High-temperature-resistant rust-proof composite passivation method for high-performance metal soft magnetic powder

Abstract

The invention discloses a high-temperature-resistant rust-proof composite passivation method for high-performance metal soft magnetic powder, and belongs to the technical field of metal soft magnetic materials, the method comprises the following two steps: 1, dispersing soluble silicate, molybdate, cerium salt, nickel salt, strontium salt and a key component nano silicon dioxide in a diluent, and uniformly stirring; mixing and coating with metal soft magnetic powder, and then drying to form an inorganic composite passivation layer; and 2, carrying out surface treatment on the powder by using an organic silicon resin prepolymer and a coupling agent, and carrying out heat treatment and curing to form an organic-inorganic hybrid enhancement layer. By introducing nano silicon dioxide and constructing a hybrid structure, the compactness, binding force and high-temperature stability of the passivation layer are remarkably improved; the obtained passivated metal soft magnetic powder has excellent comprehensive performance.

Description

Technical Field

[0001] This invention relates to the technical field of soft magnetic materials, and in particular to a composite passivation method for the surface of soft magnetic powder that combines excellent high-temperature resistance, rust prevention and environmental friendliness. Background Technology

[0002] Soft magnetic powder is a key material for manufacturing high-frequency inductors, transformers, and other components. To reduce eddy current losses, the magnetic powder particles must undergo insulation and passivation treatment. With increasingly stringent environmental regulations such as RoHS and REACH, which impose stricter requirements on the environmental performance of materials, the traditional chromate passivation method has been phased out. Phosphating, due to its poor temperature resistance (e.g., easy decomposition at temperatures above 160℃) and insufficient rust prevention, is unsuitable for high-end applications.

[0003] Based on this, Chinese patent document CN110202129A discloses a composite passivation method that is both high-temperature resistant and rust-proof, which includes: 1) adding soluble strontium salt, soluble silicate, and soluble nickel salt to a solvent, stirring, adding soft magnetic metal powder, and continuing to stir and heat to volatilize; 2) adding soluble molybdate, soluble cerium salt, and diatomaceous earth to a solvent, stirring, adding the soft magnetic metal powder from step 1, stirring to volatilize the solvent, and drying; 3) adding a coupling agent to a solvent, stirring, adding the dried soft magnetic metal powder from step 2, stirring to volatilize the solvent, and drying at 60℃~100℃, after which the soft magnetic metal powder passes through a standard sieve of 300 mesh or higher; the beneficial effect of this technical solution is that electronic components made of the passivated soft magnetic metal powder have excellent insulation and do not decompose within the range of 200℃, and can maintain high insulation and high rust-proof characteristics for a long time.

[0004] However, existing technologies employing composite passivation methods such as silicates, molybdates, cerium salts, and nickel salts have improved performance to some extent. But there is still room for further improvement, as follows: 1. Temperature resistance limit: The insulation and structural stability of the passivation layer may still be reduced in long-term working environments exceeding 200°C.

[0005] 2. Environmental friendliness: The formula still uses a certain amount of nickel salt, which poses environmental and health risks.

[0006] 3. Process efficiency: The process involves three steps, resulting in a relatively long process flow and high energy consumption.

[0007] 4. Overall performance: The density, toughness, and compatibility with organic coating agents of the passivation layer need to be further improved.

[0008] Therefore, it is of great significance to develop a new passivation method with higher performance, more environmental protection, and more efficient process. Summary of the Invention

[0009] Therefore, it is necessary to provide a high-performance composite passivation method for high-temperature resistant and rust-proof metal soft magnetic powder to address technical issues such as how to improve the temperature resistance limit, environmental friendliness, and process efficiency of soft magnetic metal materials.

