Nickel-plated modified neodymium-iron-boron permanent magnet material and method for producing the same

Abstract

The application discloses a kind of nickel-plated modified neodymium-iron-boron permanent magnet materials and preparation method thereof, it is related to permanent magnet material technical field.The nickel-plated modified neodymium-iron-boron permanent magnet material specifically includes the following steps: S1: neodymium-iron-boron permanent magnet material is sequentially polished, polished, washed, dried, magnetron sputtering Al-Ga layer, obtains neodymium-iron-boron permanent magnet material A;S2: neodymium-iron-boron permanent magnet material A is sequentially polished, washed, dried, electrophoretic deposition TbF3 layer, thermal diffusion treatment, obtains neodymium-iron-boron permanent magnet material B;S3: neodymium-iron-boron permanent magnet material B surface electroplating NI-Co-Tb layer, obtains nickel-plated modified neodymium-iron-boron permanent magnet material.The preparation method provided by the application significantly improves the magnetic properties and corrosion resistance of permanent magnet material.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet materials technology, specifically a nickel-plated modified neodymium iron boron permanent magnet material and its preparation method. Background Technology

[0002] Neodymium iron boron (NdFeB) permanent magnets are widely used in electronics, automobiles, energy, and many other fields due to their excellent magnetic properties, making them one of the most widely used rare-earth permanent magnet materials. However, while the remanence and maximum energy product of NdFeB permanent magnets are close to their theoretical limits, their coercivity is generally only half of the theoretical value. Therefore, improving coercivity without affecting remanence and maximum energy product is a key challenge.

[0003] In existing technologies, grain boundary diffusion often employs the introduction of heavy rare earth elements, which can significantly enhance the magnetocrystalline anisotropy at grain boundaries, thereby improving the coercivity of the magnet. However, this requires the pre-preparation of a diffusion source coating on the substrate surface. Common methods, such as metal slurries, may lead to the oxidation of heavy rare earth elements during debinding or solvent evaporation, reducing their effectiveness. Furthermore, hydrogen ions generated during electroplating are easily absorbed by NdFeB materials, resulting in decreased corrosion resistance. Patent CN116544022A discloses a method for improving the performance of NdFeB magnets and a high-coercivity NdFeB magnet. This method involves depositing ferromagnetic alloy diffusion source powder onto the surface of a magnetized or magnetized NdFeB magnet under magnetic adsorption to obtain the magnet to be diffused, followed by grain boundary diffusion. However, because the substrate needs to be pre-magnetized, internal stress may increase during grain boundary diffusion, leading to microcracks and decreased corrosion resistance.

[0004] In conclusion, solving the above problems and preparing a neodymium iron boron permanent magnet material with good magnetic properties and corrosion resistance is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a nickel-plated modified neodymium iron boron permanent magnet material and its preparation method, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A method for preparing a nickel-plated modified neodymium iron boron permanent magnet material includes the following steps:

[0008] S1: The neodymium iron boron permanent magnet material is successively ground, polished, washed, dried, and magnetron sputtered with an Al-Ga layer to obtain neodymium iron boron permanent magnet material A;

[0009] S2: The neodymium iron boron permanent magnet material A is successively polished, washed, dried, electrophoretically deposited with a TbF3 layer, and thermally diffused to obtain neodymium iron boron permanent magnet material B;

[0010] S3: Electroplating a Ni-Co-Tb layer on the surface of NdFeB permanent magnet material B yields a nickel-modified NdFeB permanent magnet material.

[0011] Preferably, during the magnetron sputtering process, the target material is an Al-Ga alloy, and the vacuum level is 5×10⁻⁶. -4 Pa, working gas is argon, flow rate is 35~45 sccm, coating thickness is 0.4~0.6 μm.

[0012] Preferably, the Al-Ga alloy comprises 75-85 wt% aluminum, with the remainder being gallium.

[0013] Preferably, during the electrophoretic deposition process, the deposition solution includes the following raw materials: 10~12 g / L terbium fluoride, 1~1.5 g / L magnesium chloride, and ethanol as the solvent.

[0014] Preferably, during the electrophoretic deposition process, neodymium iron boron permanent magnet material A is used as the cathode, stainless steel plate is used as the anode, the distance between the cathode and the anode is 3 mm, the temperature is 25~30℃, the voltage is 100V, and the time is 140~160 seconds.

