An electric arc spraying broadband low-frequency magnetic field shielding material and a preparation method thereof

Abstract

This invention relates to the field of electromagnetic shielding technology, and more specifically, to an arc-sprayed broadband low-frequency magnetic field shielding material and its preparation method. The shielding material is a sandwich-structured unit module, with each unit module consisting of a high-permeability dielectric layer, a high-conductivity dielectric layer, and a high-saturation magnetic induction intensity dielectric layer, arranged sequentially along its thickness. This invention fully leverages the synergistic effect of each functional layer through the sandwich structure design, overcoming the technical bottleneck of traditional single-layer shielding materials that struggle to simultaneously achieve high permeability, high conductivity, and high saturation magnetic induction intensity over a wide frequency range. This significantly improves the shielding effectiveness of low-frequency magnetic fields. Employing an arc-spraying forming process, by optimizing key parameters such as current, voltage, wire feed speed, atomization pressure, thickness, spraying distance, and spraying angle, it enables rapid, uniform, and dense coating formation on large-area and complex-shaped substrate surfaces. This effectively solves the application challenges of traditional high-permeability soft magnetic metal sheets being difficult to process into complex shells and difficult to install.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic shielding technology, and more specifically, to an arc-sprayed broadband low-frequency magnetic field shielding material and its preparation method. Background Technology

[0002] With the rapid development of modern electronic technology and the high-density integration of equipment, the control systems of electronic information systems and critical infrastructure are facing increasingly severe challenges in electromagnetic security and electromagnetic interference. Important information systems in sectors vital to national economy and people's livelihoods are susceptible to leaks of classified information and electromagnetic security risks. Weapons and equipment in the defense industry face prominent issues regarding electronic countermeasures performance and survivability in complex electromagnetic environments. Meanwhile, critical control systems in industries such as power and communications are vulnerable to intentional or unintentional electromagnetic interference. In electromagnetic radiation protection, low-frequency magnetic field shielding in the DC to 500kHz frequency band is particularly challenging, as this type of interference seriously jeopardizes the overall performance of electronic information platforms.

[0003] Current research both domestically and internationally indicates that high-permeability soft magnetic metal sheets possess high shielding effectiveness in the low-frequency band. However, their performance is highly susceptible to mechanical stress and they are difficult to process into complex-shaped shells, significantly limiting their engineering applications. Furthermore, the permeability of high-permeability materials typically decreases significantly with increasing frequency above 1 kHz, and these materials often cannot simultaneously possess high saturation magnetic induction, thus hindering the achievement of efficient shielding of wide-band magnetic fields. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, one aspect of the present invention is to provide an arc-sprayed broadband low-frequency magnetic field shielding material, wherein the shielding material has a sandwich structure, the sandwich structure is a unit module, and the unit module consists of a high permeability dielectric layer, a high conductivity dielectric layer and a high saturation magnetic induction intensity dielectric layer in sequence along the thickness direction.

[0005] Preferably, the high permeability dielectric layer is an Fe-Ni based alloy coating, wherein the Fe-Ni based alloy is one of Fe-Ni alloy, FeNiMo, FeNiCu or FeNiCr alloy, and the nickel content in the Fe-Ni alloy coating is 76%~84%, and the coating thickness is 55μm~95μm.

[0006] Preferably, the highly conductive dielectric layer is a copper or silver coating, and the coating thickness is 32μm to 48μm.

[0007] Preferably, the high saturation magnetic induction intensity dielectric layer is an Fe-Ni based alloy coating, wherein the Fe-Ni based alloy is one of Fe-Ni alloy, FeNiMo, FeNiCu or FeNiCr alloy, wherein the nickel content in the Fe-Ni alloy coating is 76%~84% and the coating thickness is 135μm~255μm.

