Inorganic-organic coated amorphous soft magnetic material and preparation method thereof

Abstract

The invention discloses an inorganic-organic coated amorphous soft magnetic material and a preparation method thereof, the inorganic-organic coated amorphous soft magnetic material is obtained by firstly carrying out inorganic coating on an amorphous soft magnetic material through triethanolamine phosphate and then carrying out organic coating through epoxy resin. Through a composite coating system of triethanolamine phosphate and epoxy resin, the salt spray resistance of the material can be effectively improved, and the stability of the amorphous soft magnetic material in a corrosive environment is remarkably enhanced; meanwhile, the coating system is beneficial to reducing the dielectric constant of the material and improving the resistivity, and can synergistically improve the mechanical property and the magnetic property of the material and reduce the magnetic loss. The coating process has the characteristics of simplified flow and convenience in operation, the formed coating layer is uniform, compact and excellent in stability, and the coating process is suitable for large-scale production and has important application value and industrialization potential in the field of high-frequency inductance elements.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of soft magnetic composite materials, and particularly relates to an inorganic-organic coated amorphous soft magnetic material and a preparation method thereof. BACKGROUND

[0002] With the rapid development of consumer electronics, new energy automobile electronics and other industries, inductance components are accelerating evolution towards miniaturization, high frequency and high power density. As the functional substrate of core electromagnetic components such as inductors and transformers, the performance parameters of soft magnetic materials directly determine the electromagnetic conversion efficiency, reliability and service life of the devices, so the comprehensive requirements for low dielectric, high resistivity, corrosion resistance and stability, and mechanical adaptation are increasingly stringent.

[0003] Amorphous soft magnetic materials have become the preferred raw material for high-frequency inductors due to their high magnetic permeability, low coercivity, and narrow magnetic hysteresis loop. However, their inherent defects seriously restrict their application expansion: first, the high dielectric constant easily leads to an increase in inductance parasitic capacitance, a decrease in self-resonant frequency, and an increase in device heating and signal interference; second, the low resistivity produces significant eddy current loss in alternating magnetic field environments, which not only reduces electromagnetic conversion efficiency but also affects device stability due to Joule heat accumulation; third, the poor environmental stability makes the surface easily eroded by moisture, salt spray and other corrosive media, leading to a decline in magnetic properties, especially in high-reliability fields such as automotive electronics and aerospace, corrosion-induced magnetic core failure may directly cause system failure.

[0004] To address the above problems, insulation coating modification is a low-cost and highly adaptive solution. Existing technologies mainly use inorganic or organic single coating systems, and some schemes attempt composite coating, but all have deficiencies: Organic coating system: using phenolic resin, silicone resin and other coating agents, although the process is simple and the coating layer is flexible, it is easily decomposed and carbonized in high-temperature environments, and easily hydrolyzed and aged in long-term salt spray environments, leading to peeling of the coating layer from the substrate and loss of insulation protection ability, which cannot meet the long-term service requirements in complex working conditions.

[0005] Inorganic coating system: using phosphate, metal oxide and other coating agents, the formed coating layer has strong density and good corrosion resistance, but has inherent defects of high brittleness and easy cracking, and the preparation process requires high-temperature calcination, which is complex, high in energy consumption and difficult to scale up for mass production.

[0006] Part composite coating scheme: for example, the patent CN109545537A discloses "phosphating treatment + organic-inorganic composite coating" method, its core is that the carbonyl iron powder is first treated by phosphating with phosphoric acid or aluminum dihydrogen phosphate to form a bottom layer of phosphating film, and then the phosphating film is coated with organic silicon resin, epoxy resin and inorganic powder such as nano SiO2 and α-Al2O3. Although this scheme attempts to improve the performance through a multi-layer structure, it still has some key problems: first, the phosphating layer has a performance balance problem, the phosphating film formed by too low phosphating concentration is thin and discontinuous, which cannot effectively isolate the corrosive medium, and too high concentration will make the phosphating layer a non-magnetic phase, resulting in a significant decrease in the magnetic permeability of the material; second, the phosphating film itself has a loose structure, and the subsequent organic-inorganic coating layer is only physically adsorbed, so the interfacial adhesion is weak, and micro-cracks or interlayer peeling may occur during processing or service, and the corrosive medium can easily penetrate into the substrate through the defects; third, the inorganic coating material (nano SiO2, etc.) is simply physically mixed with the organic resin, and no chemical bond is formed with the substrate, so the overall compactness of the coating layer is insufficient, and the corrosion resistance in long-term salt spray environment is limited, and the process includes phosphating, multiple mixing, granulation and other steps, so the process is complex and the parameter control is difficult, and it is difficult to balance the magnetic performance, insulation performance and large-scale production requirements.

