Manufacturing method for low-frequency magnetic shielding material

Abstract

To provide a thermal spraying shield film capable of magnetically shielding low-frequency magnetism.SOLUTION: In a magnetic shield material and a manufacturing method thereof that deposits a shield film that shields magnetism by spraying on at least a part of the surface of a base material, a shield film 3 is formed using powder of a soft magnetic material that shields by absorbing low-frequency magnetism as a thermal spray material, and the soft magnetic material is sendust, permalloy, silicon steel, and another metal material, ferrite, or another ceramic.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention is a low-frequency magnetic shielding material of Regarding the manufacturing method. [Background technology]

[0002] Generally, electronic devices such as PCUs, sensors, and other electronic components, as well as communication devices equipped with these, are provided with electromagnetic wave shielding to prevent malfunctions and information leakage due to external electromagnetic waves or magnetism. Patent Document 1, which describes a thermal spray coating, is known as an electromagnetic wave shielding material and a method for manufacturing the same.

[0003] Furthermore, while conventional electromagnetic wave shielding materials shield high-frequency electromagnetic waves by reflecting them, they have the drawback of allowing low-frequency magnetic fields, for example, below 100 kHz, to pass through. To overcome this drawback, sheet-type low-frequency magnetic shielding materials are commercially available. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-61035 Summary of the Invention [Problem to be solved by the invention]

[0005] In contrast, sheet-type low-frequency magnetic shielding materials can be used when the substrate surface is flat, such as the cover of an electronic device, but have the disadvantage that they cannot be used on those with complex irregular shapes. On the other hand, conventional thermal spray coatings such as those described in Patent Document 1 can be formed even on substrates with irregular shapes, but materials such as sendust, which are known as soft magnetic materials (high permeability magnetic materials), can be oxidized or thermally altered during thermal spraying, which can reduce their shielding function. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a method for manufacturing a low-frequency magnetic shielding material by forming a shielding coating that shields against magnetism on at least a part of the surface of a substrate by thermal spraying, in which the shielding coating is formed using powder of a soft magnetic material that shields by absorbing magnetism in the low-frequency range as the thermal spraying material, and the magnetic shielding effect of the low-frequency magnetic shielding material is, in terms of values ​​measured by the KEC method, 0.0005 ~ 0.1 The shielding coating is formed on the substrate so that the shielding strength increases with increasing frequency in the frequency range of 100 MHz.

[0007] The thickness of the shield coating is 250 The soft magnetic material may be any one of sendust, permalloy, silicon steel, and ferrite, or a combination of two or more of these materials.

[0008] The soft magnetic material is a powdered material that has been subjected to a treatment to prevent oxidation or thermal deterioration due to thermal spraying, and the treatment to prevent deterioration is Powder material with particle size -100 / +350mesh A plating layer is formed on the surface of The particle size was increased to 50-150 μm. It may be a process of performing the above.

[0009] The spraying method may be any of plasma spraying, low pressure plasma spraying, gas flame spraying, high velocity flame spraying, cold spray spraying, high frequency plasma spraying, suspension spraying, and warm spray spraying.

[0010] After plasma spraying, gas flame spraying, high velocity flame spraying, suspension spraying or warm spray spraying, the surface of the shield coating may be subjected to a reduction and densification heat treatment.

[0011] A low-frequency magnetic shielding material having a shielding coating made of a thermal spray coating that shields against magnetism on at least a part of the surface of a substrate, wherein the shielding coating contains a soft magnetic material that shields by absorbing magnetism in the low-frequency range, and the magnetic shielding effect thereof is, in terms of values ​​measured by the KEC method,0.0005 ~ 0.1 The shielding coating is formed on the substrate so that the shielding strength increases with increasing frequency in the frequency range of 100 MHz.

[0012] The low frequency range may be 100 kHz or less.