[0015] Preferably, the heat diffusion process specifically involves operating under a vacuum of 2.5 × 10⁻⁶. -3 First, heat-treat at 850~875℃ for 9~9.5h, then heat-treat at 500~520℃ for 1.5~2h.

[0016] Preferably, in the electroplating process, the electroplating solution comprises the following raw materials: 220~240 g / L nickel sulfate hexahydrate, 35~40 g / L nickel chloride hexahydrate, 44~48 g / L cobalt sulfate heptahydrate, 10~12 g / L terbium nitrate hexahydrate, 1~1.5 g / L sodium saccharin, 18~22 g / L potassium chloride, 28~30 g / L boric acid, 0.1~0.2 g / L sodium dodecyl sulfate, and the pH is 4.5~5.5.

[0017] Preferably, during the electroplating process, the current density is 1.5~2A / dm³. 2 The time is 25~30 minutes and the temperature is 45~50℃.

[0018] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: In this application, an Al-Ga layer is sequentially magnetron sputtered on the surface of a NdFeB permanent magnet material, followed by electrophoretic deposition of a TbF3 layer as a composite diffusion source, and then an Ni-Co-Tb layer is electroplated, thereby improving the magnetic properties and corrosion resistance of the permanent magnet material.

[0019] In the magnetron sputtering of the Al-Ga layer, the small atomic size of aluminum and gallium allows them to penetrate well into the surface of the NdFeB magnet material, enhancing the adhesion between the coating and the substrate, filling tiny gaps, improving corrosion resistance, and preventing hydrogen ions generated during subsequent electrophoretic deposition and electroplating processes from penetrating into the substrate material and causing hydrogen embrittlement. Furthermore, during the subsequent thermal diffusion process, the low melting point of the aluminum and gallium alloys leads to a eutectic reaction near the NdFeB element, lowering the melting point of the NdFeB-rich phase, improving wettability, reducing interfacial energy, and enhancing uniformity, while also increasing the material's corrosion resistance and magnetic properties.

[0020] In the electrophoretic deposition of the TbF3 layer, terbium fluoride electrophoretically deposited and Al-Ga layers sputtered by magnetron sputtering are used as a composite diffusion source for grain boundary diffusion. During this process, aluminum and gallium can effectively improve the structure of the magnet's grain boundary phase, forming a continuous grain boundary phase, promoting the diffusion of terbium into the magnet's interior, and refining the grains. Tb enters the magnet's interior along the grain boundaries, replacing some of the neodymium in the main phase to form a shell structure, improving the anisotropic field, significantly enhancing the magnet's coercivity, and minimizing the decrease in remanence. Aluminum can increase the diffusion depth of Tb and improve coercivity, while gallium can refine the grains and increase the proportion of the grain boundary phase, comprehensively improving the magnetic properties. Using an aluminum-gallium alloy with an aluminum content of 75-85 wt% can maximize the electrode potential of the grain boundaries, while simultaneously modifying and stabilizing the neodymium-rich grain boundaries, significantly improving corrosion resistance and magnetic properties. In this invention, the Al-Ga layer is placed on the side close to the magnet. Although the grain boundary diffusion time required for terbium fluoride on the side close to the magnet material is relatively longer, the Al-Ga layer preferentially forms a transition environment for terbium diffusion, thereby increasing the diffusion depth of terbium and improving uniformity, thus greatly improving the coercivity of the magnet.

[0021] In the process of electroplating Ni-Co-Tb layer, by introducing a small amount of terbium, it can enter the lattice in the nickel-cobalt alloy layer to form a more stable alloy layer. This helps to further improve the density of the coating, reduce the corrosion current density in corrosive environments, increase corrosion resistance, and improve the bonding performance with the first two thermally diffused coatings, preventing the coating from falling off. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that the following quantities are by weight. There are no special restrictions on the suppliers of all raw materials involved in this invention. Exemplary examples include: aluminum gallium alloy target material, provided by Hebei Ruichi New Material Co., Ltd.; TbF3, with a particle size of 0.1~1μm; CAS number of nickel sulfate hexahydrate: 15244-37-8; CAS number of nickel chloride hexahydrate: 7791-20-0; CAS number of cobalt sulfate heptahydrate: 10026-24-1; CAS number of terbium nitrate hexahydrate: 13451-19-9; CAS number of sodium saccharin: 128-44-9; CAS number of sodium dodecyl sulfonate: 2386-53-0.

