Neodymium-iron-boron magnet

Abstract

The utility model provides a neodymium-iron-boron magnet. The neodymium-iron-boron magnet comprises a neodymium-iron-boron base body, a metal layer and an organic film layer which are sequentially arranged. Wherein the metal layer comprises a matrix layer and a rough layer close to one side of the organic film layer; the roughness Ra of the surface of one side, close to the organic film layer, of the rough layer is 0.25-0.38 [mu] m. According to the utility model, the binding force between the organic film layer and the metal layer can be improved without penetrating through the electroplated metal layer, and the corrosion resistance of the neodymium-iron-boron magnet is improved.

Description

Technical Field

[0001] This utility model relates to the field of neodymium iron boron magnet technology, and in particular to a neodymium iron boron magnet. Background Technology

[0002] Magnetic materials have wide applications in strategic fields such as aviation, aerospace, military, and electronic components. Permanent magnet materials refer to magnets that retain their strong magnetism even after the external magnetic field is removed. Permanent magnet materials mainly include five categories: permanent magnet ferrites, iron-chromium-cobalt based permanent magnet materials, AlNiCo based permanent magnet materials, rare earth permanent magnet materials, and composite permanent magnet materials.

[0003] As a third-generation rare-earth permanent magnet material, NdFeB is widely used in various fields due to its abundant raw material resources, mature and simple processing technology, and low cost. Its extremely high magnetic energy product, coercivity, and energy density, along with good thermal and time stability and strong resistance to external magnetic field interference, make NdFeB magnets a major player in the production of modern industrial electronic components, enabling the miniaturization, thinning, and weight reduction of various motors, magnetic separation instruments, and meters.

[0004] However, under external conditions, neodymium iron boron permanent magnet materials are prone to oxidation and hydrogen absorption reactions, leading to corrosion. Generally, alloying or surface treatment methods are used for corrosion prevention. Existing solutions involve forming an epoxy film layer on the surface of the neodymium iron boron substrate to improve the substrate's corrosion resistance and insulation properties. However, the epoxy film layer has poor wear resistance, and damage to the epoxy film layer will reduce the substrate's corrosion resistance. Therefore, a metal underlay film layer can be formed on the surface of the substrate to further ensure the substrate's corrosion resistance.

[0005] However, the metal base film is usually formed by electroplating, and its surface is smooth. If an epoxy film is formed on the surface of the electroplated metal layer by spraying, the adhesion between the epoxy film and the metal base film is poor, and the epoxy film is prone to peeling off.

[0006] Therefore, it is necessary to improve the layer structure of NdFeB magnets to enhance their corrosion resistance. Utility Model Content

[0007] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a neodymium iron boron magnet. By forming a rough layer on the surface of the metal layer, it can not only ensure that the surface of the neodymium iron boron substrate has a complete substrate layer, but also the roughness Ra of the rough layer is moderate, which can enhance the bonding force between the organic film layer and the metal layer and improve the corrosion resistance.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] This utility model provides a neodymium iron boron magnet, characterized in that the neodymium iron boron magnet comprises a neodymium iron boron substrate, a metal layer, and an organic film layer arranged sequentially; wherein, the metal layer comprises a substrate layer and a roughened layer on the side adjacent to the organic film layer; the neodymium iron boron substrate and the roughened layer are completely isolated by the substrate layer; the surface roughness Ra of the roughened layer on the side adjacent to the organic film layer is 0.25 to 0.38 μm, for example, it can be 0.25 μm, 0.27 μm, 0.28 μm, 0.3 μm, 0.31 μm, 0.33 μm, 0.34 μm, 0.36 μm, 0.37 μm, or 0.38 μm, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0010] The neodymium iron boron magnet provided by this utility model has a base layer and a rough layer near the organic film layer in the metal layer. The rough layer can significantly increase the bonding force with the organic film layer, and the base layer can ensure the corrosion resistance of the neodymium iron boron matrix. This can expand the application prospects of neodymium iron boron magnets in many fields such as automotive industry, electronic products, wind power, elevators, industrial robots, and aerospace.

[0011] In this invention, both the rough layer and the substrate layer are metal layers, wherein the rough layer is obtained by sandblasting an electroplated metal layer.

