Cobalt-based amorphous alloy strip for magnetic probe of leakage current sensor and heat treatment method thereof

Abstract

The present application discloses a cobalt-based amorphous alloy strip for a leakage current sensor magnetic probe and a heat treatment method thereof. The heat treatment method comprises the following steps: a first heat treatment of the cobalt-based amorphous alloy strip, heating it to 480-520°C and keeping it warm; water quenching the cobalt-based amorphous alloy strip after the first heat treatment to room temperature; a second heat treatment of the cobalt-based amorphous alloy strip after the water quenching, heating it to 120-160°C, while applying an external magnetic field along the length direction of the cobalt-based amorphous alloy strip and keeping it warm; water quenching the cobalt-based amorphous alloy strip after the second heat treatment to room temperature. The present application performs a two-stage heat treatment on the cobalt-based amorphous alloy strip, so that the cobalt-based amorphous alloy strip has low saturation magnetization, low coercivity, high magnetic permeability and high hysteresis loop squareness, while achieving a significant attenuation of inductance under micro-current.

Description

Technical Field

[0001] The present application relates to a leakage current sensor, and in particular to a cobalt-based amorphous alloy strip of a magnetic probe of the leakage current sensor and a heat treatment method thereof. Background Art

[0002] Leakage current sensors are crucial components of photovoltaic systems. Their primary function is to detect leakage current regardless of whether the system is connected to the AC grid and the AC circuit breaker is closed. A leakage current sensor utilizes soft magnetic materials to establish a low-reluctance channel, detecting current and converting it into a digital signal. Leakage current sensors utilize the fluxgate principle to measure weak magnetic fields by analyzing the nonlinear relationship between the magnetization intensity and magnetic field strength of the soft magnetic material under saturation excitation of an alternating magnetic field. Soft magnetic materials are the core material of leakage current sensors, and their magnetic properties and inductance determine the sensor's sensitivity, linearity, accuracy, and measurement range.

[0003] In the process of realizing this application, the applicant found that the current cobalt-based amorphous alloys have at least the following technical problems, such as:

[0004] 1. Chinese patent CN108091466A discloses methods for preparing cobalt-based amorphous alloys, cobalt-based amorphous alloy strips, and cobalt-based amorphous alloy cores. The alloys are composed of Co, Fe, Mo, Si, and B. The heat treatment process involves holding the alloy at 400-460°C for 10-60 minutes under a protective atmosphere. The resulting cobalt-based amorphous alloy cores exhibit low loss, low coercivity, high permeability, and high remanence, suitable for applications in magnetic amplifiers and other fields. However, the heat treatment process disclosed in this patent is only suitable for cobalt-based amorphous alloy cores, which exhibit high coercivity, exceeding 3.7 A / m.

[0005] 2. Chinese patent CN110983112A discloses a cobalt-based amorphous soft magnetic alloy for precision current detection and its preparation method. The alloy has the general formula: CoxFeyMozSinBm. The heat treatment process involves holding at 430-450°C for 10-60 minutes under vacuum or a protective atmosphere while applying a 600-1000 Gs longitudinal magnetic field. The resulting cobalt-based amorphous alloy exhibits high squareness, low coercivity, and low losses. However, this patent aims to improve the low squareness and high losses of existing amorphous alloys and does not disclose the alloy's inductance attenuation trend under low currents.

[0006] 3. Chinese patent CN115369340A discloses a cobalt-based amorphous alloy core, its preparation method, and application. The cobalt-based amorphous alloy core is made of CoxFeySizBmMon and is heat-treated at 420-490°C for 20-200 minutes in a vacuum, nitrogen, or rare gas atmosphere while applying a longitudinal magnetic field. This significantly increases the core's initial magnetic permeability and reduces its coercive force. However, the longitudinal magnetic heat treatment process disclosed in this patent is suitable for cobalt-based amorphous alloy cores and has strict process requirements, limiting the heating rate to 3-11°C / min and the cooling rate to 4-15°C / min.