[0024] In the following examples, parts refer to parts by weight, and all raw materials mentioned above and others not mentioned are commercially available.

[0025] Neodymium iron boron permanent magnet materials include the following elements: neodymium: 23.1%, praseodymium: 6.1%, boron: 1.18%, cobalt: 0.24%, with the balance being iron.

[0026] Example 1: The preparation method of nickel-plated modified NdFeB permanent magnet material includes the following steps:

[0027] S1: The outer surface of the NdFeB permanent magnet material is sanded to 2000 grit with sandpaper, polished to a mirror finish with a polishing machine, ultrasonically cleaned with ethanol and acetone respectively, dried, and transferred to a vacuum chamber. Using an Al-Ga alloy (Al-Ga alloy includes 80wt% aluminum, the remainder being gallium) as the target material, it is subjected to a vacuum of 5×10⁻⁶. -4 At Pa, argon was used as the working gas, and an Al-Ga layer with a thickness of 0.5 μm was sputtered by magnetron sputtering at a flow rate of 40 sccm to obtain neodymium iron boron permanent magnet material A;

[0028] S2: The neodymium iron boron permanent magnet material A is polished, washed, dried, and transferred to the deposition solution. Using neodymium iron boron permanent magnet material A as the cathode and a stainless steel plate as the anode, with a cathode-anode distance of 3 mm, a TbF3 layer is electrophoretically deposited at a temperature of 2℃ and a voltage of 100V for 150 seconds. After washing and drying, the material is then placed under a vacuum of 2.5 × 10⁻⁶. -3 The material is first heat-treated at 860℃ for 9 hours, and then heat-treated at 510℃ for 2 hours to obtain neodymium iron boron permanent magnet material B; wherein, the preparation method of the deposition solution is to add terbium fluoride and magnesium chloride to anhydrous ethanol and ultrasonically disperse for 30 minutes to obtain a deposition solution containing 10 g / L terbium fluoride and 1.5 g / L magnesium chloride.

[0029] S3: Applying a current density of 1.5 A / dm² to the surface of neodymium iron boron permanent magnet material B. 2A Ni-Co-Tb layer was formed by electroplating at 50℃ for 30 min, followed by annealing at 510℃ for 2 h to obtain nickel-modified NdFeB permanent magnet material. The electroplating solution included the following raw materials: 230 g / L nickel sulfate hexahydrate, 36 g / L nickel chloride hexahydrate, 46 g / L cobalt sulfate heptahydrate, 10 g / L terbium nitrate hexahydrate, 1 g / L sodium saccharin, 20 g / L potassium chloride, 30 g / L boric acid, 0.1 g / L sodium dodecyl sulfate, and pH 5.

[0030] Example 2: The preparation method of nickel-plated modified NdFeB permanent magnet material includes the following steps:

[0031] S1: The outer surface of the NdFeB permanent magnet material is sanded to 2000 grit with sandpaper, polished to a mirror finish with a polishing machine, ultrasonically cleaned with ethanol and acetone respectively, dried, and transferred to a vacuum chamber. Using an Al-Ga alloy (Al-Ga alloy includes 75wt% aluminum, the remainder being gallium) as the target material, it is subjected to a vacuum of 5×10⁻⁶. -4 At Pa, argon was used as the working gas, and an Al-Ga layer with a thickness of 0.5 μm was sputtered by magnetron sputtering at a flow rate of 40 sccm to obtain neodymium iron boron permanent magnet material A;

[0032] S2: The neodymium iron boron permanent magnet material A is polished, washed, dried, and transferred to the deposition solution. Using neodymium iron boron permanent magnet material A as the cathode and a stainless steel plate as the anode, with a cathode-anode distance of 3 mm, a TbF3 layer is electrophoretically deposited at a temperature of 2℃ and a voltage of 100V for 150 seconds. After washing and drying, the material is then placed under a vacuum of 2.5 × 10⁻⁶. -3 The material is first heat-treated at 860℃ for 9 hours, and then heat-treated at 510℃ for 2 hours to obtain neodymium iron boron permanent magnet material B; wherein, the preparation method of the deposition solution is to add terbium fluoride and magnesium chloride to anhydrous ethanol and ultrasonically disperse for 30 minutes to obtain a deposition solution containing 10 g / L terbium fluoride and 1.5 g / L magnesium chloride.

