Neodymium-iron-boron magnet and preparation method and application thereof

Abstract

The invention provides a neodymium-iron-boron magnet and a preparation method and application thereof. A neodymium-iron-boron magnet assembly comprises a neodymium-iron-boron substrate, a copper layer and an organic layer which are sequentially arranged. The copper layer comprises a copper substrate layer and a copper surface treatment layer from the neodymium iron boron substrate to the outside; the roughness Ra of the copper surface treatment layer is 0.25-0.40 [mu] m, the material of the copper surface treatment layer comprises copper oxide, and the copper surface treatment layer and the neodymium iron boron matrix are completely isolated by the copper matrix layer. The neodymium-iron-boron magnet provided by the invention can improve the binding force between the organic layer and the copper layer, can be suitable for environments such as collision, and further ensures the corrosion resistance of the neodymium-iron-boron substrate.

Description

Technical Field

[0001] The present invention relates to the technical field of neodymium iron boron, and in particular to a neodymium iron boron magnet, a preparation method thereof, and an application thereof. Background Art

[0002] Sintered neodymium iron boron magnets are widely used in many fields such as the automotive industry, electronic products, wind power, elevators, industrial robots, aerospace, etc. due to their excellent magnetic properties. However, neodymium iron boron magnets have poor chemical stability and are prone to oxidation during daily use, especially electrochemical corrosion in a humid and hot environment. Therefore, surface treatment of the magnets is required before application to improve the corrosion resistance of the magnets.

[0003] Conventional surface anti-corrosion treatment methods can be divided into: electroplating, electroless plating, electrophoresis, coating, vacuum plating, etc., to obtain a metal or alloy film layer, a polymer film layer, a chemical conversion film layer, and a composite film layer.

[0004] In an acidic or alkaline environment and when the surface of the magnet is insulated, an epoxy film layer is formed by electrophoresis or coating process. This process has little environmental pollution and high thickness consistency. Among them, the coating process has a simple operation process and high working efficiency. However, in the process of preparing the composite film layer, how to improve the bonding force between the epoxy film layer and other film layers needs to be further solved. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a neodymium iron boron magnet, a preparation method thereof, and an application thereof. By performing oxidation treatment on the surface of the electroplated copper layer, the dense and smooth copper layer surface is transformed into a loose and high-surface-roughness copper oxide, so as to improve the subsequent bonding force with the organic layer and enhance the service effect of the neodymium iron boron magnet in a bumpy environment.

[0006] To achieve this purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect, the present invention provides a neodymium iron boron magnet, which includes a neodymium iron boron substrate, a copper layer, and an organic layer arranged in sequence; from the neodymium iron boron substrate outwards, the copper layer includes a copper matrix layer and a copper surface treatment layer; the roughness Ra of the copper surface treatment layer is 0.25 - 0.40 μm; the material of the copper surface treatment layer includes copper oxide, and the copper surface treatment layer is completely separated from the neodymium iron boron substrate by the copper matrix layer.

[0008] The neodymium iron boron magnet provided by the present invention forms a copper surface treatment layer with copper oxide on the surface of the copper matrix layer of the copper layer. Not only is the surface roughness Ra between 0.25 and 0.40 μm, which can increase the contact area between the organic layer and the copper layer surface, thereby improving the bonding force between the organic layer and the copper layer; moreover, compared with the smooth and dense copper matrix layer, the copper oxide not only has a high roughness but also is loose, which can form a better physical adsorption effect during the epoxy resin coating process, better form a gripping force with the epoxy resin, and improve the bonding force; furthermore, in the copper oxide, copper is in the +1 or +2 valence state, and oxygen is in the -2 valence state, which can interact with the epoxy group or hydroxyl group in the epoxy resin, thereby improving the bonding effect with the epoxy resin.

[0009] Specifically, the surface roughness Ra of the copper surface treatment layer is 0.25 - 0.40 μm. For example, it can be 0.25 μm, 0.27 μm, 0.28 μm, 0.29 μm, 0.3 μm, 0.31 μm, 0.32 μm, 0.33 μm, 0.34 μm, 0.35 μm, 0.36 μm, 0.37 μm, 0.38 μm, 0.39 μm or 0.40 μm, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable, and preferably it is 0.28 - 0.38 μm.

[0010] Through extensive research by researchers, it has been found that when the surface roughness Ra of the copper surface treatment layer is within the range of 0.28 - 0.38 μm, it has a better bonding rate with the organic layer and better corrosion resistance.

[0011] Preferably, the copper surface treatment layer is uniformly distributed on the copper matrix layer and covers the entire area of the copper matrix layer.

[0012] Preferably, the thickness of the copper layer is 3 - 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, etc., but is not limited to the listed values. Other unlisted values within this range are equally applicable.

[0013] In the present invention, the thickness of the copper layer is only 3 - 10 μm, which is relatively thin. And the present invention needs to ensure that the neodymium iron boron matrix is not oxidized. Therefore, when performing the copper surface treatment, it is necessary to ensure that a complete copper matrix layer (i.e., the entire surface of the neodymium iron boron matrix is covered with copper) is still covered on the surface of the neodymium iron boron matrix to ensure the oxidation resistance and corrosion resistance of the neodymium iron boron magnet.

[0014] Preferably, the thickness of the copper matrix layer is 2-9 μm, for example, it can be 2 μm, 2.2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm or 9 μm, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0015] In the present invention, preferably, the thickness of the copper matrix layer is controlled within 2-9 μm, which can not only ensure excellent bonding effect with the organic layer, but also ensure excellent oxidation resistance and corrosion resistance of the NdFeB magnet.

[0016] Preferably, the thickness of the NdFeB matrix is 1-10 mm, for example, it can be 1 mm, 1.4 mm, 1.5 mm, 1.6 mm, 2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, 4.0 mm, 4.5 mm, 5.0 mm, 5.5 mm, 6.0 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm or 10 mm, etc.

[0017] Preferably, the thickness of the organic layer is 8-30 μm, for example, it can be 8 μm, 10.5 μm, 12.9 μm, 15.4 μm, 17.8 μm, 20.3 μm, 22.7 μm, 25.2 μm, 27.6 μm or 30 μm, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0018] Preferably, the organic layer is an epoxy resin layer.

