Preparation method of soft magnetic composite powder

Abstract

The invention relates to a preparation method of soft magnetic composite powder, which comprises the following steps: S1, mixing carbonyl iron powder with a phosphoric acid-acetone solution, stirring and drying at 20-40 DEG C, and cleaning; s2, mixing magnetic powder with a silane coupling agent-acetone solution, and stirring and drying at 20-40 DEG C; s3, mixing the magnetic powder with the amorphous magnetic powder-acetone solution, and stirring and drying at 20-40 DEG C; s4, mixing the magnetic powder with a resin-acetone solution, stirring, drying, granulating, and carrying out vacuum drying; s5, adding the zinc stearate lubricant into the magnetic powder, and uniformly stirring; and S6, pressing the magnetic powder to form a magnetic ring, and curing for 1.5-2.5 hours at the temperature of 160-180 DEG C. The method has the beneficial effects that the direct current bias capability is improved on the premise of ensuring the magnetic conductivity, and the stability of the magnetic conductivity can be ensured under the condition of high frequency.

Description

Technical Field

[0001] This invention relates to the field of soft magnetic composite materials technology, and specifically to a method for preparing soft magnetic composite powder. Background Technology

[0002] Electronic products are iterating towards miniaturization, high density, and high-speed transmission. The soft magnetic composite materials used to fabricate integrally molded inductors require high permeability, high saturation magnetic induction intensity, and low loss.

[0003] In the prior art, adhesives are usually added to magnetic powder to promote molding. However, the permeability and DC bias capability of inductors molded using this method alone are relatively weak. Therefore, it is necessary to pre-treat the magnetic powder to improve the permeability and DC bias capability of the inductor. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application proposes a method for preparing soft magnetic composite powder, which improves its DC bias capability while ensuring magnetic permeability, and can guarantee the stability of magnetic permeability at high frequencies.

[0005] The following is the technical solution of the present invention: a method for preparing soft magnetic composite powder, comprising the following steps: S1. Mix carbonyl iron powder with phosphoric acid-acetone solution, stir and dry at 20℃-40℃, then wash. S2. Mix the magnetic powder with the silane coupling agent-acetone solution and stir and dry at 20℃-40℃; S3. Mix the magnetic powder with the amorphous magnetic powder-acetone solution and stir and dry at 20℃-40℃; S4. Mix the magnetic powder with the resin-acetone solution, stir and dry, then granulate and vacuum dry. S5. Add zinc stearate lubricant to the magnetic powder and stir until homogeneous; S6. Press the magnetic powder into a magnetic ring and cure it at 160℃-180℃ for 1.5-2.5 hours.

[0006] In a preferred embodiment of the present invention, in S1, the D50 of the carbonyl iron powder is 8μm-10μm.

[0007] As a preferred embodiment of the present invention, in S1, the phosphoric acid-acetone solution is composed of 0.1-0.3 parts of dilute phosphoric acid with a concentration of 3% and 2.5-7.5 parts of acetone, with 100 parts of carbonyl iron powder as the basis.

[0008] As a preferred embodiment of the present invention, in S2, the silane coupling agent-acetone solution is composed of 0.1-0.3 parts of silane coupling agent and 2.5-7.5 parts of acetone, with 100 parts of carbonyl iron powder as the basis.

[0009] As a preferred embodiment of the present invention, in S3, the amorphous magnetic powder-acetone solution is composed of 4-6 parts of amorphous magnetic powder and 16-24 parts of acetone, with 100 parts of carbonyl iron powder as the basis.

[0010] As a preferred embodiment of the present invention, the D50 of the amorphous magnetic powder is 4μm-6μm.

[0011] As a preferred embodiment of the present invention, in S4, the resin-acetone solution is composed of 1 part acrylic resin, 0.8 parts modified silicone resin, 0.1 parts plasticizer, 0.1 parts accelerator and 10 parts acetone, based on 100 parts carbonyl iron powder.

