Iron-silicon-aluminum soft magnetic composition and preparation method thereof

Abstract

The invention discloses a Fe-Si-Al soft magnetic composition which comprises the following components in percentage by mass: 76-83% of Fe; 7%-12% of Si; 4 to 8 percent of Al; 0.2 to 1.0 percent of Nb; 0.1 to 0.8 percent of Mo; 0.3 to 1.5 percent of Cu; 0.1 to 0.5 percent of B; and 0.02 to 0.1 percent of C. Alloy components are optimized, microalloying elements such as Nb, Mo, Cu and B are added, the high-frequency magnetic performance of the material is remarkably improved, high-pressure nitrogen or argon atomization is adopted, spherical powder with the uniform particle size is obtained, the magnetic performance is improved, loss is reduced, acid pickling and passivating treatment are adopted, the powder insulativity is improved, surface oxidation is reduced, and the long-term stability is improved; by accurately controlling the sintering temperature, the heat preservation time and the cooling rate, the compactness and the magnetic performance of the material are improved, the performance of the soft magnetic material can be integrally and effectively improved, and application requirements of high-frequency electronic equipment are met.

Description

Technical Field

[0001] The present invention relates to the technical field of soft magnetic materials, and in particular to an iron-silicon-aluminum soft magnetic composition and a preparation method thereof. Background Art

[0002] Iron-silicon-aluminum soft magnetic alloy is a kind of soft magnetic alloy with high initial permeability, containing about 9.5% silicon and about 5.6% aluminum. Iron-silicon-aluminum soft magnetic alloy has good soft magnetic properties because both the magnetocrystalline anisotropy constant and the saturation magnetostriction are close to zero.

[0003] Iron-silicon-aluminum soft magnetic alloy has good soft magnetic properties because both the magnetocrystalline anisotropy constant and the saturation magnetostriction are close to zero; the initial permeability is about 18.75 mH / m, the maximum permeability reaches 137.5 mH / m, the coercivity is 3.2 A / m, and the magnetic saturation value is 1.10 T. In addition, due to the high content of silicon and aluminum, the alloy has a high resistivity, low eddy current loss, high hardness, good wear resistance, and also has good oxidation resistance, corrosion resistance and low stress sensitivity.

[0004] Iron-silicon-aluminum (Fe-Si-Al) soft magnetic alloy is widely used in high-frequency power electronic equipment, transformers, magnetic components and other fields due to its excellent magnetic properties, low eddy current loss and good corrosion resistance. However, the existing iron-silicon-aluminum soft magnetic materials still have problems such as high magnetic loss and unstable magnetic permeability under high-frequency conditions. Therefore, here we propose an iron-silicon-aluminum soft magnetic composition and a preparation method thereof. Summary of the Invention

[0005] In order to solve the above technical deficiencies, the present invention adopts a modified technical solution. An iron-silicon-aluminum soft magnetic composition, by mass percentage, includes: Fe: 76 - 83%; Si: 7 - 12%; Al: 4 - 8%; Nb: 0.2 - 1.0%; Mo: 0.1 - 0.8%; Cu: 0.3 - 1.5%; B: 0.1 - 0.5%; C: 0.02 - 0.1%.

[0006] As a further preferred embodiment of the present invention, it also includes a combination of mass percentages, wherein Fe - 79%, Si - 10%, Al - 6%, Nb - 0.5%, Mo - 0.3%, Cu - 0.8%, B - 0.2%, C - 0.05%

[0007] As a further preferred embodiment of the present invention, it also includes a combination of mass percentages, wherein Fe - 80%, Si - 8%, Al - 5%, Nb - 0.7%, Mo - 0.5%, Cu - 1.0%, B - 0.3%, C - 0.08%.

[0008] As a further preferred embodiment of the present invention, the specific manufacturing method includes the following steps

[0009] S1, Alloy Melting: Select high-purity iron, silicon, aluminum and other alloying elements, accurately weigh them according to the proportion, and carry out melting in a vacuum induction furnace or an electric arc furnace to prevent oxidation and impurity contamination. Control the melting temperature at 1600 - 1700 °C and stir for 30 - 60 minutes to ensure the uniform distribution of alloy elements, and then pour the molten alloy into ingots.

[0010] S2, Atomization and Powder Making: Use high-pressure nitrogen or argon atomization technology to spray the molten metal into fine powders.

