Switch cabinet high-temperature-resistant high-magnetic-conductivity nanocrystalline soft magnetic alloy strip and preparation method thereof

Abstract

The application relates to the technical field of metal materials, and discloses a high-temperature-resistant high-magnetic-conductivity nanocrystalline soft magnetic alloy strip for a switch cabinet and a preparation method thereof. The preparation method comprises the following steps: S1: taking Si, B, Nb, Mo, Cu and Fe as raw materials, melting, and spraying the molten steel obtained after melting onto a copper roller provided with a rapid cooling device and rotating at a high speed to prepare a base strip; S2: under a transverse magnetic field, longitudinally applying a pulling force to the base strip, and annealing to obtain a nanocrystalline soft magnetic alloy base material; S3: mixing SiO2 sol and Al2O3 sol to obtain a mixed sol, coating the mixed sol on the surface of the nanocrystalline soft magnetic alloy base material, and heat-insulating and sintering to obtain a high-magnetic-conductivity nanocrystalline soft magnetic alloy strip; and S4: coating a moisture-resistant and heat-resistant paint on the surface of the high-magnetic-conductivity nanocrystalline soft magnetic alloy strip, and solidifying to obtain a high-temperature-resistant high-magnetic-conductivity nanocrystalline soft magnetic alloy strip.

Description

Technical Field

[0001] This invention relates to the field of metal materials technology, and discloses a high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip for switchgear and its preparation method. Background Technology

[0002] Nanocrystalline soft magnetic alloys are a type of magnetic functional material characterized by high permeability, low coercivity, and low loss, making them suitable for applications in intelligent switchgear. Their performance directly determines the overall performance of the switchgear. With rapid technological advancements, higher demands are being placed on the permeability of nanocrystalline soft magnetic materials. Simultaneously, the resistance to damp heat in existing nanocrystalline soft magnetic materials still needs improvement: The application scenarios for nanocrystalline soft magnetic alloy strips commonly involve high temperature and high humidity conditions. Insufficient resistance to damp heat can lead to a significant degradation in properties such as permeability, reducing material lifespan and increasing the risk of failure. Current technologies often improve the damp heat resistance of nanocrystalline soft magnetic alloy strips through surface coatings, but the overall improvement is limited and may even affect the permeability of the strip itself. Therefore, researching a high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip for switchgear and its preparation method is of great significance. Summary of the Invention

[0003] The purpose of this invention is to provide a high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip for switchgear and its preparation method, so as to solve the problems mentioned in the background art.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip for switchgear, comprising the following steps:

[0005] S1: Take Si, B, Nb, Mo, Cu and Fe as raw materials, smelt them, and spray the molten steel obtained after smelting onto a copper roller equipped with a rapid cooling device and rotating at high speed to obtain the basic strip.

[0006] S2: Under a transverse magnetic field, a tensile force is applied longitudinally to the base strip and annealed to obtain a nanocrystalline soft magnetic alloy substrate;

[0007] S3: Mix SiO2 sol and Al2O3 sol to obtain a mixed sol. Coat the mixed sol onto the surface of a nanocrystalline soft magnetic alloy substrate, heat preservation, and sintering to obtain a high-permeability nanocrystalline soft magnetic alloy strip.

[0008] S4: Coat the surface of the high permeability nanocrystalline soft magnetic alloy strip with a moisture-resistant coating and cure to obtain a high-temperature resistant and high permeability nanocrystalline soft magnetic alloy strip.

[0009] Preferably, in S1, the base strip comprises the following raw materials, by mass percentage: 3-6% Si, 8-12% B, 3-5% Nb, 0.5-1% Mo, 1-3% Cu, with the remainder being Fe;

[0010] The specific smelting process is as follows: two smelting processes are carried out. The temperature of the first smelting is 1500~1600℃, the vacuum degree is 0.1~0.2Pa, and the smelting time is 1.5~2h. After cooling, the second smelting is carried out. The temperature of the second smelting is 1200~1300℃, and the smelting time is 0.5~1h.

[0011] Preferably, in S2, the transverse magnetic field is 50~60mT, the longitudinal tensile force is 20~30MPa, and the specific annealing process is: treatment at 250~300℃ for 2~3h, treatment at 350~400℃ for 2~3h.