[0007] 4. Chinese patent CN117867417A discloses a cobalt-based amorphous soft magnetic alloy material, its preparation method, and application. The material's chemical composition is CoaFebMocSidBeCfMg, where M is at least one of the elements V, Cr, Mn, and Nb. The alloy material has a saturation magnetic induction intensity below 0.5 T and a coercive force below 1 A / m. The heat treatment process involves maintaining a constant temperature of 400-560°C in a vacuum environment for 10-60 minutes. However, the alloy composition disclosed in this patent is diverse and complex, and the inductance decay trend of the alloy under low currents is not disclosed.

[0008] Therefore, current cobalt-based amorphous alloys have been optimized through alloy composition ratios and improved preparation processes, which have, to a certain extent, reduced their saturation magnetization and coercivity, while increasing their magnetic permeability and hysteresis loop rectangularity. However, none of these materials meet the requirements of low saturation magnetization, low coercivity, high magnetic permeability, and high hysteresis loop rectangularity, while also achieving rapid inductance decay under low currents. This makes it difficult to prepare cobalt-based amorphous alloys suitable for use in leakage current sensor magnetic probes. Therefore, it is of great significance to develop a heat treatment method for cobalt-based amorphous alloy strips used in leakage current sensor magnetic probes to improve the sensitivity, accuracy, and response speed of leakage current sensors. Summary of the Invention

[0009] To solve the above technical problems, the present invention provides a cobalt-based amorphous alloy strip for a magnetic probe of a leakage current sensor and a heat treatment method thereof. The specific technical solution is as follows:

[0010] In a first aspect, a method for heat treating a cobalt-based amorphous alloy strip of a leakage current sensor magnetic probe is provided, comprising the following steps: performing a first heat treatment on the cobalt-based amorphous alloy strip, heating it to 480-520°C and keeping it warm; water quenching the cobalt-based amorphous alloy strip after the first heat treatment to room temperature; performing a second heat treatment on the cobalt-based amorphous alloy strip after the water quenching, heating it to 120-160°C, while applying an external magnetic field along the length direction of the cobalt-based amorphous alloy strip, and keeping it warm; and water quenching the cobalt-based amorphous alloy strip after the second heat treatment to room temperature.

[0011] In one embodiment, the cobalt-based amorphous alloy strip is subjected to a first heat treatment and a second heat treatment in a vacuum environment or an inert gas atmosphere.

[0012] In one embodiment, the vacuum degree of the vacuum environment of the Co-based amorphous alloy strip is lower than 5×10-3 Pa.

[0013] In one embodiment, when the cobalt-based amorphous alloy strip is subjected to the first heat treatment, the holding time is 10 minutes.

[0014] In one embodiment, when the cobalt-based amorphous alloy strip is subjected to the second heat treatment, the holding time is 10 minutes.

[0015] In one embodiment, when the Co-based amorphous alloy strip is subjected to the second heat treatment, the intensity of the external magnetic field is 80 kA / m.

[0016] In one embodiment, the composition of the cobalt-based amorphous alloy strip is Co67Fe4Mo1.5Si16.5B11, the strip width is 1-2 mm, and the thickness is 25-30 μm.

[0017] In a second aspect, a cobalt-based amorphous alloy strip for a leakage current sensor magnetic probe is provided, which is prepared by the heat treatment method for the cobalt-based amorphous alloy strip for a leakage current sensor magnetic probe according to any one of the first aspects.

[0018] In one embodiment, the coercive force of the cobalt-based amorphous alloy strip is 0.16-0.36 A / m, the initial inductance value at 200 μA / 1 kHz is 447-534 μH, and the inductance attenuation ratio at a micro-current of 20 mA is 75.1%-79%.

[0019] According to one of the embodiments, the saturation field of the Co-based amorphous alloy strip under micro-current is 11-15 A / m.