[0010] A high-temperature resistant, rust-resistant composite passivation method for high-performance soft magnetic metal powder, comprising the following steps: Step 1: Disperse soluble silicates, soluble molybdates, soluble cerium salts, soluble nickel salts, soluble strontium salts, and nano-silica in a diluent to form a composite passivation solution; then, add soft magnetic metal powder for coating treatment, and after drying, form an inorganic composite passivation layer; Step 2: Dissolve the silicone resin prepolymer and coupling agent in a diluent to form a reinforcing liquid; then add the metal soft magnetic powder treated in step 1 for surface treatment, and heat-treat to crosslink and cure the silicone resin. Finally, sieve to obtain the passivated metal soft magnetic powder.

[0011] Specifically, in the above steps, each component, by weight, includes: Soft magnetic powder: 100 parts; Soluble silicates: 1.0~4.0 parts; Soluble molybdate: 0.05~0.8 parts; Soluble cerium salts: 0.1~1.5 parts; Soluble nickel salt: 0~0.3 parts; Soluble strontium salts: 0.05~0.8 parts; Nano-silica: 0.1~1.0 parts; Organosilicon resin prepolymer: 0.5~2.0 parts; Coupling agent: 0.05~1.0 parts; Total diluent: 150-550 parts.

[0012] Furthermore, the drying in step one adopts a spray drying process with the following conditions: inlet temperature 100~130℃ and outlet temperature 70~90℃; the heat treatment conditions in step two are: treatment at 100~150℃ for 60~120 minutes.

[0013] Furthermore, the metal soft magnetic powder is one of carbonyl iron powder, atomized iron powder, FeSi-based soft magnetic powder, FeNi-based soft magnetic powder, FeSiAl-based soft magnetic powder, amorphous soft magnetic powder, or nanocrystalline soft magnetic powder.

[0014] Furthermore, the metal soft magnetic powder is one of carbonyl iron powder, atomized iron powder, FeSi-based soft magnetic powder, FeNi-based soft magnetic powder, FeSiAl-based soft magnetic powder, amorphous soft magnetic powder, or nanocrystalline soft magnetic powder.

[0015] Furthermore, the soluble molybdate is at least one of ammonium molybdate, sodium molybdate, zinc molybdate, or calcium molybdate.

[0016] Furthermore, the soluble cerium salt is at least one of cerium nitrate, cerium sulfate, or cerium chloride.

[0017] Furthermore, the soluble nickel salt is at least one of nickel sulfate, nickel nitrate, nickel chloride, or nickel sulfamate; preferably, the amount of the soluble nickel salt added is 0 to 0.1 parts.

[0018] Furthermore, the soluble strontium salt is at least one of strontium nitrate, strontium hydroxide, or strontium chloride.

[0019] Furthermore, the nano-silica is oleophilic nano-silica modified with a silane coupling agent, with a particle size range of 10~50nm; the coupling agent is a silane coupling agent; and the diluent is one or a mixture of several of water, ethanol, acetone, and isopropanol.

[0020] In summary, this invention discloses a high-temperature resistant, rust-resistant composite passivation method for high-performance metal soft magnetic powder. This method aims to solve the problems of insufficient temperature resistance, poor rust prevention, and environmental issues caused by nickel content in existing phosphating methods and similar passivation technologies. The method includes two steps: First, soluble silicates, molybdates, cerium salts, nickel salts, strontium salts, and the key component nano-silica are dispersed in a diluent, mixed with metal soft magnetic powder, coated, and dried to form an inorganic composite passivation layer; Second, the powder is surface-treated with an organosilicon resin prepolymer and a coupling agent, and then cured by heat treatment to form an organic-inorganic hybrid reinforcement layer. This invention significantly improves the density, bonding strength, and high-temperature stability of the passivation layer by introducing nano-silica and constructing a hybrid structure. The resulting passivated metal soft magnetic powder has excellent comprehensive performance: insulation resistance ≥2.5 GΩ, insulation retention rate >89% after aging at 250℃ / 100 hours, no rust after 72 hours of neutral salt spray testing, and magnetic permeability loss rate <4%. The process of this invention is highly efficient and environmentally friendly, and is suitable for preparing soft magnetic powders for high-frequency, high-reliability electronic components. Detailed Implementation