[0019] Preferably, the material of the NdFeB matrix includes 28-32.5 wt% of R, 1.0-2.5 wt% of M, 0.8-1.2 wt% of boron (B), and the balance of iron (Fe), where R includes at least praseodymium (Pr) and neodymium (Nd), and also includes 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.

[0020] Specifically, the content of R can be, for example, 28 wt%, 28.2 wt%, 28.5 wt%, 28.8 wt%, 29 wt%, 29.2 wt%, 29.5 wt%, 29.8 wt%, 30 wt%, 30.2 wt%, 30.5 wt%, 30.8 wt%, 31 wt%, 31.2 wt%, 31.5 wt%, 32 wt%, 32.2 wt% or 32.5 wt%, etc. The content of M can be, for example, 1.0 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.8 wt%, 2.0 wt%, 2.2 wt%, 2.3 wt% or 2.5 wt%, etc.

[0021] In a second aspect, the present invention provides a surface treatment method for a neodymium iron boron substrate, and the neodymium iron boron magnet described in the first aspect is obtained by the surface treatment method.

[0022] Among them, the surface treatment method includes: electroplating copper on the surface of the neodymium iron boron substrate to form an initial electroplated copper layer, obtaining a first substrate; converting the surface of the initial electroplated copper layer into copper oxide to form a copper surface treatment layer, obtaining a second substrate; and forming an organic layer on the surface of the copper surface treatment layer to obtain the neodymium iron boron magnet.

[0023] The surface treatment method provided in the second aspect of the present invention forms copper oxide on the surface of the initial electroplated copper layer, improves the surface roughness, and increases the bonding force with the organic layer. Subsequently, the organic layer can be applied by coating. This not only has a simple process flow but also results in excellent performance of the neodymium iron boron magnet.

[0024] Preferably, the thickness of the initial electroplated copper 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, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0025] Preferably, the surface roughness of the initial electroplated copper layer is less than 0.2 μm.

[0026] Preferably, the method for forming the copper surface treatment layer includes electrochemical anodic oxidation treatment.

[0027] Preferably, the electrochemical treatment solution for the electrochemical anodic oxidation treatment includes alkali: 80 to 200 g / L, molybdate: 0.1 to 10 g / L, and EDTA: 0.1 to 20 g / L.

[0028] By adopting the electrochemical anodic oxidation treatment, the present invention forms copper oxide on the surface of the original electroplated copper layer. The copper oxide is relatively porous, improving the adhesion points of the sprayed organic layer, and thus increasing the bonding force between the sprayed epoxy film layer and the copper layer. Among them, the electrochemical anodic oxidation treatment has the advantage of being able to form uniform, dense, and thickness - controllable copper oxide, avoiding problems such as uneven oxidation or over - oxidation.

[0029] It should be further noted here that the uniformity of oxidation is crucial for the performance of the final NdFeB magnet. Under certain process conditions, local over-oxidation and local non-oxidation occur. Although the final surface roughness Ra is in the range of 0.25 - 0.40 μm, due to the non-uniform oxidation, only locally on the surface of the copper layer is firmly combined with the organic layer, while the bonding force of some parts with the organic layer is insufficient. During service, these areas with insufficient bonding force are extremely prone to peeling off, ultimately resulting in insufficient corrosion resistance of the NdFeB magnet.

[0030] Specifically, the alkali: 80 - 200 g / L, for example, it can be 80 g / L, 94 g / L, 107 g / L, 120 g / L, 134 g / L, 147 g / L, 160 g / L, 174 g / L, 187 g / L or 200 g / L, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0031] Preferably, the alkali includes sodium hydroxide and / or potassium hydroxide.

[0032] Molybdate: 0.1 - 10 g / L, for example, it can be 0.1 g / L, 1.2 g / L, 2.3 g / L, 3.4 g / L, 4.5 g / L, 5.6 g / L, 6.7 g / L, 7.8 g / L, 8.9 g / L or 10 g / L, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0033] Preferably, the molybdate includes sodium molybdate and / or ammonium molybdate.

[0034] EDTA: 0.1 - 20 g / L, for example, it can be 0.1 g / L, 2.4 g / L, 4.6 g / L, 6.8 g / L, 9 g / L, 11.2 g / L, 13.4 g / L, 15.6 g / L, 17.8 g / L or 20 g / L, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0035] As mentioned above, the thickness of the initial electroplated copper layer in the present invention is only 3 - 10 μm. Due to the relatively thin thickness of the initial electroplated copper layer, different from the surface oxidation treatment of conventional copper parts, in the present invention, while oxidizing, it is necessary to ensure that the relatively thin initial electroplated copper layer is not penetrated by oxidation. Moreover, in order to balance the bonding force with the organic layer and the anti-corrosion performance of the NdFeB magnet itself, the present invention needs to strictly control the depth of the oxidation treatment and avoid the situation of local penetration.

[0036] In order to overcome the above process problems, the present invention preferably controls the concentration of each component during the electrochemical anodic oxidation treatment within the above range, which can provide a relatively stable and suitable oxidation effect.

[0037] Preferably, the current density of the electrochemical anodic oxidation treatment is 0.5 - 5 A / m 2 , for example, it can be 0.5 A / m 2 , 1 A / m 2 , 1.5 A / m 2 , 2 A / m 2 , 2.5 A / m 2 , 3 A / m 2 , 3.5 A / m 2 , 4 A / m 2 , 4.5 A / m 2 or 5 A / m 2 etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0038] The present invention further preferably has the current density of the electrochemical anodic oxidation treatment within the above range, which is matched with the alkali concentration, maintains a stable oxidation rate during the electrochemical anodic oxidation treatment, and controls the oxidation depth.

[0039] Preferably, the temperature of the electrochemical anodic oxidation treatment is 60 - 110 °C, for example, it can be 60 °C, 66 °C, 72 °C, 77 °C, 83 °C, 88 °C, 94 °C, 99 °C, 105 °C or 110 °C etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0040] Preferably, the time of the electrochemical anodic oxidation treatment is 30 - 90 s, for example, it can be 30 s, 37 s, 44 s, 50 s, 57 s, 64 s, 70 s, 77 s, 84 s or 90 s etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0041] Preferably, before the electrochemical anodic oxidation treatment, the copper surface treatment layer is first preheated in an electrochemical treatment solution.

