Modified iron-nickel magnetic powder core and preparation method and application thereof

Abstract

The invention relates to a modified iron-nickel magnetic powder core and a preparation method and application thereof, and the preparation method comprises the following steps: putting an iron-nickel magnetic powder core subjected to insulation coating and annealing treatment into an acid solution, standing, enabling the surface of the iron-nickel magnetic powder core to react with the acid solution to generate a salt mixture coating layer, and obtaining the modified iron-nickel magnetic powder core. A pickling method is adopted, the iron-nickel magnetic powder core subjected to insulation coating and annealing treatment is subjected to surface treatment, an acid solution reacts with metal elements on the surface of the iron-nickel magnetic powder core to generate a salt mixture coating layer containing iron and nickel, and the coating layer plays an insulation role; therefore, the resistance of the iron-nickel magnetic powder core can be improved, the loss can be reduced, the performance of the modified iron-nickel magnetic powder core can be obviously improved, and the situation that the surface resistance is low, the loss is high and the service life is long due to decomposition of an insulating layer caused by incomplete insulation coating or too high heat treatment temperature, insufficient atmosphere protection and the like of the iron-nickel magnetic powder core is avoided. And normal use cannot be realized.

Description

Technical Field

[0001] This invention relates to the field of iron-nickel magnetic powder core technology, and in particular to a modified iron-nickel magnetic powder core, its preparation method, and its application. Background Technology

[0002] Metal powder cores, as a novel type of soft magnetic material, are widely used in inductors, reactors, and transformers, serving as an indispensable product in electronic materials. With the development of electronic devices towards higher frequencies and smaller sizes, the requirements for metal powder cores are becoming increasingly stringent. Like soft magnetic products, metal powder cores specifically require high surface resistivity, low loss, and high saturation magnetic induction. Among them, iron-nickel alloy powder cores, due to their excellent physical properties such as high permeability, high resistivity, low hysteresis, and low eddy current loss, have become the preferred material for many high-performance applications.

[0003] Current research on the preparation of iron-nickel magnetic powder cores is extensive. The preparation process typically involves insulating the core and high-temperature annealing. To improve the permeability of the iron-nickel magnetic powder core, the heat treatment temperature is generally increased to above 600℃. However, this preparation method still has the following problems: First, the insulation coating may not match the corresponding preparation process, resulting in incomplete insulation coating, leading to low surface resistance and increased losses. Second, excessively high heat treatment temperatures or insufficient atmosphere protection can cause the insulating film to decompose, also resulting in low surface resistance and increased losses. Consequently, the annealed iron-nickel magnetic powder cores may become unusable. Furthermore, due to the high cost of iron-nickel raw materials and the high manufacturing costs, when iron-nickel magnetic powder cores become unusable due to poor performance, they must be scrapped, leading to high scrapping costs.

[0004] In existing preparation processes, it is common practice to spray epoxy resin or other paints onto the surface of iron-nickel alloy soft magnetic materials after coating with insulating materials and annealing. For example, CN106205929A discloses a method for preparing iron-nickel metal magnetic powder cores, including (1) smelting and powdering; (2) particle size combination; (3) magnetic powder ball milling; (4) heat treatment; (5) chemical coating; (6) oxidation film formation; (7) secondary insulating coating; (8) pressing and molding; (9) magnetic core annealing; and (10) painting. In this preparation method, after coating and core annealing, the core is cured by spraying paint to obtain the finished magnetic core. For example, CN102306528A discloses a soft magnetic material of iron-nickel alloy with a magnetic permeability of μ=125 and its manufacturing method, including (1) powder preparation; (2) powder roasting; (3) pressing and forming; (4) heat treatment; (5) surface coating. In this preparation method, after heat treatment, the surface of the soft magnetic material of iron-nickel alloy is coated with epoxy resin paint to obtain the soft magnetic material of iron-nickel alloy.

[0005] It is evident that in existing iron-nickel metal magnetic powder core manufacturing processes, even with surface treatment of the coated insulating material and annealed iron-nickel alloy soft magnetic material, the only improvement lies in physical coating with paint or similar methods to provide insulation, withstand voltage, and rust prevention. This does not alter the core's inherent resistance and losses. Furthermore, existing physical coating methods cannot modify iron-nickel metal magnetic powder cores that are unusable due to incomplete insulation coating, excessively high heat treatment (annealing) temperatures (>600℃), or insufficient atmosphere protection, resulting in low surface resistance, high losses, and overall unusable performance.