[0013] The aforementioned The soft magnetic material may be any of sendust, permalloy, silicon steel, or ferrite, or a combination of two or more of these materials. [Effects of the Invention]

[0014] According to the present invention configured as described above, the magnetic frequency to be shielded is limited to a low frequency range rather than the entire range, and a soft magnetic material powder is used as the thermal spray material, so it is easy to select a material that will not deteriorate the shielding function during thermal spraying as a material for at least a portion of the thermal spray material. By thermally spraying the thermal spray material composed of appropriate materials in this way onto at least a portion of the surface of the substrate, it is possible to obtain a desired shielding coating and easily accommodate substrates with complex shapes such as uneven surfaces. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a cross-sectional view of a low-frequency magnetic shielding material. [Figure 2] FIG. 1 is a schematic cross-sectional view of sendust powder with electroless nickel plating (Ni-P). [Figure 3] This is an electron microscope (SEM) image of sendust powder after Ni-P plating. [Figure 4] (A) to (C) are energy dispersive X-ray (EDX) images showing the distribution of Ni, Fe, and P in Ni-P plated sendust powder, respectively. [Figure 5] This is an SEM image of a coating formed by plasma spraying Ni-P plated Sendust powder. [Figure 6](A) to (E) are EDX images showing the distribution of Fe, Si, Al, Ni, and P in the coating of FIG. 5, respectively. [Figure 7] (A) to (C) are different analysis positions in the same SEM image as the film cross section shown in FIG. 5, and EDX images (X-ray diffraction pattern diagrams) corresponding to the analysis positions. [Figure 8] This is an SEM image of the cross section of a coating sprayed with Sendust powder by cold spray (CS). [Figure 9] (A) to (E) are EDX images showing the distribution of O, Mg, Al, Si, and Fe in the coating of Figure 8, respectively. [Figure 10] (A) and (B) are different analysis positions in the SEM image of the coating shown in Figure 8 and EDX images (X-ray diffraction pattern diagrams) corresponding to the analysis positions. [Figure 11] 1 is a graph comparing the measured values ​​of magnetic shielding properties for low-frequency magnetic fields obtained by plasma spraying Ni-P plated Sendust powder with the measurement limit value. [Figure 12] 1 is a graph comparing the measured values ​​of the magnetic shielding properties of untreated Sendust powder sprayed by cold spray (CS) with the measurement limit value for low frequency magnetic fields. [Figure 13] 1 is an SEM image showing an example of a particle of Ni-P plated permalloy. [Figure 14] (A) to (E) are images showing the distribution of C, O, P, Fe, and Ni as dots in EDX analysis of Ni-P plated permalloy. [Figure 15] (A) shows a predetermined analysis position in the SEM image shown in FIG. 13, and (B) is an EDX image corresponding to the analysis position shown in (A). [Figure 16] (A) shows a predetermined analysis position different from that of FIG. 15 in the SEM image shown in FIG. 13, and (B) is an EDX image corresponding to the analysis position shown in (A). [Figure 17] is an SEM image of a coating formed by plasma spraying Ni-P plated permalloy powder. [Figure 18] 18(A) to 18(F) are EDX images showing the distribution of C, O, P, Fe, Ni, and Zn in the coating shown in FIG. 17. [Figure 19] (A) shows a predetermined analysis position in the same SEM image as the film cross section shown in FIG. 17, and (B) is an EDX image corresponding to the analysis position shown in (A). [Figure 20] (A) shows a predetermined analysis position different from that shown in FIG. 19 in the same SEM image as the film cross section shown in FIG. 17, and (B) is an EDX image corresponding to the analysis position shown in (A). [Figure 21] (A) shows a predetermined analysis position different from that shown in FIGS. 19 and 20 in the same SEM image as the film cross section shown in FIG. 17, and (B) is an EDX image corresponding to the analysis position shown in (A). [Figure 22] This is a graph comparing the measured values ​​of magnetic shielding properties for low-frequency magnetic fields between plasma sprayed Ni-P plated permalloy powder and the measurement limit value. [Figure 23] is an SEM image showing an example of a permalloy particle that has not been Ni-P plated. [Figure 24] (A) to (F) are images showing the distribution of C, O, Si, S, Fe, and Ni as dots in EDX analysis of permalloy that has not been Ni-P plated. [Figure 25] This is an SEM image of a coating formed by plasma spraying permalloy powder without Ni-P plating. [Figure 26] 26(A) to 26(D) are EDX images showing the distribution of C, O, Fe, and Ni in the film shown in FIG. [Figure 27] (A) shows a predetermined analysis position in the same SEM image as the film cross section shown in FIG. 25, and (B) is an EDX image corresponding to the analysis position shown in (A). [Figure 28] (A) shows a predetermined analysis position different from that shown in FIG. 27 in the same SEM image as the film cross section shown in FIG. 25, and (B) is an EDX image corresponding to the analysis position shown in (A). [Figure 29] This is a graph comparing the measured values ​​of magnetic shielding properties for low-frequency magnetic fields between plasma-sprayed permalloy powder without Ni-P plating and the measurement limit value. [Figure 30]This is an SEM image showing an example of an iron-based amorphous particle that has been Ni-P plated. [Figure 31] (A) to (F) are images showing the distribution of C, O, Si, P, Fe, and Ni as dots in EDX analysis of Ni-P plated iron-based amorphous particles. [Figure 32] This is an SEM image of a coating formed by plasma spraying iron-based amorphous powder that has been plated with Ni-P. [Figure 33] 32A to 32H are EDX images showing the distribution of C, O, Si, P, Cr, Fe, Ni, and Al in the coating shown in FIG. [Figure 34] (A) shows a predetermined analysis position in the same SEM image as the film cross section shown in FIG. 32, and (B) is an EDX image corresponding to the analysis position shown in (A). [Figure 35] (A) shows a predetermined analysis position different from that shown in FIG. 34 in the same SEM image as the film cross section shown in FIG. 32, and (B) is an EDX image corresponding to the analysis position shown in (A). [Figure 36] (A) shows a predetermined analysis position different from those in FIGS. 34 and 35 in the same SEM image as the film cross section shown in FIG. 32, and (B) is an EDX image corresponding to the analysis position shown in (A). [Figure 37] 1 is a graph comparing the measured values ​​of magnetic shielding properties for low-frequency magnetic fields of a plasma-sprayed Ni-P plated iron-based amorphous powder with the measurement limit value. [Figure 38] This is an SEM image showing an example of an iron-based amorphous particle that is not plated with Ni-P. [Figure 39] (A) to (E) are dot images showing the distribution of C, Al, Si, Cr, and Fe in an iron-based amorphous material that has not been plated with Ni-P, as determined by EDX analysis. [Figure 40] 1 is a graph comparing the measured values ​​of magnetic shielding properties for low-frequency magnetic fields at the measurement limit and a plasma sprayed iron-based amorphous powder without Ni-P plating. DETAILED DESCRIPTION OF THE INVENTION