[0020] In the embodiments of the present application, a high-temperature stress relief heat treatment is first performed on the cobalt-based amorphous alloy strip at 480-520°C, which can significantly eliminate internal stress, reduce magnetic domain pinning, significantly reduce coercivity, and increase the initial inductance value of the alloy under low current. The cobalt-based amorphous alloy strip is then subjected to a suitable low-temperature longitudinal magnetic field heat treatment at 120-160°C to induce longitudinal easy-axis anisotropy and enhance its effect during the magnetization process, making the magnetic domains regular and wide, with a magnetic domain width of more than 380 μm, further reducing the magnetic domain pinning effect, significantly improving the initial inductance value and inductance attenuation ratio of the alloy under low current, and reducing its anti-saturation ability. The present application performs a two-stage heat treatment on the cobalt-based amorphous alloy strip, thereby enabling the cobalt-based amorphous alloy strip to have low saturation magnetization intensity, low coercive force, high magnetic permeability and high hysteresis loop rectangularity, while achieving a significant attenuation of inductance under micro-current. This is of great significance to the cobalt-based amorphous alloy strip and its application in the magnetic probe of the leakage current sensor. In addition, the heat treatment method of the present application has a simple process, which can greatly reduce the energy consumption in the material preparation process, and is conducive to promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0022] Figure 1 This is a flow chart of the steps of the heat treatment method of the cobalt-based amorphous alloy strip of the leakage current sensor magnetic probe of the present application;

[0023] Figure 2 The inductance of the cobalt-based amorphous alloy prepared in Example 1 of the present application changes with frequency under different microcurrents;

[0024] Figure 3 This is the demagnetized magnetic domain structure of the cobalt-based amorphous alloy prepared in Example 1 of the present application;

[0025] Figure 4 This is the demagnetized magnetic domain structure of the cobalt-based amorphous alloy prepared in Comparative Example 2 of the present application;

[0026] Figure 5 The inductance of the cobalt-based amorphous alloy prepared in Comparative Example 3 of the present application changes with frequency under different microcurrents. DETAILED DESCRIPTION

[0027] The following will illustrate the embodiments of the present application with reference to the accompanying drawings. In these drawings, the same reference numerals represent the same or similar components or method processes.

[0028] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0029] See also Figure 1 , which is a step flow chart of the heat treatment method of the cobalt-based amorphous alloy strip of the leakage current sensor magnetic probe of the present application; as shown in the figure, the heat treatment method of the cobalt-based amorphous alloy strip of the leakage current sensor magnetic probe of this embodiment is mainly suitable for the leakage current sensor of the photovoltaic system, improving the sensitivity, accuracy and response speed of the leakage current sensor. In this embodiment, the heat treatment method of the cobalt-based amorphous alloy strip of the leakage current sensor magnetic probe includes the following steps S1 to S4. First, perform step S1 to heat treat the cobalt-based amorphous alloy strip for the first time, heat it to 480-520℃, and keep it warm. The cobalt-based amorphous alloy strip is first heat treated in a vacuum environment or an inert gas atmosphere. Specifically, a cobalt-based amorphous alloy strip with a composition of Co67Fe4Mo1.5Si16.5B11, a strip width of 1-2 mm, and a thickness of 25-30 μm is selected. The cobalt-based amorphous alloy strip is heated from room temperature to 480-520°C in a vacuum environment with a vacuum degree of less than 5×10-3 Pa and held at this temperature for 10 minutes. Then, step S2 is performed to cool the cobalt-based amorphous alloy strip to room temperature after the first heat treatment. Steps S1 and S2 complete the first stage of heat treatment of the cobalt-based amorphous alloy strip. High-temperature stress relief heat treatment at 480-520°C significantly eliminates internal stress, reduces magnetic domain pinning, significantly reduces coercivity, and improves the initial inductance of the alloy under low currents.

