A high-frequency and low-power iron-silicon-aluminum soft magnetic material, its preparation method and application

Abstract

The present invention belongs to the technical field of soft magnetic materials, and discloses a high-frequency low-loss iron-silicon-aluminum soft magnetic material, a preparation method thereof and an application. The preparation method is as follows: phytic acid is added to an aqueous alcohol solution for dissolution, and then an aluminum alkoxide solution is added for mixing reaction to obtain an aluminum phytic acid sol, and then the aluminum phytic acid sol is mixed uniformly with a silica sol to obtain an insulating coating solution; the iron-silicon-aluminum soft magnetic alloy powder is coated with the above insulating coating solution, and then heated to 300-800 °C for heat treatment to obtain an alloy powder with a silica-aluminum phosphate composite insulating coating; finally, it is mixed with a binder and pressed into a shape, and then heated to 600-900 °C for annealing treatment to obtain a high-frequency low-loss iron-silicon-aluminum soft magnetic material. The present invention uses an insulating coating solution prepared by mixing an aluminum phytic acid sol and a silica sol to perform insulating coating on the soft magnetic alloy powder, which can significantly improve the insulating coating effect and reduce the high-frequency loss of the magnetic ring product.

Description

Technical Field

[0001] The present invention belongs to the technical field of soft magnetic materials, and particularly relates to a high-frequency and low-loss FeSiAl soft magnetic material, a preparation method thereof and an application thereof. Background Art

[0002] FeSiAl soft magnetic alloy refers to a high magnetic permeability soft magnetic alloy mainly composed of iron, silicon and aluminum, also known as sendust alloy. The remarkable feature of this alloy is that it has a magnetic anisotropy coefficient and a saturation magnetostriction coefficient approaching zero. Compared with other soft magnetic alloy materials, FeSiAl soft magnetic alloy materials have comprehensive advantages such as low loss, high resistance, low cost and no noise, making it highly favored.

[0003] The iron-silicon-aluminum magnetic core is mainly applied to the high-frequency field. With the increase of the working frequency, the rate of increase in eddy current loss is very fast. Eddy current loss not only reduces the performance of the magnetic core, but also causes the device to heat up. With the improvement of electronic technology, the requirements for magnetic devices are getting higher and higher, mainly developing in the direction of miniaturization and high frequency, and higher requirements are put forward for magnetic loss and temperature rise performance. In order to reduce the energy loss caused by eddy current loss, reducing the conductivity of the magnetic core and increasing its resistivity become the key. The commonly used treatment method is to carry out insulation coating treatment on the surface of the magnetic core particles. For example, in the patent document with the publication number CN1965379A, a soft magnetic material containing composite magnetic particles is disclosed. The composite magnetic particles are composed of metal magnetic particles mainly composed of Fe and an insulating coating layer covering the metal magnetic particles. The insulating coating layer contains iron phosphate compound and aluminum phosphate compound. The atomic ratio of Fe contained in the contact surface of the insulating coating layer in contact with the metal magnetic particles is greater than the atomic ratio of Fe contained in the surface of the insulating coating layer. The atomic ratio of A contained in the surface of the insulating coating layer in contact with the metal magnetic particles is less than the atomic ratio of A1 contained in the surface of the insulating coating layer. With this structure, iron loss can be reduced. Its main technology lies in that the contact surface of the insulating coating layer in contact with the metal magnetic particles is formed by a layer containing a large amount of phosphoric acid and Fe. The layer containing a large amount of phosphoric acid and Fe has high adhesion to Fe, thereby improving the adhesion between the metal magnetic particles and the insulating coating layer. Therefore, in pressure molding, the insulating coating layer hardly breaks and the increase of eddy current loss can be suppressed. In addition, the surface of the insulating coating layer is formed by a layer containing a large amount of phosphoric acid and at least one atom selected from A1, Si, Mn, Ti, Zr, and Zn. Compared with the layer containing a large amount of phosphoric acid and Fe, the layer containing a large amount of phosphoric acid and at least one atom selected from A1, Si, Mn, Ti, Zr, and Zn has excellent high-temperature stability. Therefore, when it is heat-treated at high temperature, the soft magnetic material does not break. In addition, this layer also inhibits the decomposition of the layer formed on the contact surface of the insulating coating layer in contact with the metal magnetic particles. Therefore, the heat resistance of the insulating coating layer can be improved, and the hysteresis loss of the powder magnetic core prepared by pressure molding this soft magnetic material can be reduced without reducing the eddy current loss. Therefore, the iron loss of the powder magnetic core can be reduced.