[0012] Preferably, in S3, the mass ratio of SiO2 sol to Al2O3 sol is (2~3):1;

[0013] The insulation process is as follows: maintain the temperature at 90~100℃ for 5~8 minutes;

[0014] The sintering process is as follows: sintering at 400~450℃ for 1~1.5h.

[0015] Preferably, the preparation of the moisture-resistant coating includes the following steps: taking an epoxy resin composition, a modified filler, and a curing agent, mixing them, and diluting them to obtain the moisture-resistant coating;

[0016] The epoxy resin composition is a composition of bisphenol A type epoxy resin, naphthalene-containing epoxy resin, or multifunctional epoxy resin.

[0017] The modified filler is a composition of hyperbranched silane-modified composite filler, phenyl-modified composite filler, and fluorine-modified composite filler.

[0018] Preferably, in the moisture-resistant coating, the mass ratio of epoxy resin composition, modified filler, and curing agent is (9~11):(4~5):(5~6).

[0019] The epoxy resin composition is a bisphenol A type epoxy resin, a naphthalene-containing epoxy resin, or a multifunctional epoxy resin in a mass ratio of (6~7):(2~3):(0.5~1.5).

[0020] The modified fillers are hyperbranched silane-modified composite fillers, phenyl-modified composite fillers, and fluorine-modified composite fillers with a mass ratio of (5~6):(2~3):(2~3).

[0021] Preferably, the preparation of the phenyl-modified composite filler includes the following steps: take the composite filler, add it to an ethanol aqueous solution and stir evenly, add N-phenyl-γ-aminopropyltrimethoxysilane, adjust the pH to 4~5, heat to 50~60℃ and stir for 5~6h, filter and dry to obtain the phenyl-modified composite filler;

[0022] The preparation of the fluorine-modified composite filler includes the following steps: take the composite filler, add it to an ethanol aqueous solution and stir evenly, add 1H,1H,2H,2H-nonafluorohexyltrimethoxysilane, adjust the pH to 4~5, heat to 50~60℃ and stir for 5~6h, filter and dry to obtain the fluorine-modified composite filler.

[0023] The preparation of the hyperbranched silane modified composite filler includes the following steps: taking γ-aminopropyltrimethoxysilane and epichlorohydrin, heating to 30~40℃ and holding for 4~5h under nitrogen protection, heating to 70~80℃ and holding for 3~4h, heating to 90~100℃ and holding for 10~20min to obtain hyperbranched silane;

[0024] Take the composite packing material, add it to an ethanol aqueous solution and stir evenly. Add hyperbranched silane, adjust the pH to 4-5, heat to 50-60℃ and stir for 15-20 hours. Filter and dry to obtain hyperbranched silane modified composite packing material.

[0025] Preferably, in the phenyl-modified composite filler, the mass ratio of the composite filler to N-phenyl-γ-aminopropyltrimethoxysilane is (6~8):(0.5~1).

[0026] In the fluorine-modified composite filler, the mass ratio of the composite filler to 1H,1H,2H,2H-nonafluorohexyltrimethoxysilane is (6~8):(0.5~1).

[0027] In the hyperbranched silane, the molar ratio of γ-aminopropyltrimethoxysilane to epichlorohydrin is 1:(1~1.2).

[0028] In the hyperbranched silane-modified composite filler, the mass ratio of the composite filler to the hyperbranched silane is (6~8):(3~4).

[0029] The composite filler is a mixture of sol, mica, and talc in a mass ratio of (7~8):(1~2):(0.5~1).

[0030] Preferably, the thickness of the base strip is 12~16μm; the coating thickness of the mixed sol is 1.5~2μm; and the coating thickness of the moisture-resistant coating is 1~1.5μm.

[0031] Compared with the prior art, the beneficial effects achieved by the present invention are: the basic strip material includes Si, B, Nb, Mo, Cu and Fe, and the high temperature stability and magnetic permeability are balanced by precisely controlling the ratio.

[0032] Annealing under transverse magnetic field and longitudinal tensile conditions reduces coercivity and increases permeability. The annealing process further eliminates internal stress and defects, optimizes the microstructure, and helps improve stability under humid and hot conditions.