[0006] Therefore, how to provide a simple method to modify iron-nickel metal magnetic powder cores that have low surface resistance and high loss due to incomplete insulation coating, excessively high heat treatment temperature, or insufficient atmosphere protection, so as to obtain products with qualified loss and normal use, has become an urgent problem to be solved. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a modified iron-nickel magnetic powder core, its preparation method, and its application. The method employs acid pickling to treat the surface of the iron-nickel magnetic powder core after insulation coating and annealing. An acid solution reacts chemically with the metal elements on the surface of the iron-nickel magnetic powder core, generating a partial coating layer of iron and nickel salt mixture. This coating layer provides insulation, thereby increasing the resistivity of the iron-nickel magnetic powder core and reducing losses. This significantly improves the performance of the modified iron-nickel magnetic powder core, preventing the insulation layer from decomposing due to incomplete insulation coating, excessively high heat treatment temperatures (>600℃), or insufficient atmosphere protection, which would otherwise result in low surface resistivity, high losses, and unusable conditions.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a modified iron-nickel magnetic powder core, the method comprising the following steps:

[0010] The iron-nickel magnetic powder core, after insulation coating and annealing, is placed in an acid solution and left to stand, allowing the surface of the iron-nickel magnetic powder core to react with the acid solution to form a salt mixture coating layer, thus obtaining a modified iron-nickel magnetic powder core.

[0011] This invention employs an acid pickling method to treat iron-nickel magnetic powder cores that suffer from low surface resistance and high losses due to incomplete insulation coating, excessively high heat treatment temperature (>600℃), or insufficient atmosphere protection. The acid solution reacts with the metal elements on the surface of the iron-nickel magnetic powder core to generate a coating layer of iron and nickel salts. This coating layer provides insulation, increases the surface resistance of the iron-nickel magnetic powder core, reduces eddy current losses, and decreases coercivity (Hc), thus reducing hysteresis losses and achieving overall loss reduction. This significantly improves the performance of the modified iron-nickel magnetic powder core, preventing it from being unusable due to low surface resistance and high losses.

[0012] The preparation method of this invention is simple. A one-step acid washing surface treatment can achieve the effect of improving the surface resistance of iron-nickel magnetic powder cores and reducing losses. There is no need for additional organic insulating material coating or other steps, and it also avoids the use of a large amount of organic reagents. It can modify iron-nickel magnetic powder cores that cannot be used normally due to low surface resistance and high losses on a large scale, so that they can be used normally in various electronic components such as inductors, filters or transformers, reducing scrap costs, saving production costs, and improving production efficiency.

[0013] As a preferred technical solution of the present invention, the surface resistance of the iron-nickel magnetic powder core after insulation coating and annealing treatment is <2KΩ, for example 0.1KΩ, 0.2KΩ, 0.3KΩ, 0.4KΩ, 0.5KΩ, 0.6KΩ, 0.7KΩ, 0.8KΩ, 0.9KΩ, 1.0KΩ, 1.5KΩ or 1.8KΩ, etc.

[0014] Preferably, the loss of the iron-nickel magnetic powder core after insulation coating and annealing is 500-550 kW / m. 3 For example, 505kW / m 3 510kW / m 3 515kW / m 3 520kW / m 3 530kW / m 3 540kW / m 3 Or 550kW / m 3 wait.

[0015] As a preferred technical solution of the present invention, the surface resistivity of the modified iron-nickel magnetic powder core is 20KΩ-1000KΩ, such as 20KΩ, 50KΩ, 100KΩ, 150KΩ, 200KΩ, 250KΩ, 300KΩ, 350KΩ, 400KΩ, 450KΩ, 500KΩ, 550KΩ, 600KΩ, 650KΩ, 700KΩ, 750KΩ, 800KΩ, 850KΩ, 900KΩ, 950KΩ, or 1000KΩ.

