Magnetic core and preparation method and application thereof

Abstract

The invention relates to a magnetic core and a preparation method and application thereof, the magnetic core comprises a body and a shielding layer coating the outer surface of the body, and the material of the body comprises a composite magnetic conductive material and at least one iron element; the composite magnetic conductive material comprises a strip-shaped molybdenum oxide matrix and a polymer layer wrapping the outer surface of the molybdenum oxide matrix, magnetic conductive particles are embedded in the polymer layer, the magnetic conductive particles are distributed in the circumferential direction of the molybdenum oxide matrix, and the magnetic conductive particles comprise SnCl2 particles and metallic tin particles. The magnetic core not only has excellent anti-saturation capability, but also has the characteristics of low insertion loss in a low-frequency environment and high insertion loss in a high-frequency environment, when the magnetic core is applied to a choking coil, the choking coil can be applied to the high-frequency environment, and the magnetic core has high transmission efficiency on useful signals and strong interference suppression capability on useless signals.

Description

Technical Field

[0001] The present invention relates to the technical field of chokes, and particularly to a magnetic core, a preparation method thereof and an application thereof. Background Art

[0002] With the rapid development of electronic power, the power consumption of electronic devices continues to increase, and the current of electronic devices also increases accordingly. This will cause more serious radiation interference from the electronic devices to the outside, generating corresponding common-mode interference. A choke is a component that can limit current. It mainly consists of a coil and a magnetic core, and can limit the current in the circuit, thereby protecting other components from overcurrent damage. However, traditional chokes will generate certain energy losses during operation, resulting in a reduction in the efficiency of the entire circuit. Especially in high-frequency applications, due to the resistance and losses of the choke itself, more heat will be generated in the circuit, and the power consumption will also increase. Therefore, there are limitations in the use of high-power electronic devices. Summary of the Invention

[0003] Based on this, in view of the above technical problems, it is necessary to provide a magnetic core, a preparation method thereof and an application thereof; this magnetic core not only has excellent anti-saturation ability, but also has the characteristics of low insertion loss in a low-frequency environment and high insertion loss in a high-frequency environment. When it is applied to a choke, the choke can be applied in a high-frequency environment, has a high transmission efficiency for useful signals, and a strong interference suppression ability for useless signals.

[0004] The present invention discloses a magnetic core, which includes a body and a shielding layer coated on the outer surface of the body. The material of the body includes a composite magnetic conductive material and at least one iron-based element;

[0005] Among them, the composite magnetic conductive material includes a strip-shaped molybdenum oxide matrix and a polymer layer coated on the outer surface of the molybdenum oxide matrix. Magnetic conductive particles are embedded in the polymer layer, and the magnetic conductive particles are distributed along the circumferential direction of the molybdenum oxide matrix. Among them, the magnetic conductive particles include SnCl 2 particles and metallic tin particles.

[0006] In one embodiment, the mass ratio of the iron-based element to the composite magnetic conductive material is 1:1 - 1:3.

[0007] In one embodiment, the iron-based element includes at least one of iron, nickel or cobalt. When the iron-based element includes iron, nickel and cobalt, the mass ratio of iron to nickel is 2:1 - 5:1, and the mass ratio of iron to cobalt is 2:1 - 5:1.

[0008] In one embodiment, the magnetic conductive particles are distributed on the same circumference around the molybdenum oxide matrix.

[0009] In one embodiment, the polymer layer includes a first polymer layer and a second polymer layer sequentially coated on the outer surface of the molybdenum oxide matrix, and the magnetic particles are embedded between the first polymer layer and the second polymer layer.

[0010] In one embodiment, the composite magnetic conductive material satisfies at least one of the following conditions:

[0011] (1) The mass ratio of the SnCl 2 particles to the metallic tin particles is 1:2 - 1:3;

[0012] (2) The mass fraction of the magnetic particles in the composite magnetic conductive material is 15% - 25%;

[0013] (3) The mass fraction of the molybdenum oxide matrix in the composite magnetic conductive material is 20% - 30%;

[0014] (4) The ratio of the total mass of the first polymer layer and the second polymer layer to the mass of the magnetic particles is 2:1 - 4:1;

[0015] (5) The material of the first polymer layer is selected from at least one of polypyrrole, polyaniline, or polythiophene, and the material of the second polymer layer is selected from at least one of polypyrrole, polyaniline, or polythiophene;

[0016] (6) When the molybdenum oxide matrix is in a circular tube shape, the length of the molybdenum oxide matrix is 2 μm - 10 μm, the inner diameter is 700 nm - 900 nm, and the outer diameter is 900 nm - 1100 nm.

[0017] In one embodiment, the material of the shielding layer includes at least one of aluminum, silver, copper, or graphene; and / or, the thickness of the shielding layer is 1 nm - 3 mm.