[0042] It should be noted that in the step of the electrochemical anodic oxidation treatment, preheating first is very crucial. As mentioned before, during the electrochemical anodic oxidation treatment, it is necessary to ensure the uniformity and stability of oxidation and avoid the situation of local penetration. The present invention first makes the copper surface contact with the alkaline solution in advance to accelerate the formation of the surface oxide film. Under alkaline conditions, an oxide film will gradually form on the copper surface, and the main component is copper oxide. This oxide film can play a certain protective role in the subsequent electrochemical reaction and helps to stabilize the electrode reaction process. Thus, the oxidation depth of the electrochemical anodic oxidation treatment can be more precisely controlled, and it can be ensured that the local part of the entire initial electroplated copper layer will not be oxidized through.

[0043] Preferably, the preheating time is 1 to 10 minutes, for example, it can be 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes or 10 minutes, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0044] Preferably, the preheating temperature is 60 to 80 °C, for example, it can be 60 °C, 63 °C, 65 °C, 67 °C, 69 °C, 72 °C, 74 °C, 76 °C, 78 °C or 80 °C, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0045] Preferably, after the electrochemical anodic oxidation treatment, a phosphating treatment is carried out.

[0046] The present invention can further carry out a phosphating treatment to further improve the corrosion resistance of the neodymium iron boron magnet and the bonding force with the organic layer.

[0047] Preferably, the phosphating solution for the phosphating treatment includes phosphoric acid: 15 - 50 g / L, fluoboric acid: 10 - 25 g / L, sodium molybdate or ammonium molybdate: 0.3 - 5 g / L, aromatic hydrocarbon nitro compound (such as sodium m-nitrobenzenesulfonate) 1 - 10 g / L, and the balance is water.

[0048] Specifically, phosphoric acid: 15 - 50 g / L, for example, it can be 15 g / L, 16 g / L, 17 g / L, 18 g / L, 20 g / L, 22 g / L, 24 g / L, 25 g / L, 28 g / L, 30 g / L, 32 g / L, 35 g / L, 38 g / L, 40 g / L, 42 g / L, 45 g / L or 50 g / L, etc. Fluoboric acid: 10 - 25 g / L, for example, it can be 10 g / L, 12 g / L, 14 g / L, 15 g / L, 18 g / L, 20 g / L, 22 g / L, 24 g / L or 25 g / L, etc. Sodium molybdate or ammonium molybdate: 0.3 - 5 g / L, for example, it can be 0.3 g / L, 0.5 g / L, 1 g / L, 1.2 g / L, 1.5 g / L, 2.0 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L or 5 g / L, etc. Aromatic hydrocarbon nitro compound: 1 - 10 g / L, for example, it can be 1 g / L, 1.5 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L or 10 g / L, etc.

[0049] Preferably, the method for forming the copper surface treatment layer includes chemical roughening treatment; the chemical roughening treatment includes: infiltrating the surface of the initial electroplated copper layer with a chemical roughening treatment solution and performing washing.

[0050] The present invention can also oxidize the surface of the initial electroplated copper layer by means of chemical roughening treatment. First, an attachment of copper oxide and copper phosphate is formed on the surface of the copper layer, and then the copper phosphate attachment is removed to achieve the roughening effect on the surface of the initial electroplated copper layer, improve the surface roughness of the initial electroplated copper layer, and provide more attachment points for the organic layer.

[0051] Preferably, the chemical roughening treatment solution includes a corrosion agent: 5 - 50 mg / L, an oxidizing agent: 0.5 - 15 g / L, sodium m-nitrobenzenesulfonate: 1 - 50 g / L, and an inhibitor: 0.1 - 0.5 g / L.

[0052] The chemical roughening treatment solution of the present invention includes a corrosion agent, an oxidizing agent, sodium m-nitrobenzenesulfonate, and an inhibitor. Since the chemical treatment solution has acidity and oxidizing property, the initial electroplated copper layer is oxidized by the oxidizing agent to generate copper oxide. The copper oxide reacts with the corrosion agent (phosphoric acid) to form copper phosphate deposited on the surface of the copper layer / copper oxide layer. By regulating the components of the treatment solution, especially the inhibitor, the two reactions are balanced to ensure that the oxidation efficiency is greater than the corrosion efficiency (forming copper phosphate). Since the adhesion of copper phosphate on the surface is weak, the copper phosphate attached to the surface can be removed by subsequent water washing, achieving the roughening effect on the surface of the electroplated copper layer, and thus improving the bonding force between the sprayed epoxy film layer and the copper layer.

[0053] Among them, the corrosion agent: 5 - 50 mg / L, for example, can be 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, 40 mg / L, 45 mg / L or 50 mg / L, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0054] The oxidizing agent: 0.5 - 15 g / L, for example, can be 0.5 g / L, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 10 g / L, 11 g / L, 12 g / L, 13 g / L, 14 g / L or 15 g / L, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0055] Sodium m-nitrobenzenesulfonate: 1 - 50 g / L, for example, can be 1 g / L, 7 g / L, 12 g / L, 18 g / L, 23 g / L, 29 g / L, 34 g / L, 40 g / L, 45 g / L or 50 g / L, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0056] Corrosion inhibitor: 0.1 - 0.5 g / L. For example, it can be 0.1 g / L, 0.15 g / L, 0.19 g / L, 0.24 g / L, 0.28 g / L, 0.33 g / L, 0.37 g / L, 0.42 g / L, 0.46 g / L or 0.5 g / L, etc. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0057] Preferably, the corrosion agent includes phosphoric acid.

[0058] Preferably, the oxidizing agent includes nitric acid and / or hydrogen peroxide.

[0059] Preferably, the corrosion inhibitor includes hexamethylenetetramine and / or benzotriazole.

[0060] The present invention preferably adopts the above corrosion inhibitor, which can better control the uniformity and oxidation rate of oxidation. On the basis of ensuring that the initial electroplated copper layer is not penetrated, it can accurately control the thickness of the surface treatment, taking into account the magnetic properties, corrosion and oxidation resistance, and bonding strength with the organic layer of the neodymium iron boron magnet.

[0061] Preferably, the infiltration time is 10 - 90 s. For example, it can be 10 s, 19 s, 28 s, 37 s, 46 s, 55 s, 64 s, 73 s, 82 s or 90 s, etc. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0062] Preferably, the temperature of the chemical coarsening treatment solution is 5 - 35 °C. For example, it can be 5 °C, 6 °C, 7 °C, 8 °C, 9 °C, 10 °C, 12 °C, 14 °C, 15 °C, 18 °C, 20 °C, 22 °C, 24 °C, 25 °C, 28 °C, 30 °C, 32 °C or 35 °C, etc.