[0030] Then, step S3 is performed to heat treat the cobalt-based amorphous alloy strip after water quenching for the second time, heating it to 120-160°C, while applying an external magnetic field along the length direction of the cobalt-based amorphous alloy strip and keeping it warm. The cobalt-based amorphous alloy strip is heat treated for the second time in a vacuum environment or an inert gas atmosphere. Specifically, the cobalt-based amorphous alloy strip obtained by the first stage heat treatment is heated from room temperature to 120-160°C in a vacuum environment with a vacuum degree of less than 5×10-3 Pa, while applying an external magnetic field along the length direction of the strip, i.e., a longitudinal magnetic field, and keeping it warm for 10 minutes, and then water quenching it to room temperature. The intensity of the external magnetic field in the second stage is 80 kA / m. Finally, step S4 is performed to water quench the cobalt-based amorphous alloy strip after the second heat treatment to room temperature. The second stage heat treatment of the cobalt-based amorphous alloy strip is achieved through steps S3 and S4. The cobalt-based amorphous alloy strip is subjected to appropriate low-temperature longitudinal magnetic field heat treatment at 120-160°C to induce longitudinal easy-axis anisotropy and enhance its effect in the magnetization process, making the magnetic domain regular and widened, with the magnetic domain width reaching more than 380 μm, further reducing the magnetic domain pinning effect, significantly improving the initial inductance value and inductance attenuation ratio of the alloy under microcurrent, and reducing its anti-saturation ability.

[0031] As described above, the cobalt-based amorphous alloy strip prepared by the aforementioned heat treatment method for a leakage current sensor magnetic probe exhibits a coercive force of 0.16-0.36 A / m, an initial inductance of 447-534 μH at 200 μA / 1 kHz, and an inductance attenuation ratio of 75.1%-79% at a microcurrent of 20 mA. The saturation magnetic field of the cobalt-based amorphous alloy strip under microcurrent is 11-15 A / m. The heat treatment method for a cobalt-based amorphous alloy strip for a leakage current sensor magnetic probe of this embodiment, through a two-stage heat treatment of the cobalt-based amorphous alloy strip, can achieve a cobalt-based amorphous alloy strip with low saturation magnetization, low coercive force, high magnetic permeability, and high hysteresis loop squareness, while also achieving a significant attenuation of inductance under microcurrent. This is of great significance for cobalt-based amorphous alloy strips and their application in leakage current sensor magnetic probes. Furthermore, the heat treatment method of this embodiment is simple to process, significantly reducing energy consumption during material preparation and facilitating widespread application.

[0032] The beneficial effects of the cobalt-based amorphous alloy strip of the leakage current sensor magnetic probe and the heat treatment method thereof of the present application will be further illustrated below with reference to specific embodiments and comparative examples.

[0033] Example 1

[0034] 1. The cobalt-based amorphous alloy strip composition is Co 67 Fe4Mo 1.5 Si 16.5 B 11The strip is 1 mm wide and 30 μm thick. The cobalt-based amorphous alloy strip is cut into 6 cm long samples and placed in a heat treatment furnace. The vacuum is drawn to less than 5×10 -3 Pa, at 480, 500, 520 o C temperature for 10 min, and then the sample was water quenched and cooled to room temperature to obtain the first-stage cobalt-based amorphous alloy samples, which were recorded as 480NF, 500NF, and 520NF respectively.

[0035] 2. Place the cobalt-based amorphous alloy sample obtained from the first stage of heat treatment into a heat treatment furnace and evacuate the vacuum to less than 5×10 -3 Pa, at 120 o C temperature, an external magnetic field with a magnetic field intensity of 80 kA / m is applied along the length direction of the strip, and the temperature is kept for 10 min. Then the sample is water quenched and cooled to room temperature to obtain the second stage Co-based amorphous alloy samples, which are respectively recorded as 480NF+120MF, 500NF+120MF, and 520NF+120MF.