[0018] In the magnetic core provided by the present invention, the SnCl 2 particles embedded inside the polymer layer of the composite magnetic conductive material have excellent magnetic permeability, can form an electromagnetic path, guide the transmission direction of electromagnetic waves, and endow the composite magnetic conductive material with excellent electromagnetic energy transmission ability and electromagnetic wave traction ability; the metallic tin particles embedded inside the polymer layer have excellent electrical conductivity and can endow the tube wall of the composite magnetic conductive material with excellent electromagnetic wave shielding effect; thus, SnCl 2The particles cooperate with metallic tin particles to control the passage of electromagnetic waves in the pipeline of the composite magnetic conductive material. The composite magnetic conductive material not only has high insertion loss and can absorb electromagnetic waves, but also can control the passage of electromagnetic waves in the pipeline of the composite magnetic conductive material, has excellent magnetic conductive effect and is not prone to magnetic saturation. Furthermore, the magnetic core composed of the composite magnetic conductive material and iron-based elements also has excellent magnetic conductive effect, is not prone to magnetic saturation, has low insertion loss in a low-frequency environment and high insertion loss in a high-frequency environment, and has differential insertion loss in different frequency bands. Therefore, when it is applied to a choke coil, the choke coil can not only be applied in a high-frequency environment, but also can timely dissipate the high-frequency electromagnetic waves caused by abnormal current in the circuit, such as spike current, thereby curbing the current fluctuation in the circuit and protecting other components from overcurrent damage.

[0019] The present invention also discloses a preparation method of the magnetic core as described above, comprising the following steps:

[0020] Prepare a strip-shaped molybdenum oxide matrix;

[0021] Form a first polymer layer on the outer surface of the molybdenum oxide matrix to obtain a first intermediate;

[0022] Form magnetic conductive particles on the outer surface of the first polymer layer to obtain a second intermediate;

[0023] Form a second polymer layer on the outer surface of the second intermediate to obtain a composite magnetic conductive material;

[0024] Mix and grind the composite magnetic conductive material and iron-based elements to obtain mixed particles;

[0025] Press and sinter the mixed particles to obtain the body of the magnetic core;

[0026] Form a shielding layer on the outer surface of the body to obtain the magnetic core.

[0027] In one embodiment, the particle size of the mixed particles is 1 μm - 3 μm.

[0028] In one embodiment, in the step of pressing and sintering the mixed particles, the pressure for pressing and forming is 100 MPa - 200 MPa, and the sintering temperature is 900 °C - 1300 °C.

[0029] In the preparation method of the composite magnetic conductive material provided by the present invention, first, a strip-shaped molybdenum oxide matrix is prepared, then, a first polymer layer, magnetic conductive particles and a second polymer layer are sequentially formed on the outer surface of the molybdenum oxide matrix to obtain a composite magnetic conductive material, then, a body is prepared from the composite magnetic conductive material and iron-based elements, and finally, a shielding layer is formed on the outer surface of the body, thereby realizing the simple preparation of a magnetic core with excellent anti-magnetic saturation performance, low insertion loss in a low-frequency environment and high insertion loss in a high-frequency environment.

[0030] The present invention also discloses an inductor, which includes the magnetic core as described above.

[0031] Since the magnetic core provided by the present invention has excellent anti-magnetic saturation performance, low insertion loss in a low-frequency environment, and high insertion loss in a high-frequency environment, when the magnetic core is applied to an inductor, the inductor can not only be applied in a high-frequency environment, but also timely dissipate high-frequency electromagnetic waves caused by abnormal currents in the circuit, such as spike currents, thereby curbing current fluctuations in the circuit and protecting other components from overcurrent damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic structural diagram of an inductor and a magnetic core according to an embodiment of the present invention;

[0033] Figure 2 is a schematic cross-sectional view of an embodiment of the composite magnetic conductive material of the present invention;

[0034] Figure 3 is a schematic cross-sectional view of another embodiment of the composite magnetic conductive material of the present invention;

[0035] Figure 4 is a schematic cross-sectional view of still another embodiment of the composite magnetic conductive material of the present invention;

[0036] Figure 5 is a high-magnification scanning electron microscope image of the molybdenum oxide matrix prepared in Example 1;

[0037] Figure 6 is a high-magnification scanning electron microscope image of the second intermediate prepared in Example 1;

[0038] Figure 7 is a high-magnification scanning electron microscope image of the composite magnetic conductive material prepared in Example 1;

[0039] Figure 8 is the permeability curve of the composite magnetic conductive material prepared in Example 1;

[0040] Figure 9 is a graph showing the relationship between insertion loss and frequency of the composite magnetic conductive material prepared in Example 1 at different thicknesses;

[0041] Figure 10 is a graph showing the relationship between insertion loss and frequency of the magnetic core prepared in Example 1.

[0042] In the figure: 10, body; 101, molybdenum oxide matrix; 102, magnetic conductive particles; 103, polymer layer; 1031, first polymer layer; 1032, second polymer layer; 20, shielding layer; 30, coil. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] For the convenience of understanding the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, these embodiments or examples are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments or examples and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of the related listed items. The any and all combinations include any two related listed items, any more related listed items, or the combination of all related listed items.

[0045] As Figures 1 to 4 shown, the magnetic core provided by the present invention includes a body 10 and a shielding layer 20 coated on the outer surface of the body 10. The material of the body 10 includes a composite magnetic conductive material and at least one iron-based element.

[0046] Among them, the composite magnetic conductive material includes a strip-shaped molybdenum oxide matrix 101 and a polymer layer 103 coated on the outer surface of the molybdenum oxide matrix 101. Magnetic conductive particles 102 are embedded inside the polymer layer 103, and the magnetic conductive particles 102 are distributed along the circumferential direction of the molybdenum oxide matrix 101. Among them, the magnetic conductive particles 102 include SnCl 2 particles and metallic tin particles.

