Preparation method of environment-friendly amorphous magnetic core surface coating

Abstract

The present application relates to the technical field of material surface modification and protection, in particular to a preparation method of an environment-friendly amorphous magnetic core surface coating. The preparation method comprises the following steps: firstly, performing environment-friendly pretreatment on an iron-based amorphous magnetic core to obtain a magnetic core with a clean and activated surface; secondly, preparing a rare earth modified silicon-based inorganic passivation layer on the surface of the magnetic core in situ; thirdly, preparing a water-based modified epoxy-silicon resin composite coating, and coating the coating on the surface of the magnetic core by using an electrostatic spraying process; and finally, completing curing by using a three-stage gradient temperature curing process, and forming an environment-friendly composite insulation coating on the surface of the magnetic core. The present application adopts an environment-friendly system throughout the whole process, and the coating has excellent interface bonding force and protection performance, can effectively avoid the deterioration of the soft magnetic performance of the magnetic core, and has strong controllability of the process and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of material surface modification and protection technology, specifically to a method for preparing an environmentally friendly amorphous magnetic core surface coating. Background Technology

[0002] Ferrous-based amorphous magnetic cores, with their high saturation magnetic induction, high permeability, low high-frequency loss, and excellent DC bias resistance, have become core magnetic components in high-end power electronic devices such as high-frequency transformers, filter inductors, new energy vehicle power supplies, and photovoltaic and wind power converters. They are key materials driving the development of power electronic equipment towards higher frequencies, smaller sizes, and higher efficiency. The surface insulating coating of amorphous magnetic cores is crucial for ensuring their performance and service life. It not only needs to provide excellent interlayer insulation, oxidation resistance, and corrosion resistance, but also needs to minimize the impact on the original soft magnetic properties of the core.

[0003] There are still many shortcomings in the current technology for preparing surface coatings for amorphous magnetic cores that need to be addressed.

[0004] First, the environmental performance is seriously inadequate. Most of the existing mainstream coating systems use solvent-based coatings, which contain a large amount of volatile organic solvents such as benzene and esters, resulting in high VOC emissions. This makes it difficult to meet the increasingly stringent environmental regulations and dual-carbon targets. At the same time, the pretreatment of magnetic cores often uses strong acid and strong alkali etching and cleaning processes, which generate a large amount of hazardous waste liquid containing heavy metals, acids and alkalis. This not only pollutes the environment but also poses extremely high occupational health and safety risks.

[0005] Secondly, the coating structure and interface bonding performance have inherent defects. Existing technologies mostly use a single-layer organic insulating coating or a coating after simple passivation treatment. The passivation layer has insufficient density and weak interfacial bonding with the substrate and organic coating. Under complex working conditions such as humid heat and salt spray, problems such as coating delamination, peeling, and blistering are prone to occur, and the insulation and protection performance deteriorates rapidly.

[0006] Third, there is a prominent contradiction between the curing process and magnetic performance protection. Existing curing processes mostly adopt a high-temperature one-time curing mode, which has a high curing temperature and high energy consumption. This can easily lead to nanocrystallization of amorphous magnetic cores, resulting in magnetic performance degradation problems such as decreased permeability and increased loss. At the same time, conventional coating processes have poor uniformity and are difficult to adapt to the full surface protection of complex magnetic core structures, which can easily lead to blind spots in protection.

[0007] Fourth, it is difficult to achieve a balance between overall performance. Existing technologies cannot simultaneously achieve a synergistic improvement in environmental friendliness, high insulation, strong corrosion resistance, and excellent magnetic performance retention, making it difficult to meet the long-term, high-reliability service requirements of high-end power electronic equipment for amorphous magnetic cores. Summary of the Invention

[0008] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for preparing an environmentally friendly amorphous magnetic core surface coating.

[0009] (II) Technical Solution A method for preparing an environmentally friendly amorphous magnetic core surface coating includes the following steps: S1 Amorphous Magnetic Core Environmental Pretreatment: The iron-based amorphous magnetic core to be treated is first subjected to plasma treatment in a mixed atmosphere of argon and oxygen, then cleaned in a neutral water-based environmentally friendly cleaning solution and dried to obtain a surface-cleaned and activated amorphous magnetic core. S2 In-situ preparation of rare earth modified silicon-based inorganic passivation layer: The amorphous magnetic core treated in step S1 is immersed in water-based silicon source hydrolysate for a period of time, and after pre-curing, a rare earth modified silicon-based inorganic passivation layer is generated in-situ on the surface of the amorphous magnetic core. S3 Water-based Composite Organic Insulating Coating Application: Prepare a water-based modified epoxy-silicone resin composite coating, spray it onto the surface of the rare earth modified silicon-based inorganic passivation layer, and after drying, form a water-based composite organic insulating coating. S4 Gradient Temperature Curing: The amorphous magnetic core coated in step S3 is placed in a hot air circulating curing oven for temperature curing. After curing, it is cooled to room temperature with the oven, and finally an environmentally friendly composite insulating coating with a total thickness of 50-120μm is formed on the surface of the amorphous magnetic core.

[0010] Preferably, in step S1, the volume ratio of argon to oxygen is (8-12):1, the plasma treatment power is 80-150W, and the treatment time is 30-90s; the ultrasonic cleaning temperature of the neutral water-based environmentally friendly cleaning solution is 40-60℃, the time is 5-15min, and the ultrasonic power is 200-400W; after cleaning with the neutral water-based environmentally friendly cleaning solution, rinse with deionized water 2-3 times, and then vacuum dry in a vacuum drying oven at 60-80℃ for 10-20min.

[0011] Preferably, in step S1, the argon-oxygen volume ratio of the argon-oxygen mixture is 10:1, the plasma treatment power is 100-120W, and the treatment time is 45-60s; the neutral water-based environmentally friendly cleaning solution is a sodium sulfate aqueous solution of fatty alcohol polyoxyethylene ether with a mass fraction of 0.5-2%.

[0012] Preferably, in step S1, the ultrasonic cleaning temperature is 50℃, the ultrasonic power is 300W, and the cleaning time is 8-10min; the vacuum drying temperature is 70℃, the drying time is 15min, and the vacuum degree is -0.08~-0.1MPa.

