Method for improving soft magnetic performance of iron-based amorphous nanocrystalline magnetic core

Abstract

The invention discloses a method for improving soft magnetic performance of an iron-based amorphous nanocrystalline magnetic core. The method for improving the soft magnetic performance of the iron-based amorphous nanocrystalline magnetic core comprises the following steps that the iron-based amorphous nanocrystalline magnetic core is subjected to low-temperature annealing pretreatment under the protection of a nitrogen atmosphere, the condition of low-temperature annealing pretreatment is that heat preservation is conducted for 30-300 min at the temperature of 350-425 DEG C, and then the pretreated magnetic core is subjected to normal production annealing technological process treatment to obtain the soft magnetic performance of the iron-based amorphous nanocrystalline magnetic core. The high-performance iron-based amorphous nanocrystalline magnetic core is obtained. According to the method, the magnetic core is subjected to annealing pretreatment for a long time, so that the heating uniformity of the magnetic core in the large-scale production process is ensured, the consistency and the stability of the performance of the magnetic core are ensured, and the performance of a low-grade strip is greatly improved on the premise that the annealing process of large-scale production is not changed.

Description

Technical Field

[0001] This invention relates to the field of iron-based amorphous nanocrystalline alloy technology, and in particular to a method for improving the soft magnetic properties of iron-based amorphous nanocrystalline magnetic cores. Background Technology

[0002] FeSiBCuNb-based iron-based amorphous and nanocrystalline alloys (grade 1k107) have attracted widespread attention from scholars due to their excellent comprehensive soft magnetic properties and are among the most widely used iron-based soft magnetic strips in industrial applications to date. In industrial applications, the 100 kHz permeability of FeSiBCuNb-based iron-based amorphous and nanocrystalline magnetic cores has become a core element for evaluating a company's product competitiveness, and increasingly sophisticated applications demand higher high-frequency permeability from the cores. To improve the 100 kHz permeability of mass-produced magnetic cores using existing heat treatment processes, the strip thickness needs to be made increasingly thinner. However, the space for reducing strip thickness is limited, and thinner strips become more difficult to manufacture.

[0003] For tapes with a thickness of less than 16 μm, the core indicator of their performance in the market is their permeability at 100 kHz. Thin tapes are generally used in high-frequency applications because, in high-frequency applications, eddy current losses are affected by the skin effect, making the losses directly related to the tape thickness; the thinner the tape, the better the high-frequency performance. However, due to poor quality consistency of tapes in industrial production, tapes are generally graded based on their performance at 100 kHz during the initial inspection. The performance of low-grade tapes is increasingly unable to meet the current market demand for high-frequency, high-permeability tapes, leading to a large backlog of low-grade tapes and a sharp increase in operating costs for enterprises. Reprocessing low-grade tapes as scrap would waste even more manufacturing costs. Furthermore, the annealing process in large-scale production cannot be easily modified to avoid affecting delivery schedules. Therefore, how to eliminate the backlog of low-grade tapes has become a pressing problem for enterprises. Summary of the Invention

[0004] The purpose of this invention is to provide a method for improving the soft magnetic properties of iron-based amorphous and nanocrystalline magnetic cores. This invention involves a low-temperature pretreatment process for the magnetic core, which, without altering the annealing process for large-scale production, allows for a prolonged annealing pretreatment. This helps to ensure uniform heating of the magnetic core during the annealing process. Low-performance magnetic cores treated with the annealing process proposed in this invention can exhibit significantly improved performance after undergoing normal production annealing, effectively solving the problem of low-grade strip stock accumulation and greatly enhancing the competitiveness of enterprise products.

[0005] This invention is achieved through the following technical solutions:

[0006] This invention protects a method for improving the soft magnetic properties of iron-based amorphous nanocrystalline magnetic cores, comprising the following steps: the iron-based amorphous nanocrystalline magnetic core is subjected to low-temperature annealing pretreatment under nitrogen atmosphere protection, the conditions of which are 350℃~425℃ for 30~300 min, and the pretreated magnetic core is then processed by normal production annealing process to obtain a high-performance iron-based amorphous nanocrystalline magnetic core.