[0021] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] Specifically, the present invention discloses a high-temperature resistant, rust-proof, composite passivation method for high-performance metal soft magnetic powder, which includes the following steps: Step 1: Construction of the composite inorganic passivation layer: By weight, 0.05-0.8 parts of soluble strontium salt, 1.0-4.0 parts of soluble silicate, 0.02-0.3 parts of soluble nickel salt, 0.05-0.8 parts of soluble molybdate, 0.1-1.5 parts of soluble cerium salt, and 0.1-1.0 parts of nano-silica with a particle size of 10-50 nm are added to 50-150 parts of aqueous diluent, such as deionized water or ethanol aqueous solution, and stirred and dispersed under ultrasonic assistance for 20-40 minutes to form a uniform composite passivation solution A. 100 parts of soft magnetic metal powder were added to the composite passivation solution A, and mechanical stirring and ultrasonic treatment were combined for 60 minutes to ensure that the passivation solution fully coated the surface of the magnetic powder. The mixture was spray-dried at 80-120°C to allow the solvent to evaporate rapidly and to initially form a dense inorganic-nanocomposite passivation layer. Step 2: Organic-inorganic hybrid enhancement treatment: By weight, 0.5-2.0 parts of organosilicon resin prepolymer, such as methylphenyl silicone resin, and 0.05-1.0 parts of silane coupling agent, such as KH-550, are dissolved in 50-150 parts of organic diluent, such as ethanol or acetone, and stirred for 10 minutes to form solution B. Add the metal soft magnetic powder coated with an inorganic passivation layer obtained in the first step to solution B, and stir and react at 60-80℃ for 30-60 minutes. After the reaction is complete, the material is heat-treated in a hot air circulating oven at 100-150℃ for 60-120 minutes to allow the silicone resin to cross-link and cure, forming an interpenetrating network structure with the inorganic passivation layer, thus completing the organic-inorganic hybrid reinforcement. Finally, the passivated soft magnetic metal powder is passed through a 400-mesh standard sieve to obtain the final product.

[0023] Specifically, the metal soft magnetic powder is one of FeSi-based soft magnetic powder, FeNi-based soft magnetic powder, carbonyl iron powder, atomized iron powder, amorphous soft magnetic powder, or nanocrystalline soft magnetic powder.

[0024] Specifically, the nano-silica is oleophilic nano-silica that has been surface-modified with a silane coupling agent to improve its dispersibility in the passivation solution and its adhesion to the metal surface.

[0025] Specifically, the aqueous diluent is a mixture of deionized water and ethanol in a mass ratio, such as 1:1 to 3:1.

[0026] In summary, the beneficial effects of the high-temperature resistant and rust-proof composite passivation method for high-performance metal soft magnetic powder of the present invention are as follows: 1. Performance Improvement: By introducing nano-silica and organosilicon resin, an inorganic-organic hybrid three-dimensional network passivation layer structure is formed, which significantly improves the coating's density, toughness, and high-temperature stability above 250℃; making its insulation resistance ≥2GΩ and its salt spray resistance rust-free for 72 hours, both of which are superior to existing technical solutions.

[0027] 2. Environmentally friendly: It significantly reduces the amount of nickel salt used, by about 50% compared with existing technologies, and can use a more environmentally friendly water-based system for the first stage of treatment, reducing the emission of volatile organic compounds (VOCs).

[0028] 3. Process optimization: The existing three-step method is combined and optimized into a two-step method, and spray drying technology is used to replace traditional drying, which greatly shortens the process flow and time, improves production efficiency, and reduces energy consumption.

[0029] 4. High magnetic property retention: The mild processing technology and thinner dense passivation layer result in a magnetic permeability loss rate of less than 5%, which is better than the level of traditional processes.