[0008] Another objective of this invention is to provide a method for preparing a broadband low-frequency magnetic field shielding material by arc spraying, wherein the specific steps of the preparation method are as follows: S1. Substrate pretreatment: The aluminum alloy substrate is roughened by sandblasting; S2. Transition layer arc spraying: spraying voltage 20V ~40V, spraying current 160A~200A, spraying distance 170mm ~200mm, spraying angle 70°~90°, atomizing air pressure 0.45MPa ~0.65MPa, wire feeding speed 3.0m / min ~4.0m / min, thickness 12μm ~28μm; S3. Shielding material spraying: S3.1 High permeability layer arc spraying: spraying voltage 35V ~55V, spraying current 190A ~230A, spraying distance 140mm ~180mm, spraying angle 80~90°, atomizing air pressure 0.50MPa~0.60MPa, wire feeding speed 4.0 m / min ~5.0m / min, thickness 55μm ~95μm; S3.2 High conductivity layer arc spraying: spraying voltage 45V ~60V, spraying current 170A~200A, spraying distance 130mm~170mm, spraying angle 70°~90°, atomizing air pressure 0.65MPa ~0.75MPa, wire feeding speed 3.5 m / min ~4.5m / min, thickness 32μm ~48μm; S3.3 High Saturation Magnetic Induction Intensity Layer Arc Spraying: Spraying voltage 30~50V, spraying current 180A~220A, spraying distance 150mm~190mm, spraying angle 70°~90°, atomizing air pressure 0.55MPa~0.70MPa, wire feeding speed 4.0m / min~5.0m / min, thickness 135μm~255μm; S4. Preparation of protective layer: After the shielding material is sprayed, the surface is cleaned and dried. The protective layer is then applied by brushing and cured at 50°C. The thickness is 5μm~20μm.

[0009] Preferably, the thickness of the sandblasting roughening treatment in S1 is 0.5 mm, and the surface roughness Ra is 3.2 μm to 12.5 μm.

[0010] Preferably, the transition layer in S2 is Ni or a Ni alloy.

[0011] Preferably, the number of shielding material coating layers in S3 is 1 to 3.

[0012] Preferably, the protective layer in S4 is epoxy resin.

[0013] The beneficial effects of this invention are as follows: Wide-band, high-efficiency magnetic field shielding performance: This invention utilizes a sandwich structure design of "high permeability dielectric layer + high conductivity dielectric layer + high saturation magnetic induction intensity dielectric layer" to fully leverage the synergistic effect of each functional layer. This overcomes the technical bottleneck of traditional single shielding materials being unable to simultaneously achieve high permeability, high conductivity, and high saturation magnetic induction intensity over a wide frequency band, significantly improving the shielding effectiveness of low-frequency magnetic fields from DC to 500kHz.

[0014] Excellent machinability and conformal capability: By adopting the arc spraying forming process and optimizing key parameters such as current, voltage, wire feed speed, atomization pressure, thickness, spraying distance and spraying angle, it can achieve rapid, uniform and dense coating formation on the surface of large-area and complex-shaped substrates, effectively solving the application problems of traditional high magnetic permeability soft magnetic metal sheets being difficult to process into complex shells and difficult to construct on site.

[0015] Excellent bonding strength and durability: The coating of this invention has high bonding strength between each layer and between the coating and the substrate, and is not prone to peeling or cracking; the coating is dense and has low porosity, and has good resistance to environmental aging and mechanical stress, which significantly improves the long-term reliability and environmental adaptability of the shielding material under complex working conditions.

[0016] Wide applicability and engineering practical value: This invention can be directly sprayed onto the surface of various substrates such as irregularly shaped parts and large components. It has strong process adaptability and convenient construction. It is suitable for application scenarios with strict requirements for low-frequency magnetic field shielding, such as electronic components, key modules, military equipment, and power communication control systems. It provides a reliable technical solution to ensure the stable operation of electronic information platforms in complex electromagnetic environments.

[0017] Additional aspects and advantages of the invention will become apparent from the description which follows, or may be learned by practice of the invention. Attached Figure Description

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a design drawing of the sandwich structure unit module of the arc spraying wide-band low-frequency magnetic field shielding material of the present invention; Figure 2This is a structural design diagram of a double-layer sandwich unit module arc spraying wide-band low-frequency magnetic field shielding material according to Embodiment 2 of the present invention. Detailed Implementation

[0019] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0021] Example 1 Structural composition: matrix → transition layer (pure Ni) → high permeability layer (Fe) 21 Ni 79 → High conductivity layer (Cu) → High saturation magnetic induction layer (Fe) 51 Ni 49 → Protective layer (epoxy resin).

[0022] S1. Substrate pretreatment: The aluminum alloy substrate (thickness of 0.5 mm) is subjected to sandblasting roughening treatment, with a surface roughness Ra=6.3μm; S2. Transition layer (pure Ni) arc spraying, spraying voltage 30V, spraying current 190A, spraying distance 185mm, spraying angle 80°, atomizing air pressure 0.60MPa, wire feeding speed 3.5m / min, thickness 20μm; S3.1. High permeability layer (Fe) 21 Ni 79 Arc spraying, spraying voltage 45V, spraying current 210A, spraying distance 160mm, spraying angle 85°, atomizing air pressure 0.55MPa, wire feeding speed 4.5 m / min, thickness 80μm; S3.2. High conductivity layer (Cu) arc spraying, spraying voltage 55V, spraying current 185A, spraying distance 150mm, spraying angle 70°, atomizing air pressure 0.70MPa, wire feeding speed 4.0m / min, thickness 45μm; S3.3. High saturation magnetic induction layer (Fe) 51 Ni 49 Arc spraying, spraying voltage 40V, spraying current 200A, spraying distance 180mm, spraying angle 80°, atomizing air pressure 0.62MPa, wire feeding speed 4.5m / min, thickness 220μm; S4. Preparation of protective layer: After the composite coating material is sprayed, the surface is cleaned and dried. Then, epoxy resin is applied by brushing and cured at 50°C to a thickness of 15μm.