[0007] This invention employs a prolonged low-temperature annealing pretreatment. This long-term pretreatment at a lower temperature serves three main purposes: first, it eliminates a significant amount of thermal stress generated during rapid quenching of the strip without causing severe nucleation; second, it re-regulates the atomic order while releasing stress, further optimizing the local atomic structure; and third, the prolonged annealing ensures uniform heating of the core during large-scale production, thereby guaranteeing the consistency and stability of the core's performance. This invention addresses the problem of low-performance low-grade strip leading to inventory backlogs in existing enterprises. Without altering normal production processes, it improves the performance of low-grade strip by adding a single, prolonged low-temperature pretreatment step, demonstrating practical operability in industrial production and broad application prospects.

[0008] Preferably, the chemical formula of the iron-based amorphous nanocrystals is Fe. a Si b B c Cu d Nb e , where a, b, c, d, and e represent the atomic percentages of the corresponding components Fe, Si, B, Cu, and Nb, respectively, and satisfy the following conditions: 71.5≤a≤82.5, 8≤b≤18, 6≤c≤10, 0.25≤d≤1.50, 0≤e≤3, and a+b+c+d+e=100.

[0009] Furthermore, the chemical formula of the iron-based amorphous nanocrystals is Fe. 73.5 Si 15.5 B7Cu1Nb3.

[0010] Preferably, the low-temperature annealing pretreatment conditions are: holding at 380℃~420℃ for 30~180 min.

[0011] This invention also protects a method for preparing iron-based amorphous nanocrystalline magnetic cores, comprising the following steps:

[0012] S1. Amorphous ribbons of different thicknesses are prepared using the rapid quenching method according to the composition described above. Then, the amorphous ribbons are slit and wound into magnetic cores.

[0013] S2. Place the magnetic core obtained in step S1 into a heating container and perform low-temperature annealing pretreatment under a flowing nitrogen atmosphere. The conditions for low-temperature annealing pretreatment are 350℃~425℃ for 30~300 min. After the pretreated magnetic core is subjected to three-step vacuum annealing treatment, a high-performance iron-based amorphous nanocrystalline magnetic core is obtained.

[0014] In step S2, the pretreated magnetic core undergoes a three-step vacuum annealing process, and is then cooled in the furnace to 200℃~350℃ before being removed from the furnace and cooled to room temperature to obtain a high-performance iron-based amorphous nanocrystalline magnetic core.

[0015] Preferably, the specific steps of the low-temperature annealing pretreatment in step S2 are as follows: first, the heating container is raised to the target temperature and then a nitrogen atmosphere is introduced. Then, the magnetic core is directly placed in the tail temperature zone, and after being kept at the temperature for a specific time, the magnetic core is directly taken out and cooled to room temperature.

[0016] Preferably, the low-temperature annealing pretreatment conditions are: holding at 380℃~420℃ for 30~180 min.

[0017] The magnetic core is fed directly into the furnace when it reaches the target temperature.

[0018] Preferably, the conditions for the three-step vacuum annealing process in step S2 are as follows: in the first step, the temperature is raised from room temperature to 400℃~450℃ and held for 30~120 min; in the second step, the temperature is raised to 460℃~520℃ and held for 30~90 min; in the third step, the temperature is raised to 540℃~600℃ and held for 90~240 min.

[0019] Further optimization, the specific conditions for the three-step vacuum annealing process in step S2 are as follows: First, the temperature is raised from room temperature to 420℃ and held for 60 min; second, the temperature is raised to 480℃ and held for 60 min; third, the temperature is raised to 550℃ and held for 120 min.

[0020] Preferably, the thickness of the amorphous ribbon is 10-30 μm.

[0021] Compared with the prior art, the beneficial effects of the present invention are: by performing long-term annealing pretreatment on the magnetic core, the present invention ensures the uniformity of heating of the magnetic core during the mass production process, thereby ensuring the consistency and stability of the magnetic core performance. Without changing the annealing process of mass production, the performance of low-grade strip material is significantly improved. Attached Figure Description

[0022] Figure 1 This is a comparison chart of the 1 k permeability of the magnetic cores obtained in Examples 1-5 and Comparative Example 1 of the present invention.