[0012] As a preferred embodiment of the present invention, granulation is carried out using a 70-mesh sieve, and the vacuum drying time is 0.5-1.5 hours.

[0013] As a preferred embodiment of the present invention, in S5, the amount of zinc stearate lubricant added is 0.1 parts, based on 100 parts of carbonyl iron powder.

[0014] As a preferred embodiment of the present invention, in S6, the magnetic ring is pressed and formed under a pressure of 5T-7T to produce an inner diameter of 6mm-10mm and an outer diameter of 12mm-16mm, and after curing, the magnetic ring is surrounded by several turns of enameled wire with a diameter of 0.55mm-0.75mm.

[0015] The beneficial effects of this invention are as follows: By adopting a multi-layer construction, the decrease in magnetic permeability caused by ordinary insulation methods is avoided. Amorphous magnetic powder is introduced as a magnetic conductive layer between the acid-washed magnetic powder and the adhesive, which hardly sacrifices the overall magnetic permeability. Moreover, due to its high resistivity, the amorphous magnetic powder, along with the coating of mixed resin and additives, can reduce eddy current losses at high frequencies. This improves its DC bias capability while ensuring magnetic permeability, and also ensures the stability of magnetic permeability at high frequencies. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the preparation method of the present invention; Figure 2 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0017] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] like Figure 1 and Figure 2As shown, a method for preparing a soft magnetic composite powder includes the following steps: S1. Mix carbonyl iron powder with phosphoric acid-acetone solution, stir and dry at 20℃-40℃, then wash. S2. Mix the magnetic powder with the silane coupling agent-acetone solution and stir and dry at 20℃-40℃; S3. Mix the magnetic powder with the amorphous magnetic powder-acetone solution and stir and dry at 20℃-40℃; S4. Mix the magnetic powder with the resin-acetone solution, stir and dry, then granulate and vacuum dry. S5. Add zinc stearate lubricant to the magnetic powder and stir until homogeneous; S6. Press the magnetic powder into a magnetic ring and cure it at 170°C for 2 hours.

[0019] In step S1, carbonyl iron powder is mixed with phosphoric acid-acetone solution, stirred and dried at 20℃-40℃, and then washed, including the following steps: S101. Weigh out uninsulated carbonyl iron powder as the basic raw material; Weigh out 100 parts of carbonyl iron powder, wherein the carbonyl iron powder is not insulated and has a D50 of 9 μm.

[0020] S102, Prepare phosphoric acid-acetone solution; Weigh 0.2 parts of a 3% dilute phosphoric acid solution and dissolve it evenly in 5 parts of acetone solution to prepare a phosphoric acid-acetone solution.

[0021] S103. Add the phosphate-acetone solution to the magnetic powder, stir and dry it under a water bath heating platform, and wash it with deionized water. The solution from step S102 is added to the magnetic powder from step S101, and the mixture is stirred and dried in a water bath heating platform. The temperature during drying is controlled between 20℃ and 40℃. The dried magnetic powder is then washed with deionized water.

[0022] In step S2, the magnetic powder is mixed with a silane coupling agent-acetone solution and dried by stirring at 20℃-40℃, including the following steps: S201. Preparation of silane coupling agent-acetone solution; Weigh 0.2 parts of silane coupling agent and dissolve it evenly in 5 parts of acetone solution to prepare silane coupling agent-acetone solution.

[0023] S202. Add the silane coupling agent-acetone solution to the treated magnetic powder and stir and dry at 20℃-40℃. The solution from step S201 is added to the magnetic powder from step S103 and stirred and dried, with the drying temperature controlled between 20℃ and 40℃.

[0024] In step S3, the magnetic powder is mixed with an amorphous magnetic powder-acetone solution and dried by stirring at 20℃-40℃, including the following steps: S301. Preparation of amorphous magnetic powder-acetone solution; Weigh 20 parts of acetone solution and add it to 5 parts of amorphous magnetic powder, where D50 = 5 μm.