[0033] S3: Applying a current density of 1.5 A / dm² to the surface of neodymium iron boron permanent magnet material B. 2 A Ni-Co-Tb layer was formed by electroplating at 50℃ for 30 min, followed by annealing at 510℃ for 2 h to obtain nickel-modified NdFeB permanent magnet material. The electroplating solution included the following raw materials: 220 g / L nickel sulfate hexahydrate, 35 g / L nickel chloride hexahydrate, 44 g / L cobalt sulfate heptahydrate, 10 g / L terbium nitrate hexahydrate, 1 g / L sodium saccharin, 18 g / L potassium chloride, 28 g / L boric acid, 0.1 g / L sodium dodecyl sulfate, and pH 5.

[0034] Example 3: The preparation method of nickel-plated modified NdFeB permanent magnet material includes the following steps:

[0035] S1: The outer surface of the NdFeB permanent magnet material is sanded to 2000 grit with sandpaper, polished to a mirror finish with a polishing machine, ultrasonically cleaned with ethanol and acetone respectively, dried, and transferred to a vacuum chamber. Using an Al-Ga alloy (containing 85wt% aluminum and the remainder gallium) as the target material, the magnet is subjected to a vacuum of 5×10⁻⁶. -4 At Pa, argon was used as the working gas, and an Al-Ga layer with a thickness of 0.5 μm was sputtered by magnetron sputtering at a flow rate of 40 sccm to obtain neodymium iron boron permanent magnet material A;

[0036] S2: The neodymium iron boron permanent magnet material A is polished, washed, dried, and transferred to the deposition solution. Using neodymium iron boron permanent magnet material A as the cathode and a stainless steel plate as the anode, with a cathode-anode distance of 3 mm, a TbF3 layer is electrophoretically deposited at a temperature of 2℃ and a voltage of 100V for 150 seconds. After washing and drying, the material is then placed under a vacuum of 2.5 × 10⁻⁶. -3 The material is first heat-treated at 860℃ for 9 hours, and then heat-treated at 510℃ for 2 hours to obtain neodymium iron boron permanent magnet material B; wherein, the preparation method of the deposition solution is to add terbium fluoride and magnesium chloride to anhydrous ethanol and ultrasonically disperse for 30 minutes to obtain a deposition solution containing 10 g / L terbium fluoride and 1.5 g / L magnesium chloride.

[0037] S3: Applying a current density of 1.5 A / dm² to the surface of neodymium iron boron permanent magnet material B. 2 A Ni-Co-Tb layer was formed by electroplating at 50℃ for 30 min, followed by annealing at 510℃ for 2 h to obtain nickel-modified NdFeB permanent magnet material. The electroplating solution contained the following raw materials: 240 g / L nickel sulfate hexahydrate, 40 g / L nickel chloride hexahydrate, 48 g / L cobalt sulfate heptahydrate, 12 g / L terbium nitrate hexahydrate, 1.5 g / L sodium saccharin, 22 g / L potassium chloride, 30 g / L boric acid, 0.2 g / L sodium dodecyl sulfate, and pH 5.

[0038] Comparative Example 1: Based on Example 1, magnetron sputtering only sputters aluminum without electroplating, while the remaining processes remain unchanged, as follows:

[0039] S1: The outer surface of the NdFeB permanent magnet material is sanded to 2000 grit with sandpaper, polished to a mirror finish with a polishing machine, ultrasonically cleaned with ethanol and acetone respectively, dried, and transferred to a vacuum chamber. Using pure Al as the target material, it is subjected to a vacuum of 5×10⁻⁶. -4 At Pa, argon was used as the working gas, and an Al layer with a thickness of 0.5 μm was obtained by magnetron sputtering at a flow rate of 40 sccm to obtain neodymium iron boron permanent magnet material A;

[0040] S2: The neodymium iron boron permanent magnet material A is polished, washed, dried, and transferred to the deposition solution. Using neodymium iron boron permanent magnet material A as the cathode and a stainless steel plate as the anode, with a cathode-anode distance of 3 mm, a TbF3 layer is electrophoretically deposited at a temperature of 2℃ and a voltage of 100V for 150 seconds. After washing and drying, the material is then placed under a vacuum of 2.5 × 10⁻⁶. -3 The material is first heat-treated at 860℃ for 9 hours, and then heat-treated at 510℃ for 2 hours to obtain neodymium iron boron permanent magnet material B; wherein, the preparation method of the deposition solution is to add terbium fluoride and magnesium chloride to anhydrous ethanol and ultrasonically disperse for 30 minutes to obtain a deposition solution containing 10 g / L terbium fluoride and 1.5 g / L magnesium chloride.

