High-reliability metal soft magnetic composite material, preparation method thereof and inductor

Abstract

The invention relates to a high-reliability metal soft magnetic composite material, a preparation method thereof and an inductor. The high-reliability metal soft magnetic composite material comprises a metal soft magnetic alloy powder core, and a phosphate passivation layer, an inorganic insulating coating layer and an organic bonding coating layer which sequentially coat the surface of the metal soft magnetic alloy powder core from inside to outside, the phosphate passivation layer is a compact phosphate passivation film generated by in-situ reaction of weak acid and the surface of the metal magnetically soft alloy powder core, and the thickness of the phosphate passivation layer is 50-200 nm; the inorganic insulating coating layer is a silicon dioxide insulating film which takes a silane coupling agent as a bridge and is generated on the surface of the phosphate passivation layer in situ, and the thickness of the inorganic insulating coating layer is 100nm to 300nm; and the organic bonding coating layer is an organic coating film formed by curing a polymer adhesive, is coated on the outer surface of the inorganic insulating coating layer, and has the thickness of 200nm to 500nm. The method has the beneficial effects that the problems of uneven coating and poor batch stability of a conventional stirring process are avoided, and the industrial pain points of mold pressing cracking and bulging are solved.

Description

Technical Field

[0001] This invention relates to the field of soft magnetic composite materials technology, specifically to a high-reliability metal soft magnetic composite material, its preparation method, and an inductor. Background Technology

[0002] Molded power inductors are widely used in high-power circuits such as industrial control motherboards, graphics cards, laptops, automotive equipment, communication equipment, and medical equipment. Their core performance indicators are directly determined by the magnetic parameters, insulation performance, and structural stability of the soft magnetic composite material. Therefore, optimizing the performance of soft magnetic composite materials is the key to improving the overall performance of molded inductors.

[0003] In existing technologies, the ratio of passivation solution and the reaction process are difficult to control precisely, resulting in uneven coating of powder surface and excessive roughness, which directly deteriorates the magnetic and insulation properties of the powder core. At the same time, the single-layer coating structure cannot take into account both insulation and formability. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application proposes a high-reliability metal soft magnetic composite material, its preparation method, and an inductor. By utilizing the cavitation and dispersion effects of ultrasound, powder agglomeration is broken up, and the coating layer grows uniformly and densely on the surface of individual particles, avoiding the problems of uneven coating and poor batch stability in conventional stirring processes. Through a three-layer core-shell composite structure design, the resistivity and pressure resistance of the material are improved. The inorganic layer ensures temperature resistance, while the organic layer enhances moldability, solving the industry pain points of molding cracking and bulging.

[0005] The following is the technical solution of the present invention: a high-reliability metal soft magnetic composite material, comprising: a metal soft magnetic alloy powder core, and a phosphate passivation layer, an inorganic insulating coating layer and an organic adhesive coating layer sequentially coated on the surface of the metal soft magnetic alloy powder core from the inside out; The phosphate passivation layer is a dense phosphate passivation film formed by the in-situ reaction of weak acid with the core surface of the soft magnetic alloy powder, with a thickness of 50 nm to 200 nm. The inorganic insulating coating layer is a silicon dioxide insulating film formed in situ on the surface of the phosphate passivation layer with silane coupling agent as a bridge, and the thickness is 100nm to 300nm. The organic adhesive coating layer is an organic coating film formed by curing a polymer adhesive, which coats the outer surface of the inorganic insulating coating layer, with a thickness of 200nm to 500nm.

[0006] As a preferred embodiment of the present invention, the metal soft magnetic alloy powder core is an iron-based soft magnetic alloy powder, selected from one or more composite powders of iron-nickel soft magnetic powder, iron-nickel-molybdenum soft magnetic powder, iron-silicon-aluminum soft magnetic powder, iron-silicon soft magnetic powder and iron-silicon-chromium soft magnetic powder, and the particle size of the metal soft magnetic alloy powder core is 2μm to 50μm, passing through a 300 to 500 mesh sieve.