[0063] Preferably, the electroplating solution for electroplating copper includes copper sulfate: 15 - 30 g / L, tartrate: 15 - 30 g / L, and citric acid: 10 - 12 g / L.

[0064] Among them, 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. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0065] Tartrate: 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. However, it is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0066] 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, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0067] Preferably, the tartrate includes potassium tartrate and / or sodium tartrate.

[0068] Preferably, the temperature of the electroplating solution in the electroplated copper is 35 - 60 °C. For example, it can be 35 °C, 38 °C, 41 °C, 44 °C, 47 °C, 49 °C, 52 °C, 55 °C, 58 °C or 60 °C, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0069] Preferably, the pH value of the electroplating solution in the electroplated copper is 9 - 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, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0070] Preferably, the current density in the electroplated copper is 0.5 - 1.5 A / m 2 , for example, it can be 0.5 A / m 2 , 0.7 A / m 2 , 0.8 A / m 2 , 0.9 A / m 2 , 1 A / m 2 , 1.1 A / m 2 , 1.2 A / m 2 , 1.3 A / m 2 , 1.4 A / m 2 or 1.5 A / m 2 etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0071] Preferably, the electroplating time in the electroplated copper is 30 - 90 min. For example, it can be 30 min, 37 min, 44 min, 50 min, 57 min, 64 min, 70 min, 77 min, 84 min or 90 min, etc., but not limited to the listed values. Other unlisted values within this range are equally applicable.

[0072] Preferably, the method for forming the organic layer includes: spraying epoxy resin on the surface of the copper surface treatment layer and curing it.

[0073] Preferably, the epoxy resin solution for spraying epoxy resin comprises 55-85 wt% of epoxy resin and the balance of water, wherein the content of epoxy resin 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 not limited to the listed values, and other unlisted values within this range are equally applicable.

[0074] Preferably, the spray gun angle for spraying epoxy resin is 30-60 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 etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0075] Preferably, the spray gun pressure for spraying epoxy resin is 0.15-0.5 mPa, for example, it can be 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 etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0076] Preferably, the curing temperature is 150-200 °C, for example, it can be 150 °C, 156 °C, 162 °C, 167 °C, 173 °C, 178 °C, 184 °C, 189 °C, 195 °C or 200 °C etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0077] Preferably, the curing time is 20-50 min, for example, it can be 20 min, 24 min, 27 min, 30 min, 34 min, 37 min, 40 min, 44 min, 47 min or 50 min etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0078] As a preferred technical solution of the present invention, the surface treatment method comprises the following steps:

[0079] Electroplating copper on the surface of the neodymium iron boron substrate to form an initial electroplated copper layer, obtaining a first substrate; wherein, 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 in the electroplating copper is 35-60 °C, the pH value is 9-10.5, and the current density is 0.5-1.5 A / m 2 , and the electroplating time is 30-90 min.

[0080] First, preheat the copper surface treatment layer in an electrochemical treatment solution at 60 - 80°C for 1 - 10 minutes, and then perform electrochemical anodic oxidation treatment on the surface of the initial electroplated copper layer to convert the surface into copper oxide to form a copper surface treatment layer, obtaining a second substrate; wherein, the electrochemical treatment solution for the electrochemical anodic oxidation treatment includes alkali: 80 - 200 g / L, molybdate: 0.1 - 10 g / L, and EDTA: 0.1 - 20 g / L; the current density of the electrochemical anodic oxidation treatment is 0.5 - 5 A / m 2 , the temperature of the electrochemical anodic oxidation treatment is 60 - 110°C, and the time of the electrochemical anodic oxidation treatment is 30 - 90 s.

[0081] Optionally, after the electrochemical anodic oxidation treatment, perform phosphating treatment; the phosphating solution for the phosphating treatment includes phosphoric acid: 15 - 50 g / L, fluoboric acid: 10 - 25 g / L, sodium molybdate or ammonium molybdate: 0.3 - 5 g / L, aromatic hydrocarbon nitro compound: 1 - 10 g / L, and the remainder is water.

[0082] Spray epoxy resin on the surface of the copper surface treatment layer, wherein the epoxy resin solution for spraying epoxy resin includes 55 - 85 wt% epoxy resin and the balance water, the spray gun angle for spraying epoxy resin is 30 - 60 degrees, and the spray gun pressure is 0.15 - 0.5 mPa; then cure at 150 - 200°C for 20 - 50 minutes to form an organic layer, obtaining the NdFeB magnet.

[0083] As a preferred technical solution of the present invention, the surface treatment method includes the following steps:

[0084] Electroplate copper on the surface of the NdFeB substrate to form an initial electroplated copper layer, obtaining a first substrate; wherein, the electroplating solution includes copper sulfate: 15 - 30 g / L, tartrate: 15 - 30 g / L, and citric acid: 10 - 12 g / L; the temperature of the electroplating solution in the electroplating copper is 35 - 60°C, the pH value is 9 - 10.5, and the current density is 0.5 - 1.5 A / m 2 , and the electroplating time is 30 - 90 minutes.

[0085] Infiltrate the surface of the initial electroplated copper layer with a chemical roughening treatment solution at 5 - 35°C for 10 - 90 s, and after washing, convert the surface into copper oxide to form a copper surface treatment layer, obtaining a second substrate; wherein, the chemical roughening treatment solution includes a corrosion agent: 5 - 50 mg / L, an oxidant: 0.5 - 15 g / L, sodium metanitrobenzenesulfonate: 1 - 50 g / L, and a corrosion inhibitor: 0.1 - 0.5 g / L.

[0086] Spray epoxy resin on the surface of the copper surface treatment layer. The epoxy resin solution for spraying epoxy resin comprises 55-85 wt% of epoxy resin and the balance of water. The spray gun angle for spraying epoxy resin is 30-60 degrees, and the spray gun pressure is 0.15-0.5 mPa. Then, cure at 150-200 °C for 20-50 min to form an organic layer, thereby obtaining the NdFeB magnet.

[0087] In a third aspect, the present invention provides an application of the NdFeB magnet described in the first aspect in the fields of automotive industry, electronic products, wind power, elevators, industrial robots or aerospace.