[0012] Preferably, the thickness of the metal layer is 3 to 10 μm, for example, it can be 3 μm, 3.8 μm, 4.6 μm, 5.4 μm, 6.2 μm, 6.9 μm, 7.7 μm, 8.5 μm, 9.3 μm or 10 μm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] Preferably, the thickness of the neodymium iron boron substrate is 1 to 10 mm, for example, it can be 1 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 6 mm, 7 mm, 8 mm, 8.5 mm, 9 mm or 10 mm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0014] Preferably, the thickness of the organic film layer is 10 to 20 μm, for example, it can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] Preferably, the thickness of the roughened layer is 1 to 2 μm, for example, it can be 1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm or 2 μm, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0016] It is worth noting that in order to ensure the performance of NdFeB magnets, the thickness of the metal layer is only 3 to 10 μm. A rough layer with a thickness of 1 to 2 μm is formed in this relatively thin metal layer to balance the corrosion resistance of the NdFeB magnets and the bonding strength with the epoxy resin layer.

[0017] Preferably, the roughness Ra of the surface of the rough layer near the organic film layer is 0.28 to 0.38 μm.

[0018] The present invention further optimizes the roughness Ra of the roughened layer to be within the above-mentioned range, thus achieving a better anti-corrosion effect.

[0019] Preferably, the roughening layer completely covers the substrate layer.

[0020] Preferably, the metal layer comprises a copper layer.

[0021] Preferably, the organic film layer comprises an epoxy resin layer.

[0022] This invention does not impose any special restrictions on the specific composition of the NdFeB matrix. Any NdFeB matrix composition well known to those skilled in the art can be used. For example, the NdFeB matrix may include 28-32.5 wt% R, 1.0-2.5 wt% M, 0.8-1.2 wt% B, and the balance Fe. R includes at least praseodymium (Pr) and neodymium (Nd), and at least one of dysprosium (Dy), terbium (Tb), holmium (Ho) or gadolinium (Gd); M includes at least one of Co, Al, Cu, Ga, Zr, Nb, Ti, Mo, Sn, Hf or W.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] The neodymium iron boron magnet provided by this invention forms a rough layer on the surface of the metal layer, thereby improving the bonding force between the metal layer and the organic film layer. The pass rate of the interlayer bonding force test is above 98.5%, and it does not destroy the full coverage of the metal layer on the surface of the neodymium iron boron substrate. This significantly improves the corrosion resistance of the neodymium iron boron magnet, and the corrosion resistance of the neodymium iron boron magnet is above 192 hours. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the neodymium iron boron magnet provided in Embodiment 1 of this utility model.

[0026] In the figure, 1 is the NdFeB substrate; 2 is the metal layer; 21 is the rough layer; 22 is the substrate layer; and 3 is the organic film layer. Detailed Implementation

[0027] To facilitate understanding of this utility model, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as specific limitations on this utility model.

[0028] In this invention, the substrate layer is defined as follows: the thick layer in the metal layer with a flat cross-section and no voids that is parallel to the surface plane of the NdFeB magnet in contact with the substrate layer is called the substrate layer.

[0029] This invention does not impose any particular limitation on the specific preparation method of the neodymium iron boron magnet; any preparation method well known to those skilled in the art can be used. For example, the preparation method includes:

[0030] Copper is electroplated onto the surface of a neodymium iron boron substrate to form an initial copper plating layer, thus obtaining the first substrate;

[0031] The surface of the initial electroplated copper layer is sandblasted to form a roughened layer, thus obtaining the second substrate;

[0032] An epoxy resin layer is formed on the surface of the roughened layer to obtain the neodymium iron boron magnet.

[0033] Optionally, the blasting medium for the sandblasting process includes corundum powder and / or ceramic powder.

[0034] Optionally, the particle size of the sandblasting treatment is 80 to 200 mesh, for example, it can be 80 mesh, 94 mesh, 107 mesh, 120 mesh, 134 mesh, 147 mesh, 160 mesh, 174 mesh, 187 mesh or 200 mesh, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] Optionally, the pressure for sandblasting is 0.05 to 0.15 MPa, for example, 0.05 MPa, 0.07 MPa, 0.08 MPa, 0.09 MPa, 0.1 MPa, 0.11 MPa, 0.12 MPa, 0.13 MPa, 0.14 MPa or 0.15 MPa, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] Optionally, the partial pressure of the spray gun is 0.05 to 0.15 MPa, for example, 0.05 MPa, 0.07 MPa, 0.08 MPa, 0.09 MPa, 0.1 MPa, 0.11 MPa, 0.12 MPa, 0.13 MPa, 0.14 MPa or 0.15 MPa, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0037] Optionally, the sandblasting angle is 10 to 60 degrees, such as 10, 16, 22, 27, 33, 38, 44, 49, 55 or 60 degrees, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Optionally, the sandblasting time is 10 to 30 minutes, for example, 10 minutes, 13 minutes, 15 minutes, 17 minutes, 19 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes or 30 minutes, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] Optionally, the electroplating solution for copper plating includes copper sulfate: 15-30 g / L, tartrate: 15-30 g / L and citric acid: 10-12 g / L.