[0004] However, this prior art needs to improve the insulation coating effect through double-layer insulation coating, and the preparation process is complex and the stability is poor. Summary of the Invention

[0005] Aiming at the above-mentioned disadvantages and deficiencies of the prior art, the primary object of the present invention is to provide a preparation method of an iron-silicon-aluminum soft magnetic material with high frequency and low power consumption.

[0006] Another object of the present invention is to provide an iron-silicon-aluminum soft magnetic material with high frequency and low power consumption prepared by the above method.

[0007] Another object of the present invention is to provide the application of the above high-frequency and low-power iron-silicon-aluminum soft magnetic material in the fields of AI computing power chips, servers, and communication devices.

[0008] The object of the present invention is achieved by the following technical solutions:

[0009] A preparation method of a high-frequency and low-power iron-silicon-aluminum soft magnetic material, comprising the following preparation steps:

[0010] (1) Preparation of the insulating coating solution: Add phytic acid to an alcohol aqueous solution to dissolve it, then add an aluminum alkoxide solution and mix and react to obtain an aluminum phytic acid sol, and then mix it evenly with silica sol to obtain the insulating coating solution;

[0011] (2) Insulating coating treatment: Mix the iron-silicon-aluminum soft magnetic alloy powder evenly with the insulating coating solution in step (1), first dry to remove the solvent at a temperature of 60-100°C, and then heat-treat at a temperature of 300-800°C to obtain an alloy powder with a silica-aluminum phosphate composite insulating coating treatment;

[0012] (3) Compression molding: Mix the alloy powder with a silica-aluminum phosphate composite insulating coating treatment evenly with a binder, then inject it into a mold for compression molding, and then heat it to 600-900°C for annealing treatment to obtain a high-frequency and low-power iron-silicon-aluminum soft magnetic material.

[0013] Preferably, in step (1), the alcohol aqueous solution is an ethanol aqueous solution with an ethanol volume percentage content of 80-95%.

[0014] Preferably, in step (1), the aluminum alkoxide solution is triethanol aluminum solution, aluminum propoxide solution, aluminum isopropoxide solution or aluminum n-butoxide solution.

[0015] Preferably, in step (1), the addition amount of the aluminum alkoxide solution makes the pH value of the reaction system 5-7.

[0016] Preferably, in step (1), the addition amount of the silica sol is 20-60% of the mass of phytic acid in terms of the content of silicon dioxide.

[0017] Preferably, in step (2), the D50 particle size of the iron-silicon-aluminum soft magnetic alloy powder is 5-15 um.

[0018] Preferably, in step (2), the addition amount of the insulating coating solution is 0.2-2% of the mass of the iron-silicon-aluminum soft magnetic alloy powder in terms of its solid content.

[0019] Preferably, in step (2), the drying to remove the solvent is carried out under vacuum conditions; the heat treatment is carried out under nitrogen protection conditions, and the heat treatment time is 3-10 h.

[0020] Preferably, the binder described in step (3) is an epoxy resin binder solution or a silicone resin binder solution.

[0021] Preferably, the addition amount of the binder described in step (3) is 0.2-1% of the mass of the alloy powder for insulation coating treatment based on its solid content.

[0022] Preferably, the temperature of the pressing and forming in step (3) is 60-100 °C, and the pressure is 500-800 MPa.

[0023] Preferably, the annealing treatment time in step (3) is 15-120 min.

[0024] A high-frequency and low-power iron-silicon-aluminum soft magnetic material is prepared by the above method.

[0025] The application of the above high-frequency and low-power iron-silicon-aluminum soft magnetic material in the fields of AI computing power chips, servers and communication equipment.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] (1) The present invention uses an insulation coating liquid prepared by mixing aluminum phytic acid sol and silica sol to perform insulation coating on iron-silicon-aluminum soft magnetic alloy powder. Among them, phytic acid molecules have good adhesion to the surface of the soft magnetic alloy powder, so the coating effect can be significantly improved. Through subsequent high-temperature heat treatment, a silica-aluminum phosphate composite coating layer with high temperature and high pressure resistance can be in-situ generated on the surface of the soft magnetic alloy powder. Among them, aluminum phosphate is used as a support carrier with high temperature resistance, improved bonding force and reduced brittleness, and silica is used as a coating component to improve insulation performance. Through the composite coating of the two, the insulation coating effect can be significantly improved, thereby improving the high-frequency power consumption performance of the product.

[0028] (2) The silica-aluminum phosphate composite insulation coating layer of the present invention can further improve the bonding force with the binder resin, thereby improving the forming density and magnetic properties of the magnetic core.