[0016] As shown in Figure 1, this invention provides a shielding material 1 for low-frequency magnetic shielding, which is used to form covers, outer boxes, shielding plates, etc. that house or shield electronic devices from the outside, and which has a substrate 2 that forms the main body of such devices, on at least a portion of the surface (specifically, part or all of the outer or inner surface) of which a coating 3 made of a soft magnetic material that shields by absorbing low-frequency electromagnetic waves of, for example, about 100 kHz is formed. The soft magnetic material is made of one or a combination of two or more of sendust, permalloy, silicon steel, other metal materials, ferrite, and other ceramic materials.

[0017] More specifically, the coating is formed (deposited) by thermal spraying a powdered soft magnetic material, and the thermal spray materials used are those shown in Table 1. This table lists examples of thermal spray materials used in the manufacturing method of a low-frequency magnetic shielding material to which the present invention is applied, and examples of thermal spraying methods for each of the thermal spray materials, confirmed through the knowledge and experiments of the present inventors, and shows sendust, permalloy, ferrite, and silicon steel, as well as thermal spraying methods that can be used for these. Note that the present invention is not limited to those shown in Table 1, as will be shown in Examples 4 and 6 below, and various materials can be selected as long as they are powders of soft magnetic materials that are suitable for low-frequency magnetic shielding.