[0030] Furthermore, the following embodiment of the method for high-temperature resistant and rust-proof composite passivation of high-performance metal soft magnetic powder of the present invention includes the following steps: S1. Take 0.1 parts of strontium nitrate, 2.5 parts of sodium silicate, 0.1 parts of nickel sulfate, 0.2 parts of ammonium molybdate, 0.5 parts of cerium nitrate, and 0.5 parts of modified nano-silica, and add them to 100 parts of a mixed solvent. The ratio of this mixed solvent is: deionized water: ethanol = 2:1. Disperse the mixture ultrasonically for 30 minutes to obtain composite passivation solution A. S2. Take 100 parts of carbonyl iron powder and add it to A. Stir mechanically at 300 rpm and simultaneously sonicate at 300W for 60 minutes. S3. The mixture is fed into a spray drying tower with an inlet temperature of 120°C and an outlet temperature of 80°C to obtain pre-coated magnetic powder; S4. Take 1.0 part of methylphenyl silicone resin prepolymer and 0.3 part of KH-550 silane coupling agent, dissolve them in 80 parts of ethanol, stir for 10 minutes to obtain solution B; S5. Add the pre-coated magnetic powder to B and stir at 70°C for 40 minutes; S6. Place the material in a 120℃ oven for heat treatment for 90 minutes; S7. Pass through a 400-mesh sieve to obtain the final passivated carbonyl iron powder.

[0031] Furthermore, the passivation powder obtained in Example 1 of the above method was mixed with 2.0% epoxy resin, granulated, pressed into magnetic rings, and the results of the test after curing are as follows: Insulation resistance: 2.5 GΩ (100V, 3s); Salt spray test: 5.0 wt.% NaCl, 72 hours, no red rust on the surface; High-temperature aging: After 250℃ / 100h, the insulation resistance retention rate is >90%; Permeability loss: @1MHz, <4%.

[0032] Comparative Example 1 was prepared using the following method for the same batch of carbonyl iron powder, and the same tests were performed. The method for Comparative Example 1 was as follows: For every 100 parts by weight of the soft magnetic metal powder, add 0.5-5.5 parts of soluble silicate, 0.01-1.0 parts of soluble molybdate, 0.05-2.5 parts of soluble cerium salt, 0.05-0.55 parts of soluble nickel salt, 0.01-1.5 parts of soluble strontium salt, 0.01-0.55 parts of diatomaceous earth, 0.01-1.55 parts of coupling agent, and 100-500 parts of diluent. These materials were added to the soft magnetic metal powder in a specific order. After the reaction was complete, the powder was dried at 70℃-100℃ for 20-360 minutes. The test results for Comparative Example 1 are as follows: Insulation resistance: 1.2 GΩ; Salt spray test: No obvious rust after 48 hours, sporadic rust spots appeared after 72 hours; High-temperature aging: After 250℃ / 100h, the insulation resistance decreases by approximately 30%; Permeability loss: ~8% at 1MHz.

[0033] The above comparison shows that the high-temperature resistant and rust-proof composite passivation method of high-performance metal soft magnetic powder of the present invention is significantly better than Comparative Example 1, i.e., the solution of the prior art, in terms of comprehensive performance.

[0034] Furthermore, several specific embodiments are disclosed below: Example 1, i.e., the preferred example: Soft magnetic powder: 100 parts carbonyl iron powder; Step 1: Composite Inorganic Passivation Soluble sodium silicate: 2.5 parts; Soluble ammonium molybdate: 0.2 parts; Soluble cerium nitrate: 0.5 parts; Soluble nickel nitrate: 0.1 parts; Soluble strontium nitrate: 0.1 parts; Nano-silica (20nm): 0.5 parts; Diluent (deionized water: ethanol = 2:1): 100 parts.

[0035] Process: Ultrasonic dispersion for 30 min, addition of magnetic powder, mechanical stirring + ultrasonic treatment for 60 min, spray drying, inlet temperature 120℃, outlet temperature 80℃.