[0040] Copper sulfate: 15-30 g / L, for example, it can be 15 g / L, 17 g / L, 19 g / L, 20 g / L, 22 g / L, 24 g / L, 25 g / L, 27 g / L, 29 g / L or 30 g / L, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] Tartrate: 15–30 g / L, for example, 15 g / L, 17 g / L, 19 g / L, 20 g / L, 22 g / L, 24 g / L, 25 g / L, 27 g / L, 29 g / L or 30 g / L, but not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] Citric acid: 10-12 g / L, for example, it can be 10 g / L, 10.3 g / L, 10.5 g / L, 10.7 g / L, 10.9 g / L, 11.2 g / L, 11.4 g / L, 11.6 g / L, 11.8 g / L or 12 g / L, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] Optionally, the tartrate includes potassium tartrate and / or sodium tartrate.

[0044] Optionally, the temperature of the electroplating solution in the electroplating copper is 35 to 60°C, for example, 35°C, 38°C, 41°C, 44°C, 47°C, 49°C, 52°C, 55°C, 58°C or 60°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Optionally, the pH value of the electroplating solution in the copper electroplating is 9 to 10.5, for example, it can be 9, 9.2, 9.4, 9.5, 9.7, 9.9, 10, 10.2, 10.4 or 10.5, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0046] Optionally, the current density in the electroplated copper is 0.5–1.5 A / m. 2 For example, it could be 0.5A / m 2 0.7A / m 2 0.8A / m 2 0.9A / m 2 1A / m 2 1.1A / m 2 1.2A / m 2 1.3A / m 2 1.4A / m 2 Or 1.5A / m 2 This includes, but is not limited to, the listed values; other unlisted values ​​within this range also apply.

[0047] Optionally, the electroplating time in the electroplated copper is 30 to 90 minutes, for example, 30 minutes, 37 minutes, 44 minutes, 50 minutes, 57 minutes, 64 minutes, 70 minutes, 77 minutes, 84 minutes or 90 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] Optionally, the method for forming the epoxy resin layer includes: spraying epoxy resin onto the surface of the copper surface treatment layer and curing it.

[0049] Optionally, the epoxy resin solution for spraying the epoxy resin comprises 55-85 wt% epoxy resin and the balance water, wherein the epoxy resin content is 55-85 wt%, for example, it can be 55 wt%, 59 wt%, 62 wt%, 65 wt%, 69 wt%, 72 wt%, 75 wt%, 79 wt%, 82 wt%, or 85 wt%, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0050] Optionally, the spray gun angle for spraying epoxy resin is 30 to 60 degrees, for example, it can be 30 degrees, 34 degrees, 37 degrees, 40 degrees, 44 degrees, 47 degrees, 50 degrees, 54 degrees, 57 degrees or 60 degrees, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0051] Optionally, the spray gun pressure for spraying epoxy resin is 0.15 to 0.5 MPa, for example, 0.15 MPa, 0.19 MPa, 0.23 MPa, 0.27 MPa, 0.31 MPa, 0.35 MPa, 0.39 MPa, 0.43 MPa, 0.47 MPa or 0.5 MPa, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0052] Optionally, the curing temperature is 150 to 200°C, for example, 150°C, 156°C, 162°C, 167°C, 173°C, 178°C, 184°C, 189°C, 195°C or 200°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0053] Optionally, the curing time is 20 to 50 minutes, for example, 20 minutes, 24 minutes, 27 minutes, 30 minutes, 34 minutes, 37 minutes, 40 minutes, 44 minutes, 47 minutes or 50 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0054] As a specific embodiment of this utility model, this utility model provides a method for preparing a neodymium iron boron magnet, the method comprising the following steps:

[0055] Copper is electroplated onto the surface of a NdFeB substrate to form an initial copper plating layer, resulting in a first substrate. The electroplating solution comprises copper sulfate (15–30 g / L), tartrate (15–30 g / L), and citric acid (10–12 g / L). The temperature of the electroplating solution is 35–60 °C, the pH is 9–10.5, and the current density is 0.5–1.5 A / m³. 2 The electroplating time is 30 to 90 minutes.

[0056] The surface of the initial electroplated copper layer is subjected to sandblasting treatment. The sandblasting medium includes corundum powder and / or ceramic powder. The particle size of the sandblasting treatment is 80-200 mesh, the sandblasting pressure is 0.05-0.15 MPa, the partial pressure of the spray gun is 0.05-0.15 MPa, the sandblasting angle is 10-60 degrees, and the sandblasting time is 10-30 minutes.