[0018] [Table 1]

[0019] The plating in Table 1 is shown as examples of powder material with a particle size of -100 / +350 mesh, with one that has been Ni-P plated (electroless nickel plating = anti-deterioration treatment) and one that has not been plated (untreated), separated into upper and lower sections. A "○" indicates that the coating has the shielding effect of the present invention, an "×" indicates that it is not possible to form a coating, and a "△ (○)" indicates that the shielding effect of the present invention is not, or is difficult to recognize, in the coating, but that a coating that can be used for the purpose can be obtained by performing a reduction / densification treatment (surface modification treatment) using HIP (hot isostatic pressing) treatment after spraying, or by appropriately selecting the materials that make up the spray material, or by performing other treatments during the spraying process itself or before or after it.

[0020] In addition to the electroless nickel plating mentioned above, it is also possible to use Cu, Ag, Ni-P, Ni-Co-P, Ni-WP, Co-P, etc. as electroless metal plating, and to adopt deterioration prevention treatments such as mechanical coating, mechanofusion, and vacuum deposition.

[0021] The HIP treatment (hot isostatic pressing) in this example is generally carried out in an Ar gas atmosphere by simultaneously applying high temperatures of several hundred to 2,000°C and isostatic pressures of several tens to 200 MPa, and is expected to have the effect of modifying the surface of the coating to make it more dense and reducing oxides.

[0022] The Ni-P plating before thermal spraying is a treatment to prevent oxidation and thermal deterioration of the soft magnetic material due to thermal spraying.

[0023] An example in which Sendust, one of the soft magnetic materials and the thermal spraying method described above, was used by plasma spraying and cold spraying will be described below.

[0024] [Example 1] In this example, the sendust used was manufactured by Daido Steel Co., Ltd. and had a particle size of -100+350 mesh and the composition shown in Table 2. In relation to the thermal spraying method, Ni-P plated sendust (plating metallization rate: 28.6 wt%) was used to prevent the loss of soft magnetic properties due to oxidation and thermal deterioration.

[0025] [Table 2]

[0026] The plasma spray gun used was a 9MB plasma spray gun (Oerlikon Metco).

[0027] The plasma spraying was carried out under the conditions of an output of 32.5 kW and a gas supply of a mixed gas of Ar and H2.

[0028] FIG. 2 is a schematic diagram of the Ni-P plated sendust particles used in the examples of the present invention. The plated sendust 4 has a central sendust particle 4b coated with a Ni-P plating layer 4a on its outer periphery. The particle size after plating is 50 to 150 mm at the largest. μm The small diameter is about several to several tens of μm.

[0029] Figure 3 is an SEM image showing an example of the above-mentioned plated sendust particles. Figures 4(A) to 4(C) are images showing the distribution of Ni, Fe, and P by dots after EDX (energy dispersive X-ray) analysis of the above-mentioned sendust. The detection data did not reveal the distribution of Al and Si contained in the sendust.

[0030] 5 to 7 show cross-sectional image data of the Ni-P plated Sendust powder when plasma sprayed under the conditions shown in

[0026] above, and FIG. 5 is an enlarged SEM (scanning electron microscope) image.

[0031] According to FIG. 5, a magnetic shielding effect against low-frequency magnetic fields is observed, as shown in FIG. 11 described later.

[0032] Figures 6(A) to (E) are EDX data images showing the distribution of Fe, Si, Al, Ni, and P as dots. (A) to (C) show that sendust components are mainly distributed, while (D) and (E) show that Ni-P plating components are distributed.

