4π*Ae, where Le is the magnetic path length of the magnetic ring, N is the fill factor, and Ae is the magnetic cross-sectional area of ​​the magnetic ring, we can calculate: μe=110000@1KHz; μe=95000@10KHz; μe=48000@100KHz.

[0080] Example 6

[0081] A method for preparing nanocrystalline magnetic rings with both high frequency and low frequency high permeability includes the following steps:

[0082] S1. Prepare Fe according to the weight ratio after chemical formula conversion. 76.6 Si 12 B 9.5 Nb 0.7 Cu 0.2 Ni 0.5 Mo 0.5 Alloy raw materials are added to a medium-frequency induction furnace and smelted at 1680℃ for about 3 hours. B is a boron-iron master alloy, and the remaining raw materials are all elemental materials. After smelting, slag is removed and the alloy is molded into a nanocrystalline alloy. The nanocrystalline alloy is then sprayed onto a constant pressure strip to produce a strip with a thickness of 15μm. An automatic winding machine is used to wind the strip into a magnetic core. When winding the magnetic core, the appropriate tension of the strip is adjusted. The strip should not be pulled too tightly when winding the magnetic core, and the filling factor is set to 0.8.

[0083] S2. Place the magnetic core to be treated in a heat treatment furnace, apply a 120T transverse magnetic field, and heat synchronously. Raise the temperature to 420℃ within 30 minutes and hold for 30 minutes for preheating. Place the preheated magnetic core in a vacuum horizontal furnace, raise the temperature to 420℃ within 60 minutes and hold for 30 minutes. Then raise the temperature to 480℃ within 60 minutes and hold for 60 minutes. Finally, raise the temperature to 560℃ within 60 minutes and hold for 90 minutes.

[0084] S3. After the magnetic core has undergone heat treatment and heat preservation, it is cooled quickly by blowing air with a blower. At the same time, a constant 120mT transverse magnetic field is maintained during the cooling process to obtain a nanocrystalline magnetic ring with both high frequency and low frequency high permeability. The size of the magnetic ring is OD*ID*HT=30*20*10mm.

[0085] The measured inductance values ​​of the nanocrystalline magnetic rings prepared in this embodiment are AL=88μH@1KHz; AL=76μH@10KHz; AL=31μH@100KHz. Based on the permeability μe=Ae*Le*1000 / N²*0.4π*Ae, where Le is the magnetic path length of the magnetic ring, N is the fill factor, and Ae is the magnetic cross-sectional area of ​​the magnetic ring, we can calculate: μe=137000@1KHz; μe=118000@10KHz; μe=48500@100KHz.

[0086] Comparative Example 1

[0087] This comparative example prepares nanocrystalline magnetic rings using commercially available 1K107:Fe as the raw material. 73.5 Nb3Cu1Si 13.5 B9, the remaining parameters, conditions and steps are the same as in Example 1.

[0088] The measured inductance values ​​of the nanocrystalline magnetic rings prepared in this comparative example are AL=60μH@1KHz; AL=45μH@10KHz; AL=22μH@100KHz. Based on the permeability μe=Ae*Le*1000 / N²*0.4π*Ae, where Le is the magnetic path length of the magnetic ring, N is the fill factor, and Ae is the magnetic cross-sectional area of ​​the magnetic ring, we can calculate: μe=96000@1KHz; μe=72000@10KHz; μe=35000@100KHz.

[0089] Comparative Example 2

[0090] This comparative example prepares nanocrystalline magnetic rings using commercially available 1K107:Fe as the raw material. 73.5 Nb3Cu1Si 13.5 B9, the remaining parameters, conditions and steps are the same as in Example 2.

[0091] The measured inductance values ​​of the nanocrystalline magnetic rings prepared in this comparative example are AL=70μH@1KHz; AL=42μH@10KHz; AL=18μH@100KHz. Based on μe=Ae*Le*1000 / N²*0.4π*Ae, where Le is the magnetic circuit length of the magnetic ring, N is the fill factor, and Ae is the magnetic cross-sectional area of ​​the magnetic ring, we can calculate: μe=112000@1KHz; μe=67300@10KHz; μe=28800@100KHz.

[0092] As can be seen from Comparative Examples 1 and 2, the magnetic rings made of conventional alloys have a permeability of less than 40,000 at a high frequency of 100 kHz, less than 75,000 at a low frequency of 10 kHz, and less than 115,000 at a low frequency of 1 kHz.

[0093] Comparative Example 3

[0094] The heat treatment process for preparing the nanocrystalline magnetic ring in this comparative example is as follows:

[0095] (1) Horizontal furnace process: Heat up to 420℃ for 60 minutes and hold for 30 minutes, then heat up to 480℃ for 60 minutes and hold for 60 minutes, then heat up to 560℃ for 90 minutes and hold for 90 minutes. After taking out the magnetic core;

[0096] (2) Horizontal magnetic furnace process: The magnetic core is then placed in a heat treatment furnace, heated to 420℃ for 60 minutes, and then kept at that temperature for 60 minutes with a magnetic field strength of 100mT.

[0097] The remaining parameters, conditions, and steps are the same as in Example 1.