[0041] Comparative Example 2: Based on Example 1, magnetron sputtering only sputters gallium without electroplating, while the remaining processes remain unchanged, as follows:

[0042] S1: The outer surface of the NdFeB permanent magnet material is sanded to 2000 grit with sandpaper, polished to a mirror finish with a polishing machine, ultrasonically cleaned with ethanol and acetone respectively, dried, and transferred to a vacuum chamber. Using pure Ga as the target material, it is subjected to a vacuum of 5×10⁻⁶. -4 At Pa, argon was used as the working gas, and an Al-Ga layer with a thickness of 0.5 μm was sputtered by magnetron sputtering at a flow rate of 40 sccm to obtain neodymium iron boron permanent magnet material A;

[0043] S2: The neodymium iron boron permanent magnet material A is polished, washed, dried, and transferred to the deposition solution. Using neodymium iron boron permanent magnet material A as the cathode and a stainless steel plate as the anode, with a cathode-anode distance of 3 mm, a TbF3 layer is electrophoretically deposited at a temperature of 2℃ and a voltage of 100V for 150 seconds. After washing and drying, the material is then placed under a vacuum of 2.5 × 10⁻⁶. -3 The material is first heat-treated at 860℃ for 9 hours, and then heat-treated at 510℃ for 2 hours to obtain neodymium iron boron permanent magnet material B; wherein, the preparation method of the deposition solution is to add terbium fluoride and magnesium chloride to anhydrous ethanol and ultrasonically disperse for 30 minutes to obtain a deposition solution containing 10 g / L terbium fluoride and 1.5 g / L magnesium chloride.

[0044] Comparative Example 3: Based on Example 1, a TbF3 layer was directly deposited by electrophoresis without electroplating, and the remaining processes remained unchanged, as follows:

[0045] S1: The outer surface of the NdFeB permanent magnet material was sanded to 2000 grit with sandpaper, polished to a mirror finish with a polishing machine, ultrasonically cleaned with ethanol and acetone respectively, dried, and transferred to a deposition solution. Using NdFeB permanent magnet material A as the cathode and a stainless steel plate as the anode, with a cathode-anode distance of 3 mm, a TbF3 layer was electrophoretically deposited at a temperature of 2℃ and a voltage of 100V for 150 seconds. After washing and drying, the material was then placed under a vacuum of 2.5 × 10⁻⁶. -3The material is first heat-treated at 860℃ for 9 hours, and then heat-treated at 510℃ for 2 hours to obtain neodymium iron boron permanent magnet material B; wherein, the preparation method of the deposition solution is to add terbium fluoride and magnesium chloride to anhydrous ethanol and ultrasonically disperse for 30 minutes to obtain a deposition solution containing 10 g / L terbium fluoride and 1.5 g / L magnesium chloride.

[0046] Comparative Example 4: Based on Example 1, a TbF3 layer was first deposited by electrophoresis, followed by an aluminum layer, without electroplating. The remaining processes remained unchanged, as follows:

[0047] S1: The outer surface of the NdFeB permanent magnet material is sanded to 2000 grit with sandpaper, polished to a mirror finish with a polishing machine, ultrasonically cleaned with ethanol and acetone respectively, dried, and transferred to deposition solution A. Using NdFeB permanent magnet material A as the cathode and a stainless steel plate as the anode, with a cathode-anode distance of 3 mm, a TbF3 layer is electrophoretically deposited at a temperature of 2℃ and a voltage of 100V for 150 seconds. After washing and drying, the material is transferred to deposition solution B. Using NdFeB permanent magnet material as the cathode and a stainless steel plate as the anode, with a cathode-anode distance of 3 mm, an Al layer is electrophoretically deposited at a temperature of 2℃ and a voltage of 100V for 150 seconds. After washing and drying, the material is then deposited under a vacuum of 2.5 × 10⁻⁶. -3 The material is first heat-treated at 860℃ for 9 hours, and then at 510℃ for 2 hours to obtain neodymium iron boron permanent magnet material B. The deposition solution A is prepared by adding terbium fluoride and magnesium chloride to anhydrous ethanol and ultrasonically dispersing for 30 minutes to obtain a deposition solution containing 10 g / L terbium fluoride and 1.5 g / L magnesium chloride. Alternatively, the deposition solution A is prepared by adding aluminum powder and magnesium chloride to anhydrous ethanol and ultrasonically dispersing for 30 minutes to obtain a deposition solution containing 8 g / L aluminum powder and 1.5 g / L magnesium chloride.