[0033] Figures 7(A) to (C) show SEM (top) and EDX (bottom) (X-ray diffraction patterns) of different regions (three locations indicated by spectra 3, 2, and 5) in Figure 5. In Figure 7, in addition to the Fe-Si-Al (sendust) region and Ni-P region, there are also regions where it appears that Fe and Ni are partially alloyed. Figure 7(C) also shows a composition that appears to be an alloy of sendust and Ni-P, and this region is considered to be an alloy similar to permalloy (Fe50, Ni50).

[0034] [Example 2] In this example, untreated Sendust powder (without plating) was used to form a thermal spray coating by CS (cold spray). The coating conditions were: Working gas: N2 gas pressure: 3.0 MPa gas temperature : 400℃ Spraying distance: 15mm. Figures 8 to 10 are images of coatings formed by cold spraying untreated sendust powder (without plating). Figure 8 is an SEM image of the cross section of the formed coating. The white granular parts of the coating represent sendust, and the white part below that represents the substrate (the black part is the mold fixing material).

[0035] Figures 9(A) to (E) show the distribution of O, Mg, Al, Si, and Fe in the coating portion of Figure 8 as a distribution of white dots. Figure 9(A) shows almost no O (oxygen), indicating the absence of oxides, and it can be seen that deterioration due to oxidation is suppressed.

[0036] Figures 10(A) and (B) show different areas represented by spectrum 2 and spectrum 3 in the cross section of the coating shown in Figure 8, as well as EDX (X-ray diffraction pattern diagrams) of the sendust particles (white granular parts) in each area. Although Fe, Al, and Si were detected in all areas, there was no O, indicating the absence of oxides, and it is clear that deterioration due to oxidation was suppressed.

[0037] Figures 11 and 12 compare the magnetic shielding effectiveness of the thermal spray coatings of Examples 1 and 2 with the measurement limit of low-frequency magnetic shielding. The KEC method was used to measure the magnetic shielding effectiveness. Both examples demonstrate roughly the same shielding effectiveness as conventional sheet-like low-frequency magnetic shielding materials, making them fully suitable for practical use. In Figures 11 and 12, the upper line a0 represents the measurement limit, and the lower lines a1 and a2 represent the actual measured values.

[0038] [Example 3] In this example, powder of permalloy (soft magnetic material) manufactured by Sanyo Special Steel Co., Ltd. and having a particle size of 45 to 106 μm was used as the thermal spray material. The composition of the permalloy is as shown in Table 3. In addition, to prevent loss of soft magnetic properties due to oxidation and thermal deterioration associated with thermal spraying, the surface of the permalloy was plated with Ni-P. Furthermore, in a step prior to thermal spraying of this permalloy, a thermal spray material containing 99.99 wt% or more of Zn (hereinafter simply referred to as Zn) was sprayed in advance onto the coating surface in order to improve adhesion, and then the permalloy was sprayed onto this coating surface.

[0039] [Table 3]

[0040] Fig. 13 is an SEM image showing an example of a particle of Ni-P plated permalloy, and Figs. 14(A) to (E) are images showing the distribution of C, O, P, Fe, and Ni as dots obtained by EDX analysis of Ni-P plated permalloy. Fig. 15(A) shows a predetermined analysis position in the SEM image shown in Fig. 13, (B) is an EDX image corresponding to the analysis position shown in (A), and Fig. 16(A) shows a predetermined analysis position different from Fig. 15 in the SEM image shown in Fig. 13, and (B) is an EDX image corresponding to the analysis position shown in (A).

[0041] The Zn was sprayed by arc spraying using an M-9000 spray gun (TAFA) as the arc spray gun, so that the thickness of the coating made of Zn was 50 to 100 μm.

[0042] The Ni-P plated permalloy was sprayed by plasma spraying using a 9MB plasma spray gun (Oerlikon Metco). The plasma spraying was performed under conditions of a current of 500 A, a voltage of 65 V, an output of 32.5 kW, and an atmospheric gas mixture of Ar and H. The spraying was performed so that the thickness of the permalloy coating was 200 μm thicker than the thickness of the Zn coating.