[0057] Epoxy resin is sprayed onto the surface of the copper surface treatment layer, wherein the epoxy resin solution for spraying the epoxy resin comprises 55-85 wt% epoxy resin and the balance water, the spray gun angle for spraying the epoxy resin is 30-60 degrees, and the spray gun pressure is 0.15-0.5 mPa; then it is cured at 150-200℃ for 20-50 min to form an epoxy resin layer, thereby obtaining the neodymium iron boron magnet.

[0058] The present invention will now be described in detail with reference to its specific product structure.

[0059] Example 1

[0060] This embodiment provides a neodymium iron boron magnet, such as... Figure 1 As shown, the NdFeB magnet comprises, in sequence, a NdFeB substrate 1 (specifically composed of 28.5 wt% PrNd, 2 wt% Dy, 0.6 wt% Co, 0.15 wt% Cu, 0.25 wt% Ga, 0.4 wt% Al, 0.98 wt% B, and the balance Fe), a metal layer 2, and an epoxy film layer 3 (the epoxy resin grade is E44); wherein, the metal layer 2 comprises a substrate layer 22 and a roughened layer 21 on the side adjacent to the epoxy film layer. The NdFeB substrate 1 and the roughened layer 21 are completely isolated by the substrate layer 22. The metal layer 2 is made of copper, i.e., a copper layer. The roughened layer 21 completely covers the substrate layer 22.

[0061] The surface roughness Ra of the roughened layer 21 near the epoxy film layer 3 is 0.32 μm. The thickness of the metal layer 2 is 4 μm. The thickness of the neodymium iron boron substrate 1 is 1.5 mm. The thickness of the epoxy film layer 3 is 15 μm. The thickness of the roughened layer 21 is 1.5 μm.

[0062] Example 2

[0063] This embodiment provides a neodymium iron boron (NdFeB) magnet, comprising a NdFeB substrate (same as in Embodiment 1), a metal layer, and an epoxy film layer (epoxy resin grade E44) sequentially disposed therefrom; wherein, the metal layer comprises a substrate layer and a roughening layer on the side adjacent to the epoxy film layer. The NdFeB substrate and the roughening layer are completely isolated by the substrate layer. The metal layer is made of copper, i.e., a copper layer. The roughening layer completely covers the substrate layer.

[0064] The surface roughness Ra of the roughened layer near the epoxy film is 0.38 μm. The thickness of the metal layer is 10 μm. The thickness of the NdFeB substrate is 5 mm. The thickness of the epoxy film is 20 μm. The thickness of the roughened layer is 2.0 μm.

[0065] Example 3

[0066] This embodiment provides a neodymium iron boron (NdFeB) magnet, comprising a NdFeB substrate (same as in Embodiment 1), a metal layer, and an epoxy film layer (epoxy resin grade E44) sequentially disposed therefrom; wherein, the metal layer comprises a substrate layer and a roughening layer on the side adjacent to the epoxy film layer. The NdFeB substrate and the roughening layer are completely isolated by the substrate layer. The metal layer is made of copper, i.e., a copper layer. The roughening layer completely covers the substrate layer.

[0067] The surface roughness Ra of the roughened layer near the epoxy film is 0.25 μm. The thickness of the metal layer is 3 μm. The thickness of the NdFeB substrate is 10 mm. The thickness of the epoxy film is 10 μm. The thickness of the roughened layer is 1.0 μm.

[0068] Comparative Example 1

[0069] This comparative example provides a neodymium iron boron magnet, which is the same as that in Example 1 except that the roughness Ra of the surface of the roughened layer near the epoxy film layer is 0.20 μm, and will not be described again here.

[0070] Comparative Example 2

[0071] This comparative example provides a neodymium iron boron magnet, which is the same as that in Example 1 except that the roughness Ra of the surface of the roughened layer near the epoxy film layer is 0.45 μm, and will not be described again here.

[0072] Comparative Example 3

[0073] This comparative example provides a neodymium iron boron magnet. Except for the fact that the metal layer is not sandblasted, i.e. only the substrate layer is present, i.e. the roughness Ra of the surface of the metal layer near the epoxy film layer is 0.15 μm, the rest of the neodymium iron boron magnet is the same as that in Example 1, and will not be repeated here.

[0074] Test method:

[0075] 1) PCT test (high pressure accelerated aging test): 120±2℃, 100%RH, 0.2MPa, 24 hours as one cycle, observe once in each cycle and record the corrosion of the product surface.

