Method for insulating a soft magnetic powder material and use thereof

Abstract

The application belongs to the technical field of soft magnetic composite material preparation, and particularly relates to an insulation coating method for soft magnetic powder material and application. The insulation coating method comprises the following steps: (1) uniformly mixing low-melting-point metal or alloy powder, silica sol, silane coupling agent and hot curing resin glue solution to obtain coating slurry; (2) uniformly mixing soft magnetic powder and the coating slurry of step (1), and then performing hot-pressing curing forming at a temperature of 60-100 DEG C and under vacuum condition, and then performing hot-pressing sintering treatment under a temperature higher than the melting point of the low-melting-point metal or alloy powder and under an oxygen-containing atmosphere condition to obtain the insulation-coated soft magnetic powder material. The insulation coating method of the application combines the advantages of the organic material insulation coating method and the inorganic material insulation coating method, overcomes the respective defects, and significantly improves the stability and insulation coating effect of the insulation coating layer.

Description

Technical Field

[0001] This invention belongs to the field of soft magnetic composite material preparation technology, specifically relating to an insulating coating method and application of soft magnetic powder material. Background Technology

[0002] Soft magnetic metallic materials possess high permeability and low coercivity, making them widely used in the radio electronics industry, precision instruments, and remote and automatic control systems. Based on their composition, soft magnetic metallic materials mainly include iron-nickel (FeNi) soft magnetic alloys, iron-aluminum (FeAl) soft magnetic alloys, iron-cobalt (FeCo) soft magnetic alloys, iron-silicon (FeSi) soft magnetic alloys, and iron-silicon-aluminum (FeSiAl) soft magnetic alloys. With the advancement of electronic technology, the requirements for magnetic devices are becoming increasingly stringent, primarily moving towards miniaturization and high-frequency operation, placing higher demands on magnetic loss and temperature rise performance.

[0003] Although soft magnetic materials in metals possess high permeability and low coercivity, their low resistivity leads to significant eddy current losses in high-frequency applications. These losses not only degrade the core's performance but also cause overheating, thus limiting their use. Therefore, insulating the surface of the magnetic powder core is a crucial solution. Insulating the core isolates the metal powder particles from direct contact, thereby increasing the resistivity and reducing eddy current losses in high-frequency applications.

[0004] The main methods for insulating and coating soft magnetic metal powders include organic material insulation coating and inorganic material insulation coating. Organic material insulation coating involves mixing and bonding the soft magnetic metal powder with organic binder resin. This method has the advantages of strong adhesion to the soft magnetic powder and uniform coating. However, organic binder resins have low heat resistance and are prone to decomposition during subsequent heat treatment, causing defects in the coating structure and reducing material density, thus affecting the material's magnetic properties. Inorganic material insulation coating generally uses metal oxides to insulatingly coat the soft magnetic powder. However, the adhesion between metal oxides and soft magnetic powder is weak, making it difficult to form a uniform coating. Existing technologies generally require complex physical or chemical coating processes to achieve good coating results. For example, patent CN 104759619 B uses the adsorption-diffusion reaction of phosphoric acid and boric acid to prepare an insulating coating layer; patent CN 110434326 B uses the chemical precipitation hydrothermal reaction of aluminum salts to prepare a lithium aluminum oxide coating layer; and patent CN 112643038 B uses a vacuum melting system and a gas atomization coating system to achieve the coating of metal oxide insulating layers. Patent CN 114242369 B uses a coating-diffusion oxidation method with Nd, Dy, and Tb to prepare an oxide insulating layer. However, the above-mentioned insulating coating methods generally have high requirements for processes and equipment, and their industrial production stability is poor. Therefore, providing an insulating coating method for soft magnetic powder with simple process control is the technical problem that this invention aims to solve. Summary of the Invention

[0005] In view of the shortcomings and deficiencies of the existing technology, the primary objective of this invention is to provide an insulating coating method for soft magnetic powder materials.

[0006] Another object of the present invention is to provide a soft magnetic powder material prepared by the above method.