[0047] In the magnetic core provided by the present invention, the material of the body 10 includes a specific composite magnetic conductive material. Among them, the molybdenum oxide matrix 101 in the composite magnetic conductive material can endow the composite magnetic conductive material with good chemical stability and thermal stability, so that the composite magnetic conductive material remains intact in high-temperature and corrosive environments.

[0048] At the same time, the SnCl 2 particles embedded inside the polymer layer 103 in the composite magnetic conductive material have excellent magnetic permeability, can form an electromagnetic path, guide the transmission direction of electromagnetic waves, and endow the composite magnetic conductive material with excellent electromagnetic energy transmission ability and electromagnetic wave traction ability; the metallic tin particles embedded inside the polymer layer 103 have excellent electrical conductivity and can endow the tube wall of the composite magnetic conductive material with excellent electromagnetic wave shielding effect; thus, SnCl 2The particles cooperate with the metallic tin particles to control the passage of electromagnetic waves in the pipeline of the composite magnetic conductive material. As a result, the composite magnetic conductive material not only has high insertion loss and can absorb electromagnetic waves, but also can control the passage of electromagnetic waves in the pipeline of the composite magnetic conductive material, has excellent magnetic conductivity, and is not prone to magnetic saturation.

[0049] Furthermore, the magnetic core composed of the composite magnetic conductive material and the iron-based element also has excellent magnetic conductivity, is not prone to magnetic saturation, has low insertion loss in a low-frequency environment, and high insertion loss in a high-frequency environment, with differential insertion losses in different frequency bands. Therefore, when it is applied to a choke coil, the choke coil can not only be used in a high-frequency environment, but also timely dissipate the high-frequency electromagnetic waves caused by abnormal currents in the circuit, such as spike currents, thereby curbing the current fluctuations in the circuit and protecting other components from overcurrent damage.

[0050] The shape of the magnetic core is preferably cylindrical or U-shaped; in the body 10 of the magnetic core, the mass ratio of the iron-based element to the composite magnetic conductive material affects the filtering frequency band and insertion loss. In one embodiment, the mass ratio of the iron-based element to the composite magnetic conductive material is 1:1 - 1:3, including but not limited to 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, or 1:3, so that the magnetic core has lower insertion loss in a low-frequency environment and higher insertion loss in a high-frequency environment, and has both low loss and broadband filtering characteristics.

[0051] To better control the passage of electromagnetic waves in the pipeline of the composite magnetic conductive material, in one embodiment, the mass ratio of SnCl 2 particles to the metallic tin particles is 1:2 - 1:3, including but not limited to 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, or 1:3.

[0052] In the composite magnetic conductive material, the mass fraction of the magnetic conductive particles 102 in the composite magnetic conductive material is preferably 15% - 25%, including but not limited to 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, or 25%, so that the composite magnetic conductive material has both excellent magnetic conductivity and processing performance.

[0053] In one embodiment, the mass fraction of the molybdenum oxide matrix 101 in the composite magnetic conductive material is 20% - 30%, including but not limited to 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%, so that the composite magnetic conductive material has both excellent magnetic conductivity and forming effect.

[0054] It should be noted that the strip-shaped molybdenum oxide matrix 101 can be a solid structure, a hollow structure, or a partially hollow structure. When the strip-shaped molybdenum oxide matrix 101 is a hollow structure, the polymer layer 103 may extend and fill the head and tail ends of the molybdenum oxide matrix 101; when the strip-shaped molybdenum oxide matrix 101 is a hollow structure, the strip-shaped molybdenum oxide matrix 101 can be in the shape of a circular tube or a square tube. Preferably, the strip-shaped molybdenum oxide matrix 101 is in the shape of a circular tube, so that the polymer layer 103 can be more evenly coated on the outer surface of the molybdenum oxide matrix 101. Furthermore, the magnetic particles 102 can be more evenly distributed along the circumferential direction of the molybdenum oxide matrix 101.

[0055] When the strip-shaped molybdenum oxide matrix 101 is in the shape of a circular tube, the length of the molybdenum oxide matrix 101 affects the magnetic conduction effect, and the inner diameter and outer diameter affect the bonding effect between the molybdenum oxide matrix 101 and the polymer layer 103. In one embodiment, the length of the molybdenum oxide matrix 101 is 2 μm - 10 μm, including but not limited to 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, the inner diameter is 700 nm - 900 nm, including but not limited to 700 nm, 720 nm, 740 nm, 760 nm, 780 nm, 800 nm, 820 nm, 840 nm, 860 nm, 880 nm, or 900 nm, and the outer diameter is 900 nm - 1100 nm, including but not limited to 900 nm, 910 nm, 920 nm, 930 nm, 940 nm, 950 nm, 960 nm, 970 nm, 980 nm, 990 nm, 1000 nm, or 1100 nm. It can be understood that the inner wall of the molybdenum oxide matrix 101 can also be coated with the polymer layer 103, and the magnetic particles 102 can also be embedded in the polymer layer 103.

[0056] When the magnetic particles 102 are embedded in the polymer layer 103, as Figure 2 shown, the magnetic particles 102 can be distributed on the same circumference outside the molybdenum oxide matrix 101, or as Figure 3 shown, they can be distributed in a discrete state along the circumferential direction of the molybdenum oxide matrix 101. Preferably, the magnetic particles 102 are all distributed on the same circumference outside the molybdenum oxide matrix 101 as Figure 2 shown, so as to improve the electromagnetic passing rate and make the composite magnetic conductive material have a more excellent magnetic conduction effect.