[0036] 3. Test the cobalt-based amorphous alloy sample obtained by the above heat treatment:

[0037] (1) The hysteresis loops of cobalt-based amorphous alloy samples obtained by two-stage heat treatment were measured using a DC hysteresis loop measuring instrument (BH Curve Tracer, EXPH-100) in a magnetic field of 1 kA / m. The coercive forces of the samples were measured to be 0.30, 0.16, and 0.32 A / m, respectively, and the saturation fields were 12, 11, and 14 A / m, respectively.

[0038] (2) Using an impedance analyzer (Agilent 4294 A), the inductance of the 500NF+120MF sample was tested under a micro-current of 200 μA-20 mA to see how it changes with frequency. Figure 2 As shown in the figure, at a frequency of 1 kHz and a microcurrent of 200 μA, the sample's inductance was measured to be 534 μH. The inductance first increases sharply, then decreases sharply, with increasing current intensity. The sample's inductance reaches its maximum at a current of 1 mA. As the current intensity continues to increase, the inductance begins to gradually decrease. When the current intensity continues to increase to 20 mA, the inductance drops significantly to 112 μH, a 79% decrease from the 200 μA value, indicating that the sample is nearing saturation.

[0039] (3) The magnetic domain structure of the demagnetized state of the 500NF+120MF sample was observed using a magneto-optical Kerr microscope (MOKE, 4-873 K / 950 MT). Figure 3As shown in Figure 3, the sample exhibits broad, strip-shaped magnetic domains oriented longitudinally, with a domain width exceeding 380 μm. The domain walls are regular, straight, and smooth, with no obvious pinning sites. This indicates that heat treatment using a low-temperature longitudinal magnetic field can induce longitudinal easy-axis anisotropy, effectively eliminating the pinning effect during the magnetization process. This explains the significant improvement in the sample's coercivity and initial inductance.

[0040] Example 2

[0041] 1. The cobalt-based amorphous alloy strip composition is Co 67 Fe4Mo 1.5 Si 16.5 B 11 The strip is 2 mm wide and 25 μm thick. The cobalt-based amorphous alloy strip is cut into 6 cm long samples and placed in a heat treatment furnace. The vacuum is drawn to less than 5×10 -3 Pa, at 500 o C for 10 min, and then the sample was water quenched and cooled to room temperature to obtain the first-stage Co-based amorphous alloy sample, which was recorded as 500NF.

[0042] 2. Place the cobalt-based amorphous alloy sample obtained from the first stage of heat treatment into a heat treatment furnace and evacuate the vacuum to less than 5×10 -3 Pa, 140, 160 o C temperature conditions, an external magnetic field is applied along the length direction of the strip with a magnetic field intensity of 80 kA / m, and the temperature is kept for 10 min. Then the sample is water quenched and cooled to room temperature to obtain the second stage Co-based amorphous alloy samples, which are respectively recorded as 500NF+140MF and 500NF+160MF.

[0043] 3. Test the cobalt-based amorphous alloy sample obtained by the above heat treatment:

[0044] (1) The hysteresis loops of cobalt-based amorphous alloy samples obtained by two-stage heat treatment were measured using a DC hysteresis loop measuring instrument (BH Curve Tracer, EXPH-100) in a magnetic field of 1 kA / m. The coercive forces of the samples were measured to be 0.34 and 0.36 A / m, respectively, and the saturation fields were 14 and 15 A / m, respectively.

[0045] (2) An impedance analyzer (Agilent 4294 A) was used to test the inductance of the samples at a micro-current of 200 μA-20 mA and its frequency variation. At a frequency of 1 kHz, the inductance of the samples was measured to be 449 and 447 μH at 200 μA, and 104 and 109 μH at 20 mA, respectively. The inductance attenuation ratios were 76.8% and 75.6%, respectively.

[0046] Comparative Example 1

[0047] 1. The cobalt-based amorphous alloy strip composition is Co 67 Fe4Mo 1.5 Si 16.5 B 11 The strip is 1 mm wide and 30 μm thick. The cobalt-based amorphous alloy strip is cut into 6 cm long samples and placed in a heat treatment furnace. The vacuum is drawn to less than 5×10 -3 Pa, at 500 o C for 10 min, and then the sample was water quenched and cooled to room temperature to obtain the first-stage Co-based amorphous alloy sample, which was recorded as 500NF.