[0088] Compared with the prior art, the present invention has at least the following beneficial effects:

[0089] (1) The NdFeB magnet provided by the present invention sequentially forms an electroplated copper layer and an organic layer on the surface of the NdFeB substrate, and the bonding force between the organic layer and the copper layer is strong. In a special application environment, due to external forces such as bumps, the tolerance of the organic layer can be improved. Under preferred conditions, the qualified rate of the bonding force test between the film layers is above 98%, and the corrosion resistance of the NdFeB magnet is above 216 h.

[0090] (2) The surface treatment method of the NdFeB substrate provided by the present invention can form a copper oxide layer on the surface of the initial electroplated copper layer, and can form an organic layer on its surface through a coating process, and the bonding force is excellent. The preparation method is simple and the working efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0091] Figure 1 is a schematic structural diagram of the NdFeB magnet prepared in Example 1 of the present invention.

[0092] In the figure, 1, NdFeB substrate; 2, copper layer; 21, copper surface treatment layer; 22, copper substrate layer; 3, organic layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0093] To facilitate the understanding of the present invention, the following examples are listed for the present invention. Those skilled in the art should understand that the examples are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0094] The definition of the copper substrate layer in the present invention: on a cross-section parallel to the surface plane in contact with the NdFeB magnet and the copper substrate layer, all is copper, and the thickness layer without copper oxide is denoted as the copper substrate layer.

[0095] Example 1

[0096] This embodiment provides a neodymium iron boron magnet, which includes a neodymium iron boron substrate 1, a copper layer 2, and an organic layer 3 arranged in sequence; from the neodymium iron boron substrate outwards, the copper layer includes a copper matrix layer 22 and a copper surface treatment layer 21; the material of the copper surface treatment layer 21 includes copper oxide; the copper surface treatment layer is completely separated from the neodymium iron boron substrate by the copper matrix layer, the copper surface treatment layer covers all regions of the copper matrix layer, and is evenly distributed on the copper matrix layer.

[0097] This embodiment also provides a surface treatment method for the above neodymium iron boron substrate, that is, the preparation method of the above neodymium iron boron magnet. The surface treatment method includes:

[0098] Electroplating copper on the surface of a neodymium iron boron substrate (specific composition: PrNd 28.5wt%, Dy 2wt%, Co 0.6wt%, Cu 0.15wt%, Ga 0.25wt%, Al 0.4wt%, B 0.98wt%, Fe balance) to form an initial electroplated copper layer, obtaining a first substrate; wherein, the electroplating solution includes copper sulfate: 20g / L, sodium tartrate: 20g / L, and citric acid: 11g / L; the temperature of the electroplating solution in the electroplating copper is 50°C, the pH value is 10.0, and the current density is 1.0A / m 2 , and the electroplating time is 60min.

[0099] First, preheat the first substrate in an electrochemical treatment solution at 70°C for 7min, and then perform electrochemical anodic oxidation treatment on the surface of the initial electroplated copper layer to convert the surface into copper oxide to form a copper surface treatment layer, obtaining a second substrate; wherein, the electrochemical treatment solution for the electrochemical anodic oxidation treatment includes sodium hydroxide: 150g / L, sodium molybdate: 5g / L, and EDTA: 10g / L; the current density of the electrochemical anodic oxidation treatment is 2.0A / m 2 , the temperature of the electrochemical anodic oxidation treatment is 70°C, and the time of the electrochemical anodic oxidation treatment is 85s.

[0100] Spray epoxy resin on the surface of the copper surface treatment layer. The epoxy resin solution for spraying epoxy resin includes 75wt% epoxy resin (grade E21) and the balance of water. The spray gun angle for spraying epoxy resin is 40 degrees, and the spray gun pressure is 0.25mPa; then cure at 180°C for 40min to form an epoxy resin layer, obtaining the neodymium iron boron magnet.

[0101] Example 2

[0102] This embodiment provides a neodymium iron boron magnet, which includes a neodymium iron boron matrix, a copper layer, and an organic layer arranged in sequence; from the neodymium iron boron matrix outwards, the copper layer includes a copper matrix layer and a copper surface treatment layer; the material of the copper surface treatment layer includes copper oxide. The copper surface treatment layer is completely separated from the neodymium iron boron matrix by the copper matrix layer, the copper surface treatment layer covers all areas of the copper matrix layer, and is evenly distributed on the copper matrix layer.

[0103] This embodiment also provides a surface treatment method for the above-mentioned neodymium iron boron matrix, that is, the preparation method of the above-mentioned neodymium iron boron magnet. The surface treatment method includes:

[0104] Electroplating copper on the surface of the neodymium iron boron matrix (with the specific composition the same as that in Example 1) to form an initial electroplated copper layer, obtaining a first matrix; wherein, the electroplating solution includes copper sulfate: 30 g / L, potassium sodium tartrate: 30 g / L, and citric acid: 12 g / L; the temperature of the electroplating solution in the electroplating copper is 60 °C, the pH value is 10.5, and the current density is 0.5 A / m 2 , and the electroplating time is 90 min.

[0105] First, preheat the first matrix in an electrochemical treatment solution at 80 °C for 1 min, and then perform electrochemical anodic oxidation treatment on the surface of the initial electroplated copper layer to convert the surface into copper oxide to form a copper surface treatment layer, obtaining a second matrix; wherein, the electrochemical treatment solution for the electrochemical anodic oxidation treatment includes potassium hydroxide: 200 g / L, sodium molybdate: 0.1 g / L, and EDTA: 0.1 g / L; the current density of the electrochemical anodic oxidation treatment is 5 A / m 2 , the temperature of the electrochemical anodic oxidation treatment is 110 °C, and the time of the electrochemical anodic oxidation treatment is 30 s.

[0106] Spray epoxy resin on the surface of the copper surface treatment layer. The epoxy resin solution for spraying epoxy resin includes 85 wt% epoxy resin (brand E21) and the balance of water. The spray gun angle for spraying epoxy resin is 30 degrees, and the spray gun pressure is 0.15 mPa; then cure at 200 °C for 20 min to form an epoxy resin layer, obtaining the neodymium iron boron magnet.