[0057] Furthermore, as Figure 4 shown, the polymer layer 103 includes a first polymer layer 1031 and a second polymer layer 1032 that are sequentially coated on the outer surface of the molybdenum oxide matrix 101, and the magnetic particles 102 are embedded between the first polymer layer 1031 and the second polymer layer 1032.

[0058] Among them, the material of the polymer layer 103 is selected from at least one of polypyrrole, polyaniline or polythiophene. When the polymer layer 103 includes a first polymer layer 1031 and a second polymer layer 1032, the material of the first polymer layer 1031 is selected from at least one of polypyrrole, polyaniline or polythiophene, and the material of the second polymer layer 1032 is selected from at least one of polypyrrole, polyaniline or polythiophene. The materials of the first polymer layer 1031 and the second polymer layer 1032 may be the same or different. Since polypyrrole has excellent electrical conductivity, thermal stability and chemical stability, etc., therefore, the material of the polymer layer 103 is selected from polypyrrole, and the materials of the first polymer layer 1031 and the second polymer layer 1032 are both preferably selected from polypyrrole.

[0059] Preferably, the ratio of the total mass of the first polymer layer 1031 and the second polymer layer 1032 to the mass of the magnetic particles 102 is 2:1 - 4:1, including but not limited to 2:1, 2.5:1, 3:1, 3.5:1 or 4:1.

[0060] The type and content of iron-based elements affect the filtering frequency band of the magnetic core. In one embodiment, the iron-based elements include iron, nickel and cobalt. Among them, the mass ratio of iron to nickel is 2:1 - 5:1, including but not limited to 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1 or 5:1; the mass ratio of iron to cobalt is 2:1 - 5:1, including but not limited to 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1 or 5:1.

[0061] The shielding layer 20 in the magnetic core provided by the present invention can not only improve the corrosion resistance of the magnetic core, but also reduce magnetic leakage. In one embodiment, the material of the shielding layer 20 includes at least one of aluminum, silver, copper or graphene; preferably, the thickness of the shielding layer 20 is 1nm - 3mm, including but not limited to 1mm, 1.5mm, 2mm, 2.5mm or 3mm.

[0062] The present invention also provides a preparation method of the magnetic core as described above, including the following steps:

[0063] S10, preparing a strip-shaped molybdenum oxide matrix 101;

[0064] S20, forming a first polymer layer 1031 on the outer surface of the molybdenum oxide matrix 101 to obtain a first intermediate;

[0065] S30, forming magnetic particles 102 on the outer surface of the first polymer layer 1031 to obtain a second intermediate;

[0066] S40, forming a second polymer layer 1032 on the outer surface of the second intermediate to obtain a composite magnetic material;

[0067] S50. Mix the composite magnetic conductive material with iron-based elements and grind them to obtain mixed particles;

[0068] S60. Press and sinter the mixed particles to obtain the main body 10 of the magnetic core;

[0069] S70. Form a shielding layer 20 on the outer surface of the main body 10 to obtain the magnetic core.

[0070] In the preparation method of the composite magnetic conductive material provided by the present invention, first, prepare a strip-shaped molybdenum oxide matrix 101. Then, sequentially form the first polymer layer 1031, magnetic conductive particles 102, and the second polymer layer 1032 on the outer surface of the molybdenum oxide matrix 101 to obtain the composite magnetic conductive material. Then, use the composite magnetic conductive material and iron-based elements as raw materials to obtain the main body 10. Finally, form a shielding layer 20 on the outer surface of the main body 10, thereby realizing the simple preparation of a magnetic core with excellent anti-magnetic saturation performance, low insertion loss in a low-frequency environment, and high insertion loss in a high-frequency environment.

[0071] In step S10, there is no limitation on the method for preparing the molybdenum oxide matrix 101, as long as the obtained molybdenum oxide matrix 101 is strip-shaped.

[0072] In one embodiment, the hydrothermal method is used to prepare the strip-shaped molybdenum oxide matrix 101. The steps include: adding an acid to an aqueous solution containing molybdate and performing a hydrothermal reaction under the condition of an external magnetic field. In order to make the obtained molybdenum oxide matrix 101 be in a circular tubular shape, preferably, the microstructure of the molybdate is circular tubular, the intensity of the magnetic field is 50 mT - 100 mT, including but not limited to 50 mT, 60 mT, 70 mT, 80 mT, 90 mT, or 100 mT, the mass ratio of molybdate to acid is 1:1 - 4:1, including but not limited to 1:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1, 3:1, 3.2:1, 3.4:1, 3.6:1, 3.8:1, or 4:1; the temperature of the hydrothermal reaction is 200°C - 400°C, including but not limited to 200°C, 220°C, 240°C, 260°C, 280°C, 300°C, 320°C, 340°C, 360°C, 380°C, or 400°C; the reaction time is 6 h - 12 h, including but not limited to 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, or 12 h.

[0073] In one embodiment, the molybdate includes at least one of ammonium molybdate or sodium molybdate.

[0074] In step S20, in order to better disperse the molybdenum oxide matrix 101, before the step of forming the first polymer layer 1031 on the outer surface of the molybdenum oxide matrix 101, first mix the molybdenum oxide matrix 101 with hydrochloric acid and perform ultrasonic treatment.