[0025] S302. Add the amorphous magnetic powder-acetone solution to the treated magnetic powder and stir and dry at 20℃-40℃. The solution from step S301 is added to the magnetic powder prepared in step S202 and stirred and dried, with the drying temperature controlled between 20℃ and 40℃.

[0026] In step S4, the magnetic powder is mixed with the resin-acetone solution, stirred and dried, then granulated and vacuum dried, including the following steps: S401, Prepare resin-acetone solution; Weigh 1 part acrylic resin, 0.8 parts modified silicone resin, 0.1 part plasticizer, and 0.1 part accelerator, and dissolve them evenly in 10 parts acetone solution to prepare a resin-acetone solution. S402. Add the resin-acetone solution to the treated magnetic powder, stir and dry, then granulate through a 70-mesh sieve and vacuum dry for 1 hour.

[0027] The resin-acetone solution from step S401 is added to the magnetic powder from step S302, stirred and dried, then granulated through a 70-mesh sieve, and finally vacuum dried for 1 hour.

[0028] In step S5, zinc stearate lubricant is added to the magnetic powder and stirred evenly. Specifically, 0.1 parts of zinc stearate lubricant are weighed and added to the magnetic powder from step S402, and stirred evenly.

[0029] In step S6, the magnetic powder is pressed into a magnetic ring and cured at 170°C for 2 hours, including the following steps: S601. Weigh a certain amount of magnetic powder, press it into a magnetic ring under 6T pressure, and measure the strength of the green ring. Weigh 2.000g of the magnetic powder from step S5, and weigh six portions in total. Press them into magnetic rings with an inner diameter of 8mm and an outer diameter of 14mm under a pressure of 6T. Measure and record the strength of the green ring.

[0030] S602. Cure the magnetic ring at 170℃ for 2 hours, allow it to cool naturally, then wind it and leave the leads. The magnetic ring was cured at a constant temperature of 170℃ for 2 hours and then allowed to cool naturally. After curing, wrap 13 turns of 0.65mm enameled wire around the magnetic ring and then strip the enamel, leaving a lead length of 3cm-5cm.

[0031] S603, Measure permeability and DC bias capability at a specific frequency; The magnetic permeability and DC bias capability of the magnetic ring were measured and recorded at frequencies of 1MHz, 500KHz and 100KHz, respectively, with a magnetic field strength of 100Oe.

[0032] Comparative Example 1 Unlike the examples, this comparative example did not perform the preparation and stirring of the phosphoric acid-acetone solution in step S1, the silane coupling agent-acetone solution in step S2, and the amorphous magnetic powder-acetone solution in step S3 after weighing the carbonyl iron powder. Instead, it directly proceeded to steps S4, S5, and S6.

[0033] Comparative Example 2 Unlike the examples, this comparative example did not perform the preparation and stirring of the phosphoric acid-acetone solution in step S1 after weighing the carbonyl iron powder, but directly proceeded to steps S2, S3, S4, S5 and S6.

[0034] Comparative Example 3 Unlike the examples, this comparative example, after weighing the carbonyl iron powder, prepared and stirred the phosphoric acid-acetone solution in step S1 and the silane coupling agent-acetone solution in step S2, but did not prepare and stir the amorphous magnetic powder-acetone solution in step S3. Instead, it directly proceeded to steps S4, S5 and S6.

[0035] Performance tests were performed on the embodiments of the present invention and Comparative Examples 1 to 3. The test parameters included: magnetic permeability and DC bias capability. The magnetic permeability and DC bias capability of the magnetic ring were measured and recorded at frequencies of 1MHz, 500KHz and 100KHz, respectively, with a magnetic field strength of 100Oe. The test parameter values ​​are shown in Table 1.

[0036] Table 1. Test parameter values.