[0048] 2. Place the cobalt-based amorphous alloy sample obtained from the first stage of heat treatment into a heat treatment furnace and evacuate the vacuum to less than 5×10 -3 Pa, 100, 180 o C temperature conditions, an external magnetic field with a magnetic field intensity of 80 kA / m is applied along the length direction of the strip, and the temperature is kept for 10 min. Then the sample is water quenched and cooled to room temperature to obtain the second stage Co-based amorphous alloy samples, which are respectively recorded as 500NF+100MF and 500NF+180MF.

[0049] 3. Test the cobalt-based amorphous alloy sample obtained by the above heat treatment:

[0050] (1) Using an impedance analyzer (Agilent 4294 A), the inductance of the samples was tested at a microcurrent of 200 μA-20 mA and the frequency variation. At a frequency of 1 kHz, the inductance of the samples was measured to be 423 and 410 μH at 200 μA, and 149 and 152 μH at 20 mA, respectively. The inductance attenuation ratios were 64.8% and 62.9%, respectively. It can be seen that the cobalt-based amorphous alloy samples prepared by conventional stress relief heat treatment and longitudinal magnetic heat treatment have higher initial inductance values, but if the longitudinal magnetic heat treatment temperature is too low or too high, a high inductance attenuation ratio cannot be obtained.

[0051] Comparative Example 2

[0052] 1. The cobalt-based amorphous alloy strip composition is Co 67 Fe4Mo 1.5 Si 16.5 B 11 The strip is 1 mm wide and 30 μm thick. The cobalt-based amorphous alloy strip is cut into 6 cm long samples and placed in a heat treatment furnace. The vacuum is drawn to less than 5×10 -3 Pa, at 460, 500, 540 oC for 10 min, and then the sample was water quenched and cooled to room temperature to obtain cobalt-based amorphous alloy samples, which were recorded as 440NF, 500NF, and 540NF.

[0053] 2. Test the cobalt-based amorphous alloy sample obtained by the above heat treatment:

[0054] (1) The hysteresis loops of cobalt-based amorphous alloy samples obtained by two-stage heat treatment were measured using a DC hysteresis loop measuring instrument (BH Curve Tracer, EXPH-100) in a magnetic field of 1 kA / m. The coercive forces of the samples were measured to be 0.71, 0.60, and 34.1 A / m, respectively. The saturation fields of the 440NF and 500NF samples were 35 and 33 A / m, respectively.

[0055] (2) Using an impedance analyzer (Agilent 4294 A), the inductance of the sample under a micro-current of 200 μA-20 mA was tested to see how it changes with frequency. At a frequency of 1 kHz, the inductance of the sample at 200 μA was 377, 385, and 85 μH, respectively. At 20 mA, the inductance was 153, 147, and 78 μH, respectively. The inductance attenuation ratios were 59.4%, 61.8%, and 8.2%, respectively. It can be seen that when only ordinary stress relief heat treatment is used, the inductance of the sample is not high, and a significant attenuation of the inductance cannot be achieved. Especially when the ordinary stress relief heat treatment temperature is higher than 540 o C, the initial inductance value and attenuation ratio of the sample are greatly reduced, which is related to the crystallization of the sample at this temperature.

[0056] (3) The magnetic domain structure of the demagnetized state of the 500NF sample was observed using a magneto-optical Kerr microscope (MOKE, 4-873 K / 950 MT), as shown in Figure 3. Figure 4 As shown, it can be seen that the magnetic domain morphology of the sample is mainly composed of o The curved, flat domain walls broaden the magnetic domains, and no stress-induced fine fingerprint-like domains are observed, indicating that the heat treatment effectively eliminates internal stress. However, the domains still exhibit numerous angular corners and bifurcations, and the domain wall edges are uneven, indicating a strong pinning effect. Consequently, the sample has a relatively high coercivity and saturation field of 0.60 and 33 A / m, respectively.