[0007] In summary, the existing single inorganic or organic coating system and part of the composite coating scheme cannot meet the comprehensive performance requirements of low dielectric constant, high resistivity, environmental stability and high interfacial adhesion, and it is difficult to meet the technical requirements of the development of electronic components to high frequency and high reliability. Therefore, developing a composite coating technology that can optimize the above-mentioned performances has become a key technical problem to solve the application bottleneck of amorphous soft magnetic materials. SUMMARY

[0008] In view of the core problems of the existing inorganic coating layer of amorphous soft magnetic material, the organic coating layer is easy to peel off, and the composite system is separated, the present application provides an inorganic-organic coated amorphous soft magnetic material and a preparation method thereof. The present application innovatively replaces the traditional phosphating layer and single inorganic coating agent with triethanolamine phosphate, utilizes the stable coordination bond between the phosphate group in the molecule and the iron ion on the surface of the amorphous substrate, the interfacial affinity of the ethanolamine chain hydroxyl group and the defect filling effect of the tertiary nitrogen atom, and constructs a dense inorganic adsorption layer on the surface of the amorphous powder without high temperature calcination, thereby avoiding the inherent problems of the phosphating layer from the root; then a chemical bridge is built by a silane coupling agent, so that the three-dimensional flexible network formed by the curing of the epoxy resin is covalently connected with the inorganic layer to construct an integrated composite coating structure of "inorganic dense protection-organic flexible toughening". Through the synergistic regulation of the low dielectric properties of the inorganic phase and the molecular structure of the organic phase, the comprehensive optimization of the dielectric constant reduction, the resistivity improvement and the salt spray resistance enhancement is realized, the core magnetic properties such as the magnetic permeability and the low magnetic loss are guaranteed, and finally the high-performance amorphous soft magnetic material meeting the requirements of high-frequency inductors, new energy vehicle electronics and other harsh scene requirements is obtained.

[0009] The present application is to achieve the purpose, using the following technical solutions: A preparation method of inorganic-organic coated amorphous soft magnetic material, comprising the following steps: Step 1, surface pretreatment of amorphous soft magnetic material Take 100-200g of amorphous soft magnetic material, add 200-400mL of solvent, and clean under ultrasonic conditions for 20-30min; after cleaning, dry the material in a vacuum environment or inert atmosphere at 50-60℃ for 1-3h to obtain clean and activated amorphous soft magnetic material matrix.

[0010] This step can remove oil stains and oxidation impurities on the surface of the amorphous soft magnetic material, activate the surface active sites, and lay a foundation for the firm combination of the subsequent coating layer.

[0011] Step 2, triethanolamine phosphate coating Add triethanolamine phosphate to the solvent and stir until completely dispersed; then add the amorphous soft magnetic material treated in step 1, and stir at a stirring speed of 300-500rpm at room temperature for 12-14h to make the triethanolamine phosphate firmly combined with the material surface through coordination bond; after the reaction is completed, wash the product with solvent for 3-5 times to remove unreacted triethanolamine phosphate; then dry the product in a vacuum oven at 60-85℃ for 2-3h, grind and sieve to obtain triethanolamine phosphate coated amorphous soft magnetic material. The mass fraction of triethanolamine phosphate in the amorphous soft magnetic material is 15-35%.

[0012] This step can form a dense inorganic coating layer that is strongly combined with the matrix.