[0011] S3, Powder Surface Treatment: Pickle the atomized powders to remove oxides and impurities, then carry out drying treatment, and carry out passivation treatment on them.

[0012] S4, Press the powders into shape;

[0013] S5, Sintering and Heat Treatment.

[0014] As a further preferred embodiment of the present invention, in step S2, control the gas pressure at 3 - 6 MPa, control the atomization temperature at 1400 - 1750 °C, obtain spherical powders with uniform particle sizes, and control the powder particle size range between 10 - 100 μm.

[0015] As a further preferred embodiment of the present invention, in step S3, pickling and impurity removal: Immerse the powders in a 5 - 10% nitric acid solution at room temperature to 60 °C for 5 - 15 minutes to remove surface oxides and impurities. After completion, carry out ultrasonic cleaning: Use deionized water or alcohol for ultrasonic cleaning for 5 - 10 minutes to thoroughly remove residual acid solution and impurities, then carry out drying treatment. Place the powders in a vacuum drying oven at 80 - 120 °C and dry for 1 - 3 hours to ensure that the powder surface is clean without residual liquid. Passivation treatment: Use phosphate or silane coating to form a uniform insulating layer on the powder surface to reduce eddy current loss. Immerse the powders in a 0.5 - 3% phosphate or silane solution, stir for 10 - 30 minutes, control the temperature at 100 - 150 °C and dry for 30 - 60 minutes to complete.

[0016] As a further preferred embodiment of the present invention, in step S4, use wear-resistant high-strength steel molds, and coat the mold surface with a release agent. For the pressing process, use cold isostatic pressing forming technology with a pressure of 300 - 800 MPa or hot press sintering forming technology with a pressure of 900 - 1100 °C. Fill the powders in layers, and use vibration-assisted pressing to reduce the porosity. Add an organic binder PVA and burn it out during subsequent processing.

[0017] As a further preferred embodiment of the present invention, in step S5, during the sintering stage, sintering is carried out in a hydrogen or vacuum environment, the temperature is controlled at 1000 - 1250 °C, and heat preservation is carried out for 1 - 5 hours to promote the densification of powder sintering. A stepped heating method is adopted, with a heating rate of 5 - 10 °C / min, annealing treatment is carried out, low-temperature annealing treatment at 600 - 800 °C is adopted, and the cooling process is carried out with a controlled cooling rate of 5 - 20 °C / min.

[0018] Beneficial effects

[0019] The optimized alloy composition of the present invention significantly improves the high-frequency magnetic properties of the material by adding microalloying elements such as Nb, Mo, Cu, and B. High-pressure nitrogen or argon atomization is used to obtain spherical powders with uniform particle sizes, improving the magnetic properties and reducing losses. Pickling and passivation treatments are used to improve the powder insulation, reduce surface oxidation, and improve long-term stability. By precisely controlling the sintering temperature, heat preservation time, and cooling rate, the material density and magnetic properties are improved. Overall, the performance of the soft magnetic material can be effectively enhanced, meeting the application requirements of high-frequency electronic devices. Specific embodiments

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] The present invention provides a technical solution: a Fe-Si-Al soft magnetic composition, including by mass percentage: Fe: 76 - 83%; Si: 7 - 12%; Al: 4 - 8%; Nb: 0.2 - 1.0%; Mo: 0.1 - 0.8%; Cu: 0.3 - 1.5%; B: 0.1 - 0.5%; C: 0.02 - 0.1%.

[0022] It also includes the following combinations by mass percentage, where Fe - 79%, Si - 10%, Al - 6%, Nb - 0.5%, Mo - 0.3%, Cu - 0.8%, B - 0.2%, C - 0.05%.

[0023] It also includes the following combinations by mass percentage, where Fe - 80%, Si - 8%, Al - 5%, Nb - 0.7%, Mo - 0.5%, Cu - 1.0%, B - 0.3%, C - 0.08%.

[0024] It includes the following steps

[0025] S1, Alloy Melting: Select high-purity iron, silicon, aluminum and other alloying elements, accurately weigh them according to the proportion, and carry out melting in a vacuum induction furnace or an electric arc furnace to prevent oxidation and impurity contamination. Control the melting temperature at 1600 - 1700 °C and stir for 30 - 60 minutes to ensure the uniform distribution of alloy elements, and then pour the molten alloy into ingots.