[0076] 2) The bonding strength between the film layers is tested by the 100-grid test; the test standards are: ASTM D3002 D3359 DIN EN ISO 2409 test, and the judgment standard is: 4B, that is, if there are small pieces peeling off at the intersection of the cuts, and the actual damage in the grid area does not exceed 5%, it is considered qualified. Take 50 magnets and test them by the 100-grid test to calculate the pass rate.

[0077] 3) Film thickness test: The film thickness was tested using the grinding mirror method. The coating was observed under a microscope, and six points on the coating were randomly selected for testing. The average thickness of the six points was taken as the thickness of the coating on that surface. The same method was used to test the thickness of the coating on other surfaces. The final thickness value was the average of the thicknesses on the six surfaces.

[0078] 4) Roughness Ra test of copper surface treatment layer and initial electroplated copper layer: Use a roughness measuring instrument to measure the roughness of multiple groups (e.g., ten groups) in different sampling areas of the first plating layer to be tested, and then calculate the average value.

[0079] The test results of the above embodiments and comparative examples are shown in Table 1.

[0080] Table 1

[0081] Interlayer adhesion test pass rate / % Corrosion resistance of neodymium iron boron magnets / h Example 1 99 192 Example 2 98.6 192 Example 3 98.5 192 Comparative Example 1 All were unqualified. 24 Comparative Example 2 All were unqualified. 24 Comparative Example 3 All were unqualified. 24

[0082] The following points can be observed from Table 1:

[0083] (1) As can be seen from the comprehensive examples 1 to 3, the neodymium iron boron magnet provided by this utility model can improve the bonding force between the organic film layer and the metal layer without penetrating the electroplated metal layer, and improve the corrosion resistance of the neodymium iron boron magnet. The pass rate of the interlayer bonding force test is above 98.5%, and the corrosion resistance of the neodymium iron boron magnet is above 192h.

[0084] (2) Based on the comprehensive results of Example 1 and Comparative Examples 1 to 3, it can be seen that the roughness Ra of the contact with the organic layer in Comparative Examples 1 and 3 is relatively low, resulting in the failure rate of the interlayer bonding force test. Moreover, the corrosion resistance of the NdFeB magnet is only 24h, which is significantly lower than that of Example 1. In Comparative Example 2, the roughness Ra of the surface of the rough layer near the epoxy film layer is as high as 0.45μm. Although the roughness Ra is larger, the gripping force on the organic layer is weakened, resulting in the failure rate of the interlayer bonding force test. Furthermore, during the sandblasting process, some areas penetrate the metal layer, resulting in even worse corrosion resistance of the NdFeB. This shows that by forming a rough layer on the surface of the metal layer and controlling the roughness within a reasonable range, this invention can not only prevent the metal layer from being penetrated, but also improve the bonding force with the organic layer.

[0085] This utility model has been described in detail through the above embodiments. However, this utility model is not limited to the above detailed features, that is, it does not mean that this utility model must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvements to this utility model, equivalent substitutions for the selected technical features, additions of auxiliary technical features, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this utility model.

Claims

1. A neodymium iron boron magnet, characterized in that, The neodymium iron boron magnet comprises a neodymium iron boron substrate, a metal layer, and an organic film layer arranged sequentially. The metal layer includes a substrate layer and a roughened layer on the side closest to the organic film layer; The neodymium iron boron matrix and the roughened layer are completely isolated by the matrix layer; The roughness Ra of the surface of the rough layer near the organic film layer is 0.25 to 0.38 μm.

2. The neodymium iron boron magnet according to claim 1, characterized in that, The thickness of the metal layer is 3 to 10 μm.

3. The neodymium iron boron magnet according to claim 1 or 2, characterized in that, The thickness of the neodymium iron boron substrate is 1 to 10 mm.

4. The neodymium iron boron magnet according to claim 1, characterized in that, The thickness of the organic film layer is 10–20 μm.

5. The neodymium iron boron magnet according to claim 1, characterized in that, The thickness of the roughened layer is 1–2 μm.

6. The neodymium iron boron magnet according to claim 1, characterized in that, The surface roughness Ra of the roughened layer near the organic film layer is 0.28–0.38 μm.

7. The neodymium iron boron magnet according to claim 1, characterized in that, The roughened layer completely covers the substrate layer.

8. The neodymium iron boron magnet according to claim 1, characterized in that, The metal layer includes a copper layer.

9. The neodymium iron boron magnet according to claim 1, characterized in that, The organic film layer includes an epoxy resin layer.

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