[0033] SiO2 sol and Al2O3 sol are mixed to obtain a mixed gel, which is then coated on the surface of a nanocrystalline soft magnetic alloy substrate and sintered to form a dense and continuous coating, thereby improving insulation.

[0034] Since the coating obtained by sintering the mixed sol still has pores, a layer of moisture-resistant heat-resistant coating is applied. This coating uses an epoxy resin composition as the matrix, incorporating naphthalene-containing epoxy resin. The condensed aromatic ring structure helps improve moisture-resistant heat properties. Multifunctional epoxy resin is also added to enhance moisture-resistant heat resistance by increasing the degree of crosslinking. Modified fillers are also introduced into the moisture-resistant heat-resistant coating. These fillers consist of a mixed sol, mica, and talc. The mixed sol strengthens the interlayer bonding, the mica has a sheet-like structure with good water resistance, and the talc reduces pores, further blocking moisture. The modified fillers include phenyl-modified composite fillers and fluorine-modified composite fillers, which not only improve filler dispersibility but also enhance moisture and heat resistance. The introduction of naphthalene-containing epoxy resin, multifunctional epoxy resin and various inorganic fillers causes the coating to have high viscosity and brittleness, which leads to a decrease in coating quality and a decrease in resistance to damp heat. Therefore, hyperbranched silane modified composite fillers are also introduced. The hyperbranched silane structure helps to improve the overall toughness and can also act as a diluent to balance the overall resistance to damp heat, rigidity and toughness of the coating.

[0035] The thickness of the two coating layers mentioned above also needs to be controlled. If the thickness is too large, the adhesion will decrease, leading to a decrease in resistance to damp heat and also affecting the magnetic permeability.

[0036] In summary, this method produces nanocrystalline soft magnetic alloy strips that are both resistant to high temperature and humidity and have high magnetic permeability by controlling the proportion of metal raw materials, a specific annealing process, and two coatings with controlled thickness. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] It should be noted that there are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplary examples include: SiO2 sol (50nm); Al2O3 sol (50nm); bisphenol A epoxy resin (E51); naphthalene-containing epoxy resin (naphthoquinone type epoxy resin XY643); multifunctional epoxy resin (ARALDITE MY 0510); curing agent (4,4'-diaminodiphenyl sulfone); mica (5000 mesh); talc (8000 mesh).

[0039] Unless otherwise specified, all figures below are parts by weight or mass ratios.

[0040] Example 1: S1: Take 5%Si, 10%B, 4%Nb, 0.5%Mo, 2%Cu, and 78.5%Fe, and melt them at 1500℃ and 0.2Pa vacuum for 2 hours. After cooling, melt them at 1200℃ for 50 minutes. Spray the molten steel obtained after melting onto a copper roller equipped with a rapid cooling device and rotating at high speed through a nozzle to obtain a basic strip with a thickness of 15μm and a width of 2mm.

[0041] S2: Apply a longitudinal tensile force of 25MPa to the base strip, apply a transverse magnetic field of 55mT, and treat at 300℃ for 2h and 400℃ for 2h to obtain a nanocrystalline soft magnetic alloy substrate.

[0042] S3: Mix SiO2 sol and Al2O3 sol at a mass ratio of 2:1 to obtain a mixed sol. Coat the mixed sol onto the surface of a nanocrystalline soft magnetic alloy substrate with a thickness of 2μm, hold at 100℃ for 6min, and sinter at 450℃ for 1h to obtain a high permeability nanocrystalline soft magnetic alloy strip.

[0043] S4: Mix the sol, mica, and talc in a mass ratio of 7:2:0.5 to obtain the composite filler:

[0044] Take 8 parts of composite filler, add them to 80 parts of 75wt% ethanol aqueous solution and stir evenly. Add 1 part of N-phenyl-γ-aminopropyltrimethoxysilane, adjust the pH to 5, heat to 60℃ and stir for 6 hours. Filter and dry to obtain phenyl-modified composite filler.

[0045] Take 8 parts of composite packing and add them to 80 parts of 75wt% ethanol aqueous solution and stir evenly. Add 1 part of 1H,1H,2H,2H-nonafluorohexyltrimethoxysilane, adjust the pH to 5, heat to 60℃ and stir for 6 hours, filter and dry to obtain fluorine-modified composite packing.