[0036] Step 2: Organic-inorganic hybridization enhancement: Organosilicon resin prepolymer (methylphenyl type): 1.0 part; Silane coupling agent (KH-550): 0.3 parts; Diluent (ethanol): 80 parts.

[0037] Process: After stirring and dissolving, add the powder from the first step of the process, stir at 70℃ for 40 minutes, heat treat at 120℃ for 90 minutes, and pass through a 400-mesh sieve.

[0038] Example 2, namely the high temperature resistant example: Soft magnetic powder: 100 parts FeSiCr alloy powder; Step 1: Composite Inorganic Passivation Soluble potassium silicate: 3.5 parts; Soluble sodium molybdate: 0.5 parts; Soluble cerium sulfate: 0.8 parts; Soluble nickel aminosulfonate: 0.05 parts (very low nickel content); Soluble strontium hydroxide: 0.2 parts; Nano-silica (50nm): 0.8 parts; Diluent (deionized water): 150 parts.

[0039] Process: Ultrasonic dispersion for 40 min, addition of magnetic powder, mechanical stirring + ultrasonic treatment for 60 min, and drying at 100℃ for 120 min.

[0040] Step 2: Organic-inorganic hybridization enhancement: Organosilicon resin prepolymer: 1.8 parts; Silane coupling agent (KH-792): 0.2 parts; Diluent (acetone): 60 parts.

[0041] Process: After stirring and dissolving, add the powder from the first step of the process, stir at 80℃ for 30 minutes, heat treat at 150℃ for 60 minutes, and pass through a 400-mesh sieve.

[0042] The second embodiment is characterized by increasing the content of silicate and cerium salts and using higher temperature heat treatment, aiming to pursue the ultimate temperature resistance performance, such as making its temperature resistance performance greater than 280°C.

[0043] Example 3, namely, the low-cost and environmentally friendly example: Soft magnetic powder: 100 parts atomized iron powder; Step 1: Composite Inorganic Passivation Soluble sodium silicate: 1.5 parts; Soluble calcium molybdate: 0.1 parts; Soluble cerium nitrate: 0.2 parts; Soluble nickel salts: 0 parts (completely nickel-free); Soluble strontium nitrate: 0.05 parts; Nano-silica (30nm): 0.2 parts; Diatomaceous earth: 0.2 parts (partially replaces nanomaterials to reduce costs); Diluent (deionized water: ethanol = 3:1): 120 parts.

[0044] Process: Ultrasonic dispersion for 20 min, magnetic powder added and mechanically stirred for 60 min, and then dried at 80℃ for 180 min.

[0045] Step 2: Organic-inorganic hybridization enhancement: Organosilicon resin prepolymer: 0.6 parts; Silane coupling agent (DL-602): 0.1 parts; Diluent (ethanol): 50 parts.

[0046] Process: After stirring and dissolving, add the powder from the first step of the process, stir at 60℃ for 60 minutes, heat treat at 100℃ for 120 minutes, and pass through a 400-mesh sieve.

[0047] The characteristics of this third embodiment are: by completely removing nickel salts and using some calcium molybdate and diatomaceous earth, the raw material cost and environmental impact are significantly reduced while maintaining good performance.

[0048] Furthermore, the experimental data and test basis for the high-temperature resistant and rust-proof composite passivation method of high-performance metal soft magnetic powder of the present invention are further revealed as follows: I. Sample Preparation Comparative Example 1 (CE-1): Passivated carbonyl iron powder prepared using the formulation and process of the aforementioned Comparative Example 1.

[0049] Example 1 (EMB-1): Passivated carbonyl iron powder prepared according to a preferred embodiment of the present invention.

[0050] Example 2 (EMB-2): Passivated FeSiCr alloy powder prepared in the high-temperature resistant example of the present invention.

[0051] Example 3 (EMB-3): Passivated atomized iron powder prepared in the low-cost and environmentally friendly example of the present invention.