[0016] Preferably, the loss of the modified iron-nickel magnetic powder core is 400-495 kW / m. 3 For example, 400kW / m 3 410kW / m 3 420kW / m 3 430kW / m 3 440kW / m 3 450kW / m 3 460kW / m 3 470kW / m 3 480kW / m 3 490kW / m 3 Or 495kW / m 3 wait.

[0017] As a preferred embodiment of the present invention, the pH value of the acid solution is 1-4, such as 1, 1.5, 2, 2.5, 3, 3.5 or 4.

[0018] In this invention, the pH value of the acid solution is 1-4. This can avoid the problems of passivation or excessive surface reaction due to excessively high acid concentration, which would result in no significant improvement in losses or even a continuous increase. It can also avoid the problem of excessively low acid concentration, which would result in a slow reaction rate and fail to achieve the goal of reducing losses.

[0019] Preferably, the acid solution comprises any one or a combination of at least two of nitric acid, phosphoric acid, hydrochloric acid, or sulfuric acid.

[0020] As a preferred technical solution of the present invention, the reaction temperature is 20℃-80℃, such as 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃ or 90℃.

[0021] Preferably, the reaction time is 1 min to 20 min, such as 1 min, 3 min, 5 min, 8 min, 10 min, 13 min, 15 min, 18 min, or 20 min.

[0022] In this invention, the reaction time is 1 min to 20 min. On the one hand, this allows for a more complete surface treatment, and on the other hand, it prevents excessive reaction from causing no significant improvement in the wear of the iron-nickel magnetic powder core, resulting in superior overall performance of the modified iron-nickel magnetic powder core.

[0023] As a preferred technical solution of the present invention, the thickness of the salt mixture coating layer is 0.5μm-10μm, such as 0.5μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm or 10μm.

[0024] In this invention, the thickness of the salt mixture coating layer is 0.5μm-10μm, which can fully play the role of insulation, thereby effectively improving the surface resistance of the modified iron-nickel magnetic powder core and reducing losses. At the same time, it will not cause damage to the microstructure of the magnetic core due to excessive insulation layer thickness. In addition, if the insulation layer is too thick, too much salt mixture coating layer will accumulate on the surface, which will also disrupt the magnetic domain arrangement and increase hysteresis loss. At the same time, if the insulation layer is too thick, the resistance will increase when current passes through, generating more heat, and the loss may actually increase.

[0025] Preferably, the composition of the salt mixture coating layer includes a mixture of iron salts and nickel salts.

[0026] As a preferred embodiment of the present invention, after the reaction is completed, the process further includes cleaning and drying.

[0027] Preferably, the cleaning process includes immersing the surface of the reacted iron-nickel magnetic powder core in deionized water.

[0028] Preferably, the cleaning time is 1s-300s, such as 30s, 100s, 150s, 200s, 250s or 300s.

[0029] Preferably, the drying temperature is 60℃-100℃, such as 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃.

[0030] It should be noted that the drying time is not specifically limited in this invention. It is sufficient to completely remove the residual deionized water on the surface. For example, it can be 0.5h, 1h or 2h.

[0031] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0032] After insulation coating and annealing, the surface resistivity is <2KΩ and the loss is 500-550kW / m. 3 The iron-nickel magnetic powder core is placed in an acidic solution with a pH of 1-4 and allowed to stand. The surface of the iron-nickel magnetic powder core reacts with the acidic solution at 20℃-80℃ for 1-20 minutes, forming a coating layer of iron and nickel salts with a thickness of 0.5μm-10μm. The surface of the reacted iron-nickel magnetic powder core is then immersed in deionized water for 1-300 seconds and dried at 60℃-100℃ to remove residual deionized water, resulting in a surface resistivity of 20KΩ-1000KΩ and a loss of 400-495kW / m. 3 Modified iron-nickel magnetic powder core.

[0033] It should be noted that the preparation of the iron-nickel magnetic powder core after insulation coating and annealing temperature treatment in this invention is a conventional technical solution. In the preparation process of iron-nickel magnetic powder core, any technical solution that can be used for insulation coating and annealing treatment is applicable to this invention.

[0034] By way of example, the present invention provides a method for preparing an iron-nickel magnetic powder core, the method comprising the following steps:

[0035] (1) Smelting to obtain gas atomized powder; (2) Adding silicon dioxide; (3) Powder heat treatment; (4) Controlling powder particle size; (5) Chemical coating; (6) Physical coating; (7) Press molding; (8) Magnetic core annealing.