[0075] In one embodiment, the step of forming the first polymer layer 1031 on the outer surface of the molybdenum oxide matrix 101 includes: mixing the molybdenum oxide matrix 101 with hydrochloric acid and a first polymer monomer, and stirring under an applied magnetic field to obtain a first intermediate.

[0076] In one embodiment, the intensity of the applied magnetic field is 50 mT - 100 mT, including but not limited to 50 mT, 60 mT, 70 mT, 80 mT, 90 mT, or 100 mT.

[0077] In one embodiment, the mass ratio of the first polymer monomer to the molybdenum oxide matrix 101 is 1:2 - 1:5, including but not limited to 1:2, 1:2.25, 1:2.5, 1.2.75, 1:3, 1:3.25, 1:3.5, 1:3.75, 1:4, 1:4.25, 1:4.5, 1:4.75, or 1:5.

[0078] In one embodiment, the temperature of stirring is 150°C - 300°C, including but not limited to 150°C, 200°C, 250°C, or 300°C, and the time is 1 - 2.5 h, including but not limited to 1 h, 1.5 h, 2 h, or 2.5 h.

[0079] In step S30, in one embodiment, the step of forming the magnetic particles 102 on the outer surface of the first polymer layer 1031 includes: mixing the first intermediate with SnCl 2 and hydrochloric acid, and successively performing ultrasonic treatment, electroreduction treatment, and applied magnetic field treatment.

[0080] It should be noted that ultrasonic treatment can introduce chloride ions into the conjugated chain structure of the first polymer layer 1031, thereby effectively reducing the band gap of the first polymer, increasing the electron mobility, and endowing the first polymer with conductivity. Electroreduction treatment can reduce Sn 2+ ions to metallic Sn, further improving the conductivity of the first polymer. Thus, under the action of the applied magnetic field treatment, SnCl 2 particles and metallic tin particles can overcome the energy barrier and jump to the surface of the first polymer layer 1031.

[0081] In one embodiment, in the step of ultrasonic treatment, the frequency is 30 kHz - 35 kHz, including but not limited to 30 kHz, 31 kHz, 32 kHz, 33 kHz, 34 kHz or 35 kHz, the power is 50 W - 100 W, including but not limited to 50 W, 60 W, 70 W, 80 W, 90 W or 100 W, the temperature is 30°C - 45°C, including but not limited to 30°C, 35°C, 40°C or 45°C, and the time is 0.5 h - 6 h, including but not limited to 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h, 2 h, 3 h, 4 h, 5 h or 6 h.

[0082] In order to better control the passage of electromagnetic waves in the pipeline of the composite magnetic conductive material, in one embodiment, in the step of electroreduction treatment, the voltage is 2 V - 3 V, including but not limited to 2 V, 2.2 V, 2.4 V, 2.6 V, 2.8 V or 3 V, the temperature is 30°C - 45°C, including but not limited to 30°C, 35°C, 40°C or 45°C, and the time is 0.5 h - 1 h, including but not limited to 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h or 1 h.

[0083] In one embodiment, in the step of magnetic field treatment, the intensity of the electromagnetic field is 100 mT - 200 mT, including but not limited to 100 mT, 110 mT, 120 mT, 130 mT, 140 mT, 150 mT, 160 mT, 170 mT, 180 mT, 190 mT or 200 mT.

[0084] In step S40, the present invention does not limit the manner of forming the second polymer layer 1032 on the outer surface of the second intermediate, as long as the second polymer layer 1032 can wrap the magnetic conductive particles 102.

[0085] In one embodiment, the step of forming the second polymer layer 1032 on the outer surface of the second intermediate includes: mixing and stirring the second intermediate and the second polymer; preferably, the mass ratio of the second intermediate to the second polymer is 1:10 - 1:15, including but not limited to 1:10, 1:11, 1:12, 1:13, 1:14 or 1:15, the stirring temperature is 95°C - 105°C, including but not limited to 95°C, 100°C or 105°C, and the time is 1 h - 2 h, including but not limited to 1 h, 1.5 h or 2 h.

[0086] In step S50, the particle size of the mixed particles affects the loss and filtering frequency band of the magnetic core. In one embodiment, the particle size of the mixed particles is 1 μm - 3 μm, including but not limited to 1 μm, 2 μm or 3 μm.

[0087] In step S60, in one embodiment, in the step of pressing the mixed particles into shape and sintering, the pressing pressure is 100MPa-200MPa, including but not limited to 100MPa, 120MPa, 140MPa, 160MPa, 180MPa or 200MPa, and the sintering temperature is 900℃-1300℃, including but not limited to 900℃, 1000℃, 1100℃, 1200℃ or 1300℃.

[0088] In step S70 , the present invention does not limit the manner of forming the shielding layer 20 on the outer surface of the body 10 . In one embodiment, the shielding material is sprayed on the outer surface of the body 10 to form the shielding layer 20 .

[0089] The invention also discloses a choke coil, comprising the magnetic core as described above.

[0090] In one embodiment, the choke coil further includes a coil 30 wound around a magnetic core.

[0091] Since the magnetic core provided by the present invention has excellent anti-magnetic saturation performance, low insertion loss in low-frequency environment, and high insertion loss in high-frequency environment, when the magnetic core is applied to the choke, the choke can be used in a high-frequency environment, and has high transmission efficiency for useful signals and strong interference suppression capability for useless signals.

[0092] Hereinafter, the magnetic core and its preparation method and application will be further described through the following specific embodiments.