[0007] As a preferred embodiment of the present invention, the raw material for the phosphate passivation layer is a passivation solution, which includes a weak acid and a solvent. The weak acid is selected from one or more of phosphoric acid, ammonium dihydrogen phosphate, sodium ammonium hydrogen phosphate, oxalic acid and nitrate, and the solvent is selected from one or more of distilled water, ethyl acetate, acetone, ethanol, isopropanol and p-xylene. The amount of weak acid used is 0.1wt% to 1.0wt% of the mass of the metal soft magnetic alloy powder core.

[0008] As a preferred embodiment of the present invention, the raw materials for the inorganic insulating coating layer include a silane coupling agent and tetraethyl orthosilicate. The silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and vinyltriethoxysilane, and is used in an amount of 0.2wt% to 12wt% of the core mass of the soft magnetic alloy powder. The amount of tetraethyl orthosilicate is used in an amount of 0.1wt% to 1.0wt% of the core mass of the soft magnetic alloy powder.

[0009] As a preferred embodiment of the present invention, the raw materials of the organic adhesive coating layer include an adhesive and an organic solvent. The adhesive is selected from one or more of epoxy resin, silicone resin, polyamide resin, polypropylene silicone resin, tetraethyl orthosilicate, polyvinyl alcohol and biphenyl-type phenolic epoxy resin, and the amount used is 1.0 wt% to 4.0 wt% of the mass of the inorganically coated powder. The organic solvent is selected from one or more of ethyl acetate, acetone, ethanol, isopropanol and p-xylene, and the amount used is 8 wt% to 15 wt% of the mass of the inorganically coated powder.

[0010] A method for preparing a high-reliability soft magnetic metal composite material includes the following steps: S1. Screen the soft magnetic alloy powder of the metal with a preset particle size, weigh it according to the preset mass after sieving, and set it aside. S2. Prepare passivation solution. Add the passivation solution and the soft magnetic alloy powder to an ultrasonic stirring tank and complete the passivation reaction under low temperature ultrasonic conditions. After the reaction is completed, clean, dry and sieve to obtain passivation powder. S3. Prepare a silane coupling agent solution. Add the silane coupling agent solution, tetraethyl orthosilicate and passivation powder to an ultrasonic stirring tank and complete the in-situ coating reaction under ultrasonic conditions at room temperature. After the reaction is completed, dry and sieve to obtain inorganic coated powder. S4. Mix the organic solvent and adhesive evenly, add the inorganic coating powder to the mixture, stir and mix, then sieve and dry to obtain granulated powder.

[0011] As a preferred embodiment of the present invention, in S2, the solvent of the passivation solution is freshly prepared distilled water at 5°C to 10°C, the passivation reaction temperature is 5°C to 18°C, the ultrasonic dispersion system cyclic vibration time is 8 min to 12 min, the drying temperature after passivation is 60°C to 90°C, the drying time is 20 min to 40 min, and the dried powder passes through a 300 to 500 mesh sieve.

[0012] As a preferred embodiment of the present invention, in S3, the in-situ coating reaction temperature is 20°C to 25°C, the ultrasonic dispersion system cyclic vibration time is 8 min to 12 min, the drying temperature after reaction is 60°C to 90°C, the drying time is 10 min to 30 min, and the dried powder passes through a 300 to 500 mesh sieve.

[0013] As a preferred embodiment of the present invention, in S4, the drying temperature after organic coating is 50°C to 80°C, the drying time is 30 min to 60 min, and the granulated powder is obtained by passing through a 40 to 200 mesh sieve.

[0014] An inductor includes: a magnetic core body and a metal coil embedded inside the magnetic core body, which are sequentially molded and heat-treated; In the compression molding step, a lubricant is added to the granulated powder. The lubricant is selected from one or more of graphite, hexagonal boron nitride, zinc stearate and microcrystalline wax. The amount of lubricant is 0.1wt% to 0.9wt% of the mass of the granulated powder. The compression molding pressure is 11T to 13T. The heat treatment process involves a gradient heating process in a N2 atmosphere at -0.09 MPa, specifically: heating from room temperature to 150℃ for 40 min and holding for 40 min; heating to 300℃ for 40 min and holding for 40 min; heating to 450℃ for 40 min and holding for 40 min; heating to 600℃ for 40 min and holding for 40 min; and heating to 700℃ to 720℃ for 40 min and holding for 60 min; wherein the heating rate is 1.5℃ / min to 6℃ / min.