[0036] Secondly, the present invention also provides a modified iron-nickel magnetic powder core, which is prepared according to the preparation method described in the first aspect.

[0037] Thirdly, the present invention also provides an application of the modified iron-nickel magnetic powder core, wherein the modified iron-nickel magnetic powder core prepared by the preparation method described in the first aspect, or the modified iron-nickel magnetic powder core described in the second aspect, is applied to electronic components.

[0038] Preferably, the electronic component includes any one of an inductor, a filter, or a transformer.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects:

[0040] 1) The preparation method of the present invention is simple. A one-step acid washing surface treatment can achieve the effect of improving the surface resistance of the iron-nickel magnetic powder core and reducing loss. There is no need for additional organic insulating material coating or other steps, and the use of a large amount of organic reagents is also avoided, saving production costs and improving production efficiency.

[0041] 2) The preparation method adopted in this invention can modify iron-nickel magnetic powder cores that are unusable due to incomplete insulation coating, excessively high heat treatment temperature (>600℃), insufficient atmosphere protection, etc., which result in low surface resistance, high loss and other defects. This allows them to be used normally in various electronic components such as inductors, filters or transformers, reducing scrap costs.

[0042] 3) This invention utilizes an acid solution to chemically react with the metallic elements on the surface of the iron-nickel magnetic powder core, generating a coating layer containing a mixture of iron and nickel salts. This coating layer provides insulation, thereby increasing the resistivity of the iron-nickel magnetic powder core and reducing losses, resulting in a surface resistivity of 20KΩ-1000KΩ and a loss of 400-495kW / m. 3 The modified iron-nickel magnetic powder core shows a significant improvement in performance. Attached Figure Description

[0043] Figure 1 This is the BH curve of the modified iron-nickel magnetic powder core prepared in Example 1 of this invention. Detailed Implementation

[0044] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0045] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0046] The iron-nickel magnetic powder core used in the specific embodiments of the present invention, after insulation coating and annealing temperature treatment, is prepared by the following method:

[0047] (1) Smelting to obtain gas atomized powder; (2) Adding silicon dioxide; (3) Powder heat treatment; (4) Controlling powder particle size; (5) Chemical coating; (6) Physical coating; (7) Press molding; (8) Magnetic core annealing.

[0048] Surface resistivity < 2KΩ and power loss 500-550kW / m were selected. 3 The iron-nickel magnetic powder core (tested at 100 kHz and 100 mT) was modified.

[0049] Example 1

[0050] This embodiment provides a method for preparing a modified iron-nickel magnetic powder core, the method comprising the following steps:

[0051] After insulation coating and annealing, the surface resistivity is 0.2KΩ and the loss is 515kW / m. 3 The iron-nickel magnetic powder core was placed in a nitric acid solution with a pH of 3 and allowed to stand. The surface of the iron-nickel magnetic powder core reacted with the nitric acid solution at 50°C for 3 minutes to generate a mixed coating layer containing iron nitrate and nickel nitrate with a thickness of 5 μm. The surface of the iron-nickel magnetic powder core after reaction was immersed in deionized water for 60 seconds and dried at 80°C to remove the residual deionized water on the surface, thus obtaining the modified iron-nickel magnetic powder core.

[0052] Example 2

[0053] This embodiment provides a method for preparing a modified iron-nickel magnetic powder core, the method comprising the following steps:

[0054] After insulation coating and annealing, the surface resistivity is 1KΩ and the loss is 546kW / m. 3The iron-nickel magnetic powder core was placed in a nitric acid solution with a pH of 2 and allowed to stand. The surface of the iron-nickel magnetic powder core reacted with the nitric acid solution at 40°C for 10 minutes to generate a mixed coating layer containing iron nitrate and nickel nitrate with a thickness of 4 μm. The surface of the iron-nickel magnetic powder core after reaction was immersed in deionized water for 30 seconds and dried at 80°C to remove the residual deionized water on the surface, thus obtaining the modified iron-nickel magnetic powder core.