[0013] Preferably, in step S2, the water-based silicon source hydrolysate is prepared by mixing deionized water, a dual silicon source precursor, a rare earth modifier, and a pH adjuster in a mass ratio of 100:(8-15):(0.2-0.8):(0.5-2). The dual silicon source precursor is a mixture of γ-aminopropyltriethoxysilane and tetraethyl orthosilicate in a mass ratio of (1-3):1. The rare earth modifier is cerium nitrate or lanthanum nitrate, and the pH adjuster is citric acid. The pH value of the water-based silicon source hydrolysate is adjusted to 5.5-6.5.

[0014] Preferably, in step S2, the mass ratio of γ-aminopropyltriethoxysilane to tetraethyl orthosilicate in the dual silicon source precursor is 2:1, the amount of rare earth modifier added is 0.3-0.5% of the total mass of the hydrolysate, the pH value of the hydrolysate is 6.0, and the hydrolysate is pre-hydrolyzed at 30°C for 15-30 minutes after preparation before use.

[0015] Preferably, in step S2, the immersion coating temperature is 35-55℃, the immersion coating time is 60-120s, and after removal, it is pre-cured at 40-60℃ for 5-10min to generate a rare earth modified silicon-based inorganic passivation layer with a thickness of 80-200nm on the magnetic core surface.

[0016] Preferably, in step S2, the dip coating temperature is 40-45℃, the dip coating time is 80-100s, the pull-out rate is 3mm / s, the pre-curing temperature is 50℃, the pre-curing time is 8min, and the thickness of the rare earth modified silicon-based inorganic passivation layer generated in situ is 100-150nm.

[0017] Preferably, in step S3, the water-based modified epoxy-silicone resin composite coating is prepared by mixing water-based modified epoxy resin, water-based hydroxyl silicone resin, water-based curing agent, and deionized water in a mass ratio of (30-40):(10-20):(5-10):(40-50). The solid content of the composite coating is 30-45%, and the viscosity measured at 25°C using a Forco-4 cup is 20-50 s. The water-based modified epoxy-silicone resin composite coating is applied to the surface of the rare earth modified silicon-based inorganic passivation layer using an electrostatic spraying process. After each spraying, the coating is pre-baked at 50-70°C for 8-15 minutes.

[0018] Preferably, in step S3, the water-based modified epoxy resin is a water-based bisphenol A modified epoxy resin with an epoxy equivalent of 400-600 g / eq; the water-based hydroxyl silicone resin has a hydroxyl content of 3-5% and a number average molecular weight of 3000-8000; the water-based curing agent is a water-based aliphatic isocyanate curing agent; the composite coating has a solid content of 35-40% and a viscosity of 30-40 s measured at 25°C using a Forco-4 cup.

[0019] Preferably, in step S3, the electrostatic spraying voltage is 60kV, the spraying distance is 20cm, the single spraying thickness is 15μm, the number of sprayings is 3, the pre-baking temperature after each spraying is 60℃, and the pre-baking time is 10min.

[0020] Preferably, in step S4, a three-stage gradient temperature curing process is adopted. In the first stage, the temperature is increased to 80-100℃ at a rate of 2-3℃ / min and held for 15-30min. In the second stage, the temperature is increased to 120-140℃ at a rate of 1-2℃ / min and held for 20-40min. In the third stage, the temperature is increased to 160-180℃ at a rate of 1-2℃ / min and held for 30-60min.

[0021] Preferably, in step S4, the three-stage gradient temperature curing process is as follows: the first stage heats up to 90°C at a rate of 2°C / min and holds for 20 min; the second stage heats up to 130°C at a rate of 1.5°C / min and holds for 30 min; the third stage heats up to 170°C at a rate of 1°C / min and holds for 45 min.

[0022] Preferably, after step S4 is cooled to room temperature in the furnace, the process further includes step S5, a water-based environmentally friendly sealing post-treatment step: immersing the amorphous magnetic core with an environmentally friendly composite insulating coating on its surface into a sealing solution at a temperature of 35-40℃ for 15-25 seconds, then uniformly lifting it out at a speed of 1-3 mm / s, blowing away any residual liquid at the edges of the amorphous magnetic core with clean, oil-free compressed air, and then drying it in a hot air circulating oven at 80℃ for 8-12 minutes to complete the sealing post-treatment; the sealing solution is prepared by mixing deionized water and γ-glycidoxypropyltrimethoxysilane, with the mass fraction of γ-glycidoxypropyltrimethoxysilane being 0.5-1.0%.

[0023] (iii) Beneficial technical effects Compared with existing technologies, the beneficial effects of this invention are: Adopting a water-based environmental protection system, it abandons the traditional solvent-based coatings and acid-alkali etching pretreatment processes, reducing the emission of volatile organic compounds and the generation of hazardous waste liquids from the source, meeting the requirements of green and low-carbon environmental protection, significantly reducing the cost of waste treatment and occupational health and safety risks in the production process, and has good industrial environmental protection adaptability.

[0024] Through a two-step composite coating structure design, a rare-earth modified silicon-based inorganic passivation layer is first prepared in situ on the magnetic core surface. This not only fills and passivates the micro-defects on the magnetic core surface, improving the substrate's oxidation and corrosion resistance, but also provides sufficient active binding sites for the subsequent organic coating. This significantly improves the interfacial bonding between the coating and the substrate, and between the inorganic and organic layers, effectively solving the industry pain points of traditional coatings being prone to delamination, peeling, and blistering. The composite coating structure achieves synergistic performance between the inorganic passivation layer and the organic insulating layer, greatly improving the coating's insulation and protection performance and long-term service stability under complex working conditions.

[0025] The gradient low-temperature curing process avoids the damage to the microstructure of the amorphous magnetic core caused by high-temperature curing, effectively suppresses the degradation of the soft magnetic properties of the magnetic core, and at the same time, the step-by-step curing mode improves the density of the coating and reduces coating defects such as pinholes and bubbles. With the optimized coating process, uniform coating of the entire surface of the complex structure of the magnetic core is achieved, eliminating blind spots in protection, and the process is highly controllable and suitable for large-scale industrial production. Attached Figure Description

[0026] Figure 1 This is a flowchart of a method for preparing an environmentally friendly amorphous magnetic core surface coating disclosed in this invention; Figure 2 This is a line graph comparing the neutral salt spray tolerance time and damp heat resistance test time of the examples and comparative examples; Figure 3 This is a bar chart comparing the effective permeability retention rate and total coating thickness of the embodiments and comparative examples; Figure 4 This is a radar comparison chart created by standardizing the dimensions of the performance comparison data of the examples and comparative examples. Detailed Implementation

[0027] according to Figures 1 to 4 The specific embodiments of the present invention are as follows: This specific embodiment elaborates on the implementation details of the preparation method of the environmentally friendly amorphous magnetic core surface coating of the present invention. The feasibility and performance advantages of the technical solution of the present invention are verified through parameter gradient design. The raw materials and instruments used are all industrial-grade general specifications and can be directly adapted to large-scale industrial production.