[0046] γ-aminopropyltrimethoxysilane and epichlorohydrin were mixed in a molar ratio of 1:1.2, and the mixture was heated to 35°C and held for 5 h under nitrogen protection, then heated to 80°C and held for 4 h, and then heated to 100°C and held for 15 min to obtain hyperbranched silane.

[0047] Take 8 parts of composite packing and add them to 80 parts of 75wt% ethanol aqueous solution and stir evenly. Add 4 parts of hyperbranched silane, adjust the pH to 5, heat to 60℃ and stir for 20h. Filter and dry to obtain hyperbranched silane modified composite packing.

[0048] Mix hyperbranched silane-modified composite filler, phenyl-modified composite filler, and fluorine-modified composite filler in a mass ratio of 5:3:3 to obtain the modified filler.

[0049] A mixture of bisphenol A type epoxy resin, naphthalene-containing epoxy resin, and multifunctional epoxy resin in a mass ratio of 6:3:1 is obtained to obtain an epoxy resin composition.

[0050] Take 100 parts of epoxy resin composition, 45 parts of modified filler and 60 parts of curing agent and mix them. Dilute with xylene to a solid content of 25 wt% to obtain a moisture-resistant coating.

[0051] A heat-resistant coating with a thickness of 1 μm was applied to the surface of a high-permeability nanocrystalline soft magnetic alloy strip. After drying, the coating was cured at 80℃ for 2 h, 140℃ for 1 h, and 180℃ for 1 h to obtain a high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip.

[0052] Example 2: S1: Take 5%Si, 10%B, 4%Nb, 0.5%Mo, 2%Cu, and 78.5%Fe, and melt them at 1500℃ and 0.2Pa vacuum for 2 hours. After cooling, melt them at 1200℃ for 50 minutes. Spray the molten steel obtained after melting onto a copper roller equipped with a rapid cooling device and rotating at high speed through a nozzle to obtain a basic strip with a thickness of 15μm and a width of 2mm.

[0053] S2: Apply a longitudinal tensile force of 25MPa to the base strip, apply a transverse magnetic field of 55mT, and treat at 300℃ for 2h and 400℃ for 2h to obtain a nanocrystalline soft magnetic alloy substrate.

[0054] S3: Mix SiO2 sol and Al2O3 sol at a mass ratio of 3:1 to obtain a mixed sol. Coat the mixed sol onto the surface of a nanocrystalline soft magnetic alloy substrate with a thickness of 2μm, hold at 100℃ for 6min, and sinter at 450℃ for 1h to obtain a high-permeability nanocrystalline soft magnetic alloy strip.

[0055] S4: Mix the sol, mica, and talc in a mass ratio of 8:2:1 to obtain the composite filler:

[0056] Take 8 parts of composite filler, add them to 80 parts of 75wt% ethanol aqueous solution and stir evenly. Add 1 part of N-phenyl-γ-aminopropyltrimethoxysilane, adjust the pH to 5, heat to 60℃ and stir for 6 hours. Filter and dry to obtain phenyl-modified composite filler.

[0057] Take 8 parts of composite packing and add them to 80 parts of 75wt% ethanol aqueous solution and stir evenly. Add 1 part of 1H,1H,2H,2H-nonafluorohexyltrimethoxysilane, adjust the pH to 5, heat to 60℃ and stir for 6 hours, filter and dry to obtain fluorine-modified composite packing.

[0058] γ-aminopropyltrimethoxysilane and epichlorohydrin were mixed in a molar ratio of 1:1.2, and the mixture was heated to 35°C and held for 5 h under nitrogen protection, then heated to 80°C and held for 4 h, and then heated to 100°C and held for 15 min to obtain hyperbranched silane.

[0059] Take 8 parts of composite packing and add them to 80 parts of 75wt% ethanol aqueous solution and stir evenly. Add 4 parts of hyperbranched silane, adjust the pH to 5, heat to 60℃ and stir for 20h. Filter and dry to obtain hyperbranched silane modified composite packing.

[0060] Mix hyperbranched silane-modified composite filler, phenyl-modified composite filler, and fluorine-modified composite filler in a mass ratio of 6:3:3 to obtain the modified filler.

[0061] A mixture of bisphenol A type epoxy resin, naphthalene-containing epoxy resin, and multifunctional epoxy resin in a mass ratio of 7:2:1 is obtained to obtain an epoxy resin composition.