[0055] Example 3

[0056] This embodiment provides a method for preparing a modified iron-nickel magnetic powder core, the method comprising the following steps:

[0057] After insulation coating and annealing, the surface resistivity is 0.8KΩ and the loss is 520kW / m. 3 The iron-nickel magnetic powder core was placed in a nitric acid solution with a pH of 3.5 and allowed to stand. The surface of the iron-nickel magnetic powder core reacted with the nitric acid solution at 60°C for 5 minutes to generate a mixed coating layer containing iron nitrate and nickel nitrate with a thickness of 8 μm. The surface of the iron-nickel magnetic powder core after reaction was immersed in deionized water for 200 seconds and dried at 70°C to remove the residual deionized water on the surface, thus obtaining the modified iron-nickel magnetic powder core.

[0058] Example 4

[0059] This embodiment provides a method for preparing a modified iron-nickel magnetic powder core, the method comprising the following steps:

[0060] After insulation coating and annealing, the surface resistivity is 0.7KΩ and the loss is 518kW / m. 3 The iron-nickel magnetic powder core was placed in a nitric acid solution with a pH of 1 and allowed to stand. The surface of the iron-nickel magnetic powder core reacted with the nitric acid solution at 20°C for 20 minutes to generate a mixed coating layer containing iron nitrate and nickel nitrate with a thickness of 10 μm. The surface of the iron-nickel magnetic powder core after reaction was immersed in deionized water for 300 seconds and dried at 60°C to remove the residual deionized water on the surface, thus obtaining the modified iron-nickel magnetic powder core.

[0061] Example 5

[0062] This embodiment provides a method for preparing a modified iron-nickel magnetic powder core, the method comprising the following steps:

[0063] After insulation coating and annealing, the surface resistivity is 1KΩ and the loss is 530kW / m. 3The iron-nickel magnetic powder core was placed in a nitric acid solution with a pH of 2 and allowed to stand. The surface of the iron-nickel magnetic powder core reacted with the nitric acid solution at 80°C for 1 minute to generate a mixed coating layer containing iron nitrate and nickel nitrate with a thickness of 0.5 μm. The surface of the iron-nickel magnetic powder core after reaction was immersed in deionized water for 60 seconds and dried at 100°C to remove the residual deionized water on the surface, thus obtaining the modified iron-nickel magnetic powder core.

[0064] Example 6

[0065] This embodiment provides a method for preparing a modified iron-nickel magnetic powder core. The difference between this method and that of Embodiment 1 is that the core has a surface resistivity of 0.2 kΩ and a loss of 515 kW / m. 3 The iron-nickel magnetic powder core was placed in a phosphoric acid solution with a pH of 3 to obtain a mixed coating layer containing iron phosphate and nickel phosphate. The remaining preparation methods and parameters were consistent with those in Example 1.

[0066] Example 7

[0067] This embodiment provides a method for preparing a modified iron-nickel magnetic powder core. The difference between this method and that of Embodiment 1 is that the core has a surface resistivity of 0.2 kΩ and a loss of 515 kW / m. 3 The iron-nickel magnetic powder core was placed in a hydrochloric acid solution with a pH of 3 to obtain a mixed coating layer containing ferric chloride and nickel chloride. The remaining preparation methods and parameters were consistent with those in Example 1.

[0068] Example 8

[0069] This embodiment provides a method for preparing a modified iron-nickel magnetic powder core. The difference between this method and that of Embodiment 1 is that the core has a surface resistivity of 0.2 kΩ and a loss of 515 kW / m. 3 The iron-nickel magnetic powder core was placed in a sulfuric acid solution with a pH of 3 to obtain a mixed coating layer containing iron sulfate and nickel sulfate. The remaining preparation methods and parameters were consistent with those in Example 1.

[0070] Example 9

[0071] This embodiment provides a method for preparing a modified iron-nickel magnetic powder core. The difference between this method and Example 1 is that the reaction time is 25 minutes, while the rest of the preparation method and parameters are the same as in Example 1.

[0072] Example 10

[0073] This embodiment provides a method for preparing a modified iron-nickel magnetic powder core. The difference between this method and Example 1 is that the thickness of the mixed coating layer containing iron nitrate and nickel nitrate is 0.2 μm, while the rest of the preparation method and parameters are the same as in Example 1.