[0023] After testing, the magnetic field shielding effectiveness of the broadband low-frequency magnetic field shielding material is ≥20dB (DC~500kHz, field strength is 6Gs).

[0024] Example 2 Structural composition: matrix → transition layer (pure Ni) → high permeability layer (Fe) 21 Ni 79 → High conductivity layer (Cu) → High saturation magnetic induction layer (Fe) 45 Ni 55 → High permeability layer (Fe) 21 Ni 79 → High conductivity layer (Cu) → High saturation magnetic induction layer (Fe) 45 Ni 55 → High permeability layer (Fe) 21 Ni 79 → High conductivity layer (Cu) → High saturation magnetic induction layer (Fe) 45 Ni 55 → Protective layer (epoxy resin).

[0025] S1. Substrate pretreatment: The aluminum alloy substrate (thickness of 0.5 mm) is subjected to sandblasting roughening treatment, with a surface roughness Ra=7.6μm; S2. Transition layer (Ni-Al) arc spraying, spraying voltage 35V, spraying current 195A, spraying distance 180mm, spraying angle 80°, atomizing air pressure 0.65MPa, wire feeding speed 3.0m / min, thickness 15μm; S3.1. High permeability layer (Fe) 21 Ni 79 Arc spraying, spraying voltage 50V, spraying current 215A, spraying distance 155mm, spraying angle 85°, atomizing air pressure 0.60MPa, wire feeding speed 4.0 m / min, thickness 60μm; S3.2. High conductivity layer (Cu) arc spraying, spraying voltage 60V, spraying current 190A, spraying distance 145mm, spraying angle 70°, atomizing air pressure 0.70MPa, wire feeding speed 3.5m / min, thickness 35μm; S3.3. High saturation magnetic induction layer (Fe) 51 Ni 49Arc spraying, spraying voltage 45V, spraying current 210A, spraying distance 175mm, spraying angle 80°, atomizing air pressure 0.65MPa, wire feeding speed 4.0m / min, thickness 180μm; S3.4. Repeat S3.1 to S3.3 twice; S4. Preparation of protective layer: After the composite coating material is sprayed, the surface is cleaned and dried. Then, an organosilicon sealant is applied by brushing and cured at 50°C to a thickness of 10μm.

[0026] After testing, the magnetic field shielding effectiveness of the broadband low-frequency magnetic field shielding material is ≥45dB (DC~500kHz, field strength 10Gs).

[0027] Comparative Example 1 Structural composition: matrix → transition layer (pure Ni) → high permeability layer (Fe) 21 Ni 79 → Protective layer (epoxy resin).

[0028] S1. Substrate pretreatment: The aluminum alloy substrate (thickness of 0.5 mm) is subjected to sandblasting roughening treatment, with a surface roughness Ra=6.3μm; S2. Transition layer (pure Ni) arc spraying, spraying voltage 30V, spraying current 190A, spraying distance 185mm, spraying angle 80°, atomizing air pressure 0.60MPa, wire feeding speed 3.5m / min, thickness 20μm; S3. High permeability layer (Fe) 21 Ni 79 Arc spraying, spraying voltage 45V, spraying current 210A, spraying distance 160mm, spraying angle 85°, atomizing air pressure 0.55MPa, wire feeding speed 4.5 m / min, thickness 80μm; S4. Preparation of protective layer: After the composite coating material is sprayed, the surface is cleaned and dried. Then, epoxy resin is applied by brushing and cured at 50°C to a thickness of 15μm.

[0029] After testing, the magnetic field shielding effectiveness of the broadband low-frequency magnetic field shielding material is ≥10dB (DC~500kHz, field strength is 6Gs).