[0026] S2, Atomization and Powder Making: Use high-pressure nitrogen or argon atomization technology to spray the molten metal into fine powders.

[0027] S3, Powder Surface Treatment: Pickle the atomized powders to remove oxides and impurities, then carry out drying treatment and passivation treatment on them.

[0028] S4, Press the powders into shape;

[0029] S5, Sintering and Heat Treatment.

[0030] 5. The preparation method of an iron-silicon-aluminum soft magnetic composition according to claim 4, characterized in that in step S2, control the gas pressure at 3 - 6 MPa, control the atomization temperature at 1400 - 1750 °C to obtain spherical powders with uniform particle sizes, and control the powder particle size range between 10 - 100 μm.

[0031] In step S3, Pickling and Impurity Removal: Immerse the powders in a 5 - 10% nitric acid solution at room temperature to 60 °C for 5 - 15 minutes to remove surface oxides and impurities. After completion, carry out ultrasonic cleaning: Use deionized water or alcohol for ultrasonic cleaning for 5 - 10 minutes to thoroughly remove residual acid solution and impurities, then carry out drying treatment. Place the powders in a vacuum drying oven at 80 - 120 °C and dry for 1 - 3 hours to ensure that the powder surface is clean without residual liquid. Passivation Treatment: Use phosphate or silane coating to form a uniform insulating layer on the powder surface to reduce eddy current loss. Immerse the powders in a 0.5 - 3% phosphate or silane solution, stir for 10 - 30 minutes, control the temperature at 100 - 150 °C and dry for 30 - 60 minutes to complete.

[0032] In step S4, Use wear-resistant and high-strength steel molds, and coat the mold surface with a release agent. For the pressing process, use cold isostatic pressing forming technology with a pressure of 300 - 800 MPa or hot pressing and sintering forming technology with a pressure of 900 - 1100 °C. Fill the powders in layers and use vibration-assisted pressing to reduce the porosity. Add an organic binder PVA and burn it out during the subsequent treatment process.

[0033] In step S5, during the sintering stage, sintering is carried out in a hydrogen or vacuum environment. The temperature is controlled at 1000 - 1250 °C and held for 1 - 5 hours to promote the densification of powder sintering. A stepped heating method is adopted, with a heating rate of 5 - 10 °C / min. Annealing treatment is carried out with a low-temperature annealing treatment at 600 - 800 °C. For the cooling process, a controlled cooling rate of 5 - 20 °C / min is used.

[0034] Example 1

[0035] Melting of Fe - 79%, Si - 10%, Al - 6%, Nb - 0.5%, Mo - 0.3%, Cu - 0.8%, B - 0.2%, C - 0.05% alloy: High-purity iron, silicon, aluminum and other alloying elements are selected and accurately weighed according to the proportion. Melting is carried out in a vacuum induction furnace or an electric arc furnace to prevent oxidation and impurity contamination. The melting temperature is controlled at 1700 °C and stirred for 60 minutes to ensure the uniform distribution of alloying elements. The molten alloy is cast into ingots and subjected to homogenization annealing treatment to eliminate casting defects. Atomization powder making: The molten metal is sprayed into fine powder by using high-pressure nitrogen or argon atomization technology. The gas pressure is controlled at 6 MPa and the atomization temperature at 1600 °C to obtain spherical powder with uniform particle size. The particle size range of the powder is controlled within 100 μm. Powder screening is carried out to remove oversized or undersized powder and improve the powder quality. Powder surface treatment: Pickling and impurity removal: The powder is soaked in a 10% nitric acid solution at room temperature to 60 °C for 15 minutes to remove surface oxides and impurities. Ultrasonic cleaning: Ultrasonic cleaning is carried out with deionized water or alcohol for 10 minutes to thoroughly remove residual acid solution and impurities. Drying treatment: The powder is placed in a vacuum drying furnace at 120 °C and dried for 3 hours to ensure that the powder surface is clean without residual liquid. Passivation treatment: A phosphate or silane coating is used to form a uniform insulating layer on the powder surface to reduce eddy current loss. The powder is immersed in a 0.5 - 3% phosphate or silane solution and stirred for 30 minutes. At a low temperature of 150 °C, it is dried for 60 minutes to ensure that the coating is uniform and stable. Powder pressing and forming:

[0036] Mold preparation: Wear-resistant high-strength steel molds are used, and a mold release agent is coated on the mold surface to reduce friction and loss. Pressing process: Cold isostatic pressing (800 MPa) or hot press sintering (1100 °C) forming technology is adopted. The powder is filled in layers, and vibration-assisted pressing is used to reduce the porosity. A small amount of organic binder, such as PVA, can be added to improve the forming density and burned out during subsequent processing. Demolding treatment: The demolding speed and direction are controlled to prevent cracks and structural defects and improve the finished product rate.