[0062] Take 100 parts of epoxy resin composition, 40 parts of modified filler and 60 parts of curing agent and mix them. Dilute with xylene to a solid content of 25 wt% to obtain a moisture-resistant coating.

[0063] A heat-resistant coating with a thickness of 1 μm was applied to the surface of a high-permeability nanocrystalline soft magnetic alloy strip. After drying, the coating was cured at 80℃ for 2 h, 140℃ for 1 h, and 180℃ for 1 h to obtain a high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip.

[0064] Example 3: S1: Take 5%Si, 10%B, 4%Nb, 0.5%Mo, 2%Cu, and 78.5%Fe, and melt them at 1500℃ and 0.2Pa vacuum for 2 hours. After cooling, melt them at 1200℃ for 50 minutes. Spray the molten steel obtained after melting onto a copper roller equipped with a rapid cooling device and rotating at high speed through a nozzle to obtain a basic strip with a thickness of 15μm and a width of 2mm.

[0065] S2: Apply a longitudinal tensile force of 25MPa to the base strip, apply a transverse magnetic field of 55mT, and treat at 300℃ for 2h and 400℃ for 2h to obtain a nanocrystalline soft magnetic alloy substrate.

[0066] S3: Mix SiO2 sol and Al2O3 sol at a mass ratio of 2:1 to obtain a mixed sol. Coat the mixed sol onto the surface of a nanocrystalline soft magnetic alloy substrate with a thickness of 2μm, hold at 100℃ for 6min, and sinter at 450℃ for 1h to obtain a high permeability nanocrystalline soft magnetic alloy strip.

[0067] S4: Mix the sol, mica, and talc in a mass ratio of 7:1:1 to obtain the composite filler:

[0068] Take 8 parts of composite filler, add them to 80 parts of 75wt% ethanol aqueous solution and stir evenly. Add 1 part of N-phenyl-γ-aminopropyltrimethoxysilane, adjust the pH to 5, heat to 60℃ and stir for 6 hours. Filter and dry to obtain phenyl-modified composite filler.

[0069] Take 8 parts of composite packing and add them to 80 parts of 75wt% ethanol aqueous solution and stir evenly. Add 1 part of 1H,1H,2H,2H-nonafluorohexyltrimethoxysilane, adjust the pH to 5, heat to 60℃ and stir for 6 hours, filter and dry to obtain fluorine-modified composite packing.

[0070] γ-aminopropyltrimethoxysilane and epichlorohydrin were mixed in a molar ratio of 1:1.2, and the mixture was heated to 35°C and held for 5 h under nitrogen protection, then heated to 80°C and held for 4 h, and then heated to 100°C and held for 15 min to obtain hyperbranched silane.

[0071] Take 8 parts of composite packing, add 80 parts of 75wt% ethanol aqueous solution and stir evenly, add 3 parts of hyperbranched silane, adjust the pH to 5, heat to 60℃ and stir for 20h, filter and dry to obtain hyperbranched silane modified composite packing.

[0072] Mix hyperbranched silane-modified composite filler, phenyl-modified composite filler, and fluorine-modified composite filler in a mass ratio of 5:3:3 to obtain the modified filler.

[0073] Bisphenol A type epoxy resin, naphthalene-containing epoxy resin, and multifunctional epoxy resin were mixed in a mass ratio of 6:2:1.5 to obtain an epoxy resin composition.

[0074] Take 100 parts of epoxy resin composition, 40 parts of modified filler and 60 parts of curing agent and mix them. Dilute with xylene to a solid content of 25 wt% to obtain a moisture-resistant coating.

[0075] A heat-resistant coating with a thickness of 1 μm was applied to the surface of a high-permeability nanocrystalline soft magnetic alloy strip. After drying, the coating was cured at 80℃ for 2 h, 140℃ for 1 h, and 180℃ for 1 h to obtain a high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip.

[0076] Comparative Example 1 (the amount of each component added in the modified filler was changed, and the rest was the same as in Example 1): Hyperbranched silane modified composite filler, phenyl modified composite filler and fluorine modified composite filler were mixed in a mass ratio of 3:4:4 to obtain the modified filler.

