Iron-silicon-aluminum powder, magnetic core and preparation method of iron-silicon-aluminum powder

Abstract

The invention provides Fe-Si-Al powder, a magnetic core and a preparation method of the Fe-Si-Al powder. The preparation method of the Fe-Si-Al powder comprises the steps that Fe-Si-Al raw powder is subjected to heat treatment and then screened, coarse powder and part of fine powder are removed, and the Fe-Si-Al powder is obtained; the coarse powder is oversize powder of 150-250 meshes, and the fine powder is undersize powder of 350-450 meshes. By controlling the components and the granularity of the powder and performing heat treatment on the powder to remove stress, the Fe-Si-Al powder has low coercive force, and has low loss and excellent superposition performance after insulation coating.

Description

Technical Field

[0001] The invention relates to the field of soft magnetic materials, and in particular to Sendust powder, a magnetic core and a preparation method thereof. Background Art

[0002] Soft magnetic materials are an important type of basic functional materials in the development of modern economy and society. Soft magnetic materials play the role of energy transfer, conversion and coupling in devices and have electromagnetic conversion functions. Therefore, they are widely used in communications, power equipment, information technology, automatic control and other fields. Soft magnetic materials can be divided into metal soft magnetic materials, soft magnetic composite materials and ferrite soft magnetic materials. Among them, soft magnetic composite materials are made of metal soft magnetic powder particles through insulation coating, pressing molding, annealing and other processes to prepare magnetic powder cores of different shapes.

[0003] Sendust soft magnetic material is a kind of metal soft magnetic material. Sendust soft magnetic material has low coercivity and small hysteresis loss. Sendust soft magnetic material has constant magnetic permeability within a certain frequency and no noise. It does not contain precious metals and has a high cost performance. Therefore, it is widely used in line filters, noise filters, energy storage inductors and other fields. It is a very important type of metal soft magnetic material.

[0004] At present, in order to use low-cost Sendust powder to replace traditional ferrite or other soft magnetic materials, in the high-frequency field, especially in the fields of one-piece molded inductors and injection molded inductors, there is an urgent need to provide a high magnetic permeability and low loss composite magnetic powder core and its preparation method. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a sendust powder, a magnetic core and a preparation method thereof. The present invention controls the composition and particle size of the powder and removes stress by heat treatment of the powder. The sendust powder has low coercivity and has low loss and excellent superposition performance after insulation coating.

[0006] In a first aspect, the present invention provides a method for preparing sendust powder, comprising: heat treating sendust raw powder, then sieving and removing coarse powder and part of fine powder to obtain sendust powder; the coarse powder is powder on a 150-250 mesh sieve, and the fine powder is powder under a 350-450 mesh sieve.

[0007] The invention provides control of composition and particle size, sieving out coarse powder and a certain proportion of fine powder to obtain a particle size ratio with optimal performance, and at the same time further reduces the coercive force of sendust powder by pre-heat treatment of the original powder in a nitrogen atmosphere.

[0008] Preferably, the fine powder is sieved out to account for 10% to 30% of the total weight.

[0009] More preferably, the coarse powder is powder on a 200-mesh sieve; and / or, the fine powder is powder under a 400-mesh sieve; and / or, the fine powder removed by screening accounts for 20% of the total weight.

[0010] More preferably, the temperature of the pre-heat treatment is 740-760°C, preferably 750°C.

[0011] Preferably, the sendust powder contains 8.3-8.9 wt% Si, 5.1-5.7 wt% Al, and the remainder is Fe and unavoidable impurities.

[0012] In the present invention, by further optimizing the above particle size ratio and pre-heat treatment, a lower coercive force Sendust powder is obtained, which has lower hysteresis loss in high-frequency usage scenarios.

[0013] In a second aspect, the sendust powder provided by the present invention is obtained by the above-mentioned preparation method; the sendust powder has D10>10μm and D90<80μm.

[0014] Preferably, the Sendust powder has D10 ≥ 15 μm and D90 ≤ 70 μm.

[0015] Preferably, the D10 of the Sendust powder is 16-18.5 μm, and the D90 is 60-65 μm.

[0016] In the present invention, when the particle size of the sendust powder is 17-17.5 μm, and D90 is 60-63 μm, the best technical effect is achieved.

[0017] More preferably, the sendust powder has a hardness of 280-400 Hv and a coercive force of 0.2-0.7 Oe.

[0018] Preferably, the sendust powder has a hardness of 280-320 Hv and a coercive force of 0.2-0.3 Oe.

[0019] In a third aspect, the present invention provides a magnetic core, using the Sendust powder obtained by the above-mentioned preparation method or the above-mentioned Sendust powder.