[0023] Figure 2This is a comparison chart of the 10 k permeability of the magnetic cores obtained in Examples 1-5 and Comparative Example 1 of the present invention.

[0024] Figure 3 This is a comparison chart of the 100 k permeability of the magnetic cores obtained in Examples 1-5 and Comparative Example 1 of the present invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are considered to be commercially available materials and reagents that can be obtained through conventional markets and other commercial channels.

[0026] Example 1

[0027] A method for preparing an iron-based amorphous nanocrystalline magnetic core includes the following steps:

[0028] S1. Preparation of Fe using rapid quenching method 73.5 Si 15.5 B7Cu1Nb3, 14-16 μm thick strip, is slit and wound into magnetic cores according to the size of 25×20×10 mm.

[0029] S2. First, raise the furnace temperature to 420℃, introduce nitrogen gas, and then push the magnetic core obtained in step S1 into the tunnel furnace for 30 minutes. After holding at this temperature, remove the core and cool it to room temperature. Then, perform vacuum annealing on the pretreated core using the normal production annealing process. The vacuum level is -0.1 MPa. The normal production annealing process is a three-stage vacuum annealing process, as follows: Place the magnetic core in the vacuum annealing furnace, raise the furnace temperature to 420℃ within 60 minutes, and hold for 60 minutes; then raise the temperature to 480℃ at a rate of 3℃ / min and hold for 60 minutes; then raise the temperature to 550℃ at a rate of 1℃ / min and hold for 120 minutes. After holding, wait for the magnetic core to cool to 300℃ before removing it from the furnace and cooling it to room temperature to obtain a high-performance magnetic core.

[0030] Example 2

[0031] Similar to Example 1, except that after nitrogen gas is introduced, the magnetic core obtained in step S1 is pushed into the tunnel furnace and kept at a constant temperature for 60 minutes before being taken out of the furnace and cooled to room temperature.

[0032] Example 3

[0033] Similar to Example 1, except that after nitrogen gas is introduced, the magnetic core obtained in step S1 is pushed into the tunnel furnace and kept at a constant temperature for 90 minutes before being taken out of the furnace and cooled to room temperature.

[0034] Example 4

[0035] Similar to Example 1, except that after nitrogen gas is introduced, the magnetic core obtained in step S1 is pushed into the tunnel furnace and kept at a constant temperature for 120 minutes before being taken out of the furnace and cooled to room temperature.

[0036] Example 5

[0037] Similar to Example 1, except that after nitrogen gas is introduced, the magnetic core obtained in step S1 is pushed into the tunnel furnace and kept at a constant temperature for 180 min before being taken out of the furnace and cooled to room temperature.

[0038] Comparative Example 1

[0039] Similar to Example 1, except that no pretreatment step was performed; instead, vacuum annealing was directly carried out using the normal production annealing process. The specific process is as follows: the magnetic core was placed in a vacuum annealing furnace at a vacuum level of -0.1 MPa. The furnace temperature was raised to 420°C within 60 minutes and held for 60 minutes. Then, the temperature was raised to 480°C at a rate of 3°C / min and held for 60 minutes. Next, the temperature was raised to 550°C at a rate of 1°C / min and held for 120 minutes. After the holding period, the magnetic core was allowed to cool to 300°C before being removed from the furnace and cooled to room temperature to obtain a high-performance magnetic core.

[0040] The high-performance magnetic cores obtained in Examples 1-5 and Comparative Example 1 were subjected to permeability testing, and the test results are shown in Figure 1.

[0041] Table 1. Permeability of Examples 1-5 and Comparative Example 1 at frequencies of 1 k, 10 k, and 100 k.

[0042]

[0043] From Table 1 and Figure 1-3 It can be observed that the 1k permeability of the magnetic core made from low-grade tape after long-term low-temperature pretreatment decreases slightly but remains at a high level, while the 100 kHz permeability, which is the standard for classifying tape grades, is significantly improved, resulting in superior overall performance. The 100 kHz permeability is increased by 8%-14%, meeting the performance requirements of higher-grade tapes.