[0015] The beneficial effects of this invention are: 1. In this invention, the three-layer core-shell composite structure design improves the resistivity and pressure resistance of the material, effectively suppresses eddy current loss, and at the same time, the inorganic layer ensures temperature resistance and the organic layer improves formability, thus solving the industry pain points of cracking and bulging in integrally molded inductors. 2. In this invention, the cavitation effect and dispersion effect of ultrasound break up powder agglomeration, and the coating layer grows uniformly and densely on the surface of a single particle, avoiding the problems of uneven coating and poor batch stability in conventional stirring processes. 3. In this invention, a segmented gradient heating heat treatment process is adopted. Through multi-stage heating and heat preservation, the internal stress of molding is gradually eliminated, the magnetic domain structure is optimized, and the hysteresis loss is reduced. 4. This invention can effectively block the intrusion of corrosive media, can pass the 24-hour salt spray test without rust, and has excellent resistance to high and low temperatures and damp heat, which can meet the application requirements of high reliability scenarios such as automotive electronics. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the core-shell encapsulation structure of the metal soft magnetic composite material of the present invention; Figure 2 This is a flowchart illustrating the preparation method of the present invention; Figure 3 This is a diagram illustrating the bridging mechanism of the silane coupling agent of the present invention. Figure 4 This is a comparison diagram of the granulated powder of the present invention after 24 hours of salt spray test; Figure 5 This is a comparison diagram of the 24H salt spray test of the magnetic ring of the present invention; In the figure: 1. Soft magnetic alloy powder core; 2. Phosphate passivation layer; 3. Inorganic insulating coating layer; 4. Organic adhesive coating layer. Detailed Implementation

[0017] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0018] Example 1 like Figure 1 As shown, a high-reliability metal soft magnetic composite material is a core-shell multilayer composite coating structure, including: a metal soft magnetic alloy powder core 1, and a phosphate passivation layer 2, an inorganic insulating coating layer 3, and an organic adhesive coating layer 4 sequentially coated on the surface of the metal soft magnetic alloy powder core 1 from the inside to the outside.

[0019] The core 1 of the metal soft magnetic alloy powder is an iron-based soft magnetic alloy powder, selected from one or more composite powders of iron-nickel soft magnetic powder, iron-nickel-molybdenum soft magnetic powder, iron-silicon-aluminum soft magnetic powder, iron-silicon soft magnetic powder, and iron-silicon-chromium soft magnetic powder; the particle size is 2μm to 50μm, and it passes through a 300 to 500 mesh sieve to improve the uniformity of powder particle size.

[0020] The phosphate passivation layer 2 is a dense phosphate passivation film with a thickness of 50 nm to 200 nm, formed by the in-situ reaction of a weak acid with the surface of the soft magnetic alloy powder core 1. The raw material for the phosphate passivation layer 2 is a passivation solution, which includes a weak acid and a solvent. The weak acid is selected from one or more of phosphoric acid, ammonium dihydrogen phosphate, sodium ammonium hydrogen phosphate, oxalic acid, and nitrates. The solvent is selected from one or more of distilled water, ethyl acetate, acetone, ethanol, isopropanol, and p-xylene. The amount of weak acid used is 0.1 wt% to 1.0 wt% of the mass of the soft magnetic alloy powder core 1.

[0021] The inorganic insulating coating layer 3 is a silicon dioxide insulating film formed in situ on the surface of the phosphate passivation layer 2 using a silane coupling agent as a bridge, with a thickness of 100 nm to 300 nm. The raw materials for the inorganic insulating coating layer 3 include a silane coupling agent and tetraethyl orthosilicate; the silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and vinyltriethoxysilane, and its amount is 0.2 wt% to 12 wt% of the mass of the metal soft magnetic alloy powder core 1; the amount of tetraethyl orthosilicate is 0.1 wt% to 1.0 wt% of the mass of the metal soft magnetic alloy powder core 1.