[0028] Experimental raw materials and instruments 1. Core raw materials The substrate to be processed is an iron-based amorphous magnetic core, grade 1K101, with dimensions of 30mm outer diameter, 20mm inner diameter, and 10mm height. The surface of the magnetic core is free from obvious corrosion, deformation, and mechanical damage. Gaseous raw materials: High-purity argon, purity ≥99.999%; High-purity oxygen, purity ≥99.999%; Pretreatment cleaning raw material: Sodium fatty alcohol polyoxyethylene ether sulfate (AES), industrial grade, active ingredient content 70%; Inorganic passivation layer raw materials: γ-aminopropyltriethoxysilane KH550, industrial grade, effective content ≥98%; tetraethyl orthosilicate TEOS, industrial grade, silica content ≥28%; cerium nitrate (analytical grade, purity ≥99.5%), lanthanum nitrate (analytical grade, purity ≥99.5%), citric acid (analytical grade, purity ≥99.5%). Organic insulating coating raw materials: waterborne bisphenol A modified epoxy resin (industrial grade, epoxy equivalent 400-600g / eq, solid content 50%), waterborne hydroxyl silicone resin (industrial grade, hydroxyl content 3-5%, number average molecular weight 3000-8000, solid content 60%), waterborne aliphatic isocyanate curing agent (industrial grade, NCO content 18-20%). Post-sealing treatment material: γ-glycidyl etheroxypropyltrimethoxysilane (KH560, industrial grade, effective content ≥98%). Solvent: Deionized water, resistivity ≥18.2MΩ・cm.

[0029] 2. Test instruments and equipment Atmospheric pressure low-temperature plasma treatment equipment, model: PT-10S; CNC constant temperature ultrasonic cleaner, model: KQ-500DE; Vacuum drying oven, model: DZF-6050; Thermostatic water bath, model: HH-S4; Digital display electric mixer, model: JJ-1A; Electrostatic spraying machine, model: W-71; Hot air circulating curing oven, model: DHG-9240A; Coat-4 viscosity cup; High-precision electronic balance, accuracy 0.1mg; Paint film thickness gauge; insulation resistance tester; salt spray test chamber; soft magnetic property tester.

[0030] Example 1

[0031] This embodiment provides a method for preparing an environmentally friendly amorphous magnetic core surface coating, specifically including the following steps: S1 amorphous magnetic core environmental pretreatment First, the 1K101 iron-based amorphous toroidal magnetic core to be processed was blown away with clean, oil-free compressed air to remove surface dust and debris. It was then laid flat in a single layer in the cavity of the atmospheric pressure low-temperature plasma treatment equipment. The cavity was closed and evacuated until the cavity pressure was below 10 Pa. A mixture of argon and oxygen was then introduced, with the volume ratio of argon to oxygen controlled at 8:1. The gas was continuously introduced until the cavity returned to atmospheric pressure and the gas flow rate was kept stable. The plasma treatment power was set to 80 W and the continuous treatment time was 90 s to complete the plasma surface activation and micro-etching treatment.

[0032] After treatment, the magnetic core was immediately transferred into a neutral water-based environmentally friendly cleaning solution preheated to 40°C. The cleaning solution was a 0.5% (w / w) aqueous solution of fatty alcohol polyoxyethylene ether sodium sulfate. After the magnetic core was completely submerged, ultrasonic cleaning was started. The ultrasonic power was set to 200W, and the cleaning was performed continuously for 15 minutes. After ultrasonic cleaning, the magnetic core was removed and rinsed repeatedly with deionized water three times to thoroughly remove the residual cleaning solution from the surface. Then, it was immediately placed in a vacuum drying oven preheated to 60°C. The vacuum degree was set to -0.08MPa, and the core was vacuum dried continuously for 20 minutes. After removal, the core was placed in a desiccator to cool to room temperature, resulting in a clean and activated amorphous magnetic core. Secondary contamination of the magnetic core surface was avoided throughout the process.

[0033] In-situ preparation of S2 rare earth modified silicon-based inorganic passivation layer A water-based silicon source hydrolysate was prepared in advance. By mass, 100 parts deionized water, 8 parts dual silicon source precursor, 0.2 parts rare earth modifier, and 0.5 parts pH adjuster were weighed sequentially. The dual silicon source precursor was a mixture of γ-aminopropyltriethoxysilane and tetraethyl orthosilicate in a 1:1 mass ratio. The rare earth modifier was cerium nitrate, and the pH adjuster was citric acid. First, deionized water was added to a constant-temperature water bath reactor equipped with a stirrer. The stirrer was started and the speed was controlled at 300 rpm. Citric acid and cerium nitrate were added sequentially, and the mixture was stirred until completely dissolved. Then, the prepared dual silicon source precursor was slowly added dropwise. After the addition was complete, the mixture was stirred continuously for 5 minutes until the system was homogeneous. Subsequently, the pH of the system was finely adjusted to 5.5 with citric acid. The stirring speed was kept constant, and the water bath temperature was controlled at 30℃. Pre-hydrolyzing was performed for 15 minutes to obtain a clear, transparent, and stable water-based silicon source hydrolysate.

[0034] The amorphous magnetic core processed in step S1 was immersed in the above hydrolysate at a constant speed using a special insulating hanger. The temperature of the immersion coating system was controlled to be stable at 35°C. The suspension angle of the magnetic core was adjusted to ensure complete immersion and no air bubbles adhering to the inner hole and corners of the magnetic core. The immersion coating time was 120s. After the immersion coating was completed, the magnetic core was vertically removed from the hydrolysate at a constant lifting speed of 3mm / s. It was then suspended to drain excess liquid droplets from the surface for 30s. Immediately afterward, it was placed in a hot air circulating oven preheated to 40°C for pre-curing for 10min. After removal, it was placed in a desiccator to cool to room temperature. Finally, a rare earth modified silicon-based inorganic passivation layer with a thickness of 80nm was generated in situ on the surface of the magnetic core.