[0029] (3) The present invention adopts one-step insulation coating treatment, which can simplify the production process and reduce the production cost. Specific embodiments

[0030] The following examples are used to further describe the present invention in detail, but the implementation manners of the present invention are not limited thereto.

[0031] Example 1

[0032] A preparation method of a high-frequency and low-power iron-silicon-aluminum soft magnetic material, comprising the following preparation steps:

[0033] (1) Preparation of insulating coating liquid: Add phytic acid to an ethanol aqueous solution with an ethanol volume percentage of 85% to dissolve it, then add an ethanol solution of aluminum isopropoxide and mix them for reaction. By controlling the addition amount of aluminum isopropoxide, make the pH value of the reaction system 6 to obtain an aluminum phytate sol. Then mix it evenly with silica sol. The addition amount of silica sol is 40% of the mass of phytic acid in terms of the content of silicon dioxide, and an insulating coating liquid with a solid content of 20% is obtained.

[0034] (2) Insulating coating treatment: Mix the Fe-Si-Al soft magnetic alloy powder with a D50 particle size of 10 μm evenly with the insulating coating liquid in step (1) by high-speed stirring. The addition amount of the insulating coating liquid is 0.5% of the mass of the Fe-Si-Al soft magnetic alloy powder in terms of its solid content. First, vacuum dry at 80 °C to remove the solvent, and then heat-treat at 500 °C for 5 h under nitrogen protection to obtain an alloy powder with a silica-aluminum phosphate composite insulating coating treatment.

[0035] (3) Compression molding: Mix the alloy powder with a silica-aluminum phosphate composite insulating coating treatment evenly with an epoxy resin ethanol solution binder (solid content 15%). The epoxy resin content is 0.4% of the mass of the alloy powder with an insulating coating treatment. Then inject it into a ring-shaped mold and compress it at a pressure of 600 MPa and a temperature of 80 °C. Then heat it to 750 °C under nitrogen protection for annealing treatment for 60 min to obtain a high-frequency low-power Fe-Si-Al soft magnetic material (magnetic ring).

[0036] The outer diameter of the magnetic ring obtained in this example is 10 mm, the inner diameter is 6 mm, the height is 3.4 mm, and the density is 5.892 g / cm 3 , the inductance value L is 16.60 μH, and the high-frequency loss (1 MHz / 50 mT) is 1091 kW / m 3 .

[0037] Example 2

[0038] A preparation method of a high-frequency low-power Fe-Si-Al soft magnetic material, including the following preparation steps:

[0039] (1) Preparation of insulating coating liquid: Add phytic acid to an ethanol aqueous solution with an ethanol volume percentage of 90% to dissolve it, then add an ethanol solution of aluminum triethanolate and mix them for reaction. By controlling the addition amount of aluminum triethanolate, make the pH value of the reaction system 5 to obtain an aluminum phytate sol. Then mix it evenly with silica sol. The addition amount of silica sol is 20% of the mass of phytic acid in terms of the content of silicon dioxide, and an insulating coating liquid with a solid content of 20% is obtained.

[0040] (2) Insulation coating treatment: Mix the iron-silicon-aluminum soft magnetic alloy powder with a D50 particle size of 5 μm and the insulation coating liquid in step (1) evenly by high-speed stirring. The addition amount of the insulation coating liquid is 1.5% of the mass of the iron-silicon-aluminum soft magnetic alloy powder based on its solid content. First, vacuum dry at 80 °C to remove the solvent, and then heat-treat at 600 °C for 6 h under nitrogen protection to obtain the alloy powder with silica-aluminum phosphate composite insulation coating treatment.

[0041] (3) Compression molding: Mix the alloy powder with silica-aluminum phosphate composite insulation coating treatment and the epoxy resin ethanol solution binder (solid content 15%) evenly. The epoxy resin content is 0.6% of the mass of the alloy powder with insulation coating treatment. Then inject it into a ring mold, compress and mold at a pressure of 700 MPa and a temperature of 80 °C, and then heat-treat at 750 °C for 60 min under nitrogen protection to obtain the high-frequency low-power iron-silicon-aluminum soft magnetic material (magnetic ring).

[0042] The outer diameter of the magnetic ring obtained in this example is 10 mm, the inner diameter is 6 mm, the height is 3.4 mm, and the density is 5.827 g / cm 3 , the inductance value L is 15.33 μH, and the high-frequency loss (1 MHz / 50 mT) is 1150 kW / m 3 .