[0057] Comparative Example 3

[0058] 1. The cobalt-based amorphous alloy strip composition is Co 67 Fe4Mo 1.5 Si 16.5 B 11 The strip is 1 mm wide and 30 μm thick. The cobalt-based amorphous alloy strip is cut into 6 cm long samples and placed in a heat treatment furnace. The vacuum is drawn to less than 5×10 -3 Pa, at 480o At a temperature of 480 MF, an external magnetic field with a strength of 80 kA / m was applied along the length direction of the strip and kept warm for 10 min. The sample was then water quenched and cooled to room temperature to obtain a cobalt-based amorphous alloy sample, which was recorded as 480 MF.

[0059] 2. Test the cobalt-based amorphous alloy sample obtained by the above heat treatment:

[0060] (1) Using an impedance analyzer (Agilent 4294 A), the inductance of the test sample under a micro-current of 200 μA-20 mA changes with frequency, such as Figure 5 As shown in the graph, at a frequency of 1 kHz, the inductance of the sample at 200 μA and 20 mA was measured to be 347 and 114 μH, respectively, with an inductance attenuation ratio of 67.1%. This indicates that the cobalt-based amorphous alloy sample prepared by longitudinal magnetic heat treatment at high temperature can achieve a high inductance attenuation ratio, but its initial inductance value is not high.

[0061] The inductance values ​​and inductance attenuation ratios of the cobalt-based amorphous alloy strips under the corresponding heat treatment conditions of Examples 1-2 and Comparative Examples 1-3, and at microcurrents of 200 μA and 20 mA, are as follows:

[0062] serial number Heat treatment conditions Ls-200μA (μH) Ls-20mA (μH) Ls attenuation ratio Example 1 480NF+120MF 468 113 75.9% Example 1 500NF+120MF 534 112 79.0% Example 1 520NF+120MF 486 121 75.1% Example 2 500NF+140MF 449 104 76.8% Example 2 500NF+160MF 447 109 75.6% Comparative Example 1 500NF+100MF 423 149 64.8% Comparative Example 1 500NF+180MF 410 152 62.9% Comparative Example 2 460NF 377 153 59.4% Comparative Example 2 500NF 385 147 61.8% Comparative Example 2 540NF 85 78 8.2% Comparative Example 3 480MF 347 114 67.1%

[0063] As shown in Examples 1-2 and Comparative Examples 1-3, the cobalt-based amorphous alloy produced by this embodiment, which utilizes high-temperature stress relief heat treatment combined with appropriate low-temperature longitudinal magnetic field heat treatment, can simultaneously achieve high initial inductance values ​​and high inductance attenuation ratios. Its initial inductance values ​​at a microcurrent of 200 μA reach 447-534 μH, and its inductance attenuation ratio at a current of 20 mA reaches 75.1-79%. However, if the longitudinal magnetic field heat treatment temperature is too low or too high, a high inductance attenuation ratio cannot be achieved. Using only conventional stress relief heat treatment results in a low initial inductance value for the alloy and fails to achieve significant inductance attenuation. Using only high-temperature longitudinal magnetic field heat treatment can achieve a higher inductance attenuation ratio, but the initial inductance value of the alloy is still low. Therefore, the cobalt-based amorphous alloy strip used in the leakage current sensor magnetic probe of this embodiment, produced through a two-stage heat treatment process, achieves significant improvements in both initial inductance and inductance attenuation ratio at microcurrents.