[0098] The measured inductance values ​​of the nanocrystalline magnetic rings prepared in this comparative example are AL=75μH@1KHz; AL=50μH@10KHz; AL=23μH@100KHz. Based on the permeability μe=Ae*Le*1000 / N²*0.4π*Ae, where Le is the magnetic path length of the magnetic ring, N is the fill factor, and Ae is the magnetic cross-sectional area of ​​the magnetic ring, we can calculate: μe=120000@1KHz; μe=80100@10KHz; μe=36800@100KHz.

[0099] As can be seen from Comparative Example 3, although the alloy specific to this invention is used but conventional heat treatment processes are employed, high permeability at low frequencies can be achieved, but the permeability decreases at high frequencies, making it impossible to achieve both simultaneously.

[0100] The permeability of the nanocrystalline magnetic rings prepared in Examples 1 and 2 and Comparative Example 2 at different frequencies is summarized in Table 1 below.

[0101] Table 1

[0102]

[0103] As can be seen from Table 1, the nanocrystalline magnetic ring prepared by the present invention has a permeability of not less than 20,000 at a high frequency of 200kHz; a permeability of not less than 45,000 at a high frequency of 100kHz; and a permeability of not less than 120,000 at a low frequency below 10kHz. In contrast, the magnetic rings prepared by conventional alloys (Comparative Examples 1 and 2) or conventional heat treatment processes (Comparative Example 3) have lower permeability than the present invention, regardless of whether the frequency is high or low.

[0104] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing nanocrystalline magnetic rings with both high frequency and low frequency high permeability, characterized in that, The preparation method includes the following steps: The nanocrystalline alloy is fabricated into a strip with a thickness of 14-16 μm, and then wound into a magnetic core to be processed using an automatic winding machine; the chemical formula of the nanocrystalline alloy is: Fe (100-x-y-z-a-b-c) Si x B y Nb z Cu a Ni b M c； Where, 8 ≤ x ≤ 13, 8 ≤ y ≤ 10, 0 ≤ z < 1, 0 ≤ a ≤ 2, 2 ≤ b ≤ 5, 0.5 ≤ c ≤ 3; M is Co; A stepped distributed heat treatment process was used to perform transverse magnetization heat treatment on the magnetic core to be treated. After rapid cooling by blast air, the ring is removed from the furnace to obtain a nanocrystalline magnetic ring with both high frequency and low frequency high permeability; during the rapid cooling process by blast air, a transverse magnetic field with an intensity of 100~150mT is maintained. The stepped distributed heat treatment process includes preheating under transverse magnetic conditions and segmented heating and holding under vacuum heat treatment, specifically including: The magnetic core to be processed is placed in a heat treatment furnace, a transverse magnetic field is applied, and the temperature is heated to the first set temperature, followed by heat preservation and preheating treatment. The preheated magnetic core is placed in a vacuum horizontal furnace. The vacuum level is required to be below -0.1MPa. The temperature is first raised to the first set temperature and held; then raised to the second set temperature and held; and finally raised to the third set temperature and held.

2. The method for preparing a nanocrystalline magnetic ring with both high frequency and low frequency high permeability according to claim 1, characterized in that, The first set temperature is 410~430℃, and the preheating treatment is held for 25~35 minutes; In a vacuum horizontal furnace, the magnetic core is held at a first set temperature of 410~430℃ for 25~35 minutes; The second set temperature is set to 470~490℃ and held for 55~65 minutes; The third set temperature is set to 550~570℃ and kept at that temperature for 85~95 minutes; The transverse magnetic field strength in the stepped distributed heat treatment process is set to 100~150mT.

3. The method for preparing a nanocrystalline magnetic ring with both high frequency and low frequency high permeability according to claim 1, characterized in that, The steps for fabricating nanocrystalline alloys into strips are as follows: Prepare the raw materials for Fe-Si-B-Nb-Cu-Ni-M alloy according to the weight ratio after chemical formula conversion, add the raw materials to the medium frequency induction furnace, and heat to 1600~1680℃ for melting; After smelting, slag is removed and the alloy is molded to produce a nanocrystalline alloy. Nanocrystalline alloys are sprayed using a constant pressure stripping device to produce strips with a thickness of 14~16μm.

4. The method for preparing a nanocrystalline magnetic ring with both high frequency and low frequency high permeability according to claim 3, characterized in that, B uses a boron-iron master alloy, while the remaining raw materials are all elemental materials.

5. The method for preparing a nanocrystalline magnetic ring with both high frequency and low frequency high permeability according to claim 1, characterized in that, The fill factor of the magnetic core to be processed is set to 0.75~0.

8.

6. A nanocrystalline magnetic ring possessing both high-frequency and low-frequency high permeability, characterized in that, The nanocrystalline magnetic ring is prepared by the preparation method according to any one of claims 1 to 5.

7. The nanocrystalline magnetic ring with both high frequency and low frequency high permeability according to claim 6, characterized in that, The permeability of the nanocrystalline magnetic ring is not less than 45,000 at a high frequency of 100 kHz; the permeability of the nanocrystalline alloy is not less than 120,000 at a low frequency below 10 kHz.

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