[0007] Another object of the present invention is to provide the application of the above-mentioned soft magnetic powder material in magnetic powder cores in the fields of AI computing chips, servers and communication equipment.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] An insulating coating method for soft magnetic powder material includes the following steps:

[0010] (1) Mix low melting point metal or alloy powder with silica sol, silane coupling agent and thermosetting resin liquid evenly to obtain coating slurry;

[0011] (2) Mix the soft magnetic powder with the coating slurry in step (1) evenly, first hot press and solidify it under a temperature of 60~100℃ and vacuum conditions, and then hot press and sinter it under a temperature higher than the melting point of low melting point metal or alloy powder and an oxygen-containing atmosphere to obtain the soft magnetic powder material with insulating coating.

[0012] Further, the low-melting-point metal or alloy powder mentioned in step (1) is at least one metal powder selected from Al, Mg, Zn, Sn, and Bi, or an alloy powder of at least two of the above metals.

[0013] Furthermore, the average particle size of the low-melting-point metal or alloy powder is 0.2~10μm.

[0014] Further, the silane coupling agent mentioned in step (1) is at least one of methylsilane coupling agent, aminosilane coupling agent, epoxysilane coupling agent, and vinylsilane coupling agent. The silane coupling agent of this invention is used to improve the bonding strength and compatibility between silica sol, low-melting-point metal or alloy powder and organic resin, thereby improving the coating effect.

[0015] Further, the thermosetting resin liquid mentioned in step (1) is an epoxy resin liquid, an acrylic resin liquid, or an organosilicon resin liquid. The organic resin liquid of the present invention has good bonding force with soft magnetic powder and low melting point metal or alloy powder, and can provide good mixing dispersion and bonding and coating effect after curing.

[0016] Further, in step (1), the mass ratio of the low-melting-point metal or alloy powder to the silica sol, silane coupling agent, and thermosetting resin is (30~60):100:(2~10):(30~60). The silica sol in this invention functions to form a good SiO2 insulating coating layer after hot-pressing sintering. The low-melting-point metal or alloy powder melts and fills the air gaps generated by the high-temperature oxidation and decomposition of the thermosetting resin during hot-pressing sintering, providing good support for the SiO2 insulating coating layer, reducing its brittleness, and further forming a metal oxide-SiO2 composite insulating coating layer through in-situ oxidation under oxygen-containing atmosphere conditions, thereby improving the stability and insulating coating effect of the insulating coating layer.

[0017] Further, the soft magnetic powder mentioned in step (2) is iron-nickel (FeNi) soft magnetic alloy powder, iron-aluminum (FeAl) soft magnetic alloy powder, iron-cobalt (FeCo) soft magnetic alloy powder, iron-silicon (FeSi) soft magnetic alloy powder or iron-silicon-aluminum (FeSiAl) soft magnetic alloy powder with a particle size of 0.5~20μm.

[0018] Further, the mass ratio of the soft magnetic powder to the coating slurry in step (2) is 100:(1~10).

[0019] Furthermore, the oxygen-containing atmosphere mentioned in step (2) is an air atmosphere or a mixture of oxygen and argon. This invention allows for convenient adjustment of the oxidation degree of low-melting-point metal or alloy powders during sintering by controlling the partial pressure of oxygen in the oxygen-containing atmosphere, thereby regulating magnetic and insulating properties.

[0020] Furthermore, the temperature of the hot pressing sintering treatment in step (2) is 800~1200℃, the pressure is 500~800MPa, and the time is 10~90min.

[0021] A soft magnetic powder material is prepared by the above method.

[0022] The above-mentioned soft magnetic powder materials are used in magnetic powder cores in the fields of AI computing chips, servers, and communication equipment.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] (1) The insulation coating method of the present invention combines the advantages of strong bonding force and uniform coating of organic material insulation coating method and the advantages of high temperature resistance of inorganic material insulation coating method. It uses low melting point metal or alloy powder as high temperature bonding support structure and forms a composite insulation layer with SiO2, which significantly improves the stability of insulation coating layer and insulation coating effect.

[0025] (2) The insulation coating method of the present invention has simple process control, convenient performance adjustment, and is suitable for industrial application. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, all raw materials used in the following embodiments are commercially available conventional raw materials in the art.