[0035] S3 water-based composite organic insulating coating A water-based modified epoxy-silicone resin composite coating was prepared in advance. By weight, 30 parts of water-based modified epoxy resin, 10 parts of water-based hydroxyl silicone resin, 5 parts of water-based curing agent, and 40 parts of deionized water were weighed in sequence. The water-based modified epoxy resin was water-based bisphenol A modified epoxy resin with an epoxy equivalent of 400 g / eq; the water-based hydroxyl silicone resin had a hydroxyl content of 3% and a number average molecular weight of 3000; and the water-based curing agent was a water-based aliphatic isocyanate curing agent. The preparation process is as follows: First, deionized water is added to a sealed mixing vessel equipped with a high-speed dispersion device. Low-speed stirring (300 rpm) is started, and waterborne bisphenol A modified epoxy resin and waterborne hydroxyl silicone resin are added in sequence. Stirring is continued for 15 minutes until the system is completely mixed and uniform. Then, waterborne aliphatic isocyanate curing agent is slowly added dropwise. Stirring is continued for 10 minutes while maintaining the stirring speed, resulting in a uniform coating system. The coating performance is then tested. The solid content of the coating is controlled to 30% by fine-tuning the amount of deionized water. The viscosity of the coating is measured to be 20s using a Forecast cup at a constant temperature of 25℃. The coating is then sealed and allowed to stand for 10 minutes for curing before use.

[0036] The composite coating was applied to the surface of the amorphous magnetic core after step S2 using an electrostatic spraying process. The electrostatic spraying voltage was set to 60kV, the spraying distance to 20cm, the atomizing pressure to 0.3MPa, the spray gun moving speed to 10cm / s, the dry film thickness of a single spray was controlled to 15μm, and the total number of sprays was 3. After each spraying, the magnetic core was immediately placed in a hot air circulating oven preheated to 50℃ for 15min for pre-baking. After being taken out and cooled to room temperature, the next spraying was performed. The uniformity of the coating was controlled throughout the process, with no drips, pinholes, or missed areas.

[0037] S4 gradient low temperature curing molding After completing the spraying and pre-baking in step S3, the amorphous magnetic cores are laid flat on a tray in a hot air circulating curing oven, with a 5mm gap between the cores to ensure uniform hot air circulation. After closing the oven door, a three-stage gradient heating curing process is used for curing and shaping. The specific process parameters are as follows: In the first stage, the temperature is uniformly increased to 80℃ at a heating rate of 2℃ / min, and then held for 30 minutes after reaching the target temperature to complete the initial leveling of the coating and solvent evaporation; in the second stage, the temperature is uniformly increased to 120℃ at a heating rate of 1℃ / min, and then held for 40 minutes after reaching the target temperature to complete the initial cross-linking and curing of the resin; in the third stage, the temperature is uniformly increased to 160℃ at a heating rate of 1℃ / min, and then held for 60 minutes after reaching the target temperature to complete the complete cross-linking of the resin and densification of the coating. After all the holding stages are completed, heating is stopped, the oven door is closed, and the magnetic cores are allowed to cool naturally to room temperature before being removed. At this point, the basic structure of the composite insulating coating is formed on the surface of the amorphous magnetic cores.

[0038] S5 Water-Based Environmentally Friendly Sealing Post-Treatment After cooling in step S4, the amorphous magnetic core undergoes a sealing treatment. A water-based sealing solution is prepared in advance. By weight, 99.5 parts deionized water and 0.5 parts γ-glycidyl etheroxypropyltrimethoxysilane are weighed and stirred at 300 rpm for 10 minutes at room temperature until completely homogeneous, yielding a 0.5% water-based sealing solution. The sealing solution is transferred to a constant temperature water bath, heated to 35°C and maintained at a stable temperature. The cured amorphous magnetic core is then completely immersed in the sealing solution using a special fixture, with slight... Shake the hanger to expel air bubbles from the inner hole of the magnetic core, ensuring that the magnetic core is completely submerged without any residual air bubbles. After soaking for 25 seconds, lift the magnetic core vertically at a uniform lifting speed of 1 mm / s. After suspending for 30 seconds, immediately blow away any residual liquid at the edges and inner holes of the magnetic core with clean, oil-free compressed air. Then, place it in a hot air circulating oven preheated to 80°C to dry for 12 minutes. After removing it, cool it to room temperature. Finally, an environmentally friendly composite insulating coating with a total thickness of 50 μm is formed on the surface of the amorphous magnetic core, completing the entire preparation process.

[0039] Example 2

[0040] This embodiment provides a method for preparing an environmentally friendly amorphous magnetic core surface coating, specifically including the following steps: S1 amorphous magnetic core environmental pretreatment First, the 1K101 iron-based amorphous toroidal magnetic core to be processed was blown away with clean, oil-free compressed air to remove surface dust and debris. It was then laid flat in a single layer in the cavity of the atmospheric pressure low-temperature plasma treatment equipment. The cavity was closed and evacuated until the cavity pressure was below 10 Pa. Then, a mixture of argon and oxygen was introduced, with the volume ratio of argon to oxygen controlled at 10:1. The gas was continuously introduced until the cavity returned to atmospheric pressure and the gas flow rate was kept stable. The plasma treatment power was set to 120 W and the continuous treatment time was 60 s to complete the plasma surface activation and micro-etching treatment.

[0041] After treatment, the magnetic core was immediately transferred into a neutral water-based environmentally friendly cleaning solution preheated to 50°C. The cleaning solution was a 1.2% (w / w) aqueous solution of sodium fatty alcohol polyoxyethylene ether sulfate. After the magnetic core was completely submerged, ultrasonic cleaning was started. The ultrasonic power was set to 300W and the cleaning was performed continuously for 10 minutes. After ultrasonic cleaning, the magnetic core was removed and rinsed repeatedly with deionized water three times to thoroughly remove the residual cleaning solution from the surface. Then, it was immediately placed in a vacuum drying oven preheated to 70°C. The vacuum degree was set to -0.09MPa and the vacuum was performed continuously for 15 minutes. After removal, it was placed in a desiccator to cool to room temperature, resulting in a clean and activated amorphous magnetic core. Secondary contamination of the magnetic core surface was avoided throughout the process.