[0052] Comparative Example 2 (CE-2): To verify nanotechnology The key role is to prepare a product with the exact same composition and process as EMB-1, but without the addition of nanoparticles. The sample.

[0053] All samples were processed using a uniform subsequent process: mixed with 2.0 wt.% E-20 epoxy resin and granulated, then pressed into toroidal cores with dimensions of Φ20.3 mm x Φ12.7 mm x 6.35 mm (equivalent to a TDKEP7 standard magnetic ring) under 500 MPa pressure, cured at 180°C for 1 hour, and then subjected to performance tests. II. Test Items, Basis, and Data Results Table 1: Test Results of Basic Performance of Magnetic Core

[0054] Table 2: Environmental Reliability Test Results

[0055] Table 3: Physical and Chemical Properties

[0056] III. Data Analysis and Conclusions 1. Insulation and High-Temperature Resistance: The initial insulation resistance and retention rate after high-temperature aging of EMB-1 and EMB-2 are significantly higher than those of CE-1. This directly proves that nano-insulation... The filling effect and the high-temperature stable network formed by the silicone resin work together to create a denser and more stable insulation layer.

[0057] The data for CE-2 deteriorated sharply, even worse than the original scheme, strongly demonstrating the effectiveness of nanotechnology. It is an indispensable key component in this invention, rather than a simple replacement that can be omitted.

[0058] 2. Rust Prevention Performance: Salt spray and pressure cooker tests show that the corrosion resistance of the embodiments of this invention, such as EMB-1 and EMB-2, far exceeds that of existing technologies. This is due to the synergistic corrosion inhibition effect of molybdate / cerium salt and the physical barrier of the denser passivation layer against corrosive media. While EMB-3 outperforms CE-1, it is slightly inferior to EMB-1, reflecting a balance between cost and performance, but its "nickel-free" characteristic is a significant advantage.

[0059] 3. Magnetic property protection: The permeability loss rate in all embodiments of the present invention is lower than that in the comparative example. The thinner, more uniform passivation layer reduces the occupation of non-magnetic volume, thereby better preserving the inherent magnetic properties of the magnetic powder.

[0060] 4. Environmental friendliness: EMB-3 has successfully achieved "nickel-free" production, while EMB-1 and EMB-2 have also significantly reduced nickel content, meeting the requirements of environmental regulations.

[0061] In summary, the improved passivation method provided by this invention has achieved significant progress in terms of insulation, high temperature resistance, rust prevention, retention of magnetic properties, and environmental friendliness, especially through the introduction of nanotechnology. The organic-inorganic hybrid structure overcomes the fundamental shortcomings of traditional technical solutions. The data from Comparative Example 2 are crucial, demonstrating that omitting key components leads to a significant performance degradation, thus illustrating the non-obviousness of the present invention's technical solution.

[0062] In summary, this invention discloses a high-temperature resistant, rust-resistant composite passivation method for high-performance metal soft magnetic powder, comprising two steps: First, soluble silicates, molybdates, cerium salts, nickel salts, strontium salts, and the key component nano-silica are dispersed in a diluent, mixed with the metal soft magnetic powder, coated, and dried to form an inorganic composite passivation layer; second, the powder is surface-treated using an organosilicon resin prepolymer and a coupling agent, and then cured by heat treatment to form an organic-inorganic hybrid reinforcement layer. This invention significantly improves the density, adhesion, and high-temperature stability of the passivation layer by introducing nano-silica and constructing a hybrid structure. The resulting passivated metal soft magnetic powder exhibits excellent comprehensive performance: insulation resistance ≥2.5 GΩ, insulation retention rate >89% after aging at 250℃ / 100 hours, no rust after 72 hours of neutral salt spray testing, and permeability loss <4%. This invention has the advantages of high efficiency and environmental friendliness, and is suitable for preparing soft magnetic powders for high-frequency, high-reliability electronic components.