[0037] Sintering and heat treatment: Sintering stage: Sintering is carried out in a hydrogen or vacuum environment, with the temperature controlled at 1250 °C and held for 5 hours to promote the densification of powder sintering. A stepped heating method (such as heating at a rate of 10 °C / min) is adopted to reduce thermal stress and improve the microstructure uniformity. Annealing treatment:

[0038] Low-temperature annealing treatment at 800 °C is adopted to eliminate internal stress, optimize the grain structure, and improve magnetic properties. Keep the annealing environment clean (such as using pure hydrogen protection) to reduce oxidation and impurity pollution. Cooling process: Adopt a controlled cooling method (such as 20 °C / min) to avoid cracks and non-uniform microstructure caused by rapid cooling. A stepped cooling technique (such as holding at 600 °C for 1 hour and then slowly cooling) can be adopted to improve the magnetic properties and mechanical strength of the material.

[0039] Example 2

[0040] Among them, Fe - 80%, Si - 8%, Al - 5%, Nb - 0.7%, Mo - 0.5%, Cu - 1.0%, B - 0.3%, C - 0.08%.

[0041] Alloy melting: Select high-purity iron, silicon, aluminum and other alloying elements, and accurately weigh them according to the proportion. Melting is carried out in a vacuum induction furnace or an arc furnace to prevent oxidation and impurity pollution. The melting temperature is controlled at 1600 °C and stirred for 30 minutes to ensure the uniform distribution of alloying elements. Pour the molten alloy into an ingot and carry out homogenization annealing treatment to eliminate casting defects. Atomization powder making: Adopt high-pressure nitrogen or argon atomization technology to spray the molten metal into fine powder. Control the gas pressure at 3 MPa and the atomization temperature at 1400 °C to obtain spherical powder with uniform particle size, and the powder particle size range is controlled at 10 μm. Carry out powder screening to remove too large or too small powder and improve the powder quality. Powder surface treatment: Acid pickling and impurity removal: Immerse the powder in a 5% nitric acid solution at room temperature to 60 °C for 5 minutes to remove surface oxides and impurities. Ultrasonic cleaning: Use deionized water or alcohol for ultrasonic cleaning for 5 minutes to thoroughly remove residual acid solution and impurities. Drying treatment: Place the powder in a vacuum drying furnace at 80 °C and dry for 1 hour to ensure that the powder surface is clean and free of residual liquid.

[0042] Passivation treatment: Adopt phosphate or silane coating to form a uniform insulating layer on the powder surface to reduce eddy current loss. Immerse the powder in a 0.5% phosphate or silane solution and stir for 10 minutes. Bake at a low temperature of 100 °C for 30 minutes to ensure that the coating is uniform and stable. Powder pressing and forming:

[0043] Mold Preparation: Use wear-resistant high-strength steel molds and coat the mold surface with a release agent to reduce friction and wear. Compression Process: Adopt cold isostatic pressing (300 MPa) or hot press sintering (900 °C) forming technology. Fill the powder in layers and use vibration-assisted pressing to reduce porosity. A small amount of organic binder, such as PVA, can be added to improve the forming density and burned out during subsequent processing. Demolding Treatment: Control the demolding speed and direction to prevent cracks and structural defects and improve the finished product rate. Sintering and Heat Treatment: Sintering Stage: Sinter in a hydrogen or vacuum environment at a temperature of 1000 °C for 1 hour to promote the densification of powder sintering. Adopt a stepped heating method (such as heating at a rate of 5 °C / min) to reduce thermal stress and improve the microstructure uniformity. Annealing Treatment: Adopt a low-temperature annealing treatment at 600 °C to eliminate internal stress, optimize the grain structure, and improve magnetic properties. Keep the annealing environment clean (such as using pure hydrogen protection) to reduce oxidation and impurity contamination. Cooling Process: Adopt a controlled cooling method (such as 5 °C / min) to avoid cracks and non-uniform microstructure caused by rapid cooling. A stepped cooling technology (such as slow cooling after holding at 600 °C for 1 hour) can be used to improve the magnetic properties and mechanical strength of the material.