[0107] Example 3

[0108] This embodiment provides a neodymium iron boron magnet, which includes a neodymium iron boron matrix, a copper layer, and an organic layer arranged in sequence; from the neodymium iron boron matrix outwards, the copper layer includes a copper matrix layer and a copper surface treatment layer; the material of the copper surface treatment layer includes copper oxide. The copper surface treatment layer is completely separated from the neodymium iron boron matrix by the copper matrix layer, the copper surface treatment layer covers all areas of the copper matrix layer, and is evenly distributed on the copper matrix layer.

[0109] This embodiment also provides a surface treatment method for the above-mentioned neodymium-iron-boron substrate, that is, the preparation method of the above-mentioned neodymium-iron-boron magnet. The surface treatment method includes:

[0110] Electroplating copper on the surface of the neodymium-iron-boron substrate (with the same specific composition as in Example 1) to form an initial electroplated copper layer, obtaining a first substrate; wherein, the electroplating solution includes copper sulfate: 20 g / L, potassium sodium tartrate: 30 g / L, and citric acid: 10 g / L; the temperature of the electroplating solution in the electroplating copper is 40 °C, the pH value is 10.0, and the current density is 1.1 A / m 2 , and the electroplating time is 60 min.

[0111] Soak the surface of the initial electroplated copper layer with a chemical roughening treatment solution at 30 °C for 75 s, and after washing, convert the surface into copper oxide to form a copper surface treatment layer, obtaining a second substrate; wherein, the chemical roughening treatment solution includes phosphoric acid: 45 mg / L, nitric acid: 10 g / L, sodium m-nitrobenzenesulfonate: 30 g / L, and hexamethylenetetramine: 0.4 g / L.

[0112] Spray epoxy resin on the surface of the copper surface treatment layer. The epoxy resin solution for spraying epoxy resin includes 75 wt% epoxy resin (brand E44) and the balance of water. The spray gun angle for spraying epoxy resin is 45 degrees, and the spray gun pressure is 0.3 mPa; then cure at 165 °C for 30 min to form an epoxy resin layer, obtaining the neodymium-iron-boron magnet.

[0113] Example 4

[0114] This embodiment provides a neodymium-iron-boron magnet, which includes a neodymium-iron-boron substrate, a copper layer, and an organic layer arranged in sequence; from the neodymium-iron-boron substrate outwards, the copper layer includes a copper matrix layer and a copper surface treatment layer; the material of the copper surface treatment layer includes copper oxide. The copper surface treatment layer is completely separated from the neodymium-iron-boron substrate by the copper matrix layer. The copper surface treatment layer covers all regions of the copper matrix layer and is evenly distributed on the copper matrix layer.

[0115] This embodiment also provides a surface treatment method for the above-mentioned neodymium-iron-boron substrate, that is, the preparation method of the above-mentioned neodymium-iron-boron magnet. The surface treatment method includes:

[0116] Electroplating copper on the surface of the neodymium-iron-boron substrate (with the same specific composition as in Example 1) to form an initial electroplated copper layer, obtaining a first substrate; wherein, the electroplating solution includes copper sulfate: 15 g / L, sodium tartrate: 30 g / L, and citric acid: 12 g / L; the temperature of the electroplating solution in the electroplating copper is 35 °C, the pH value is 10.5, and the current density is 1.5 A / m 2 , and the electroplating time is 30 min.

[0117] The surface of the initial electroplated copper layer was infiltrated with a chemical roughening treatment solution at 25 °C for 10 s, and after washing, the surface was converted into copper oxide to form a copper surface treatment layer, obtaining a second substrate; wherein, the chemical roughening treatment solution includes phosphoric acid: 50 mg / L, hydrogen peroxide: 8 g / L, sodium metanitrobenzenesulfonate: 15 g / L, and benzotriazole: 0.5 g / L.

[0118] Epoxy resin was sprayed on the surface of the copper surface treatment layer, wherein the epoxy resin solution for spraying epoxy resin includes 55 wt% epoxy resin (grade E44) and the balance water, the spray gun angle for spraying epoxy resin is 60 degrees, and the spray gun pressure is 0.5 mPa; then it was cured at 200 °C for 20 min to form an epoxy resin layer, obtaining the NdFeB magnet.

[0119] Example 5

[0120] This example provides an NdFeB magnet. The preparation method of the NdFeB magnet is the same as that of Example 1 except that the current density of the electrochemical anodic oxidation treatment is 0.1 A / m 2 except as otherwise specified, and details will not be repeated here.

[0121] Example 6

[0122] This example provides an NdFeB magnet. The preparation method of the NdFeB magnet is the same as that of Example 1 except that the concentration of sodium hydroxide is 70 g / L, and details will not be repeated here.

[0123] Example 7

[0124] This example provides an NdFeB magnet. The preparation method of the NdFeB magnet is the same as that of Example 3 except that the concentration of hexamethylenetetramine is 0.6 g / L, and details will not be repeated here.

[0125] Comparative Example 1

[0126] This comparative example provides an NdFeB magnet. The preparation method of the NdFeB magnet is the same as that of Example 1 except that no electrochemical anodic oxidation treatment is carried out, and details will not be repeated here.

[0127] Comparative Example 2

[0128] This comparative example provides an NdFeB magnet. The preparation method of the NdFeB magnet is the same as that of Example 3 except that no chemical roughening treatment and washing are carried out, and details will not be repeated here.

[0129] Comparative Example 3

[0130] Comparative Example 3 provides a NdFeB magnet. The preparation method of the NdFeB magnet is the same as that of Example 3 except that no corrosion inhibitor, hexamethylenetetramine, is added, and details are not described herein again.

[0131] Comparative Example 4

[0132] This comparative example provides a NdFeB magnet. The preparation method of the NdFeB magnet is the same as that of Example 1 except that the current density of the electrochemical anodic oxidation treatment is 5.5 A / m 2 except as otherwise specified, and details are not described herein again.

[0133] Comparative Example 5

[0134] This comparative example provides a NdFeB magnet. The preparation method of the NdFeB magnet is the same as that of Example 1 except that the concentration of sodium hydroxide is 250 g / L, and details are not described herein again.

[0135] Comparative Example 6

[0136] This comparative example provides a NdFeB magnet, which includes a NdFeB substrate, a copper layer, and an organic layer arranged in sequence; from the NdFeB substrate outwards, the copper layer includes a copper matrix layer and a rough layer; the rough layer is completely separated from the NdFeB substrate by the copper matrix layer, the rough layer covers all regions of the copper matrix layer, and is evenly distributed on the copper matrix layer. The thickness and material of the NdFeB substrate, copper layer, and organic layer are the same as those of Example 1.