[0022] The organic adhesive coating layer 4 is an organic coating film formed by curing a polymer adhesive, which coats the outer surface of the inorganic insulating coating layer 3, with a thickness of 200 nm to 500 nm. The raw materials of the organic adhesive coating layer 4 include adhesives and organic solvents. The adhesive is selected from one or more of epoxy resin, silicone resin, polyamide resin, polypropylene silicone resin, tetraethyl orthosilicate, polyvinyl alcohol, and biphenyl-type phenolic epoxy resin, and its amount is 1.0 wt% to 4.0 wt% of the mass of the inorganic coated powder. The organic solvent is selected from one or more of ethyl acetate, acetone, ethanol, isopropanol, and p-xylene, and its amount is 8 wt% to 15 wt% of the mass of the inorganic coated powder.

[0023] Example 2 like Figure 2 and Figure 3 As shown, a method for preparing a high-reliability soft magnetic metal composite material includes the following steps: S1. Screening raw materials and pre-treatment: Screen the soft magnetic alloy powder of the metal with a preset particle size, weigh it according to the preset mass after sieving and set it aside. Metallic soft magnetic alloy powder with a particle size of 2μm to 50μm is screened, and agglomerated particles and impurities are removed by passing it through a 300 to 500 mesh sieve. The powder is then weighed and set aside according to the preset mass.

[0024] S2. Passivation of powder: Prepare passivation solution, add passivation solution and metal soft magnetic alloy powder into ultrasonic stirring tank, complete the passivation reaction under low temperature ultrasonic conditions, and after the reaction is completed, clean, dry and sieve to obtain passivated powder. Weigh out a predetermined amount of weak acid and mix it with freshly prepared distilled water at 5°C to 10°C to prepare a passivation solution. The passivation liquid and the weighed soft magnetic alloy powder were poured into an ultrasonic stirring tank and circulated and vibrated for 10 minutes in an ultrasonic dispersion system at 5℃ to 18℃. The synergistic effect of ultrasonic cavitation, mechanical effect and thermal effect broke the powder agglomeration, so that the surface of each powder particle was fully in contact with the passivation liquid and an in-situ passivation reaction occurred, and a uniform and dense phosphate passivation layer 2 was generated on the powder surface. After the reaction is complete, the supernatant is poured off and the powder is dried at 60°C to 90°C for 20 to 40 minutes. The dried powder is then passed through a 300 to 500 mesh sieve to obtain passivated powder.

[0025] S3. Inorganic coating: Prepare a silane coupling agent solution, add the silane coupling agent solution, tetraethyl orthosilicate and passivation powder to an ultrasonic stirring tank, and complete the in-situ coating reaction under ultrasonic conditions at room temperature. After the reaction is completed, dry and sieve to obtain inorganic coated powder. Weigh out a predetermined amount of silane coupling agent, pour it into ethanol and stir until homogeneous to obtain a silane coupling agent solution; The silane coupling agent solution was poured into an ultrasonic stirring tank, and the preset mass of tetraethyl orthosilicate and the passivation powder obtained in step S2 were added. The mixture was circulated and vibrated for 10 minutes in an ultrasonic dispersion system at 20°C to 25°C. The powder was uniformly dispersed by the synergistic effect of ultrasound, so that the silane coupling agent was fully adsorbed on the surface of the passivation powder and catalyzed the hydrolysis and polycondensation reaction of tetraethyl orthosilicate, thus generating a dense silica inorganic insulating layer in situ on the surface of the phosphate passivation layer 2. After the reaction is complete, spread the powder out to air dry until it is slightly moist, and then dry it at 60℃ to 90℃ for 10 to 30 minutes. The dried powder is then passed through a 300 to 500 mesh sieve to obtain inorganic coated powder.

[0026] S4. Organic coating granulation: Mix the organic solvent and adhesive evenly, add the inorganic coating powder to the mixture, stir and mix, then sieve and dry to obtain granulated powder; Mix the organic solvent and adhesive evenly according to the preset ratio, slowly add the inorganic coating powder obtained in step S3 to the mixture, stir and mix for 10 to 20 minutes, so that the adhesive is evenly coated on the surface of the inorganic coating powder. Granulate the powder while it is still semi-moist, passing it through a 40 to 200 mesh sieve. Take the powder between the sieve particles and dry it at 50 to 80 degrees Celsius for 30 to 60 minutes to obtain granulated powder.