[0042] In-situ preparation of S2 rare earth modified silicon-based inorganic passivation layer A water-based silicon source hydrolysate was prepared in advance. By mass, 100 parts deionized water, 12 parts dual silicon source precursor, 0.5 parts rare earth modifier, and 1.2 parts pH adjuster were weighed sequentially. The dual silicon source precursor was a mixture of γ-aminopropyltriethoxysilane and tetraethyl orthosilicate in a mass ratio of 2:1. The rare earth modifier was lanthanum nitrate, and the pH adjuster was citric acid. First, deionized water was added to a constant-temperature water bath reactor equipped with a stirrer. The stirrer was started and the speed was controlled at 350 rpm. Citric acid and lanthanum nitrate were added sequentially, and stirred until completely dissolved. Then, the prepared dual silicon source precursor was slowly added dropwise. After the addition was complete, the mixture was stirred continuously for 8 minutes until the system was homogeneous. Subsequently, the pH of the system was finely adjusted to 6.0 with citric acid. The stirring speed was kept constant, and the water bath temperature was controlled at 30℃. Pre-hydrolyzing was performed for 25 minutes to obtain a clear, transparent, and stable water-based silicon source hydrolysate.

[0043] The amorphous magnetic core processed in step S1 was immersed in the above hydrolysate at a constant speed using a special insulating hanger. The temperature of the immersion coating system was controlled to be stable at 45°C. The suspension angle of the magnetic core was adjusted to ensure complete immersion and no air bubbles adhering to the inner hole and corners of the magnetic core. The immersion coating time was 90s. After the immersion coating was completed, the magnetic core was vertically removed from the hydrolysate at a constant lifting speed of 3mm / s. It was then suspended to drain excess liquid droplets from the surface for 30s. Immediately afterward, it was placed in a hot air circulating oven preheated to 50°C for pre-curing for 8 minutes. After removal, it was placed in a desiccator to cool to room temperature. Finally, a rare earth modified silicon-based inorganic passivation layer with a thickness of 150nm was generated in situ on the surface of the magnetic core.

[0044] S3 water-based composite organic insulating coating A water-based modified epoxy-silicone resin composite coating was prepared in advance. By weight, 35 parts of water-based modified epoxy resin, 15 parts of water-based hydroxyl silicone resin, 8 parts of water-based curing agent, and 45 parts of deionized water were weighed in sequence. The water-based modified epoxy resin was water-based bisphenol A modified epoxy resin with an epoxy equivalent of 500 g / eq; the water-based hydroxyl silicone resin had a hydroxyl content of 4% and a number average molecular weight of 5000; and the water-based curing agent was a water-based aliphatic isocyanate curing agent. The preparation process is as follows: First, deionized water is added to a sealed mixing vessel equipped with a high-speed dispersion device. Low-speed stirring (350 rpm) is started, and waterborne bisphenol A modified epoxy resin and waterborne hydroxyl silicone resin are added in sequence. Stirring is continued for 20 minutes until the system is completely mixed and uniform. Then, waterborne aliphatic isocyanate curing agent is slowly added dropwise. Stirring is continued for 15 minutes while maintaining the stirring speed, resulting in a uniform coating system. The coating performance is then tested. The solid content of the coating is controlled to 38% by fine-tuning the amount of deionized water. The viscosity of the coating is measured to be 35s using a Forecast cup at a constant temperature of 25℃. The coating is then sealed and allowed to stand for 15 minutes for curing before use.

[0045] The composite coating was applied to the surface of the amorphous magnetic core after step S2 using an electrostatic spraying process. The electrostatic spraying voltage was set to 60kV, the spraying distance to 20cm, the atomizing pressure to 0.4MPa, the spray gun moving speed to 10cm / s, the dry film thickness of a single spray was controlled to 15μm, and the total number of sprays was 3. After each spraying, the magnetic core was immediately placed in a hot air circulating oven preheated to 60℃ for 10min for pre-baking. After being taken out and cooled to room temperature, the next spraying was performed. The uniformity of the coating was controlled throughout the process, with no drips, pinholes, or missed areas.

[0046] S4 gradient low temperature curing molding After completing the spraying and pre-baking in step S3, the amorphous magnetic cores are laid flat on a tray in a hot air circulating curing oven, with a 5mm gap between the cores to ensure uniform hot air circulation. After closing the oven door, a three-stage gradient heating curing process is used for curing and shaping. The specific process parameters are as follows: In the first stage, the temperature is uniformly increased to 90℃ at a heating rate of 2℃ / min, and held for 20 minutes after reaching the target temperature to complete the initial leveling of the coating and solvent evaporation; in the second stage, the temperature is uniformly increased to 130℃ at a heating rate of 1.5℃ / min, and held for 30 minutes after reaching the target temperature to complete the initial cross-linking and curing of the resin; in the third stage, the temperature is uniformly increased to 170℃ at a heating rate of 1℃ / min, and held for 45 minutes after reaching the target temperature to complete the complete cross-linking of the resin and densification of the coating. After all the holding stages are completed, heating is stopped, the oven door is closed, and the magnetic cores are allowed to cool naturally to room temperature before being removed. At this point, the basic structure of the composite insulating coating is formed on the surface of the amorphous magnetic cores.

[0047] S5 Water-Based Environmentally Friendly Sealing Post-Treatment After cooling in step S4, the amorphous magnetic core undergoes a sealing treatment. A water-based sealing solution is prepared in advance. By weight, 99.2 parts deionized water and 0.8 parts γ-glycidyl etheroxypropyltrimethoxysilane are weighed and stirred at 350 rpm for 10 minutes at room temperature until completely homogeneous, yielding a water-based sealing solution with a weight fraction of 0.8%. The sealing solution is transferred to a constant temperature water bath, heated to 38°C and maintained at a stable temperature. The cured amorphous magnetic core is then completely immersed in the sealing solution using a special fixture, with slight... Shake the hanger to expel air bubbles from the inner hole of the magnetic core, ensuring that the magnetic core is completely submerged without any residual air bubbles. After soaking for 20 seconds, lift the magnetic core vertically at a uniform speed of 2 mm / s. After suspending for 30 seconds, immediately blow away any residual liquid at the edges and inner holes of the magnetic core with clean, oil-free compressed air. Then, place it in a hot air circulating oven preheated to 80°C to dry for 10 minutes. After removing it, cool it to room temperature. Finally, an environmentally friendly composite insulating coating with a total thickness of 80 μm is formed on the surface of the amorphous magnetic core, completing the entire preparation process.