[0093] Example 1

[0094] Ammonium molybdate, deionized water and 8 wt % nitric acid were mixed in a mass ratio of 3:1.5:2, and stirred for 20 minutes under an external 75 mT magnetic field to obtain a uniform solution. The uniform solution was transferred to a stainless steel autoclave lined with polytetrafluoroethylene, and heated at 200° C. for 12 hours and then naturally cooled to separate a precipitate. The precipitate was washed with deionized water and ethanol in turn, and dried at 50° C. for 12 hours to obtain a molybdenum oxide substrate 101. A high-magnification scanning electron microscope image of the molybdenum oxide substrate 101 is shown in FIG. Figure 5 shown.

[0095] The molybdenum oxide substrate 101 is placed in an equal mass of 7wt% hydrochloric acid for ultrasonic treatment to form a suspension, pyrrole, ammonium persulfate and 7wt% hydrochloric acid are mixed in a mass ratio of 3:1:1, and then added to the suspension, the mass ratio of the suspension to pyrrole is 3:5, and the reaction is stirred for 12 hours under the condition of an external 75mT magnetic field to form a first polypyrrole layer on the outer surface of the molybdenum oxide substrate 101 to obtain a first intermediate.

[0096] SnCl 2Mix with hydrochloric acid with a concentration of 7 wt% according to a mass ratio of 1:1 to obtain a mixed solution, and then add a first intermediate to the mixed solution to obtain a reaction solution. Among them, the mass ratio of the first intermediate to the mixed solution is 1:3. First, ultrasonically vibrate the reaction solution for 6 hours, then add the reaction solution to an electroplating bath, stir at 100 °C for 1 hour, perform a drying treatment in a vacuum oven at 50 °C, and finally perform a treatment under the condition of an external electromagnetic field of 150 mT to obtain a second intermediate. The high-magnification scanning electron micrograph of the second intermediate is as shown in Figure 6 shown.

[0097] Mix the second intermediate with polypyrrole according to a mass ratio of 1:12 to form a second polypyrrole layer to obtain a composite magnetic conductive material. The high-magnification scanning electron micrograph of the composite magnetic conductive material is as shown in Figure 7 shown. In the composite magnetic conductive material, the mass fraction of the molybdenum oxide matrix 101 is 25%, the mass fraction of the magnetic conductive particles 102 is 20%, and the mass ratio of the SnCl 2 particles to the metal tin particles is 1:2.5, and the mass fraction of the polymer layer 103 is 55%.

[0098] Mix iron, nickel, cobalt and the composite magnetic conductive material according to a mass ratio of 3:1:1:5 and grind at a speed of 500 r / min for 0.5 h to obtain mixed particles with a particle size of 1 μm - 3 μm

[0099] Press the mixed particles into an inductor with the required shape and size in a mold using a mechanical pressure of 100 MPa. Then, place the pressed inductor material in a high-temperature furnace and sinter at 1000 °C for 30 minutes in an inert environment to obtain the body 10.

[0100] Spray the shielding material aluminum on the outer surface of the body 10, and then perform an insulation treatment to form a shielding layer 20 with a thickness of 2 mm on the outer surface of the body 10 to obtain a magnetic core.

[0101] Comparative Example 1

[0102] Comparative Example 1 was carried out with reference to Example 1. The difference is that in the preparation method of the composite magnetic conductive particles 102, the magnetic conductive particles 102 are not introduced. The specific preparation method of the composite magnetic conductive material is as follows:

[0103] Mix ammonium molybdate, deionized water and nitric acid with a concentration of 8 wt% according to a mass ratio of 3:1.5:2, stir for 20 minutes under the condition of an externally applied magnetic field of 75 mT to obtain a uniform solution. Transfer the obtained uniform solution to a stainless steel autoclave lined with polytetrafluoroethylene, heat at 200 °C for 12 hours and then cool naturally, separate the precipitate, wash the precipitate with deionized water and ethanol in sequence, and dry the precipitate at 50 °C for 12 hours to obtain the molybdenum oxide matrix 101.

[0104] The molybdenum oxide matrix 101 was placed in hydrochloric acid with a concentration of 7 wt% equal in mass to it and subjected to ultrasonic treatment to form a suspension. Pyrrole, ammonium persulfate, and hydrochloric acid with a concentration of 7 wt% were mixed according to a mass ratio of 3:1:1, and then added to the suspension. Stirring reaction was carried out for 12 hours under the condition of an externally applied magnetic field of 75 mT to form a polypyrrole layer on the outer surface of the molybdenum oxide matrix 101.

[0105] Comparative Example 2

[0106] Comparative Example 2 was carried out with reference to Example 1. The difference lies in that in the preparation method of the composite magnetic conductive material, the molybdenum oxide matrix 101 is not in a strip shape but in an irregular shape. The specific preparation method of the composite magnetic conductive material is as follows:

[0107] Ammonium molybdate, deionized water, and nitric acid with a concentration of 3 wt% were mixed according to a mass ratio of 3:1.5:2 to obtain a uniform solution. The obtained uniform solution was transferred to a stainless-steel autoclave lined with polytetrafluoroethylene and heated at 200 °C for 12 hours and then naturally cooled. The precipitate was separated out, and the precipitate was dried at 50 °C for 12 hours to obtain an irregular molybdenum oxide matrix.