[0044] The amorphous and nanocrystalline soft magnetic alloy proposed in this invention improves the high-frequency permeability of low-grade strips by adding a low-temperature, long-term pretreatment step without changing the normal large-scale production process. Furthermore, it exhibits stable performance after an annealing treatment of up to 180 minutes, ensuring that its performance meets the requirements of large-scale production and normal market demand. This invention is expected to solve the problem of large-scale inventory backlog of low-grade strips for enterprises and has significant practical and economic value.

[0045] The above description of the embodiments is only for the purpose of helping to understand the technical solution and core idea of ​​the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for improving the soft magnetic properties of iron-based amorphous nanocrystalline magnetic cores, characterized in that, The process includes the following steps: the iron-based amorphous nanocrystalline magnetic core is subjected to low-temperature annealing pretreatment under nitrogen atmosphere protection. The conditions for low-temperature annealing pretreatment are 350℃~425℃ for 30~300 min. After the pretreated magnetic core is processed by the normal production annealing process, a high-performance iron-based amorphous nanocrystalline magnetic core is obtained.

2. The method according to claim 1, characterized in that, The chemical formula of the iron-based amorphous nanocrystals is Fe. a Si b B c Cu d Nb e , where a, b, c, d, and e represent the atomic percentages of the corresponding components Fe, Si, B, Cu, and Nb, respectively, and satisfy the following conditions: 71.5≤a≤82.5, 8≤b≤18, 6≤c≤10, 0.25≤d≤1.50, 0≤e≤3, and a+b+c+d+e=100.

3. The method according to claim 2, characterized in that, The chemical formula of the iron-based amorphous nanocrystals is Fe. 73.5 Si 15.5 B7Cu1Nb3.

4. The method according to claim 1, characterized in that, The conditions for low-temperature annealing pretreatment are to hold at 380℃~420℃ for 30~180 min.

5. A method for preparing an iron-based amorphous nanocrystalline magnetic core, characterized in that, Includes the following steps: S1. Based on the composition of iron-based amorphous nanocrystals, amorphous ribbons of different thicknesses are prepared by rapid quenching. Then, the amorphous ribbons are slit and wound into magnetic cores. S2. Place the magnetic core obtained in step S1 into a heating container and perform low-temperature annealing pretreatment under a flowing nitrogen atmosphere. The conditions for low-temperature annealing pretreatment are 350℃~425℃ for 30~300 min. After the pretreated magnetic core is subjected to three-step vacuum annealing treatment, a high-performance iron-based amorphous nanocrystalline magnetic core is obtained.

6. The preparation method according to claim 5, characterized in that, The iron-based amorphous nanocrystals mentioned in step S1 have the chemical formula Fe. a Si b B c Cu d Nb e , where a, b, c, d, and e represent the atomic percentages of the corresponding components Fe, Si, B, Cu, and Nb, respectively, and satisfy the following conditions: 71.5≤a≤82.5, 8≤b≤18, 6≤c≤10, 0.25≤d≤1.50, 0≤e≤3, and a+b+c+d+e=100.

7. The preparation method according to claim 5 or 6, characterized in that, The specific steps of the low-temperature annealing pretreatment in step S2 are as follows: First, heat the container to the target temperature and then introduce nitrogen atmosphere. Then, directly place the magnetic core into the tail temperature zone, keep it at the temperature for a specific time, and then directly take out the magnetic core and cool it to room temperature. The conditions for low-temperature annealing pretreatment are to keep it at 380℃~420℃ for 30~180min.

8. The preparation method according to claim 5 or 6, characterized in that, The conditions for the three-step vacuum annealing process in step S2 are as follows: First, heat the temperature from room temperature to 400℃~450℃ and hold for 30~120 min; second, continue heating to 460℃~520℃ and hold for 30~90 min; third, continue heating to 540℃~600℃ and hold for 90~240 min.

9. The preparation method according to claim 8, characterized in that, The specific conditions for the three-step vacuum annealing process in step S2 are as follows: First, the temperature is raised from room temperature to 420℃ and held for 60 min; second, the temperature is raised to 480℃ and held for 60 min; third, the temperature is raised to 550℃ and held for 120 min.

10. The preparation method according to claim 5 or 6, characterized in that, The thickness of the amorphous ribbon is 10-30 μm.

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