[0048] Example 3

[0049] This embodiment provides a method for preparing an environmentally friendly amorphous magnetic core surface coating, specifically including the following steps: S1 amorphous magnetic core environmental pretreatment First, the 1K101 iron-based amorphous toroidal magnetic core to be processed was blown away with clean, oil-free compressed air to remove surface dust and debris. It was then laid flat in a single layer in the cavity of the atmospheric pressure low-temperature plasma treatment equipment. The cavity was closed and evacuated until the cavity pressure was below 10 Pa. A mixture of argon and oxygen was then introduced, with the volume ratio of argon to oxygen controlled at 12:1. The gas was continuously introduced until the cavity returned to atmospheric pressure and the gas flow rate remained stable. The plasma treatment power was set to 150 W and the continuous treatment time was 30 s to complete the plasma surface activation and micro-etching treatment.

[0050] After treatment, the magnetic core was immediately transferred to a neutral water-based environmentally friendly cleaning solution preheated to 60°C. The cleaning solution was a 2% (w / w) aqueous solution of sodium fatty alcohol polyoxyethylene ether sulfate. After the magnetic core was completely submerged, ultrasonic cleaning was started. The ultrasonic power was set to 400W and the cleaning was performed continuously for 5 minutes. After ultrasonic cleaning, the magnetic core was removed and rinsed twice with deionized water to thoroughly remove the residual cleaning solution from the surface. Then, it was immediately placed in a vacuum drying oven preheated to 80°C. The vacuum degree was set to -0.1MPa and the core was vacuum dried continuously for 10 minutes. After removal, the core was placed in a desiccator to cool to room temperature, resulting in a clean and activated amorphous magnetic core. Secondary contamination of the magnetic core surface was avoided throughout the process.

[0051] In-situ preparation of S2 rare earth modified silicon-based inorganic passivation layer A water-based silicon source hydrolysate was prepared in advance. By mass, 100 parts deionized water, 15 parts dual silicon source precursor, 0.8 parts rare earth modifier, and 2 parts pH adjuster were weighed sequentially. The dual silicon source precursor was a mixture of γ-aminopropyltriethoxysilane and tetraethyl orthosilicate in a mass ratio of 3:1. The rare earth modifier was cerium nitrate, and the pH adjuster was citric acid. First, deionized water was added to a constant-temperature water bath reactor equipped with a stirrer. The stirrer was started and the speed was controlled at 400 rpm. Citric acid and cerium nitrate were added sequentially, and the mixture was stirred until completely dissolved. Then, the prepared dual silicon source precursor was slowly added dropwise. After the addition was complete, the mixture was stirred continuously for 10 minutes until the system was homogeneous. Subsequently, the pH of the system was finely adjusted to 6.5 with citric acid. The stirring speed was kept constant, and the water bath temperature was controlled at 30℃. Pre-hydrolyzing was performed for 30 minutes to obtain a clear, transparent, and stable water-based silicon source hydrolysate.

[0052] The amorphous magnetic core processed in step S1 is immersed in the above hydrolysate at a constant speed using a special insulating hanger. The temperature of the immersion coating system is controlled to be stable at 55°C. The suspension angle of the magnetic core is adjusted to ensure complete immersion and no air bubbles adhering to the inner hole and corners of the magnetic core. The immersion coating time is 60s. After the immersion coating is completed, the magnetic core is vertically removed from the hydrolysate at a constant lifting speed of 3mm / s. It is then suspended to drain excess liquid droplets from the surface for 30s. Immediately afterward, it is placed in a hot air circulating oven preheated to 60°C for pre-curing for 5 minutes. After removal, it is placed in a desiccator to cool to room temperature. Finally, a rare earth modified silicon-based inorganic passivation layer with a thickness of 200nm is generated in situ on the surface of the magnetic core.

[0053] S3 water-based composite organic insulating coating A water-based modified epoxy-silicone resin composite coating was prepared in advance. By weight, 40 parts of water-based modified epoxy resin, 20 parts of water-based hydroxyl silicone resin, 10 parts of water-based curing agent, and 50 parts of deionized water were weighed in sequence. The water-based modified epoxy resin was water-based bisphenol A modified epoxy resin with an epoxy equivalent of 600 g / eq; the water-based hydroxyl silicone resin had a hydroxyl content of 5% and a number average molecular weight of 8000; and the water-based curing agent was a water-based aliphatic isocyanate curing agent. The preparation process is as follows: First, deionized water is added to a sealed mixing vessel equipped with a high-speed dispersion device. Low-speed stirring (400 rpm) is started, and waterborne bisphenol A modified epoxy resin and waterborne hydroxyl silicone resin are added in sequence. Stirring is continued for 25 minutes until the system is completely mixed and uniform. Then, waterborne aliphatic isocyanate curing agent is slowly added dropwise. Stirring is continued for 20 minutes while maintaining the stirring speed, resulting in a uniform coating system. The coating performance is then tested. The solid content of the coating is controlled to be 45% by fine-tuning the amount of deionized water. The viscosity of the coating is measured to be 50 s using a Forecast cup at a constant temperature of 25℃. The coating is then sealed and allowed to stand for 20 minutes for curing before use.

[0054] The composite coating was applied to the surface of the amorphous magnetic core after step S2 using an electrostatic spraying process. The electrostatic spraying voltage was set to 60kV, the spraying distance to 20cm, the atomizing pressure to 0.5MPa, the spray gun moving speed to 10cm / s, the dry film thickness of a single spray was controlled to 15μm, and the total number of sprays was 3. After each spraying, the magnetic core was immediately placed in a hot air circulating oven preheated to 70℃ for 8 minutes for pre-baking. After being taken out and cooled to room temperature, the next spraying was performed. The uniformity of the coating was controlled throughout the process, with no drips, pinholes, or missed areas.

[0055] S4 gradient low temperature curing molding After completing the spraying and pre-baking in step S3, the amorphous magnetic cores are laid flat on a tray in a hot air circulating curing oven, with a 5mm gap between the cores to ensure uniform hot air circulation. After closing the oven door, a three-stage gradient heating curing process is used for curing and shaping. The specific process parameters are as follows: In the first stage, the temperature is uniformly increased to 100℃ at a heating rate of 3℃ / min, and held for 15 minutes after reaching the target temperature to complete the initial leveling of the coating and solvent evaporation; in the second stage, the temperature is uniformly increased to 140℃ at a heating rate of 2℃ / min, and held for 20 minutes after reaching the target temperature to complete the initial cross-linking and curing of the resin; in the third stage, the temperature is uniformly increased to 180℃ at a heating rate of 2℃ / min, and held for 30 minutes after reaching the target temperature to complete the complete cross-linking of the resin and densification of the coating. After all the holding stages are completed, heating is stopped, the oven door is closed, and the magnetic cores are allowed to cool naturally to room temperature before being removed. At this point, the basic structure of the composite insulating coating is formed on the surface of the amorphous magnetic cores.