[0013] Step 3, epoxy resin coating Take epoxy resin, curing agent, silane coupling agent, toughening agent, solvent, and triethanolamine phosphate coated amorphous soft magnetic material obtained in step 2; place the components in a mixing device, stir at a stirring speed of 300-500rpm at room temperature to mix the raw materials uniformly, and then sieve after acetone volatilization, and place until the solvent is completely volatilized to obtain inorganic-organic coated amorphous soft magnetic material. The mass ratio of epoxy resin, curing agent, silane coupling agent, toughening agent, solvent, and triethanolamine phosphate coated amorphous soft magnetic material is (2-4):(1-2):(0.5-0.75):(0.2-0.3):(12-15):100.

[0014] This step can form a flexible organic layer, improve the brittleness of the inorganic coating layer, improve the interfacial adhesion, and synergistically optimize the comprehensive performance.

[0015] Further, in step 1, the amorphous soft magnetic material is selected from at least one of Fe-Si-B-C, Fe-Si-B-P-C and Fe-Si-B-Nb-Cu, and is in a micron-sized spherical morphology.

[0016] Further, in step 2, the triethanolamine phosphate is C6H 18 NO6P or an alkyl-substituted compound thereof, a partially esterified compound of the phosphate group.

[0017] Further, in step 3: the epoxy resin is at least one of a bisphenol A type epoxy resin and a phenol aldehyde type epoxy resin. The curing agent is at least one of 4,4-diamino diphenyl sulfone, 4,4-diamino diphenyl methane and diethyl toluene diamine. The silane coupling agent is at least one of gamma-aminopropyl triethoxysilane, gamma-(2,3-epoxypropoxy) propyl trimethoxysilane and gamma-methacryloyloxy propyl trimethoxysilane. The toughening agent is at least one of polyether sulfone, polysulfone, polyether imide, polycarbonate and polyvinyl butyral.

[0018] Further, the solvent used in steps 1 to 3 is independently selected from at least one of methanol, ethanol and propylene glycol.

[0019] Compared with the prior art, the present application realizes the modification of the amorphous soft magnetic material through the composite coating design of the triethanolamine phosphate inorganic layer-epoxy resin organic layer from the chemical action, structural synergy and performance optimization, and the specific beneficial effects are embodied in: 1. Triethanolamine phosphate forms a uniform and dense inorganic coating layer on the surface of amorphous soft magnetic material through the synergistic effect of "chemical anchoring + physical barrier": the phosphate group (-PO(OH)2) in its molecule has a strong complexing ability, which can react with iron ions on the surface of amorphous soft magnetic material to form stable inner coordination bonds. The hydroxyl groups in the ethanolamine chain bind to the surface oxides / hydroxyl groups through hydrogen bonds, further enhancing the interface affinity and uniformity of coverage. The lone pair electrons on the tertiary nitrogen atom can also form coordination bonds with the empty d orbitals of metal atoms, especially in areas with thin or defective oxide layers, directly interacting with iron atoms to fill interface defects. Through the synergistic effect of these three types of functional groups, a multi-dimensional chemical adsorption layer is formed, achieving firm anchoring of the coating layer to the substrate and addressing the weak bonding problem of traditional inorganic coating layers. At the same time, the lone pair electrons in the amine group are easily adsorbed on the positively charged areas of the metal surface to form a charge adsorption layer. The phosphate groups cross-link into a film through intermolecular forces, and their polar groups can also fill interface gaps through physical adsorption, creating a dual protection structure of charge barrier + physical barrier, effectively blocking the penetration of corrosive media such as moisture and salt spray. This "chemical anchoring + physical barrier" composite coating system not only ensures that the coating layer is not easily detached or cracked through stable chemical bonds, but also blocks the corrosion path and electron conduction path through a dense physical barrier, ultimately synchronously improving the magnetic properties, dielectric properties, and corrosion resistance of amorphous soft magnetic materials, laying the foundation for subsequent epoxy resin organic coating.