[0027] It also includes the following steps: S5. Perform compression molding; Add a preset mass of lubricant to the granulated powder obtained in step S4, mix evenly, take a preset mass of powder and pre-made metal coil together and put them into a mold, mold them at room temperature under a pressure of 11T to 13T, clean the edges and burrs after demolding, and obtain an inductor blank. The lubricant is selected from one or more of graphite, hexagonal boron nitride, zinc stearate and microcrystalline wax, and the amount used is 0.1wt% to 0.9wt% of the granulated powder mass.

[0028] S6. Perform gradient heating heat treatment; The inductor blank obtained in step S5 is placed in an atmosphere furnace and subjected to gradient heating heat treatment in a N2 atmosphere at -0.09 MPa, as follows: The first stage involves raising the temperature from room temperature to 150℃ in 40 minutes and then maintaining the temperature for 40 minutes. The second stage involves raising the temperature to 300℃ in 40 minutes and maintaining the temperature for 40 minutes. The third stage involves raising the temperature to 450℃ in 40 minutes and holding it at that temperature for 40 minutes. The fourth stage involves raising the temperature to 600℃ in 40 minutes and holding it at that temperature for 40 minutes. The fifth stage involves raising the temperature to 700℃ to 720℃ over 40 minutes and holding it at that temperature for 60 minutes. The heating rate is 1.5℃ / min to 6℃ / min. After the heat preservation is completed, the furnace is naturally cooled down to obtain an integrally molded inductor.

[0029] Example 3 This embodiment provides an inductor made of a high-reliability metal soft magnetic composite material, which uses the metal soft magnetic composite material of Embodiment 1 and Embodiment 2, and includes: a magnetic core body and a metal coil embedded inside the magnetic core body.

[0030] The magnetic core body is made of granulated powder from a soft magnetic metal composite material, which is then molded and heat-treated in sequence. The magnetic core body is a closed magnetic circuit structure that is integrally pressed and formed, covering the outer periphery of the coil.

[0031] The metal coil is a pre-made flat enameled wire winding, pre-wound into a coil structure with a preset number of turns and shape, embedded inside the magnetic core body. The coil pins extend to the outside of the magnetic core body for electrical connection to the circuit board.

[0032] Example 4 This embodiment prepares a high-reliability metal soft magnetic composite material and an inductor, including the following steps: S1. Screening raw materials and pre-processing them; Take 1 kg of iron-silicon-chromium soft magnetic alloy powder with a particle size of 2 μm to 50 μm, pass it through a 400-mesh sieve, and set it aside for later use. S2. Passivate the powder; Take 0.2g of sodium ammonium hydrogen phosphate and mix it evenly with 1L of freshly prepared distilled water at a temperature of 5℃ to 10℃ to obtain a passivation solution; The passivation solution and iron-silicon-chromium alloy powder were poured into an ultrasonic stirring tank and circulated and vibrated for 10 minutes in an ultrasonic dispersion system at 5°C to 18°C. After vibration, let stand and pour off the supernatant. Wash three times with freshly prepared distilled water at 5°C to 10°C. Spread out and air dry until semi-moist. Bake at 80°C for 30 minutes. Pass the dried powder through a 400-mesh sieve to obtain passivated powder. S3. Perform inorganic coating; Take 2g of γ-aminopropyltriethoxysilane (APTES), pour it into 500mL of ethanol and stir well. Pour it into an ultrasonic stirring jar, then add 20g of tetraethyl orthosilicate (TEOS) and the passivation powder obtained in step S2. Cycle and vibrate in an ultrasonic dispersion system at 20℃ to 25℃ for 10min. After vibration, spread the powder out to air dry until slightly moist, then dry it at 80℃ for 20 minutes. The dried powder is then passed through a 400-mesh sieve to obtain inorganic coated powder. S4. Perform organic coating granulation; Take 150 mL of acetone and 40 g of organosilicon resin binder, mix them evenly, and slowly add the inorganic coating powder obtained in step S3 to the mixture. Stir and mix for 10 min, and granulate the powder through a 100-mesh sieve while it is still semi-wet. Take the powder with a particle size between 40-100 mesh and dry it at 60℃ for 45 min to obtain granulated powder. S5. Perform compression molding; Add 2g of zinc stearate lubricant to the granulated powder, mix well, take 2.5g of powder and pre-made coil and put them into the mold, and mold them at room temperature under 13T pressure. The magnetic ring size is 13mm outer diameter and 8mm inner diameter. After demolding, clean the edges and burrs to obtain the blank. S6. Perform gradient heating heat treatment; The blank was placed in an atmosphere furnace and subjected to gradient heating heat treatment under a nitrogen atmosphere of -0.09 MPa. The temperature was increased from room temperature to 150℃ in 40 min and held for 40 min; then increased to 300℃ in 40 min and held for 40 min; then increased to 450℃ in 40 min and held for 40 min; then increased to 600℃ in 40 min and held for 40 min; and finally increased to 700℃ in 40 min and held for 60 min. The heating rate was controlled between 1.5℃ / min and 6℃ / min throughout the process. After the holding period, the inductor was obtained by natural cooling with the furnace.