[0027] Example 1

[0028] An insulating coating method for soft magnetic powder material includes the following steps:

[0029] (1) Al powder with an average particle size of 2 μm is mixed with silica sol, aminosilane coupling agent KH-550 and E51 epoxy resin liquid in a mass ratio of 40:100:6:40 to obtain a coating slurry.

[0030] (2) The FeSiAl soft magnetic powder with an average particle size of 5μm is mixed with the coating slurry in step (1) at a mass ratio of 100:6. The mixture is first hot-pressed and cured under the conditions of 80℃ temperature, 600MPa pressure and vacuum. Then, it is hot-pressed and sintered for 50min under the conditions of 900℃ temperature, 600MPa pressure and O2 (10vt%) / Ar2 mixed atmosphere to obtain the soft magnetic powder material with insulation coating.

[0031] The density of the soft magnetic powder material obtained in this embodiment was tested to be 5.910 g / cm³. 3 The inductance value L is 16.82μH, and the high-frequency loss (1MHz / 50mT) is 1120kW / m. 3 .

[0032] Example 2

[0033] An insulating coating method for soft magnetic powder material includes the following steps:

[0034] (1) Sn powder with an average particle size of 1 μm is mixed with silica sol, vinyl silane coupling agent A-151 and thermosetting acrylic resin liquid in a mass ratio of 30:100:2:30 to obtain a coating slurry.

[0035] (2) The soft magnetic powder with an average particle size of 5 μm is mixed with the coating slurry in step (1) at a mass ratio of 100:5. The mixture is first hot-pressed and cured under a temperature of 70℃, a pressure of 500MPa and a vacuum. Then, it is hot-pressed and sintered for 40 minutes under a temperature of 800℃, a pressure of 500MPa and a mixed atmosphere of O2 (12vt%) / Ar2 to obtain the soft magnetic powder material with insulation coating.

[0036] The density of the soft magnetic powder material obtained in this embodiment was tested to be 5.901 g / cm³. 3 The inductance value L is 13.75μH, and the high-frequency loss (1MHz / 50mT) is 1054kW / m. 3 .

[0037] Example 3

[0038] An insulating coating method for soft magnetic powder material includes the following steps:

[0039] (1) Al powder with an average particle size of 2 μm is mixed with silica sol, epoxy silane coupling agent KH-560 and thermosetting organosilicon resin liquid in a mass ratio of 60:100:10:60 to obtain a coating slurry.

[0040] (2) FeSiAl soft magnetic powder with an average particle size of 5μm is mixed with the coating slurry in step (1) at a mass ratio of 100:4. The mixture is first hot-pressed and cured under a temperature of 90℃, a pressure of 700MPa and a vacuum. Then, it is hot-pressed and sintered for 60 minutes under a temperature of 1000℃, a pressure of 700MPa and a mixed atmosphere of O2 (8vt%) / Ar2 to obtain the soft magnetic powder material with insulating coating.

[0041] The density of the soft magnetic powder material obtained in this embodiment was tested to be 5.915 g / cm³. 3 The inductance value L is 17.34μH, and the high-frequency loss (1MHz / 50mT) is 936kW / m. 3 .

[0042] Comparative Example 1

[0043] An insulating coating method for soft magnetic powder material, compared with Example 1, is that Al powder is not added to the coating slurry in step (1), but the rest are the same.

[0044] The density of the soft magnetic powder material obtained in this comparative example was tested to be 5.785 g / cm³. 3 The inductance value L is 13.66μH, and the high-frequency loss (1MHz / 50mT) is 1921kW / m. 3 .

[0045] Comparative Example 2

[0046] An insulating coating method for soft magnetic powder material, compared with Example 1, uses an equal amount of Al2O3 powder with an average particle size of 2μm to replace Al powder, while the rest are the same.

[0047] The density of the soft magnetic powder material obtained in this comparative example was tested to be 5.724 g / cm³. 3 The inductance value L is 12.58μH, and the high-frequency loss (1MHz / 50mT) is 2351kW / m. 3 .

[0048] The comparison results between Comparative Examples 1 and 2 and Example 1 show that the present invention uses a coating slurry containing low-melting-point metal powder to bond and cure, and then performs hot pressing sintering treatment at a temperature higher than the melting point of the low-melting-point metal powder to generate a composite insulating coating layer through in-situ oxidation. This is the key to improving the material density, inductance value and insulation coating effect.