[0043] Example 3

[0044] A preparation method of a high-frequency low-power iron-silicon-aluminum soft magnetic material, including the following preparation steps:

[0045] (1) Preparation of insulation coating liquid: Dissolve phytic acid in an ethanol aqueous solution with an ethanol volume percentage of 95%, and then add an ethanol solution of aluminum isopropoxide and mix and react. Control the addition amount of aluminum isopropoxide to make the pH value of the reaction system 7 to obtain phytic acid aluminum sol. Then mix it evenly with silica sol. The addition amount of silica sol is 60% of the mass of phytic acid based on the content of silicon dioxide to obtain an insulation coating liquid with a solid content of 20%.

[0046] (2) Insulation coating treatment: Mix the iron-silicon-aluminum soft magnetic alloy powder with a D50 particle size of 15 μm and the insulation coating liquid in step (1) evenly by high-speed stirring. The addition amount of the insulation coating liquid is 1% of the mass of the iron-silicon-aluminum soft magnetic alloy powder based on its solid content. First, vacuum dry at 80 °C to remove the solvent, and then heat-treat at 700 °C for 4 h under nitrogen protection to obtain the alloy powder with silica-aluminum phosphate composite insulation coating treatment.

[0047] (3) Compression molding: The alloy powder treated with silica-aluminum phosphate composite insulation coating is mixed evenly with an ethanol solution binder (solid content 10%) of silicone resin (low-viscosity vinyl silicone oil and hydrogen-containing silicone oil bonding and curing system). The content of silicone resin is 0.2% of the mass of the alloy powder treated with insulation coating. Then it is injected into a ring-shaped mold and compression molded at a pressure of 800 MPa and a temperature of 80 °C, and then annealed at 750 °C for 60 min under nitrogen protection to obtain a high-frequency low-power iron-silicon-aluminum soft magnetic material (magnetic ring).

[0048] The outer diameter of the magnetic ring obtained in this example is 10 mm, the inner diameter is 6 mm, the height is 3.4 mm, and the density is 5.916 g / cm 3 , the inductance value L is 16.70 μH, and the high-frequency loss (1 MHz / 50 mT) is 1090 kW / m 3 .

[0049] Comparative Example 1

[0050] A preparation method of a high-frequency low-power iron-silicon-aluminum soft magnetic material includes the following preparation steps:

[0051] (1) Preparation of insulation coating liquid: Phytic acid is added to an ethanol aqueous solution with an ethanol volume percentage of 85% and dissolved, and then an ethanol solution of aluminum isopropoxide is added and mixed for reaction. By controlling the addition amount of aluminum isopropoxide, the pH value of the reaction system is 6 to obtain a phytic acid aluminum sol insulation coating liquid with a solid content of 20%.

[0052] (2) - (3) The preparation process is the same as that of Example 1.

[0053] The outer diameter of the magnetic ring obtained in this comparative example is 10 mm, the inner diameter is 6 mm, the height is 3.4 mm, and the density is 5.902 g / cm 3 , the inductance value L is 16.87 μH, and the high-frequency loss (1 MHz / 50 mT) is 1925 kW / m 3 .

[0054] It can be concluded from the comparison results with Example 1 that the inductance value of the magnetic ring obtained by simply using aluminum phosphate insulation coating treatment increases slightly, but the high-frequency loss also increases significantly. It shows that the composite of the silica coating layer is beneficial to improving the insulation performance.

[0055] Comparative Example 2

[0056] A preparation method of a high-frequency low-power iron-silicon-aluminum soft magnetic material, compared with Example 1, uses silica sol with a solid content of 20% as the insulation coating liquid, and the rest of the preparation process is the same as that of Example 1.

[0057] The outer diameter of the magnetic ring obtained in this comparative example is 10 mm, the inner diameter is 6 mm, the height is 3.4 mm, and the density is 5.680 g / cm 3 , the inductance value L is 12.93 μH, and the high-frequency loss (1 MHz / 50 mT) is 2261 kW / m 3 .

[0058] From the comparison results with Example 1, it can be concluded that the density and inductance value of the magnetic ring obtained by simply using silica insulation coating treatment are significantly reduced, and the high-frequency loss is significantly increased. It shows that the combination of the aluminum phosphate coating layer in the present invention is beneficial to improving the coating effect and can also improve the bonding performance.