[0137] The difference between the preparation method of the NdFeB magnet provided in this comparative example and that of Example 1 is only that: the surface of the initial electroplated copper layer of the first substrate is subjected to sandblasting treatment to make the roughness Ra of the rough layer be 0.371 μm to obtain a second substrate; then the same method as in Example 1 is used to spray epoxy resin on the surface of the second substrate.

[0138] Test method:

[0139] 1) PCT experiment (high-pressure accelerated aging test): 120 ± 2 °C, 100% RH, 0.2 MPa, with 24 hours as a cycle, observing once every cycle and recording the rusting situation on the product surface.

[0140] 2) The adhesion between the film layers is tested by the cross-cut test; the experimental standard is: ASTM D3002 D3359 DIN EN ISO 2409 test, and the judgment standard is: 4B, that is, there are small pieces of peeling at the intersection of the incisions, and the actual damage within the cross-cut area does not exceed 5%, then it is qualified. Take 50 magnets and calculate the pass rate through the cross-cut test.

[0141] 3) Thickness test of the film layer: The thickness of the film layer was tested by the method of mirror grinding. The coating was observed under a microscope, and 6 points on the coating were randomly selected for testing. The average value of the plating thickness at these 6 points was the thickness value of the coating on this surface. The same method was used to test the plating thickness of other surfaces. The final plating thickness value was the average value of the plating thickness of 6 surfaces.

[0142] 4) Roughness Ra test of the copper surface treatment layer and the initial electroplated copper layer: A roughness measuring instrument was used to measure multiple groups (such as ten groups) of roughness in different sampling areas of the first coating to be measured, and then the average value was calculated.

[0143] The test results of the above examples and comparative examples are shown in Table 1.

[0144] Table 1

[0145]

[0146] In Table 1, " / " indicates that there is no relevant data.

[0147] It can be seen from Table 1 as follows:

[0148] (1) From Examples 1 to 4, it can be seen that the NdFeB magnet provided by the present invention can improve the bonding force between the organic layer and the copper layer, and has stronger corrosion resistance. Among them, the qualified rate of the bonding force test between the film layers is above 98%, and the corrosion resistance of the NdFeB magnet is above 216 h;

[0149] (2) From Example 1, Example 5 and Comparative Example 4, it can be seen that the current density of the electrochemical anodic oxidation treatment in Example 1 is 2.0 A / m 2 , compared with 0.1 A / m in Example 5 2 and 5.5 A / m in Comparative Example 4 2 . In Example 1, the qualified rate of the bonding force test between the film layers is as high as 99%, and the corrosion resistance of the NdFeB magnet is 216 h. In Example 5, the qualified rate of the bonding force test between the film layers drops to 95%, and the corrosion resistance of the NdFeB magnet is only 168 h. In Comparative Example 4, although the obtained surface roughness Ra is 0.399 μm and the qualified rate of the bonding force test between the film layers is slightly improved compared with Example 5, finally, the copper oxide penetrates the copper matrix layer, resulting in no complete copper matrix layer covering the surface of the NdFeB matrix, and the final corrosion resistance is only 120 h. This shows that the current density of the electrochemical anodic oxidation treatment in the present invention is controlled within a reasonable range, which can not only improve the roughness of the copper surface treatment layer, but also avoid the penetration of the copper matrix layer, and finally the NdFeB magnet has excellent corrosion resistance;

[0150] (3) It can be seen from the comprehensive comparison of Example 1, Example 6 and Comparative Example 5 that the concentration of sodium hydroxide in Example 1 is 150 g / L. Compared with 70 g / L in Example 6 and 250 g / L in Comparative Example 5, the qualified rate of the interfacial bonding strength test of the film layer in Example 1 is as high as 99%, and the corrosion resistance of the NdFeB magnet is 216 h. In Example 6, the qualified rate of the interfacial bonding strength test of the film layer drops to 90%, and the corrosion resistance of the NdFeB magnet is only 168 h. Although the surface roughness Ra obtained in Comparative Example 5 is 0.396 μm and the qualified rate of the interfacial bonding strength test of the film layer is improved compared with Example 6, finally the copper oxide penetrates through the copper matrix layer, resulting in the surface of the NdFeB substrate not being covered by a complete copper matrix layer, and the final corrosion resistance is only 120 h. This shows that when the electrochemical anodic oxidation treatment in the present invention, the concentration of sodium hydroxide is controlled within a reasonable range, which can not only improve the roughness of the copper surface treatment layer, but also prevent the copper matrix layer from being penetrated, and finally the NdFeB magnet has excellent corrosion resistance;

[0151] (4) It can be seen from the comprehensive comparison of Example 3, Example 7 and Comparative Example 3 that the concentration of hexamethylenetetramine in Example 3 is 0.4 g / L. Compared with 0.6 g / L in Example 7 and without adding the corrosion inhibitor hexamethylenetetramine in Comparative Example 3, the qualified rate of the interfacial bonding strength test of the film layer in Example 3 is as high as 98%, and the corrosion resistance of the NdFeB magnet is 216 h. Although the surface roughness Ra in Example 7 is 0.284 μm, within the preferred range, due to the relatively high concentration of the corrosion inhibitor, the oxidation process is uneven, the qualified rate of the interfacial bonding strength test of the film layer drops to 90%, and the corrosion resistance of the NdFeB magnet is only 144 h. Although the surface roughness Ra obtained in Comparative Example 3 is 0.398 μm and the qualified rate of the interfacial bonding strength test of the film layer is improved compared with Example 7, finally the copper oxide penetrates through the copper matrix layer, resulting in the surface of the NdFeB substrate not being covered by a complete copper matrix layer, and the final corrosion resistance is only 120 h. This shows that the present invention selects to add the corrosion inhibitor hexamethylenetetramine and controls its concentration within a reasonable range, which can balance the thickness of the copper matrix layer and improve the interfacial bonding strength of the film layer;

[0152] (5) It can be seen from the comparison between Comparative Example 6 and Example 1 that in Comparative Example 6, the surface roughness of the copper layer is controlled to be the same as that in Example 1 by sandblasting, but finally the qualified rate of the interfacial bonding strength test of the film layer decreases compared with Example 1, and the corrosion resistance of the NdFeB magnet drops to 196 h. This shows that in the present invention, forming a copper surface treatment layer with oxides on the surface of the copper matrix layer, not only the roughness plays a role in improving the bonding strength, but also the copper oxides generated during the oxidation process and the microstructures formed in the copper surface treatment layer can also improve the interfacial bonding strength of the film layer and the corrosion resistance of the NdFeB magnet;

[0153] (6) It can be seen by comparing Example 1, Example 3 and Comparative Examples 1-2 that by forming a copper surface treatment layer with copper oxide and a certain roughness, and integrating the synergistic effects of the optimized oxide and roughness, the present invention can significantly improve the passing rate of the film layer adhesion test, and simultaneously improve the corrosion resistance of the neodymium iron boron magnet.