[0049] Comparative Example 3

[0050] An insulating coating method for a soft magnetic powder material, compared with Example 1, is that the coating slurry in step (1) does not contain aminosilane coupling agent KH-550, but the rest are the same.

[0051] The density of the soft magnetic powder material obtained in this comparative example was tested to be 5.862 g / cm³. 3 The inductance value L is 14.10μH, and the high-frequency loss (1MHz / 50mT) is 1533kW / m. 3 .

[0052] The comparison between Comparative Example 3 and Example 1 shows that the addition of silane coupling agent has a significant improving effect on improving material density, inductance and insulation coating effect.

[0053] Comparative Example 4

[0054] An insulating coating method for a soft magnetic powder material, compared with Example 1, is that E51 epoxy resin liquid is not added to the coating slurry in step (1), but the rest are the same.

[0055] The density of the soft magnetic powder material obtained in this comparative example was tested to be 5.903 g / cm³. 3 The inductance value L is 15.29μH, and the high-frequency loss (1MHz / 50mT) is 2158kW / m. 3 .

[0056] The comparison between Comparative Example 4 and Example 1 shows that simply using low-melting-point metal powder and silica sol for coating results in poor coating uniformity, leading to a significant increase in high-frequency loss.

[0057] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for insulating coating of soft magnetic powder material, characterized in that: Includes the following steps: (1) Mix low melting point metal or alloy powder with silica sol, silane coupling agent and thermosetting resin liquid evenly to obtain coating slurry; (2) Mix the soft magnetic powder with the coating slurry in step (1) evenly, first hot press and solidify it under a temperature of 60~100℃ and vacuum conditions, and then hot press and sinter it under a temperature higher than the melting point of the low melting point metal or alloy powder and an oxygen-containing atmosphere to form a SiO2 insulating coating layer in the silica sol. At the same time, the low melting point metal or alloy powder melts and fills the air gap generated by the high temperature oxidation and decomposition of the thermosetting resin, forming a support for the SiO2 insulating coating layer. Under the above conditions, in-situ oxidation forms a metal oxide-SiO2 composite insulating coating layer to obtain an insulating soft magnetic powder material. The low-melting-point metal or alloy powder mentioned in step (1) is at least one metal powder selected from Al, Mg, Zn, Sn, and Bi, or an alloy powder of at least two of the above metals; The soft magnetic powder mentioned in step (2) is FeNi soft magnetic alloy powder, FeAl soft magnetic alloy powder, FeCo soft magnetic alloy powder, FeSi soft magnetic alloy powder or FeSiAl soft magnetic alloy powder; The oxygen-containing atmosphere mentioned in step (2) is an air atmosphere or a mixture of oxygen and argon. The temperature of the hot pressing sintering treatment is 800~1200℃, the pressure is 500~800MPa, and the time is 10~90min.

2. The insulating coating method for a soft magnetic powder material according to claim 1, characterized in that: The average particle size of the low-melting-point metal or alloy powder is 0.2~10μm.

3. The insulating coating method for a soft magnetic powder material according to claim 1, characterized in that: The silane coupling agent mentioned in step (1) is at least one of methylsilane coupling agent, aminosilane coupling agent, epoxysilane coupling agent, and vinylsilane coupling agent; the thermosetting resin liquid is epoxy resin liquid, acrylic resin liquid, or silicone resin liquid.

4. The insulating coating method for a soft magnetic powder material according to claim 1, characterized in that: The mass ratio of the low melting point metal or alloy powder to silica sol, silane coupling agent and thermosetting resin in step (1) is (30~60):100:(2~10):(30~60).

5. The insulating coating method for a soft magnetic powder material according to claim 1, characterized in that: The average particle size of the soft magnetic powder in step (2) is 0.5~20μm.

6. The insulating coating method for a soft magnetic powder material according to claim 1, characterized in that: The mass ratio of the soft magnetic powder to the coating slurry in step (2) is 100:(1~10).

7. A soft magnetic powder material, characterized in that: It is prepared by the method described in any one of claims 1 to 6.

8. The application of the soft magnetic powder material as described in claim 7 in magnetic powder cores in the fields of AI computing chips, servers, and communication equipment.