[0056] S5 Water-Based Environmentally Friendly Sealing Post-Treatment After cooling in step S4, the amorphous magnetic core undergoes a sealing treatment. A water-based sealing solution is prepared in advance. By weight, 99.0 parts of deionized water and 1.0 part of γ-glycidyl etheroxypropyltrimethoxysilane are weighed and stirred at 400 rpm for 10 minutes at room temperature until completely homogeneous, yielding a 1.0% (w / w) water-based sealing solution. The sealing solution is transferred to a constant temperature water bath, heated to 40°C and maintained at a stable temperature. The cured amorphous magnetic core is then completely immersed in the sealing solution using a special fixture, with slight... Shake the hanger to expel air bubbles from the inner hole of the magnetic core, ensuring that the magnetic core is completely submerged without any residual air bubbles. After soaking for 15 seconds, lift the magnetic core vertically at a uniform speed of 3 mm / s. After suspending for 30 seconds, immediately blow away any residual liquid at the edges and inner holes of the magnetic core with clean, oil-free compressed air. Then, place it in a hot air circulating oven preheated to 80°C to dry for 8 minutes. After removing it, cool it to room temperature. Finally, an environmentally friendly composite insulating coating with a total thickness of 120 μm is formed on the surface of the amorphous magnetic core, completing the entire preparation process.

[0057] Comparative Example 1 This comparative example uses a conventional amorphous magnetic core surface coating preparation process and employs the same iron-based amorphous magnetic core as the example. The specific preparation steps are as follows: S1 core pretreatment The iron-based amorphous magnetic core to be treated was immersed in a 5% hydrochloric acid etching solution at 50°C for 3 minutes. After etching, it was rinsed with deionized water until the rinsing solution was neutral. Then, it was immersed in a 3% sodium hydroxide aqueous solution for 2 minutes for alkaline washing. After rinsing with deionized water until neutral, it was placed in an 80°C forced-air drying oven for 30 minutes to obtain the pretreated magnetic core.

[0058] S2 insulating coating coating To prepare a solvent-based epoxy insulating coating, weigh out 40 parts by weight of bisphenol A epoxy resin, 10 parts by weight of polyamide curing agent, 45 parts by weight of xylene, and 5 parts by weight of butyl acetate. Stir thoroughly at room temperature to obtain a solvent-based epoxy coating with a solid content of 40%. The viscosity at 25°C (Coating-4 cup) is 30 s. Apply the coating to the pretreated magnetic core surface using a conventional air spraying process. The dry film thickness of a single spray is 20 μm, and a total of 3 sprays are applied. After each spray, allow the coating to stand at room temperature for 10 minutes.

[0059] S3 Curing Molding The coated magnetic core is placed in a hot air circulating curing oven and heated directly to 180°C in one go. It is then held at that temperature for 120 minutes to complete the curing process. After curing, the core is cooled to room temperature with the oven, and finally an insulating coating with a total thickness of 80μm is formed on the surface of the magnetic core, thus completing the preparation process.

[0060] Performance Testing and Results Analysis For the amorphous magnetic core samples prepared in the above three embodiments and one comparative example, the four core dimensions of coating environmental performance, physical and mechanical properties, insulation protection performance, and magnetic property retention rate were tested according to relevant national standards and industry-standard testing methods. The testing methods are as follows: VOC content test: The test was conducted in accordance with GB / T 23984-2009 "Determination of volatile organic compounds (VOC in can) in low-VOC latex paints and varnishes"; Coating adhesion test: The test shall be conducted in accordance with GB / T 9286-1998 "Cross-cut test of paint and varnish film", with grade 0 being the best. Insulation resistance test: The volume resistivity of the magnetic core coating was tested using an insulation resistance tester under a DC voltage of 500V. Salt spray resistance test: A neutral salt spray test was conducted according to GB / T 10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test", and the time when the coating showed signs of rust and blistering was recorded. Moist heat resistance test: According to GB / T 1740-2007 "Test Method for Moist Heat Resistance of Coating Film", the test was carried out in an environment with a temperature of 40℃ and a relative humidity of 95%, and the time when the coating showed abnormality was recorded. Magnetic performance testing: A soft magnetic property tester was used to test the effective permeability and unit iron loss of the magnetic core under the conditions of f=1kHz and Bm=0.5T, and the magnetic performance retention rate was calculated (based on the original magnetic performance of the uncoated magnetic core).

[0061] The test results of the examples and comparative examples are compared in the table below: Table 1

[0062] The test results show that the environmentally friendly composite insulating coatings prepared in Examples 1-3 of this invention are significantly superior to the existing conventional process of Comparative Example 1 in all performance indicators.

[0063] In terms of environmental performance, the VOC content of the coatings in the embodiments of the present invention is all below 20g / L, which is far lower than 420g / L of Comparative Example 1. At the same time, it abandons the traditional strong acid and strong alkali etching pretreatment process, and no hazardous waste or waste liquid is generated. It realizes environmentally friendly production from the source and fully complies with the current environmental regulations and dual carbon target requirements.

[0064] In terms of interface bonding and protective performance, this invention achieves a coating adhesion level of 0-1 through a composite structure design of rare earth modified silicon-based inorganic passivation layer and organic insulating layer, which is far superior to the level 3 of Comparative Example 1. This effectively solves the industry pain point of traditional coatings being prone to delamination and peeling. At the same time, the volume resistivity is increased by more than two orders of magnitude, and the salt spray resistance and damp heat resistance are improved by more than five times, which greatly enhances the insulation protection capability and long-term service stability of the magnetic core under complex working conditions.

[0065] Regarding magnetic performance protection, the three-stage gradient low-temperature curing process adopted in this invention avoids the damage to the microstructure of the amorphous magnetic core caused by high-temperature one-time curing, effectively suppressing the magnetic performance degradation caused by the nanocrystallization of the amorphous phase. The permeability retention rate of the embodiments all reached over 97%, and the iron loss change rate was controlled within 3.5%, while the permeability retention rate of Comparative Example 1 was only 91.3%, and the iron loss increased by more than 12%, which fully verifies the excellent protection effect of the process of this invention on the soft magnetic properties of the magnetic core.