[0077] Comparative Example 2 (the coating thickness of the moisture-resistant coating was changed, and the rest was the same as in Example 1): the coating thickness of the moisture-resistant coating was 2.5 μm.

[0078] Comparative Example 3 (the amount of each component added to the epoxy resin composition was changed, and the rest was the same as in Example 1): Bisphenol A type epoxy resin, naphthalene-containing epoxy resin and polyfunctional epoxy resin were mixed in a mass ratio of 5:4:1 to obtain an epoxy resin composition.

[0079] Comparative Example 4 (the amount of each component added to the epoxy resin composition was changed, and the rest was the same as in Example 1): Bisphenol A type epoxy resin, naphthalene-containing epoxy resin and polyfunctional epoxy resin were mixed in a mass ratio of 4:3:2 to obtain an epoxy resin composition.

[0080] Performance testing: Take the high temperature resistant and high magnetic permeability nanocrystalline soft magnetic alloy strips prepared in Examples 1-3 and Comparative Examples 1-4, (1) use an AC magnetic permeability meter to measure the magnetic permeability (μ) under 1kHz and 1T conditions; (2) age at 85℃ / 85RH conditions for 1000h, measure the magnetic permeability, and calculate the decrease rate (%); see Table 1 for details;

[0081] Table 1:

[0082] magnetic permeability Permeability decrease rate after aging Example 1 71000 1.3 Example 2 71000 1.8 Example 3 70000 1.4 Comparative Example 1 68000 3.1 Comparative Example 2 60000 2.9 Comparative Example 3 65000 3.5 Comparative Example 4 63000 3.8

[0083] Comparative Example 1 varied the amounts of each component in the modified filler. Decreasing the amount of hyperbranched silane-modified composite filler and increasing the amounts of phenyl-modified and fluorine-modified composite fillers resulted in insufficient overall toughness, leading to a decrease in coating quality and performance. Conversely, reducing the amounts of phenyl-modified and fluorine-modified composite fillers resulted in insufficient heat resistance, also causing performance degradation. Comparative Example 2 varied the coating thickness of the moisture-resistant coating. Excessive coating thickness affected magnetic permeability, while insufficient thickness prevented the application of excellent moisture-resistant properties. Comparative Examples 3 and 4 varied the amounts of each component in the epoxy resin composition, both of which led to a decrease in coating quality and performance. In conclusion, strict control of the thickness and the proportions of each raw material is necessary to obtain the high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip described in this scheme.

[0084] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip for switchgear, characterized in that: Includes the following steps: S1: Take Si, B, Nb, Mo, Cu and Fe as raw materials, smelt them, and spray the molten steel obtained after smelting onto a copper roller equipped with a rapid cooling device and rotating at high speed to obtain the basic strip. S2: Under a transverse magnetic field, a tensile force is applied longitudinally to the base strip and annealed to obtain a nanocrystalline soft magnetic alloy substrate; S3: Mix SiO2 sol and Al2O3 sol to obtain a mixed sol. Coat the mixed sol onto the surface of a nanocrystalline soft magnetic alloy substrate, heat preservation, and sintering to obtain a high-permeability nanocrystalline soft magnetic alloy strip. S4: Coating the surface of a high-permeability nanocrystalline soft magnetic alloy strip with a moisture-resistant coating and curing it yields a high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip. The preparation of the moisture-resistant coating includes the following steps: mixing epoxy resin composition, modified filler, and curing agent, and diluting to obtain the moisture-resistant coating; the epoxy resin composition is a composition of bisphenol A type epoxy resin, naphthalene-containing epoxy resin, and multifunctional epoxy resin; the modified filler is a composition of hyperbranched silane modified composite filler, phenyl modified composite filler, and fluorine modified composite filler. The phenyl-modified composite filler was prepared by a composite filler and N-phenyl-γ-aminopropyltrimethoxysilane; The fluorine-modified composite filler was prepared by a composite filler and 1H,1H,2H,2H-nonafluorohexyltrimethoxysilane; The hyperbranched silane-modified composite filler is prepared from a composite filler and a hyperbranched silane; the hyperbranched silane is prepared from γ-aminopropyltrimethoxysilane and epichlorohydrin. The composite filler is obtained by mixing the mixed sol, mica and talc in a mass ratio of (7~8):(1~2):(0.5~1).