[0154] The present invention uses the above embodiments to illustrate the detailed features of the present invention, but the present invention is not limited to the above detailed features, that is, it does not mean that the present invention must rely on the above detailed features to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of the technical features selected by the present invention, the addition of auxiliary technical features, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A neodymium iron boron magnet, characterized in that, The neodymium iron boron magnet includes a neodymium iron boron substrate, a copper layer, and an organic layer arranged in sequence; Outward from the neodymium iron boron substrate, the copper layer includes a copper matrix layer and a copper surface treatment layer; The roughness Ra of the copper surface treatment layer is 0.25 - 0.40 μm; The material of the copper surface treatment layer includes copper oxide; The copper surface treatment layer is completely separated from the neodymium iron boron substrate by the copper matrix layer.

2. The neodymium iron boron magnet according to claim 1, characterized in that, The roughness Ra of the copper surface treatment layer is 0.28 - 0.38 μm Preferably, the thickness of the copper layer is 3 - 10 μm; Preferably, the thickness of the copper matrix layer is 2 - 9 μm; Preferably, the thickness of the neodymium iron boron substrate is 1 - 10 mm; Preferably, the thickness of the organic layer is 8 - 30 μm.

3. The neodymium iron boron magnet according to claim 1 or 2, characterized in that, The material of the neodymium iron boron substrate includes 28 - 32.5 wt% of R, 1.0 - 2.5 wt% of M, 0.8 - 1.2 wt% of B, and the balance of Fe, where R includes at least Pr and Nd, and also includes at least one of Dy, Tb, Ho, or Gd; M includes at least one of Co, Al, Cu, Ga, Zr, Nb, Ti, Mo, Sn, Hf, or W.

4. A surface treatment method for a neodymium iron boron substrate, characterized in that, The surface treatment method obtains the neodymium iron boron magnet according to any one of claims 1 - 3; Among them, the surface treatment method includes: Electroplating copper on the surface of the neodymium iron boron substrate to form an initial electroplated copper layer, obtaining a first substrate; Converting the surface of the initial electroplated copper layer into copper oxide to form a copper surface treatment layer, obtaining a second substrate; Forming an organic layer on the surface of the copper surface treatment layer to obtain the neodymium iron boron magnet.

5. The surface treatment method according to claim 4, wherein, The manner of forming the copper surface treatment layer includes electrochemical anodic oxidation treatment; Preferably, the electrochemical treatment solution for the electrochemical anodic oxidation treatment includes alkali: 80 - 200 g / L, molybdate: 0.1 - 10 g / L, and EDTA: 0.1 - 20 g / L; Preferably, the current density of the electrochemical anodic oxidation treatment is 0.5 to 5 A / m 2 ; Preferably, the temperature of the electrochemical anodic oxidation treatment is 60 - 110 °C; Preferably, the time of the electrochemical anodic oxidation treatment is 30 - 90 s.

6. The surface treatment method according to claim 5, characterized in that, Before the electrochemical anodic oxidation treatment, first preheat the copper surface treatment layer in the electrochemical treatment solution; Preferably, the preheating time is 1 - 10 min; Preferably, the preheating temperature is 60 - 80 °C; Preferably, after the electrochemical anodic oxidation treatment, phosphating treatment is carried out.

7. The surface treatment method according to claim 4, characterized in that, The manner of forming the copper surface treatment layer includes chemical roughening treatment; the chemical roughening treatment includes: infiltrating the surface of the initial electroplated copper layer with a chemical roughening treatment solution and washing; Preferably, the chemical roughening treatment solution includes corrosion agent: 5 - 50 mg / L, oxidant: 0.5 - 15 g / L, sodium m-nitrobenzenesulfonate: 1 - 50 g / L, and corrosion inhibitor: 0.1 - 0.5 g / L; Preferably, the corrosion agent includes phosphoric acid; Preferably, the oxidant includes nitric acid and / or hydrogen peroxide; Preferably, the corrosion inhibitor includes hexamethylenetetramine and / or benzotriazole; Preferably, the infiltration time is 10 - 90 s; Preferably, the temperature of the chemical roughening treatment solution is 5 - 35 °C.

8. The surface treatment method according to any one of claims 4 to 7, characterized in that, The electroplating solution for electroplating copper comprises copper sulfate: 15 - 30 g / L, tartrate: 15 - 30 g / L, and citric acid: 10 - 12 g / L; Preferably, the tartrate comprises potassium tartrate and / or sodium tartrate; Preferably, the temperature of the electroplating solution for electroplating copper is 35 - 60 °C; Preferably, the pH value of the electroplating solution for electroplating copper is 9 - 10.5; Preferably, the current density in the electroplated copper is 0.5 to 1.5 A / m 2 ; Preferably, the electroplating time for electroplating copper is 30 - 90 min.

9. The surface treatment method according to any one of claims 4 to 8, characterized in that, The method for forming the organic layer comprises: spraying epoxy resin on the surface of the copper surface treatment layer and curing it; Preferably, the epoxy resin solution for spraying epoxy resin comprises 55 - 85 wt% of epoxy resin and the balance of water; Preferably, the spray gun angle for spraying epoxy resin is 30 - 60 degrees; Preferably, the spray gun pressure for spraying epoxy resin is 0.15 - 0.5 mPa; Preferably, the temperature of the curing is 150 - 200 °C; Preferably, the time of the curing is 20 - 50 min.

10. Use of the neodymium iron boron magnet according to any one of claims 1 - 4 in the fields of automotive industry, electronic products, wind power, elevators, industrial robots or aerospace.

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