[0020] 2. The epoxy resin organic coating layer uniformly infiltrates and tightly covers the surface of the triethanolamine phosphate coated amorphous soft magnetic material particles, forming a three-dimensional cross-linked network after curing to firmly fix the particles. The polar groups in its molecule form stable interface adsorption with the oxides / hydroxyl groups on the material surface through van der Waals forces and hydrogen bonds, and form firm covalent bonds with the inorganic coating layer and substrate through the bridging action of silane coupling agents, creating a tight bonding system of "organic-inorganic-substrate". The organic coating layer forms a dense and continuous protective structure that effectively blocks the penetration of moisture, salt spray, and various chemical corrosive media, achieving all-around isolation of the magnetic core from the external corrosive environment. This not only solves the defects of traditional organic coating layers such as easy hydrolysis, aging, and interface peeling, but also significantly improves the long-term service stability and service life of electromagnetic components.

[0021] 3、The triethanolamine phosphate / epoxy resin composite coating layer constructed by the present application solves the problems of high dielectric, low resistivity, large magnetic loss and poor salt mist stability of the existing single coating system and part of the composite coating scheme through the synergistic regulation of the inorganic phase (triethanolamine phosphate) and the organic phase (epoxy resin): on the one hand, by means of the low dielectric property of the inorganic phase and the molecular structure design of the organic phase, the interface polarization effect is synergistically inhibited, not only the overall dielectric constant of the material is significantly reduced, but also the electronic conduction path is blocked through the dense coating layer, the resistivity is effectively improved, the parasitic capacitance and eddy current loss of the inductor are greatly reduced, at the same time, the magnetic domain disorder caused by corrosion and interface defects of the amorphous soft magnetic material particles in the processing or service process is avoided, the risk of magnetic performance degradation is reduced, the excellent magnetic permeability and low magnetic loss of the magnetic core are maintained for a long time, and the electromagnetic conversion efficiency is significantly improved; on the other hand, the composite barrier blocks the penetration path of corrosive media such as moisture and salt mist through the dense structure of the inorganic phase, and the adhesion of the coating layer is enhanced by the excellent interface compatibility of the organic phase, and the contact reaction between the corrosive medium and the magnetic core is inhibited, and the salt mist stability and service life of the material in harsh environment are greatly improved.

[0022] 4、The coating process of the present application is simple, controllable, and the prepared coating layer is uniform, dense and stable. Without complex equipment modification, it is suitable for large-scale production demand. The high-performance amorphous soft magnetic material prepared by the present application has significant application value and broad industrialization potential in the field of high-frequency inductor elements. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 SEM image of the inorganic-organic coated amorphous soft magnetic material prepared in Example 1.

[0024] Figure 2 Dielectric constant diagram of the ring inductor for testing obtained from each example and comparative example.

[0025] Figure 3 Resistivity diagram of the coated amorphous soft magnetic material obtained from each example and comparative example.

[0026] Figure 4 Appearance diagram of 12 hours, 24 hours and 48 hours salt spray test of the ring inductor for testing obtained from each example and comparative example. DETAILED DESCRIPTION

[0027] The technical solutions of the present application will be described in detail below through specific examples. The following examples are implemented on the premise of the technical solutions of the present application, and detailed implementation methods and specific operation processes are given, but the protection scope of the present application is not limited to the following examples.

[0028] Example 1 In this embodiment, the inorganic-organic coated amorphous soft magnetic material is prepared according to the following steps: Step 1, surface pretreatment of amorphous soft magnetic material Take 100 g of amorphous soft magnetic material (Fe-Si-B-C amorphous powder, micron-sized spherical morphology, average particle size 20 μm), add 200 mL of ethanol, and clean under ultrasonic conditions for 20 min; after cleaning, place the material in a vacuum environment, dry at 60°C for 2 h, and obtain a clean activated amorphous soft magnetic material substrate.

[0029] Step 2, triethanolamine phosphate coating Take 15 g of triethanolamine phosphate and add it to 500 mL of ethanol, stir until completely dispersed, then add 100 g of the above pretreated amorphous soft magnetic material (triethanolamine phosphate accounts for 15% of the mass of the amorphous soft magnetic material), and stir at a stirring speed of 300 rpm at room temperature (25°C) for 12 h; after the reaction is completed, wash the product with ethanol 3 times to remove unreacted triethanolamine phosphate; then place the product in a vacuum oven and dry at 85°C for 3 h, grind and sieve to obtain triethanolamine phosphate coated amorphous soft magnetic material.