[0064] In summary, this application provides a cobalt-based amorphous alloy strip for a leakage current sensor magnetic probe and a heat treatment method thereof. The cobalt-based amorphous alloy strip is first subjected to a high-temperature stress relief heat treatment at 480-520°C, which significantly eliminates internal stress, reduces magnetic domain pinning, significantly lowers coercivity, and increases the alloy's initial inductance under low-current conditions. The cobalt-based amorphous alloy strip is then subjected to a suitable low-temperature longitudinal magnetic field heat treatment at 120-160°C to induce longitudinal easy-axis anisotropy and enhance its effect during magnetization, regularizing and widening the magnetic domains to a width of at least 380 μm. This further reduces magnetic domain pinning, significantly increases the alloy's initial inductance and inductance attenuation ratio under low-current conditions, and reduces its anti-saturation capability. The present application performs a two-stage heat treatment on the cobalt-based amorphous alloy strip, thereby enabling the cobalt-based amorphous alloy strip to have low saturation magnetization intensity, low coercive force, high magnetic permeability and high hysteresis loop rectangularity, while achieving a significant attenuation of inductance under micro-current. This is of great significance to the cobalt-based amorphous alloy strip and its application in the magnetic probe of the leakage current sensor. In addition, the heat treatment method of the present application has a simple process, which can greatly reduce the energy consumption in the material preparation process, and is conducive to promotion and application.

[0065] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0066] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of this application, ordinary technicians in this field can also make many forms without departing from the purpose of this application and the scope of protection of the claims, all of which are within the protection of this application.

Claims

1. A heat treatment method for a cobalt-based amorphous alloy strip of a leakage current sensor magnetic probe, characterized in that: The following steps are involved: The cobalt-based amorphous alloy strip is subjected to a first heat treatment, wherein the strip is heated to 480-520°C and kept warm, wherein the cobalt-based amorphous alloy strip comprises Co 67 Fe4Mo 1.5 Si 16.5 B 11 , the strip width is 1-2 mm, the thickness is 25-30 μm, and the holding time for the first heat treatment of the cobalt-based amorphous alloy strip is 10 min; Water quenching the cobalt-based amorphous alloy strip after the first heat treatment to room temperature; The cobalt-based amorphous alloy strip after water quenching is subjected to a second heat treatment, whereby the strip is heated to 120-160° C., an external magnetic field is applied along the length direction of the cobalt-based amorphous alloy strip, and the strip is kept warm. The holding time during the second heat treatment of the cobalt-based amorphous alloy strip is 10 minutes, and the strength of the external magnetic field during the second heat treatment of the cobalt-based amorphous alloy strip is 80 kA / m. The cobalt-based amorphous alloy strip after the second heat treatment is water quenched and cooled to room temperature, and the coercive force of the cobalt-based amorphous alloy strip is 0.16-0.36 A / m, the initial inductance value at 200 μA / 1 kHz is 447-534 μH, the inductance attenuation ratio at a microcurrent of 20 mA is 75.1%-79%, and the saturation field of the cobalt-based amorphous alloy strip at a microcurrent is 11-15 A / m; The cobalt-based amorphous alloy strip is subjected to the first heat treatment and the second heat treatment in a vacuum environment or an inert gas atmosphere, and the vacuum degree of the vacuum environment of the cobalt-based amorphous alloy strip is lower than 5×10 -3 Pa.

2. A cobalt-based amorphous alloy strip for a leakage current sensor magnetic probe, characterized in that: The magnetic probe of the leakage current sensor is prepared by the heat treatment method of the cobalt-based amorphous alloy strip of the leakage current sensor magnetic probe according to claim 1.

3. The cobalt-based amorphous alloy strip for the magnetic probe of the leakage current sensor according to claim 2, characterized in that: The coercive force of the cobalt-based amorphous alloy strip is 0.16-0.36 A / m, the initial inductance value at 200 μA / 1 kHz reaches 447-534 μH, and the inductance attenuation ratio at a micro-current of 20 mA reaches 75.1%-79%.

4. The cobalt-based amorphous alloy strip for the leakage current sensor magnetic probe according to claim 2, characterized in that: The saturation field of the cobalt-based amorphous alloy strip under micro-current is 11-15 A / m.

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