[0074] Example 11

[0075] This embodiment provides a method for preparing a modified iron-nickel magnetic powder core. The difference between this method and Example 1 is that the thickness of the mixed coating layer containing iron nitrate and nickel nitrate is 12 μm, while the rest of the preparation method and parameters are the same as in Example 1.

[0076] Example 12

[0077] This embodiment provides a method for preparing a modified iron-nickel magnetic powder core. The difference between this method and that of Embodiment 1 is that the core has a surface resistivity of 0.2 kΩ and a loss of 515 kW / m. 3 The iron-nickel magnetic powder core was placed in commercially available 68% concentration (pH value of about 0) nitric acid, and the rest of the preparation method and parameters were consistent with those in Example 1.

[0078] Example 13

[0079] This embodiment provides a method for preparing a modified iron-nickel magnetic powder core. The difference between this method and that of Embodiment 1 is that the core has a surface resistivity of 0.2 kΩ and a loss of 515 kW / m. 3 The iron-nickel magnetic powder core was placed in nitric acid with a pH of 5, and the rest of the preparation method and parameters were the same as in Example 1.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing a modified iron-nickel magnetic powder core, the method comprising the following steps:

[0082] After insulation coating and annealing, the surface resistivity is 0.2KΩ and the loss is 515kW / m. 3 The modified iron-nickel magnetic powder core is obtained by spraying an insulating agent onto the surface of the iron-nickel magnetic powder core. A layer of epoxy resin paint with a thickness of 0.15 mm is sprayed onto the surface of the iron-nickel magnetic powder core, and the epoxy resin is cured at 180℃.

[0083] The surface resistivity of the modified iron-nickel magnetic powder cores provided in Examples 1-13 and Comparative Example 1 was tested using an impedance analyzer, and the BH curves were measured using a BH meter. The area of ​​the curves was calculated to obtain the loss values. The specific test results are shown in Table 1.

[0084] Figure 1 The BH curve of the modified iron-nickel magnetic powder core prepared in Example 1 of this invention is shown. As can be seen from the figure, after acid washing, the loss is 421 kW / m under the conditions of 100 kHz and 100 mT. 3 515kW / m before pickling 3 Data comparison can help reduce losses.

[0085] Table 1

[0086]

[0087]

[0088] The test results show that:

[0089] (1) As can be seen from Examples 1-8, the present invention uses acid pickling to treat the surface of the iron-nickel magnetic powder core after insulation coating and annealing. The acid solution reacts chemically with the metal elements on the surface of the iron-nickel magnetic powder core to generate a coating layer (partial coating) of iron salt and nickel salt mixture. The presence of the coating layer plays an insulating role, thereby increasing the resistance of the iron-nickel magnetic powder core itself and reducing the loss. This results in a significant improvement in the performance of the modified iron-nickel magnetic powder core. The surface resistance of the modified iron-nickel magnetic powder core can reach 40KΩ or above, and the loss can be reduced to 470kW / m. 3 Furthermore, as can be seen from Examples 1 and 6-8, washing with nitric acid significantly improves the wear of the modified iron-nickel magnetic powder core, and its overall performance is slightly better than that treated with phosphoric acid, hydrochloric acid, and sulfuric acid.

[0090] (2) As can be seen from Examples 1 and 9, the reaction time is between 1 min and 20 min. On the one hand, the surface treatment is relatively complete, and on the other hand, the excessive reaction will not lead to a significant improvement in the loss of the iron-nickel magnetic powder core. This results in better overall performance of the modified iron-nickel magnetic powder core. When the pickling time is long, the modified iron-nickel magnetic powder core is over-corroded. Even if a corresponding insulating layer is formed and the surface resistance increases, the improvement in its loss is not significant.

[0091] (3) As can be seen from Examples 1 and 10-11, the thickness of the salt mixture coating layer is 0.5μm-10μm, which can ensure that it plays a sufficient role in insulation, thereby effectively improving the surface resistance of the modified iron-nickel magnetic powder core and reducing loss. At the same time, it will not cause the problem of insignificant loss improvement due to excessive insulation layer thickness.

[0092] (4) As can be seen from Examples 1 and 12-13, when the pH value of the acid solution is 1-4, it can avoid passivation or excessive surface reaction due to excessively high acid solution concentration, which would result in no significant improvement in loss. It can also avoid the reaction rate being too slow due to excessively low acid solution concentration, which would not achieve the purpose of reducing loss.