[0030] Step 3, epoxy resin coating According to the mass ratio 2:1:0.5:0.2:12:100, take bisphenol A type epoxy resin, 4,4-diamino diphenyl sulfone (curing agent), γ-aminopropyl triethoxysilane (silane coupling agent), polyvinyl butyral (toughening agent), acetone (solvent), and the triethanolamine phosphate coated amorphous soft magnetic material obtained in step 2; place the components in a mixing device, stir at room temperature and 300 rpm for 10 min to mix the raw materials uniformly, evaporate the acetone, then pass through an 80 mesh stainless steel screen, and stand for 8 hours to remove the remaining solvent, obtaining inorganic-organic coated amorphous soft magnetic material.

[0031] Add 0.1% of release agent zinc stearate to the inorganic-organic coated amorphous soft magnetic material, mix uniformly, and then press into a magnetic ring under a pressure of 6 tons; anneal the magnetic ring at 180°C for 2 hours to obtain a test ring inductor.

[0032] Example 2 This example prepares inorganic-organic coated amorphous soft magnetic material and processes it into a test ring inductor according to the same method as Example 1, the only difference being that the mass of triethanolamine phosphate in step 2 is 25 g (25% of the mass of the amorphous soft magnetic material).

[0033] Example 3 This example prepares inorganic-organic coated amorphous soft magnetic material and processes it into a test ring inductor according to the same method as Example 1, the only difference being that the mass of triethanolamine phosphate in step 2 is 35 g (35% of the mass of the amorphous soft magnetic material).

[0034] Comparative Example 1 This comparative example prepared the organic coating type amorphous soft magnetic material alone into a test toroidal inductor, similar to Example 1, the difference is that step 2 is not performed, and the amorphous soft magnetic material treated by step 1 is directly added in step 3.

[0035] Figure 1 The SEM image of the inorganic-organic coated amorphous soft magnetic material obtained in Example 1. As can be clearly observed from the figure, the surface of the amorphous soft magnetic material particles is completely covered by a continuous and uniform composite coating layer, with no obvious bare area or coating defect, and the product particle size is about 22 μm, and the coating layer thickness is uniform.

[0036] Figure 2 The dielectric constant change curve of the test toroidal inductor obtained in each example and comparative example. As can be seen, with the increase of triethanolamine phosphate coating amount, the dielectric constant of the sample shows a continuous decreasing trend, and the dielectric constant of all samples monotonously decreases with the increase of frequency. In the high frequency region (10 7 Hz), the dielectric constant of the samples obtained in Example 1, Example 2 and Example 3 is reduced by 10.9%, 18.9% and 32.3% respectively compared with the sample of Comparative Example 1. By reducing the dielectric constant of the material, the leakage current of the inductor can be effectively reduced, the equivalent parallel capacitance in the core and the total parasitic capacitance of the inductor can be reduced, and the self-resonant frequency (SRF) of the inductor can be improved, so that it can work effectively at a higher frequency.

[0037] Figure 3 The resistivity change curve of the coated amorphous soft magnetic material prepared in each example and comparative example with frequency. As can be seen, with the increase of triethanolamine phosphate coating amount, the resistivity of the sample gradually increases. In the high frequency region (10 7 Hz), the resistivity of the sample obtained in Example 3 is increased by 218.8% compared with the resistivity of the sample of Comparative Example 1. By increasing the resistivity of the material, the eddy current loss of the composite material can be effectively reduced, and then the Joule heat of the material and the heating phenomenon of the device can be reduced, which is suitable for high frequency inductor application.

[0038] Table 1 is the mechanical and magnetic properties of the test toroidal inductor obtained in each example and comparative example. With the increase of triethanolamine phosphate coating amount, the mechanical properties of the amorphous soft magnetic material are improved, and the green strength of the sample is increased from 110 MPa to 116 MPa. At the same time, the magnetic properties of the amorphous soft magnetic material are improved, compared with Comparative Example 1, the magnetic permeability of Example 3 is increased from 35.9 to 38.8; the withstand voltage is increased from 0.7 KV to 1.7 KV, which is increased by 142.86%; the power loss is decreased by 3.95%.