[0063] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A high-temperature resistant, rust-preventive composite passivation method for high-performance soft magnetic metal powder, characterized in that, It includes the following steps: Step 1: Disperse soluble silicates, soluble molybdates, soluble cerium salts, soluble nickel salts, soluble strontium salts, and nano-silica in a diluent to form a composite passivation solution; then, add soft magnetic metal powder for coating treatment, and after drying, form an inorganic composite passivation layer; Step 2: Dissolve the silicone resin prepolymer and coupling agent in a diluent to form a reinforcing liquid; then add the metal soft magnetic powder treated in step 1 for surface treatment, and heat-treat to crosslink and cure the silicone resin. Finally, sieve to obtain the passivated metal soft magnetic powder.

2. The high-temperature resistant, rust-proof, composite passivation method for high-performance soft magnetic metal powder according to claim 1, characterized in that, Each component, by weight, includes: Soft magnetic powder: 100 parts; Soluble silicates: 1.0~4.0 parts; Soluble molybdate: 0.05~0.8 parts; Soluble cerium salts: 0.1~1.5 parts; Soluble nickel salt: 0~0.3 parts; Soluble strontium salts: 0.05~0.8 parts; Nano-silica: 0.1~1.0 parts; Organosilicon resin prepolymer: 0.5~2.0 parts; Coupling agent: 0.05~1.0 parts; Total diluent: 150-550 parts.

3. The high-temperature resistant, rust-proof, composite passivation method for high-performance metal soft magnetic powder according to claim 1, characterized in that, The drying in step one adopts a spray drying process with the following conditions: inlet temperature 100~130℃ and outlet temperature 70~90℃; the heat treatment conditions in step two are: treatment at 100~150℃ for 60~120 minutes.

4. The high-temperature resistant, rust-proof, composite passivation method for high-performance metal soft magnetic powder according to claim 1, characterized in that, The metal soft magnetic powder is one of carbonyl iron powder, atomized iron powder, FeSi-based soft magnetic powder, FeNi-based soft magnetic powder, FeSiAl-based soft magnetic powder, amorphous soft magnetic powder, or nanocrystalline soft magnetic powder.

5. The high-temperature resistant, rust-proof, composite passivation method for high-performance metal soft magnetic powder according to claim 2, characterized in that, The metal soft magnetic powder is one of carbonyl iron powder, atomized iron powder, FeSi-based soft magnetic powder, FeNi-based soft magnetic powder, FeSiAl-based soft magnetic powder, amorphous soft magnetic powder, or nanocrystalline soft magnetic powder.

6. The high-temperature resistant, rust-proof, composite passivation method for high-performance metal soft magnetic powder according to claim 2, characterized in that, The soluble molybdate is at least one of ammonium molybdate, sodium molybdate, zinc molybdate, or calcium molybdate.

7. The high-temperature resistant, rust-proof, composite passivation method for high-performance soft magnetic metal powder according to claim 2, characterized in that, The soluble cerium salt is at least one of cerium nitrate, cerium sulfate, or cerium chloride.

8. The high-temperature resistant, rust-proof, composite passivation method for high-performance soft magnetic metal powder according to claim 2, characterized in that, The soluble nickel salt is at least one of nickel sulfate, nickel nitrate, nickel chloride, or nickel sulfamate; preferably, the amount of the soluble nickel salt added is 0 to 0.1 parts.

9. The high-temperature resistant, rust-proof, composite passivation method for high-performance soft magnetic metal powder according to claim 2, characterized in that, The soluble strontium salt is at least one of strontium nitrate, strontium hydroxide, or strontium chloride.

10. A high-temperature resistant, rust-proof, composite passivation method for high-performance soft magnetic metal powder according to claim 1 or 2, characterized in that: The nano-silica is oleophilic nano-silica modified with a silane coupling agent, with a particle size range of 10~50nm; the coupling agent is a silane coupling agent; the diluent is one or a mixture of several of water, ethanol, acetone, and isopropanol.

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