2. The method for preparing the high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip for switchgear according to claim 1, characterized in that: In S1, the base strip comprises the following raw materials, by mass percentage: 3~6% Si, 8~12% B, 3~5% Nb, 0.5~1% Mo, 1~3% Cu, and the remainder is Fe; The specific smelting process is as follows: two smelting processes are carried out. The temperature of the first smelting is 1500~1600℃, the vacuum degree is 0.1~0.2Pa, and the smelting time is 1.5~2h. After cooling, the second smelting is carried out. The temperature of the second smelting is 1200~1300℃, and the smelting time is 0.5~1h.

3. The method for preparing the high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip for switchgear according to claim 1, characterized in that: In S2, the transverse magnetic field is 50~60mT, the longitudinal tensile force is 20~30MPa, and the specific annealing process is: 250~300℃ for 2~3h, 350~400℃ for 2~3h.

4. The method for preparing the high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip for switchgear according to claim 1, characterized in that: In S3, the mass ratio of SiO2 sol to Al2O3 sol is (2~3):1; The heat preservation process is: heat preservation at 90~100℃ for 5~8 minutes; the sintering process is: sintering at 400~450℃ for 1~1.5 hours.

5. The method for preparing the high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip for switchgear according to claim 1, characterized in that: In the heat-resistant coating, the mass ratio of epoxy resin composition, modified filler, and curing agent is (9~11):(4~5):(5~6); the epoxy resin composition is a bisphenol A type epoxy resin, a naphthalene-containing epoxy resin, or a multifunctional epoxy resin with a mass ratio of (6~7):(2~3):(0.5~1.5); the modified filler is a hyperbranched silane modified composite filler, a phenyl modified composite filler, or a fluorine modified composite filler with a mass ratio of (5~6):(2~3):(2~3).

6. The method for preparing the high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip for switchgear according to claim 1, characterized in that: The preparation of the phenyl-modified composite filler includes the following steps: take the composite filler, add it to an ethanol aqueous solution and stir evenly, add N-phenyl-γ-aminopropyltrimethoxysilane, adjust the pH to 4~5, heat to 50~60℃ and stir for 5~6h, filter and dry to obtain the phenyl-modified composite filler; The preparation of the fluorine-modified composite filler includes the following steps: take the composite filler, add it to an ethanol aqueous solution and stir evenly, add 1H,1H,2H,2H-nonafluorohexyltrimethoxysilane, adjust the pH to 4~5, heat to 50~60℃ and stir for 5~6h, filter and dry to obtain the fluorine-modified composite filler. The preparation of the hyperbranched silane-modified composite filler includes the following steps: γ-aminopropyltrimethoxysilane and epichlorohydrin are heated to 30-40℃ and held for 4-5 hours under nitrogen protection, then heated to 70-80℃ and held for 3-4 hours, and then heated to 90-100℃ and held for 10-20 minutes to obtain hyperbranched silane; the composite filler is taken, added to an ethanol aqueous solution and stirred evenly, then hyperbranched silane is added, the pH is adjusted to 4-5, the temperature is raised to 50-60℃ and stirred for 15-20 hours, filtered and dried to obtain the hyperbranched silane-modified composite filler.

7. The method for preparing the high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip for switchgear according to claim 6, characterized in that: In the phenyl-modified composite filler, the mass ratio of the composite filler to N-phenyl-γ-aminopropyltrimethoxysilane is (6~8):(0.5~1); in the fluorine-modified composite filler, the mass ratio of the composite filler to 1H,1H,2H,2H-nonafluorohexyltrimethoxysilane is (6~8):(0.5~1); in the hyperbranched silane, the molar ratio of γ-aminopropyltrimethoxysilane to epichlorohydrin is 1:(1~1.2); in the hyperbranched silane-modified composite filler, the mass ratio of the composite filler to the hyperbranched silane is (6~8):(3~4).

8. The method for preparing the high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip for switchgear according to claim 1, characterized in that: The thickness of the base strip is 12~16μm; the coating thickness of the mixed sol is 1.5~2μm; and the coating thickness of the moisture-resistant coating is 1~1.5μm.

9. The high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip prepared by the method for preparing the switchgear high-temperature resistant, high-permeability nanocrystalline soft magnetic alloy strip according to any one of claims 1 to 8.