[0066] Meanwhile, embodiments 1-3 of the present invention all achieved stable performance within the parameter range defined in the claims. In particular, embodiment 2 adopted the preferred process parameters of the present invention, achieving optimal overall performance, further verifying the wide process window and industrial adaptability of the technical solution of the present invention.

[0067] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an environmentally friendly amorphous magnetic core surface coating, characterized in that, Includes the following steps: S1 Amorphous Magnetic Core Environmental Pretreatment: The iron-based amorphous magnetic core to be treated is first subjected to plasma treatment in a mixed atmosphere of argon and oxygen, then cleaned in a neutral water-based environmentally friendly cleaning solution and dried to obtain a surface-cleaned and activated amorphous magnetic core. S2 In-situ preparation of rare earth modified silicon-based inorganic passivation layer: The amorphous magnetic core treated in step S1 is immersed in water-based silicon source hydrolysate for a period of time, and after pre-curing, a rare earth modified silicon-based inorganic passivation layer is generated in-situ on the surface of the amorphous magnetic core. S3 Water-based Composite Organic Insulating Coating Application: Prepare a water-based modified epoxy-silicone resin composite coating, spray it onto the surface of the rare earth modified silicon-based inorganic passivation layer, and after drying, form a water-based composite organic insulating coating. S4 Gradient Temperature Curing: The amorphous magnetic core coated in step S3 is placed in a hot air circulating curing oven for temperature curing. After curing, it is cooled to room temperature with the oven, and finally an environmentally friendly composite insulating coating is formed on the surface of the amorphous magnetic core.

2. The method for preparing the environmentally friendly amorphous magnetic core surface coating according to claim 1, characterized in that, In step S1, the volume ratio of argon to oxygen is (8-12):1, the plasma treatment power is 80-150W, and the treatment time is 30-90s; the ultrasonic cleaning temperature of the neutral water-based environmentally friendly cleaning solution is 40-60℃, the time is 5-15min, and the ultrasonic power is 200-400W; after cleaning with the neutral water-based environmentally friendly cleaning solution, rinse with deionized water 2-3 times, and then vacuum dry in a vacuum drying oven at 60-80℃ for 10-20min.

3. The method for preparing the environmentally friendly amorphous magnetic core surface coating according to claim 2, characterized in that, In step S1, the ultrasonic cleaning temperature is 50℃, the ultrasonic power is 300W, and the cleaning time is 8-10min; the vacuum drying temperature is 70℃, the drying time is 15min, and the vacuum degree is -0.08~-0.1MPa.

4. The method for preparing the environmentally friendly amorphous magnetic core surface coating according to claim 1, characterized in that, In step S2, the water-based silicon source hydrolysate is prepared by mixing deionized water, a dual silicon source precursor, a rare earth modifier, and a pH adjuster in a mass ratio of 100:(8-15):(0.2-0.8):(0.5-2). The dual silicon source precursor is a compound of γ-aminopropyltriethoxysilane and tetraethyl orthosilicate in a mass ratio of (1-3):

1. The rare earth modifier is cerium nitrate or lanthanum nitrate, and the pH adjuster is citric acid. The pH value of the water-based silicon source hydrolysate is adjusted to 5.5-6.

5.

5. The method for preparing the environmentally friendly amorphous magnetic core surface coating according to claim 1, characterized in that, In step S2, the dip coating temperature is 35-55℃, the dip coating time is 60-120s, and after removal, it is pre-cured at 40-60℃ for 5-10min.

6. The method for preparing the environmentally friendly amorphous magnetic core surface coating according to claim 1, characterized in that, In step S3, the water-based modified epoxy-silicone resin composite coating is prepared by mixing water-based modified epoxy resin, water-based hydroxyl silicone resin, water-based curing agent, and deionized water in a mass ratio of (30-40):(10-20):(5-10):(40-50). The solid content of the composite coating is 30-45%, and the viscosity measured at 25°C using a Forco-4 cup is 20-50 s. The water-based modified epoxy-silicone resin composite coating is applied to the surface of the rare earth modified silicon-based inorganic passivation layer using an electrostatic spraying process. After each spraying, the coating is pre-baked at 50-70°C for 8-15 minutes.

7. The method for preparing the environmentally friendly amorphous magnetic core surface coating according to claim 6, characterized in that, In step S3, the water-based modified epoxy resin is a water-based bisphenol A modified epoxy resin with an epoxy equivalent of 400-600 g / eq; the water-based hydroxyl silicone resin has a hydroxyl content of 3-5% and a number average molecular weight of 3000-8000; the water-based curing agent is a water-based aliphatic isocyanate curing agent; the composite coating has a solid content of 35-40% and a viscosity of 30-40 s measured at 25°C using a Forco-4 cup.

8. The method for preparing the environmentally friendly amorphous magnetic core surface coating according to claim 6, characterized in that, In step S3, the electrostatic spraying voltage is 60kV, the spraying distance is 20cm, the single spraying thickness is 15μm, the number of spraying times is 3, the pre-baking temperature after each spraying is 60℃, and the pre-baking time is 10min.

9. The method for preparing the environmentally friendly amorphous magnetic core surface coating according to claim 1, characterized in that, In step S4, a three-stage gradient temperature curing process is adopted. In the first stage, the temperature is increased to 80-100℃ at a rate of 2-3℃ / min and held for 15-30min. In the second stage, the temperature is increased to 120-140℃ at a rate of 1-2℃ / min and held for 20-40min. In the third stage, the temperature is increased to 160-180℃ at a rate of 1-2℃ / min and held for 30-60min.

10. The method for preparing the environmentally friendly amorphous magnetic core surface coating according to claim 1, characterized in that, After step S4 is cooled to room temperature in the furnace, the process also includes step S5, a water-based environmentally friendly sealing post-treatment step: the amorphous magnetic core with an environmentally friendly composite insulating coating on its surface is immersed in a sealing solution at a temperature of 35-40℃ for 15-25 seconds, and then pulled out at a uniform speed of 1-3 mm / s. The residual liquid on the edges and corners of the amorphous magnetic core is blown away with clean, oil-free compressed air, and then dried in a hot air circulating oven at 80℃ for 8-12 minutes to complete the sealing post-treatment. The sealing solution is prepared by mixing deionized water and γ-glycidoxypropyltrimethoxysilane, with the mass fraction of γ-glycidoxypropyltrimethoxysilane being 0.5-1.0%.

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