[0043] FIG. 17 is an SEM image of a coating formed by plasma spraying Ni-P plated permalloy powder, and FIGS. 18(A) to 18(F) are EDX images showing the distribution of C, O, P, Fe, Ni, and Zn in the coating shown in FIG. 17.

[0044] 19(A) shows a predetermined analysis position in an SEM image identical to the film cross-section shown in FIG. 17, and (B) is an EDX image corresponding to the analysis position shown in (A). FIG. 20(A) shows a predetermined analysis position different from that shown in FIG. 19 in an SEM image identical to the film cross-section shown in FIG. 17, and (B) is an EDX image corresponding to the analysis position shown in (A). FIG. 21(A) shows a predetermined analysis position different from that shown in FIGS. 19 and 20 in an SEM image identical to the film cross-section shown in FIG. 17, and (B) is an EDX image corresponding to the analysis position shown in (A).

[0045] Figure 22 is a graph comparing the measured magnetic shielding effect of low-frequency magnetic fields between plasma-sprayed Ni-P plated permalloy powder and the measurement limit. Incidentally, these measurements were taken using the KEC method. The upper line a0 in the graph represents the measurement limit, and the lower line a3 represents the actual measured value. It was confirmed that the shielding effect is roughly equivalent to that of conventional sheet-type low-frequency magnetic shielding materials.

[0046] [Example 4] In this example, the conditions were the same as in Example 3, except that the permalloy powder without Ni-P plating on the surface was used as the thermal spray material. Figure 23 is an SEM image showing an example of a permalloy particle without Ni-P plating, and Figures 24(A) to (F) are dot images showing the distribution of C, O, Si, S, Fe, and Ni obtained by EDX analysis of permalloy without Ni-P plating.

[0047] FIG. 25 is an SEM image of a coating formed by plasma spraying permalloy powder without Ni-P plating, and FIGS. 26(A) to 26(D) are EDX images showing the distribution of C, O, Fe, and Ni in the coating shown in FIG. 25.

[0048] Figure 27(A) shows a predetermined analysis position in the same SEM image as the film cross-section shown in Figure 25, (B) is an EDX image corresponding to the analysis position shown in (A), and Figure 28(A) shows a predetermined analysis position different from that in Figure 27 in the same SEM image as the film cross-section shown in Figure 25, (B) is an EDX image corresponding to the analysis position shown in (A). These two figures confirmed approximately the same results.

[0049] Figure 29 is a graph comparing the measured magnetic shielding properties of low-frequency magnetic fields between plasma-sprayed permalloy powder without Ni-P plating and the measurement limit. Incidentally, these measurements were taken using the KEC method. The upper line a0 in the figure is the measurement limit, and the lower line a4 is the actual measured value, confirming a shielding effect roughly equivalent to that of conventional sheet-type low-frequency magnetic shielding materials. In other words, it was confirmed that sufficient shielding effect can be ensured by selecting an appropriate spray material and processing it appropriately, even without performing treatment to prevent deterioration or reduction / densification heat treatment.

[0050] [Example 5] In this example, an iron-based amorphous powder (soft magnetic material) manufactured by Epson Atmix Corporation and having a particle size of 150 μm or less was used as the thermal spray material. The composition of the iron-based amorphous powder is shown in Table 4. In addition, to prevent the soft magnetic properties from being impaired by oxidation or thermal alteration during thermal spraying, the surface of the permalloy was plated with Ni-P.

[0051] [Table 4]

[0052] FIG. 30 is an SEM image showing an example of a Ni-P plated iron-based amorphous particle, and FIGS. 31(A) to 31(F) are dot images showing the distribution of C, O, Si, P, Fe, and Ni obtained by EDX analysis of the Ni-P plated iron-based amorphous particle.

[0053] The iron-based amorphous material was sprayed by plasma spraying using a 9MB plasma spray gun (Oerlikon Metco). The plasma spraying was performed under conditions of a current of 500 A, a voltage of 65 V, an output of 32.5 kW, and an atmospheric gas mixture of Ar and H. The spraying was performed so that the thickness of the coating made of the iron-based amorphous material was 200 μm.