[0039] Table 1 Figure 4 The annular inductors obtained in each example and the comparative example were tested for corrosion at a temperature of 35°C in a 5% NaCl salt spray for 12h, 24h and 48h. It can be seen that as the treatment time increases, the rust of each sample gradually becomes more serious. At each time period, the sample without composite coating treatment is more serious than the sample after treatment, and as the coating amount increases, the rust condition improves. After coating, the corrosion resistance can be improved, and the service life of the inductor can be prolonged.

[0040] The above merely illustrates the embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing an inorganic-organic coated amorphous soft magnetic material, characterized by: First, the amorphous soft magnetic material is inorganically coated with triethanolamine phosphate, and then organically coated with epoxy resin to obtain an inorganic-organic coated amorphous soft magnetic material.

2. The preparation method of the inorganic-organic coated amorphous soft magnetic material according to claim 1, characterized in that, Includes the following steps: Step 1: Surface pretreatment of amorphous soft magnetic materials Take 100-200g of amorphous soft magnetic material, add 200-400mL of solvent, and clean under ultrasonic conditions for 20-30min; after cleaning, place the material in a vacuum environment or inert atmosphere to dry, and obtain a clean and activated amorphous soft magnetic material matrix; Step 2: Triethanolamine phosphate coating Triethanolamine phosphate was added to a solvent and stirred until completely dispersed. Then, the amorphous soft magnetic material treated in step 1 was added and stirred for 12-14 hours. After the reaction was completed, the product was washed with solvent to remove unreacted triethanolamine phosphate. Subsequently, the product was vacuum dried, ground and sieved to obtain amorphous soft magnetic material coated with triethanolamine phosphate. Step 3: Epoxy Resin Coating The epoxy resin, curing agent, silane coupling agent, toughening agent, solvent, and the amorphous soft magnetic material coated with triethanolamine phosphate obtained in step 2 are placed in a mixing device and stirred evenly at room temperature to obtain an inorganic-organic coated amorphous soft magnetic material.

3. The method for preparing inorganic-organic coated amorphous soft magnetic materials according to claim 2, characterized in that, The amorphous soft magnetic material is selected from at least one of Fe-Si-BC, Fe-Si-BPC and Fe-Si-B-Nb-Cu, and exhibits a micron-sized spherical morphology.

4. The preparation method of the inorganic-organic coated amorphous soft magnetic material according to claim 2, characterized in that, said triethanolamine phosphate is C6H 18 NO6P or an alkyl substituted compound thereof, a partially esterified compound of the phosphate group.

5. The method for preparing the inorganic-organic coated amorphous soft magnetic material according to claim 2, characterized in that, The epoxy resin is at least one of bisphenol A type epoxy resin and phenolic type epoxy resin; the curing agent is at least one of 4,4-diaminodiphenyl sulfone, 4,4-diaminodiphenylmethane and diethyltoluenediamine; the silane coupling agent is at least one of γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane and γ-methacryloyloxypropyltrimethoxysilane; the toughening agent is at least one of polyethersulfone, polysulfone, polyetherimide, polycarbonate and polyvinyl butyral.

6. The method for preparing the inorganic-organic coated amorphous soft magnetic material according to claim 2, characterized in that, In step 2, triethanolamine phosphate accounts for 15-35% of the mass of the amorphous soft magnetic material.

7. The method for preparing inorganic-organic coated amorphous soft magnetic materials according to claim 2, characterized in that, In step 3, the mass ratio of epoxy resin, curing agent, silane coupling agent, toughening agent, solvent and triethanolamine phosphate-coated amorphous soft magnetic material is (2-4):(1-2):(0.5-0.75):(0.2-0.3):(12-15):

100.

8. The method for preparing inorganic-organic coated amorphous soft magnetic materials according to claim 2, characterized in that, The solvents used in steps 1 to 3 are each independently selected from at least one of methanol, ethanol, and propylene glycol.

9. An inorganic-organic coated amorphous soft magnetic material prepared by the preparation method according to any one of claims 1 to 8.

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