[0020] Preferably, the 20kHz magnetic permeability of the magnetic core is 68.95-70.02, the 100k / 50mT loss is less than 132.54mw / cm³, and the superposition under 100Oe is ≥59.89%.

[0021] Preferably, the method for preparing the magnetic core provided by the present invention comprises insulating and coating the sendust powder, adding 0.2% to 0.5% of a demolding lubricant, pressing it into a magnetic ring with OD=26.9mm, ID=14.7mm, and HI=11.20mm at a pressure of 20 to 24 t / cm², and annealing at 710 to 790°C.

[0022] The method for preparing low-loss and high-overlapping sendust powder provided by the present invention obtains a particle size ratio with optimal performance by controlling the composition and particle size, sieving out coarse powder and a certain proportion of fine powder, and further reduces the coercivity of the sendust powder by pre-heat treatment of the original powder. After insulation coating, a sendust powder and a magnetic core with low loss and excellent overlapping performance are obtained. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods. If no specific techniques or conditions are specified in the examples, they are all conventional methods or the techniques or conditions described in the literature in this field, or according to the product instructions. If the manufacturers of the reagents and instruments are not specified, they are all conventional products that can be purchased through regular channels.

[0025] In the embodiment of the present invention, D10, D50 and D90 are important parameters in the particle size distribution, which can describe the overall particle size distribution characteristics of the particle population. D10, D50 and D90 correspond to the particle sizes when the cumulative percentages are 10%, 50% and 90%, respectively. These parameters can be obtained from the cumulative distribution curve, which indicates the percentage of particles that are smaller than a certain particle size.

[0026] In the embodiments of the present invention, the term "-200 mesh -20% -400 mesh" means taking the powder under the 200 mesh sieve and then sifting out 20% by weight of the 400 mesh fine powder.

[0027] In the embodiment of the present invention, Hc represents the coercive force, which is used to evaluate the magnetic properties of a material and is one of the important characteristics of a magnetic material. It mainly measures the magnitude of the reverse magnetic field required to return the magnetization intensity to zero after the magnetic material is magnetized to a saturated state.

[0028] Example 1

[0029] The original powder of the sendust powder used in this embodiment is Si 8.8%wt, Al 5.2%wt, and the balance is Fe. After the original powder is heat treated at 750°C to remove stress, the powder under the 200-mesh sieve is taken and 10% by weight of the 400-mesh fine powder is sieved out. The hardness of the sendust powder is 280-320Hv, coercive force, D10, D50 and D90 are shown in Table 1. After the sendust powder is coated with insulation, 0.4% of demoulding lubricant is added, and the pressure of 21t / cm² is used to press it into a magnetic ring with OD=26.9mm, ID=14.7mm, and HI=11.20mm. After annealing at no more than 790°C for 240-300min, the magnetic core has a permeability of 69.51μ, a loss of 100k / 50mT of 115.25mw / cm³, and a superposition of 59.89% under 100Oe.

[0030] Example 2

[0031] The original powder of the sendust powder used in this embodiment is Si 8.8%wt, Al 5.2%wt, and the balance is Fe. After the original powder is heat treated at 750°C to remove stress, the powder under the 200-mesh sieve is taken and the 400-mesh fine powder accounting for 20% by weight is sieved out. The hardness of the sendust powder is 280-320Hv, coercive force, D10, D50 and D90 are shown in Table 1. After the sendust powder is coated with insulation, 0.4% of demoulding lubricant is added, and the pressure of 21t / cm² is used to press it into a magnetic ring with OD=26.9mm, ID=14.7mm, and HI=11.20mm. After annealing at no more than 790°C for 240-300min, the magnetic core has a permeability of 68.95μ, a loss of 121.04mw / cm³ at 100k / 50mT, and a superposition of 59.94% at 100Oe.

[0032] Example 3

[0033] The original powder of the sendust powder used in this embodiment is Si 8.8%wt, Al 5.2%wt, and the balance is Fe. After the original powder is heat treated at 750°C to remove stress, the powder under the 200-mesh sieve is taken and 30% of the 400-mesh fine powder is sieved out by weight. The hardness of the sendust powder is 280-320Hv, coercive force, D10, D50 and D90 are shown in Table 1. After the sendust powder is coated with insulation, 0.4% of demoulding lubricant is added, and the magnetic ring with OD=26.9mm, ID=14.7mm, and HI=11.20mm is pressed at a pressure of 21t / cm². After annealing at no more than 790°C for 240-300min, the magnetic core has a magnetic permeability of 70.02μ, a loss of 100k / 50mT of 132.54mw / cm³, and a superposition of 60.10% under 100Oe.