[0059] Comparative Example 3

[0060] A preparation method of a high-frequency and low-loss Fe-Si-Al soft magnetic material includes the following preparation steps:

[0061] (1) Preparation of insulation coating solution: Phosphoric acid is added to an ethanol aqueous solution with an ethanol volume percentage of 85% and dissolved, and then an ethanol solution of aluminum isopropoxide is added and mixed for reaction. By controlling the addition amount of aluminum isopropoxide, the pH value of the reaction system is 6 to obtain an aluminum phosphate dispersion. Then it is mixed evenly with silica sol, and the addition amount of silica sol is 40% of the mass of phosphoric acid in terms of the content of silicon dioxide, to obtain an insulation coating solution with a solid content of 20%.

[0062] (2) - (3) The preparation processes are the same as those in Example 1.

[0063] The outer diameter of the magnetic ring obtained in this comparative example is 10 mm, the inner diameter is 6 mm, the height is 3.4 mm, and the density is 5.736 g / cm 3 , the inductance value L is 13.14 μH, and the high-frequency loss (1 MHz / 50 mT) is 2837 kW / m 3 .

[0064] From the comparison results with Example 1, it can be concluded that the insulation coating effect of the insulation coating solution prepared by mixing the aluminum phosphate dispersion obtained by reacting phosphoric acid with an aluminum alkoxide solution and silica sol is significantly reduced, resulting in a significant increase in high-frequency loss.

[0065] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of a high-frequency and low-power iron-silicon-aluminum soft magnetic material, characterized in that, It includes the following preparation steps: (1) Preparation of the insulating coating solution: Phytic acid is added to an alcohol aqueous solution for dissolution, and then an aluminum alkoxide solution is added for mixing and reaction to obtain an aluminum phytic acid sol, which is then mixed evenly with silica sol to obtain the insulating coating solution; (2) Insulating coating treatment: The Fe-Si-Al soft magnetic alloy powder is mixed evenly with the insulating coating solution in step (1), first dried at 60 - 100 °C to remove the solvent, and then heated to 300 - 800 °C for heat treatment to obtain the alloy powder with a silica-aluminum phosphate composite insulating coating; (3) Compression molding: The alloy powder with a silica-aluminum phosphate composite insulating coating is mixed evenly with a binder, then injected into a mold for compression molding, and then heated to 600 - 900 °C for annealing treatment to obtain the high-frequency low-power Fe-Si-Al soft magnetic material.

2. The preparation method of a high-frequency and low-power iron-silicon-aluminum soft magnetic material according to claim 1, characterized in that, In step (1), the alcohol aqueous solution is an ethanol aqueous solution with an ethanol volume percentage of 80 - 95%; the aluminum alkoxide solution is triethanol aluminum solution, aluminum propoxide solution, aluminum isopropoxide solution or aluminum n-butoxide solution.

3. The preparation method of a high-frequency and low-power FeSiAl soft magnetic material according to claim 1, characterized in that, In step (1), the addition amount of the aluminum alkoxide solution makes the pH value of the reaction system 5 - 7; the addition amount of the silica sol, calculated by the content of silicon dioxide, is 20 - 60% of the mass of phytic acid.

4. The preparation method of a high-frequency and low-power iron-silicon-aluminum soft magnetic material according to claim 1, wherein, In step (2), the D50 particle size of the Fe-Si-Al soft magnetic alloy powder is 5 - 15 μm.

5. The preparation method of a high-frequency and low-power iron-silicon-aluminum soft magnetic material according to claim 1, wherein, In step (2), the addition amount of the insulating coating solution, calculated by its solid content, is 0.2 - 2% of the mass of the Fe-Si-Al soft magnetic alloy powder.

6. The preparation method of a high-frequency and low-power Fe-Si-Al soft magnetic material according to claim 1, characterized in that, In step (2), the drying to remove the solvent is carried out under vacuum conditions; the heat treatment is carried out under nitrogen protection conditions, and the heat treatment time is 3 - 10 h.

7. The preparation method of a high-frequency and low-power iron-silicon-aluminum soft magnetic material according to claim 1, characterized in that In step (3), the binder is an epoxy resin binder solution or an organosilicon resin binder solution; the addition amount of the binder, calculated by its solid content, is 0.2 - 1% of the mass of the alloy powder with an insulating coating.

8. The preparation method of a high-frequency and low-power iron-silicon-aluminum soft magnetic material according to claim 1, characterized in that, In step (3), the temperature of the compression molding is 60 - 100 °C, and the pressure is 500 - 800 MPa; the time of the annealing treatment is 15 - 120 min.

9. A high-frequency and low-power Fe-Si-Al soft magnetic material, characterized in that, Prepared by the method described in any one of claims 1 - 8.

10. Application of the high-frequency low-power Fe-Si-Al soft magnetic material described in claim 9 in the fields of AI computing power chips, servers and communication equipment.