[0037] As shown in Table 1, compared to Comparative Example 1 which uses an adhesive, the present invention improves its DC bias capability while ensuring magnetic permeability by constructing a multi-layer structure, and can also ensure the stability of magnetic permeability at high frequencies. Compared to Comparative Example 2 which does not have magnetic powder pretreatment, the present invention improves its DC bias capability by sacrificing a small amount of magnetic permeability after pretreatment of magnetic powder. Compared to Comparative Example 3 which does not have a magnetically conductive structure, the present invention constructs a magnetically conductive layer after magnetic powder pretreatment, thereby improving its DC bias capability and high-frequency stability while ensuring magnetic permeability.

[0038] This invention employs a multi-layer construction to avoid the decrease in magnetic permeability caused by ordinary insulation methods. Amorphous magnetic powder is introduced as a magnetic conductive layer between the acid-washed magnetic powder and the adhesive, which hardly sacrifices the overall magnetic permeability. Furthermore, due to its high resistivity, the amorphous magnetic powder, along with the coating of mixed resin and additives, can reduce eddy current losses at high frequencies, thus ensuring stability at high frequencies.

[0039] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Clearly, those skilled in the art can make various alterations and variations to the invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of equivalents of the invention, the invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a soft magnetic composite powder, characterized in that, Includes the following steps: S1. Mix carbonyl iron powder with phosphoric acid-acetone solution, stir and dry at 20℃-40℃, then wash. S2. Mix the magnetic powder with the silane coupling agent-acetone solution and stir and dry at 20℃-40℃; S3. Mix the magnetic powder with the amorphous magnetic powder-acetone solution and stir and dry at 20℃-40℃; S4. Mix the magnetic powder with the resin-acetone solution, stir and dry, then granulate and vacuum dry. S5. Add zinc stearate lubricant to the magnetic powder and stir until homogeneous; S6. Press the magnetic powder into a magnetic ring and cure it at 160℃-180℃ for 1.5-2.5 hours.

2. The method for preparing a soft magnetic composite powder according to claim 1, characterized in that, In S1, the D50 of carbonyl iron powder is 8μm-10μm.

3. The method for preparing a soft magnetic composite powder according to claim 1, characterized in that, In S1, the phosphoric acid-acetone solution consists of 0.1-0.3 parts of 3% dilute phosphoric acid and 2.5-7.5 parts of acetone, with 100 parts of carbonyl iron powder as the reference.

4. The method for preparing a soft magnetic composite powder according to claim 1, characterized in that, In S2, the silane coupling agent-acetone solution consists of 0.1-0.3 parts of silane coupling agent and 2.5-7.5 parts of acetone, with 100 parts of carbonyl iron powder as the reference.

5. The method for preparing a soft magnetic composite powder according to claim 1, characterized in that, In S3, the amorphous magnetic powder-acetone solution consists of 4-6 parts of amorphous magnetic powder and 16-24 parts of acetone, with 100 parts of carbonyl iron powder as the reference.

6. The method for preparing a soft magnetic composite powder according to claim 5, characterized in that, The D50 of amorphous magnetic powder is 4μm-6μm.

7. The method for preparing a soft magnetic composite powder according to claim 1, characterized in that, In S4, the resin-acetone solution is composed of 1 part acrylic resin, 0.8 parts modified silicone resin, 0.1 parts plasticizer, 0.1 parts accelerator and 10 parts acetone, based on 100 parts carbonyl iron powder.

8. The method for preparing a soft magnetic composite powder according to claim 7, characterized in that, Granulation is performed using a 70-mesh sieve, and vacuum drying time is 0.5-1.5 hours.

9. The method for preparing a soft magnetic composite powder according to claim 1, characterized in that, In S5, the amount of zinc stearate lubricant added is 0.1 parts, based on 100 parts of carbonyl iron powder.

10. The method for preparing a soft magnetic composite powder according to claim 1, characterized in that, In S6, the magnetic ring is pressed and molded under a pressure of 5T-7T to produce an inner diameter of 6mm-10mm and an outer diameter of 12mm-16mm. After curing, the magnetic ring is surrounded by several turns of enameled wire with a diameter of 0.55mm-0.75mm.

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