[0044]

[0045] The foregoing has shown and described the basic principles, main features and advantages of the present invention. For a person skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or essential characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

[0046] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. A person skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by a person skilled in the art.

Claims

1. A sendust soft magnetic composition, characterized in that: In terms of mass percentage, Fe: 76-83%; Si: 7-12%; Al: 4-8%; Nb: 0.2-1.0%; Mo: 0.1-0.8%; Cu: 0.3-1.5%; B：0.1-0.5％； C：0.02-0.1％。 2. A method for preparing a soft magnetic sendust composite according to claim 1, characterized in that: The following mass percentage combinations are also included, wherein Fe-79%, Si-10%, Al-6%, Nb-0.5%, Mo-0.3%, Cu-0.8%, B-0.2%, C-0.05%.

3. A method for preparing a soft magnetic sendust composite according to claim 1, characterized in that: The following mass percentage combinations are also included, including Fe-80%, Si-8%, Al-5%, Nb-0.7%, Mo-0.5%, Cu-1.0%, B-0.3%, and C-0.08%.

4. The method for preparing the sendust soft magnetic composition according to claim 1, characterized in that: The following steps are included: S1, alloy smelting: select high-purity iron, silicon, aluminum and other alloying elements, accurately weigh them in proportion, and smelt them in a vacuum induction furnace or electric arc furnace to prevent oxidation and impurity contamination. The smelting temperature is controlled at 1600-1700℃ and stirred for 30-60 minutes to ensure uniform distribution of alloying elements, and the molten alloy is cast into ingots. S2, atomization powder making: high-pressure nitrogen or argon atomization technology is used to spray the molten metal into fine powder. S3, Powder surface treatment: The atomized powder is pickled to remove oxides and impurities, then dried and passivated. S4, pressing the powder into a shape; S5, sintering and heat treatment.

5. The method for preparing the sendust soft magnetic composition according to claim 4, characterized in that: In step S2, the gas pressure is controlled at 3-6 MPa, and the atomization temperature is controlled at 1400-1750° C. to obtain spherical powder with uniform particle size, and the powder particle size range is controlled between 10-100 μm.

6. The method for preparing the sendust soft magnetic composition according to claim 4, characterized in that: In step S3, pickling and impurity removal: use 5-10% nitric acid solution to soak the powder for 5-15 minutes at room temperature to 60°C to remove surface oxides and impurities, and then perform ultrasonic cleaning after completion: use deionized water or alcohol to perform ultrasonic cleaning for 5-10 minutes to thoroughly remove residual acid and impurities, and then perform drying treatment, place the powder in a vacuum drying furnace at 80-120°C and dry it for 1-3 hours to ensure that the powder surface is clean and free of residual liquid, passivation treatment: use phosphate or silane coating to form a uniform insulating layer on the powder surface to reduce eddy current loss, immerse the powder in 0.5-3% phosphate or silane solution, stir for 10-30 minutes, control the temperature at 100-150°C and dry for 30-60 minutes, and it is completed.

7. The method for preparing the sendust soft magnetic composition according to claim 4, characterized in that: In step S4, a wear-resistant high-strength steel mold is used, and a release agent is coated on the mold surface. The pressing process adopts cold isostatic pressing technology with a pressure of 300-800MPa or hot pressing sintering technology with a pressure of 900-1100°C. The powder is layered and filled, and vibration-assisted pressing is used to reduce porosity. An organic binder PVA is added and burned out during subsequent processing.

8. The method for preparing the sendust soft magnetic composition according to claim 4, characterized in that: In step S5, during the sintering stage, sintering is performed in a hydrogen or vacuum environment, the temperature is controlled at 1000-1250°C, and the temperature is kept for 1-5 hours to promote the sintering and densification of the powder. A step-by-step heating method is used to increase the temperature at a rate of 5-10°C / min. Annealing treatment is performed at a low temperature of 600-800°C. The cooling process uses a controlled cooling rate of 5-20°C / min.

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