[0093] (5) As can be seen from Example 1 and Comparative Example 1, when a common sprayed insulating layer is used for surface treatment, although the surface resistance can be increased sharply, the corresponding loss continues to increase on the basis of the iron-nickel magnetic powder core before modification, and does not achieve the effect of reducing loss.

[0094] In summary, this invention employs an acid pickling method to treat the surface of iron-nickel magnetic powder cores after insulation coating and annealing. The acid solution reacts chemically with the metal elements on the surface of the iron-nickel magnetic powder core, generating a coating layer (partial coating) containing a mixture of iron and nickel salts. This coating layer provides insulation, thereby increasing the resistivity of the iron-nickel magnetic powder core and reducing losses. This significantly improves the performance of the modified iron-nickel magnetic powder core, preventing the insulation layer from decomposing due to incomplete insulation coating, excessively high heat treatment temperature (>600℃), or insufficient atmosphere protection, which would otherwise result in low surface resistivity, high losses, and unusable conditions.

[0095] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a modified iron-nickel magnetic powder core, characterized in that, The preparation method includes the following steps: The iron-nickel magnetic powder core, after insulation coating and annealing, is placed in an acid solution and left to stand, allowing the surface of the iron-nickel magnetic powder core to react with the acid solution to form a salt mixture coating layer, thus obtaining a modified iron-nickel magnetic powder core.

2. The preparation method according to claim 1, characterized in that, The surface resistance of the iron-nickel magnetic powder core after insulation coating and annealing treatment is <2KΩ; Preferably, the loss of the iron-nickel magnetic powder core after insulation coating and annealing is 500-550 kW / m. 3 .

3. The preparation method according to claim 1 or 2, characterized in that, The surface resistivity of the modified iron-nickel magnetic powder core is 20KΩ-1000KΩ; Preferably, the loss of the modified iron-nickel magnetic powder core is 400-495 kW / m. 3 .

4. The preparation method according to any one of claims 1-3, characterized in that, The pH value of the acid solution is 1-4; Preferably, the acid solution comprises any one or a combination of at least two of nitric acid, phosphoric acid, hydrochloric acid, or sulfuric acid.

5. The preparation method according to any one of claims 1-4, characterized in that, The reaction temperature is 20℃-80℃; Preferably, the reaction time is 1 min to 20 min.

6. The preparation method according to any one of claims 1-5, characterized in that, The thickness of the salt mixture coating layer is 0.5 μm-10 μm; Preferably, the composition of the salt mixture coating layer includes a mixture of iron salts and nickel salts.

7. The preparation method according to any one of claims 1-6, characterized in that, After the reaction is complete, the process also includes cleaning and drying; Preferably, the cleaning includes immersing the surface of the reacted iron-nickel magnetic powder core in deionized water; Preferably, the cleaning time is 1s-300s; Preferably, the drying temperature is 60℃-100℃.

8. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: After insulation coating and annealing, the surface resistivity is <2KΩ and the loss is 500-550kW / m. 3 The iron-nickel magnetic powder core is placed in an acidic solution with a pH of 1-4 and allowed to stand. The surface of the iron-nickel magnetic powder core reacts with the acidic solution at 20℃-80℃ for 1-20 minutes, forming a coating layer of iron and nickel salts with a thickness of 0.5μm-10μm. The surface of the reacted iron-nickel magnetic powder core is then immersed in deionized water for 1-300 seconds and dried at 60℃-100℃ to remove residual deionized water, resulting in a surface resistivity of 20KΩ-1000KΩ and a loss of 400-495kW / m. 3 Modified iron-nickel magnetic powder core.

9. A modified iron-nickel magnetic powder core, characterized in that, The modified iron-nickel magnetic powder core is prepared by the preparation method according to any one of claims 1-8.

10. An application of a modified iron-nickel magnetic powder core, characterized in that, The modified iron-nickel magnetic powder core prepared by the preparation method according to any one of claims 1-8, or the modified iron-nickel magnetic powder core according to claim 9, is applied to electronic components; Preferably, the electronic component includes any one of an inductor, a filter, or a transformer.

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