[0108] Comparative Example 3

[0109] Comparative Example 3 was carried out with reference to Example 1. The difference lies in that in the preparation method of the composite magnetic conductive material, a second polypyrrole layer is not formed on the surface of the first intermediate. The specific preparation method of the composite magnetic conductive material is as follows:

[0110] Ammonium molybdate, deionized water, and nitric acid with a concentration of 8 wt% were mixed according to a mass ratio of 3:1.5:2, and stirred for 20 minutes under the condition of an externally applied magnetic field of 75 mT to obtain a uniform solution. The obtained uniform solution was transferred to a stainless-steel autoclave lined with polytetrafluoroethylene and heated at 200 °C for 12 hours and then naturally cooled. The precipitate was separated out, and the precipitate was washed successively with deionized water and ethanol. The precipitate was dried at 50 °C for 12 hours to obtain the molybdenum oxide matrix 101.

[0111] The molybdenum oxide matrix 101 was placed in hydrochloric acid with a concentration of 7 wt% equal in mass to it and subjected to ultrasonic treatment to form a suspension. Pyrrole, ammonium persulfate, and hydrochloric acid with a concentration of 7 wt% were mixed according to a mass ratio of 3:1:1, and then added to the suspension. Stirring reaction was carried out for 12 hours under the condition of an externally applied magnetic field of 75 mT to form a first polypyrrole layer on the outer surface of the molybdenum oxide matrix 101 to obtain a first intermediate.

[0112] SnCl 2Mix with hydrochloric acid with a concentration of 7 wt% according to a mass ratio of 1:1 to obtain a mixed solution. Then, add a first intermediate to the mixed solution to obtain a reaction solution. Among them, the mass ratio of the first intermediate to the mixed solution is 1:3. First, ultrasonically vibrate the reaction solution for 6 hours, then add the reaction solution to an electroplating bath, stir at 100 °C for 1 hour, perform a drying treatment in a vacuum oven at 50 °C, and finally perform a treatment under the condition of an external electromagnetic field of 150 mT to directly obtain a composite magnetic conductive material.

[0113] Test Example 1

[0114] Test the magnetic properties of the composite magnetic conductive materials and magnetic cores obtained in Test Example 1 and Comparative Examples 1 to 3. The test method is as follows, and the test results are shown in Table 1; the magnetic permeability curve of the composite magnetic conductive material prepared in Example 1 is as Figure 8 shown. From Figure 8 it can be seen that in the range of 2 GHz - 4 GHz, the magnetic permeability of the composite magnetic conductive material prepared in Example 1 can reach above 1.2; the relationship diagram of the insertion loss and frequency of the composite magnetic conductive material prepared in Example 1 at different thicknesses is as Figure 9 shown. From Figure 9 it can be known that the insertion loss of the composite magnetic conductive material prepared in Example 1 can reach -48.6 dB at a thickness of 2.2 mm, and it has good insertion loss characteristics. The relationship diagram of the insertion loss and frequency of the magnetic core prepared in Example 1 is as Figure 10 shown. From Figure 10 it can be known that the insertion loss of the magnetic core prepared in Example 1 is only -0.5 dB in a low-frequency environment and can reach -33 dB in a high-frequency environment.

[0115] Absorbing performance test: Refer to "GB / T32596" to test the insertion loss of the composite magnetic conductive material in the frequency band of 2 GHz - 18 GHz, and test the insertion loss of the magnetic core in the frequency band of 400 MHz - 1000 MHz.

[0116] Magnetic permeability test: Refer to "JB / T 13536 - 2018" to test the magnetic permeability of the magnetic core in the frequency band of 2 GHz - 18 GHz and the magnetic permeability of the magnetic core in the frequency band of 0 GHz - 2 GHz.

[0117] Table 1

[0118]

[0119] Example 2

[0120] Example 2 is carried out with reference to Example 1, the difference being that the mass fraction of the magnetic conductive particles 102 in the composite magnetic conductive material is 15%.

[0121] Example 3

[0122] Example 3 was carried out with reference to Example 1, except that the mass fraction of the magnetic particles 102 in the composite magnetic material was 25%.

[0123] Example 4

[0124] Example 4 was carried out with reference to Example 1, except that the mass fraction of the molybdenum oxide matrix 101 in the composite magnetic material was 20%.

[0125] Example 5

[0126] Example 5 was carried out with reference to Example 1, except that the mass fraction of the molybdenum oxide matrix 101 in the composite magnetic material was 30%.

[0127] Example 6

[0128] Example 6 was carried out with reference to Example 1, except that the intensity of the electromagnetic field was 100 mT.

[0129] Example 7

[0130] Example 7 was carried out with reference to Example 1, except that the intensity of the electromagnetic field was 200 mT.

[0131] Example 8

[0132] Example 8 was carried out with reference to Example 1, except that the mass ratio of molybdate to acid was 1:1, the temperature of the hydrothermal reaction was 200 °C, and the reaction time was 6 h.

[0133] Example 9

[0134] Example 9 was carried out with reference to Example 1, except that the mass ratio of molybdate to acid was 4:1, the temperature of the hydrothermal reaction was 400 °C, and the reaction time was 12 h.

[0135] Example 10

[0136] Example 10 was carried out with reference to Example 1, except that the mass ratio of SnCl 2 particles to metallic tin particles was 1:2.

[0137] Example 11

[0138] Example 11 was carried out with reference to Example 1, except that the mass ratio of SnCl 2 particles to metallic tin particles was 1:3.