[0054] FIG. 32 is an SEM image of a coating formed by plasma spraying a Ni-P plated iron-based amorphous powder, and FIGS. 33(A) to 33(H) are EDX images showing the distribution of C, O, Si, P, Cr, Fe, Ni, and Al in the coating shown in FIG.

[0055] Figure 34(A) shows a predetermined analysis position in an SEM image identical to the film cross-section shown in Figure 32, (B) is an EDX image corresponding to the analysis position shown in (A), Figure 35(A) shows a predetermined analysis position different from that shown in Figure 34 in an SEM image identical to the film cross-section shown in Figure 32, (B) is an EDX image corresponding to the analysis position shown in (A), and Figure 36(A) shows a predetermined analysis position different from that shown in Figures 34 and 35 in an SEM image identical to the film cross-section shown in Figure 32, (B) is an EDX image corresponding to the analysis position shown in (A).

[0056] Figure 37 is a graph comparing the measured magnetic shielding effect of low-frequency magnetic fields between a plasma-sprayed Ni-P-plated iron-based amorphous powder and the measurement limit. Incidentally, these measurements were taken using the KEC method. The upper line a0 in the graph represents the measurement limit, and the lower line a5 represents the actual measured value, confirming that the shielding effect is roughly equivalent to that of conventional sheet-type low-frequency magnetic shielding materials.

[0057] [Example 6] In this example, the conditions were the same as in Example 5, except that the iron-based amorphous powder without Ni-P plating on the surface was used as the thermal spray material.

[0058] FIG. 38 is an SEM image showing an example of an iron-based amorphous particle that has not been Ni-P plated, and FIGS. 39(A) to 39(E) are images showing the distribution of C, Al, Si, Cr, and Fe as dots obtained by EDX analysis of an iron-based amorphous particle that has not been Ni-P plated.

[0059] Figure 40 is a graph comparing the measured magnetic shielding properties of low-frequency magnetic fields between plasma-sprayed iron-based amorphous powder without Ni-P plating and the measurement limit value. Incidentally, these measurements were taken using the KEC method. The upper line a0 in the figure is the measurement limit value, and the lower line a6 is the actual measured value, confirming that the shielding effect is roughly equivalent to that of conventional sheet-type low-frequency magnetic shielding materials. In other words, this also confirms that sufficient shielding effect can be obtained by selecting an appropriate spray material and processing it appropriately, even without performing treatment to prevent deterioration or reduction / densification heat treatment. [Explanation of symbols]

[0060] 1. Shielding material 2 Base material 3 Shield coating 4 Ni-P plated Sendust grains 4a Sendust grains 4b plating layer

Claims

1. A method for manufacturing a low-frequency magnetic shielding material, comprising the steps of: forming a shielding coating for shielding against magnetism on at least a part of a surface of a substrate by thermal spraying; A shielding coating is formed using powder of a soft magnetic material that shields by absorbing low-frequency magnetic fields as a thermal spray material. When the shielding coating is formed on the substrate, the magnetic shielding effect of the low-frequency magnetic shielding material increases with increasing frequency in a frequency range of 0.0005 to 0.1 MHz, as measured by the KEC method, the thickness of the shield coating is 250 to 300 μm, and the soft magnetic material is any one of sendust, permalloy, silicon steel, and ferrite, or a combination of two or more of these materials; The soft magnetic material is a powdered material that has been subjected to a treatment to prevent oxidation or thermal deterioration due to thermal spraying, The deterioration prevention treatment is a process in which a plating layer is formed on powder material with a particle size of -100 / +350 mesh, and the particle size is increased to 50 to 150 μm. A method for manufacturing a low-frequency magnetic shielding material.

2. After plasma spraying, gas flame spraying, high velocity flame spraying, cold spray spraying, suspension spraying, or warm spray spraying, the shield coating surface is subjected to reduction and densification heat treatment. A method for producing the low-frequency magnetic shield material according to claim 1.

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