[0034] Comparative Example 1

[0035] The original powder of the sendust powder used in this comparative example is Si 8.8%wt, Al 5.2%wt, and the balance is Fe. The powder under the 140 mesh sieve is taken, and the coercive force, D10, D50 and D90 of the sendust powder are shown in Table 1. After the sendust powder is coated with insulation, 0.4% of demoulding lubricant is added, and the pressure of 21t / cm² is used to press it into a magnetic ring with OD=26.9mm, ID=14.7mm, HI=11.20mm. After annealing at no more than 790℃ for 240-300min, the magnetic core has a permeability of 70.73μ, a loss of 157.93mw / cm³ at 100k / 50mT, and an overlap of 58.22% at 100Oe.

[0036] Comparative Example 2

[0037] The original powder of the sendust powder used in this comparative example is Si 8.8%wt, Al 5.2%wt, and the balance is Fe. After the original powder is heat treated at 750℃ to remove stress, the powder under the 140-mesh sieve is taken, and the coercive force, D10, D50 and D90 of the sendust powder are shown in Table 1. After the sendust powder is coated with insulation, 0.4% of demoulding lubricant is added, and the pressure of 21t / cm² is used to press it into a magnetic ring with OD=26.9mm, ID=14.7mm, HI=11.20mm. After annealing at no more than 790℃ for 240-300min, the magnetic core has a permeability of 70.73μ, a loss of 157.93mw / cm³ at 100k / 50mT, and an overlap of 58.22% at 100Oe.

[0038] Comparative Example 3

[0039] The original powder of the sendust powder used in this comparative example is Si 8.8%wt, Al 5.2%wt, and the balance is Fe. After the original powder is heat treated at 750℃ to remove stress, the powder under the 200-mesh sieve is taken, and the coercive force, D10, D50 and D90 of the sendust powder are shown in Table 1. After the sendust powder is coated with insulation, 0.4% of demoulding lubricant is added, and the pressure of 21t / cm² is used to press it into a magnetic ring with OD=26.9mm, ID=14.7mm, HI=11.20mm. After annealing at no more than 790℃ for 240-300min, the magnetic core has a permeability of 69.05μ, a loss of 100k / 50mT of 125.07mw / cm³, and a superposition of 58.76% under 100Oe.

[0040] Passed the "GB / T 3658-2008 Measurement method of AC magnetic properties of soft magnetic alloy ring specimens" and "GB / T 13012 Measurement method of DC magnetic properties of soft magnetic materials", tested with BH analyzer, Iwasaki SY8218 and LCR tester WK3260B+3265B.

[0041] Table 1

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing sendust powder, characterized in that: include: The sendust raw powder is heat treated, and then sieved and coarse powder and part of fine powder are removed to obtain sendust powder; the coarse powder is powder on a 150-250 mesh sieve, and the fine powder is powder under a 350-450 mesh sieve.

2. The method for preparing Sendust powder according to claim 1, characterized in that: 10% to 30% of the total weight of the fine powder is sieved off.

3. The method for preparing Sendust powder according to claim 1 or 2, characterized in that: The coarse powder is powder on a 200-mesh sieve; and / or, the fine powder is powder under a 400-mesh sieve; and / or, 20% of the total weight of the fine powder is sieved out.

4. The method for preparing Sendust powder according to any one of claims 1 to 3, characterized in that: The temperature of the heat treatment is 740-760°C.

5. The method for preparing Sendust powder according to any one of claims 1 to 4, characterized in that: The sendust raw powder contains 8.3-8.9 wt% Si, 5.1-5.7 wt% Al, and the remainder is Fe and unavoidable impurities.

6. A sendust powder, characterized in that: Obtained by the preparation method according to any one of claims 1 to 5; the sendust powder has D10>10μm and D90<80μm.

7. The Sendust powder according to claim 6, characterized in that The D10 of the Sendust powder is ≥15 μm, and D90 is ≤70 μm; preferably, the D10 of the Sendust powder is 16-18.5 μm, and D90 is 60-65 μm.

8. The Sendust powder according to claim 6 or 7, characterized in that: The sendust powder has a hardness of 280-400 Hv and a coercive force of 0.2-0.7 Oe.

9. A magnetic core, characterized in that: The Sendust powder obtained by the preparation method according to any one of claims 1 to 5 or the Sendust powder according to any one of claims 6 to 8.

10. The magnetic core according to claim 9, characterized in that The 20kHz magnetic permeability of the magnetic core is 68.95-70.02, the 100k / 50mT loss is less than 132.54mw / cm³, and the superposition under 100Oe is ≥59.89%.

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