[0139] Test Example 2

[0140] With reference to Test Example 1, the magnetic properties of the composite magnetic materials and magnetic cores obtained in Examples 2 to 11 were tested, and the test results are shown in Table 2.

[0141] Table 2

[0142]

[0143] Example 12

[0144] Example 12 was carried out with reference to Example 1, except for the mass ratio of the iron-based elements to the composite magnetic conductive material. Among them, the mass ratio of iron, nickel, cobalt and the composite magnetic conductive material is 1:1:1:9.

[0145] Example 13

[0146] Example 13 was carried out with reference to Example 1, except for the mass ratio of the iron-based elements to the composite magnetic conductive material. The mass ratio of iron, nickel, cobalt and the composite magnetic conductive material is 1:1:1:3.

[0147] Example 14

[0148] Example 14 was carried out with reference to Example 1, except that the iron-based elements only include iron. Among them, the mass ratio of iron and the composite magnetic conductive material is 1:2.

[0149] Example 15

[0150] Example 15 was carried out with reference to Example 1, except that the iron-based elements only include nickel. Among them, the mass ratio of nickel and the composite magnetic conductive material is 1:2.

[0151] Example 16

[0152] Example 16 was carried out with reference to Example 1, except that the iron-based elements only include cobalt. Among them, the mass ratio of cobalt and the composite magnetic conductive material is 1:2.

[0153] Test Example 3

[0154] With reference to Test Example 1, the magnetic properties of the composite magnetic conductive materials and magnetic cores obtained in Examples 12 to 16 were tested. The test results are shown in Table 3.

[0155] Table 3

[0156]

[0157] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0158] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A magnetic core, characterized in that: The magnetic core comprises a body and a shielding layer coated on the outer surface of the body, and the material of the body comprises a composite magnetic conductive material and at least one iron-based element; The composite magnetic conductive material includes a strip-shaped molybdenum oxide matrix and a polymer layer coated on the outer surface of the molybdenum oxide matrix, magnetic conductive particles are embedded in the polymer layer, and the magnetic conductive particles are distributed along the circumference of the molybdenum oxide matrix, wherein the magnetic conductive particles include SnCl2 particles and metal tin particles.

2. The magnetic core according to claim 1, characterized in that The mass ratio of the iron-based elements to the composite magnetic conductive material is 1:1-1:

3.

3. The magnetic core according to claim 1, characterized in that: The iron-based elements include at least one of iron, nickel or cobalt. When the iron-based elements include iron, nickel and cobalt, the mass ratio of iron to nickel is 2:1-5:1, and the mass ratio of iron to cobalt is 2:1-5:

1.

4. The magnetic core according to any one of claims 1 to 3, characterized in that: The magnetic conductive particles are distributed on the same circumference of the outer periphery of the molybdenum oxide matrix.

5. The magnetic core according to claim 4, characterized in that: The polymer layer comprises a first polymer layer and a second polymer layer sequentially coated on the outer surface of the molybdenum oxide substrate, and the magnetic conductive particles are embedded between the first polymer layer and the second polymer layer.

6. The magnetic core according to claim 5, characterized in that The composite magnetic conductive material meets at least one of the following conditions: (1) The mass ratio of the SnCl2 particles to the metal tin particles is 1:2-1:3; (2) The mass fraction of the magnetic conductive particles in the composite magnetic conductive material is 15%-25%; (3) The mass fraction of the molybdenum oxide matrix in the composite magnetic conductive material is 20%-30%; (4) The ratio of the total mass of the first polymer layer and the second polymer layer to the mass of the magnetic conductive particles is 2:1-4:1; (5) The material of the first polymer layer is selected from at least one of polypyrrole, polyaniline and polythiophene, and the material of the second polymer layer is selected from at least one of polypyrrole, polyaniline and polythiophene; (6) When the molybdenum oxide substrate is in a cylindrical shape, the length of the molybdenum oxide substrate is 2 μm-10 μm, the inner diameter is 700 nm-900 nm, and the outer diameter is 900 nm-1100 nm.

7. The magnetic core according to any one of claims 1 to 3, characterized in that: The material of the shielding layer includes at least one of aluminum, silver, copper or graphene; and / or the thickness of the shielding layer is 1nm-3mm.

8. A method for preparing a magnetic core according to any one of claims 1 to 7, characterized in that: The following steps are involved: preparing a strip-shaped molybdenum oxide matrix; forming a first polymer layer on the outer surface of the molybdenum oxide substrate to obtain a first intermediate; forming magnetic conductive particles on the outer surface of the first polymer layer to obtain a second intermediate; forming a second polymer layer on the outer surface of the second intermediate to obtain a composite magnetic conductive material; The composite magnetic conductive material is mixed with an iron-based element and ground to obtain mixed particles; Pressing the mixed particles into a shape and sintering them to obtain a main body of the magnetic core; A shielding layer is formed on the outer surface of the body to obtain a magnetic core.

9. The method for preparing a magnetic core according to claim 8, characterized in that: The particle size of the mixed particles is 1 μm-3 μm.

10. The method for preparing a magnetic core according to claim 8, characterized in that: In the step of pressing the mixed particles into a mold and sintering, the pressing pressure is 100 MPa-200 MPa, and the sintering temperature is 900° C.-1300° C.

11. A choke coil, characterized in that: Comprising the magnetic core according to any one of claims 1 to 7.

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