[0033] Comparative Example 1 The only difference between this comparative example and Example 4 is that the maximum temperature of the heat treatment in step S6 is 720°C, while the other components, amounts, process conditions and parameters are the same as in Example 4.

[0034] Comparative Example 2 The only difference between this comparative example and Example 4 is that the molding pressure in step S5 is 11T, while the other components, dosages, process conditions, and parameters are the same as in Example 4.

[0035] Comparative Example 3 The only difference between this comparative example and Example 4 is that the inorganic coating process in step S3 is omitted, and the passivated powder obtained in step S2 directly enters step S4 for organic coating granulation. The remaining components, dosages, process conditions and parameters are the same as in Example 4.

[0036] Comparative Example 4 The only difference between this comparative example and Example 4 is that: In step S2, powder passivation was performed using conventional mechanical stirring, eliminating ultrasonic vibration, and the mixture was stirred for 10 minutes. In step S3, during inorganic coating, the addition of tetraethyl orthosilicate was omitted, and only a silane coupling agent was used for surface treatment. The remaining components, dosages, process conditions, and parameters were the same as in Example 4.

[0037] Performance tests were conducted on Embodiment 4 of the present invention and Comparative Examples 1 to 4. The test parameters included: inductance value L, permeability μ, equivalent series resistance RS, quality factor Q, insulation resistance IR, blank strength and core loss.

[0038] The following tests were conducted: A MICROTEST-6377 soft magnetic material dynamic measurement device was used, with test conditions of 1V and 100kHz, to measure the inductance L, permeability μ, quality factor Q, and equivalent series resistance RS (at 1V and 1MHz); a 6220 DC source was used to apply a 30A current to measure the DC superposition characteristics of the sample; a Chroma 19073 AC / DC / IR tester was used, with a test voltage of 50V and a test time of 3s, to measure the insulation resistance IR of the sample; a push-pull force gauge was used to measure the curing strength of the sample, in kgf; and a Japan Iwasaki Communications Sy8218 BH analyzer was used, with test conditions of 500kHz / 20mT and 1MHz / 50mT, to measure the core loss of the sample. The test results are shown in Tables 1 and 2 below.

[0039] Table 1 shows the results of basic performance tests.

[0040] Table 2 shows the test results of magnetic core loss.

[0041] Based on the test data in Tables 1 and 2, and the comparison between Example 4, Comparative Example 1, and Comparative Example 2, it can be seen that the overall performance of the magnetic ring reaches its optimal level under the conditions of 13T and 700℃. As the temperature increases, the insulation performance deteriorates significantly; as the pressure decreases, the magnetic ring density decreases and the magnetic permeability deteriorates.

[0042] As can be seen from the comparison between Example 4 and Comparative Example 3, the inorganic coating layer has good pressure resistance and temperature resistance, which can ensure the stability of the coating effect of magnetic powder. However, its mechanical properties such as formability and adhesion are poor. The presence of organic matter can enhance the compatibility between the magnetic powder surface and inorganic matter, and improve the quality and density of the coating layer.