[0030] This invention achieves a significant improvement in wide-band magnetic field shielding effectiveness through a multi-layer composite structure design of a "high permeability layer + high conductivity layer + high saturation magnetic induction layer". Example 1 (single-layer sandwich structure) achieves a shielding effectiveness ≥20dB under DC~500kHz and field strength 6Gs conditions; Example 2 (double-layer sandwich structure) achieves a shielding effectiveness ≥45dB under 10Gs conditions; while Comparative Example 1 (high permeability layer only) only achieves ≥10dB. Compared to single materials, this invention improves shielding effectiveness by 2~4.5 times, effectively solving the technical bottleneck of traditional materials where permeability decreases above 1kHz and the difficulty in simultaneously achieving wide-bandwidth and high shielding effectiveness.

[0031] Meanwhile, the arc spraying process ensures high bonding strength between the coating and the substrate, and can be conformally processed on complex irregular surfaces. It overcomes the defects of traditional high magnetic permeability plates that are difficult to form and easily affected by stress, and is suitable for low-frequency magnetic field protection in the fields of electronics, military, and power.

[0032] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A wide-band low-frequency magnetic field shielding material for arc spraying, characterized in that: The shielding material has a sandwich structure, which is a unit module. The unit module consists of a high permeability dielectric layer, a high conductivity dielectric layer, and a high saturation magnetic induction intensity dielectric layer in sequence along the thickness direction.

2. The arc-sprayed broadband low-frequency magnetic field shielding material according to claim 1, characterized in that: The high magnetic permeability dielectric layer is an Fe-Ni based alloy coating, wherein the Fe-Ni based alloy is one of Fe-Ni alloy, FeNiMo, FeNiCu or FeNiCr alloy, and the nickel content in the Fe-Ni alloy coating is 76%~84%, and the coating thickness is 55μm~95μm.

3. The arc-sprayed broadband low-frequency magnetic field shielding material according to claim 1, characterized in that: The highly conductive dielectric layer is a copper or silver coating with a thickness of 32μm to 48μm.

4. The arc-sprayed broadband low-frequency magnetic field shielding material according to claim 1, characterized in that: The high saturation magnetic induction intensity dielectric layer is an Fe-Ni based alloy coating. The Fe-Ni based alloy is one of Fe-Ni alloy, FeNiMo, FeNiCu or FeNiCr alloy. The Fe-Ni alloy coating has a nickel content of 76% to 84% and a coating thickness of 135 μm to 255 μm.

5. A method for preparing a broadband low-frequency magnetic field shielding material by arc spraying according to any one of claims 1 to 4, characterized in that: The specific steps of the preparation method are as follows: S1. Substrate pretreatment: The aluminum alloy substrate is roughened by sandblasting; S2. Transition layer arc spraying: spraying voltage 20V ~40V, spraying current 160A~200A, spraying distance 170mm ~200mm, spraying angle 70°~90°, atomizing air pressure 0.45MPa ~0.65MPa, wire feeding speed 3.0m / min ~4.0m / min, thickness 12μm ~28μm; S3. Shielding material spraying: S3.1 High permeability layer arc spraying: spraying voltage 35V ~55V, spraying current 190A ~230A, spraying distance 140mm ~180mm, spraying angle 80~90°, atomizing air pressure 0.50MPa ~0.60MPa, wire feeding speed 4.0 m / min ~5.0m / min, thickness 55μm ~95μm; S3.2 High conductivity layer arc spraying: spraying voltage 45V ~60V, spraying current 170A~200A, spraying distance 130mm ~170mm, spraying angle 70°~90°, atomizing air pressure 0.65MPa ~0.75MPa, wire feeding speed 3.5 m / min ~4.5m / min, thickness 32μm ~48μm; S3.3 High Saturation Magnetic Induction Intensity Layer Arc Spraying: Spraying voltage 30~50V, spraying current 180A~220A, spraying distance 150mm~190mm, spraying angle 70°~90°, atomizing air pressure 0.55MPa~0.70MPa, wire feeding speed 4.0m / min~5.0m / min, thickness 135μm~255μm; S4. Preparation of protective layer: After the shielding material is sprayed, the surface is cleaned and dried. The protective layer is then applied by brushing and cured at 50°C. The thickness is 5μm~20μm.

6. The arc-sprayed broadband low-frequency magnetic field shielding material according to claim 5, characterized in that: The thickness of the sandblasting roughening treatment in S1 is 0.5 mm, and the surface roughness Ra is 3.2 μm to 12.5 μm.

7. The arc-sprayed broadband low-frequency magnetic field shielding material according to claim 5, characterized in that: The transition layer in S2 is Ni or a Ni alloy.

8. The arc-sprayed broadband low-frequency magnetic field shielding material according to claim 5, characterized in that: The shielding material in S3 has 1 to 3 layers.

9. The arc-sprayed broadband low-frequency magnetic field shielding material according to claim 5, characterized in that: The protective layer in S4 is epoxy resin.

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