[0043] As can be seen from the comparison between Example 4 and Comparative Example 4, the use of ultrasonic dispersion system and granulation coating machine can significantly improve the uniformity of powder surface coating, more accurately control the passivation progress, optimize the coating effect, and effectively improve the insulation and soft magnetic properties of powder.

[0044] Salt spray tests were conducted on the granulated powder and magnetic rings, such as... Figure 4 and Figure 5 As shown, the salt spray test results indicate that: after 24 hours of salt spray testing, the granulated powder and magnetic rings of Example 4, Comparative Example 3, and Comparative Example 4 showed no rust spots or rust patches on their surfaces; after 24 hours of salt spray testing, the magnetic ring of Comparative Example 3 showed slight rust spots on its surface; and after 24 hours of salt spray testing, the magnetic ring of Comparative Example 4 showed obvious rust patches on its surface.

[0045] This invention employs a three-layer core-shell composite structure design to enhance the material's resistivity and pressure resistance, effectively suppressing eddy current losses. Simultaneously, the inorganic layer ensures temperature resistance, while the organic layer improves formability, addressing industry pain points such as cracking and bulging during molding of integrally molded inductors. The cavitation and dispersion effects of ultrasound break up powder agglomeration, allowing the coating layer to grow uniformly and densely on the surface of individual particles, avoiding the uneven coating and poor batch stability issues of conventional stirring processes. A segmented gradient heating heat treatment process is used, gradually eliminating molding internal stress through multi-stage heating and holding, optimizing the magnetic domain structure and reducing hysteresis losses. It effectively blocks the intrusion of corrosive media, exhibits no rust after 24-hour salt spray testing, and demonstrates excellent resistance to high and low temperatures and damp heat, meeting the application requirements of high-reliability scenarios such as automotive electronics.

[0046] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Clearly, those skilled in the art can make various alterations and variations to the invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of equivalents of the invention, the invention is also intended to include these modifications and variations.

Claims

1. A high-reliability soft magnetic metal composite material, characterized in that, include: The core of the metal soft magnetic alloy powder, and the phosphate passivation layer, the inorganic insulating coating layer and the organic adhesive coating layer that are sequentially coated on the surface of the metal soft magnetic alloy powder core from the inside to the outside; The phosphate passivation layer is a dense phosphate passivation film formed by the in-situ reaction of weak acid with the core surface of the soft magnetic alloy powder, with a thickness of 50 nm to 200 nm. The inorganic insulating coating layer is a silicon dioxide insulating film formed in situ on the surface of the phosphate passivation layer with silane coupling agent as a bridge, and the thickness is 100nm to 300nm. The organic adhesive coating layer is an organic coating film formed by curing a polymer adhesive, which coats the outer surface of the inorganic insulating coating layer, with a thickness of 200nm to 500nm.

2. The high-reliability soft magnetic metal composite material according to claim 1, characterized in that, The core of the metal soft magnetic alloy powder is iron-based soft magnetic alloy powder, which is selected from one or more composite powders of iron-nickel soft magnetic powder, iron-nickel-molybdenum soft magnetic powder, iron-silicon-aluminum soft magnetic powder, iron-silicon soft magnetic powder and iron-silicon-chromium soft magnetic powder. The particle size of the core of the metal soft magnetic alloy powder is 2μm to 50μm and passes through a 300 to 500 mesh sieve.

3. The high-reliability soft magnetic metal composite material according to claim 1, characterized in that, The raw material for the phosphate passivation layer is a passivation solution, which includes a weak acid and a solvent. The weak acid is selected from one or more of phosphoric acid, ammonium dihydrogen phosphate, sodium ammonium hydrogen phosphate, oxalic acid and nitrate. The solvent is selected from one or more of distilled water, ethyl acetate, acetone, ethanol, isopropanol and p-xylene. The amount of weak acid used is 0.1wt% to 1.0wt% of the core mass of the soft magnetic alloy powder.

4. The high-reliability soft magnetic metal composite material according to claim 1, characterized in that, The raw materials for the inorganic insulating coating include silane coupling agent and tetraethyl orthosilicate. The silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane and vinyltriethoxysilane, and the amount used is 0.2wt% to 12wt% of the core mass of the soft magnetic alloy powder. The amount of tetraethyl orthosilicate is 0.1wt% to 1.0wt% of the core mass of the soft magnetic alloy powder.

5. The high-reliability soft magnetic metal composite material according to claim 1, characterized in that, The raw materials for the organic adhesive coating layer include an adhesive and an organic solvent. The adhesive is selected from one or more of epoxy resin, silicone resin, polyamide resin, polypropylene silicone resin, tetraethyl orthosilicate, polyvinyl alcohol, and biphenyl-type phenolic epoxy resin, and is used in an amount of 1.0 wt% to 4.0 wt% of the mass of the inorganically coated powder. The organic solvent is selected from one or more of ethyl acetate, acetone, ethanol, isopropanol, and p-xylene, and is used in an amount of 8 wt% to 15 wt% of the mass of the inorganically coated powder.

6. A method for preparing a high-reliability soft magnetic metal composite material, applicable to the high-reliability soft magnetic metal composite material according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Screen the soft magnetic alloy powder of the metal with a preset particle size, weigh it according to the preset mass after sieving, and set it aside. S2. Prepare passivation solution. Add the passivation solution and the soft magnetic alloy powder to an ultrasonic stirring tank and complete the passivation reaction under low temperature ultrasonic conditions. After the reaction is completed, clean, dry and sieve to obtain passivation powder. S3. Prepare a silane coupling agent solution. Add the silane coupling agent solution, tetraethyl orthosilicate and passivation powder to an ultrasonic stirring tank and complete the in-situ coating reaction under ultrasonic conditions at room temperature. After the reaction is completed, dry and sieve to obtain inorganic coated powder. S4. Mix the organic solvent and adhesive evenly, add the inorganic coating powder to the mixture, stir and mix, then sieve and dry to obtain granulated powder.

7. The method for preparing a high-reliability soft magnetic metal composite material according to claim 6, characterized in that, In S2, the passivation solution is freshly prepared distilled water at 5°C to 10°C, the passivation reaction temperature is 5°C to 18°C, the ultrasonic dispersion system circulates for 8 min to 12 min, the drying temperature after passivation is 60°C to 90°C, the drying time is 20 min to 40 min, and the dried powder passes through a 300 to 500 mesh sieve.

8. The method for preparing a high-reliability soft magnetic metal composite material according to claim 6, characterized in that, In S3, the in-situ coating reaction temperature is 20℃ to 25℃, the ultrasonic dispersion system cyclic vibration time is 8min to 12min, the drying temperature after reaction is 60℃ to 90℃, the drying time is 10min to 30min, and the dried powder passes through a 300 to 500 mesh sieve.

9. The method for preparing a high-reliability soft magnetic metal composite material according to claim 6, characterized in that, In S4, the organic coating is dried at a temperature of 50°C to 80°C for 30 to 60 minutes, and then passed through a 40 to 200 mesh sieve to obtain granulated powder.

10. An inductor, applicable to the preparation method of the high-reliability metal soft magnetic composite material as described in claim 6, characterized in that, include: The magnetic core body and the metal coil embedded inside the magnetic core body are sequentially molded and heat-treated. In the compression molding step, a lubricant is added to the granulated powder. The lubricant is selected from one or more of graphite, hexagonal boron nitride, zinc stearate and microcrystalline wax. The amount of lubricant is 0.1wt% to 0.9wt% of the mass of the granulated powder. The compression molding pressure is 11T to 13T. The heat treatment process was carried out in a N2 atmosphere at -0.09 MPa with a gradient temperature increase, specifically: from room temperature to 150℃ in 40 min and held for 40 min; from room temperature to 300℃ in 40 min and held for 40 min; from room temperature to 450℃ in 40 min and held for 40 min. Heat to 600℃ in 40 minutes, then maintain the temperature for 40 minutes; The temperature is raised to 700℃ to 720℃ in 40 minutes and held for 60 minutes; the heating rate is 1.5℃ / min to 6℃ / min.

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