[0048] Comparative Example 5: Based on Example 1, a TbF3 layer and an aluminum layer were simultaneously deposited by electrophoresis without electroplating, and the remaining processes remained unchanged, as follows:

[0049] S1: The outer surface of the NdFeB permanent magnet material was sanded to 2000 grit with sandpaper, polished to a mirror finish with a polishing machine, ultrasonically cleaned with ethanol and acetone respectively, dried, and transferred to a deposition solution. Using NdFeB permanent magnet material A as the cathode and a stainless steel plate as the anode, with a cathode-anode distance of 3 mm, a TbF3 layer was electrophoretically deposited at a temperature of 2℃ and a voltage of 100V for 150 seconds. After washing and drying, the material was then placed under a vacuum of 2.5 × 10⁻⁶. -3 The material is first heat-treated at 860℃ for 9 hours, and then heat-treated at 510℃ for 2 hours to obtain neodymium iron boron permanent magnet material; wherein, the preparation method of the deposition solution is to add terbium fluoride and magnesium chloride to anhydrous ethanol and ultrasonically disperse for 30 minutes to obtain a deposition solution containing 10 g / L terbium fluoride, 8 g / L aluminum powder and 1.5 g / L magnesium chloride;

[0050] Comparative Example 6: Based on Example 1, the thickness of the magnetron sputtering was increased, but electroplating was not performed, and the remaining processes remained unchanged, as follows:

[0051] S1: The outer surface of the NdFeB permanent magnet material is sanded to 2000 grit with sandpaper, polished to a mirror finish with a polishing machine, ultrasonically cleaned with ethanol and acetone respectively, dried, and transferred to a vacuum chamber. Using an Al-Ga alloy (Al-Ga alloy includes 80wt% aluminum, the remainder being gallium) as the target material, it is subjected to a vacuum of 5×10⁻⁶. -4 Under Pa, argon was used as the working gas, and an Al-Ga layer with a thickness of 1 μm was obtained by magnetron sputtering at a flow rate of 40 sccm.

[0052] S2: The neodymium iron boron permanent magnet material A is polished, washed, dried, and transferred to the deposition solution. Using neodymium iron boron permanent magnet material A as the cathode and a stainless steel plate as the anode, with a cathode-anode distance of 3 mm, a TbF3 layer is electrophoretically deposited at a temperature of 2℃ and a voltage of 100V for 150 seconds. After washing and drying, the material is then placed under a vacuum of 2.5 × 10⁻⁶. -3 The material is first heat-treated at 860℃ for 9 hours, and then heat-treated at 510℃ for 2 hours to obtain neodymium iron boron permanent magnet material B; wherein, the preparation method of the deposition solution is to add terbium fluoride and magnesium chloride to anhydrous ethanol and ultrasonically disperse for 30 minutes to obtain a deposition solution containing 10 g / L terbium fluoride and 1.5 g / L magnesium chloride.

[0053] S3: Applying a current density of 1.5 A / dm² to the surface of neodymium iron boron permanent magnet material B. 2 A Ni-Co-Tb layer was formed by electroplating at 50℃ for 30 min, followed by annealing at 510℃ for 2 h to obtain nickel-modified NdFeB permanent magnet material. The electroplating solution included the following raw materials: 230 g / L nickel sulfate hexahydrate, 36 g / L nickel chloride hexahydrate, 46 g / L cobalt sulfate heptahydrate, 10 g / L terbium nitrate hexahydrate, 1 g / L sodium saccharin, 20 g / L potassium chloride, 30 g / L boric acid, 0.1 g / L sodium dodecyl sulfate, and pH 5.

[0054] Comparative Example 7: Based on Example 1, terbium was not introduced into the electroplating solution, and the remaining processes remained unchanged, as follows:

[0055] S1: The outer surface of the NdFeB permanent magnet material is sanded to 2000 grit with sandpaper, polished to a mirror finish with a polishing machine, ultrasonically cleaned with ethanol and acetone respectively, dried, and transferred to a vacuum chamber. Using an Al-Ga alloy (Al-Ga alloy includes 80wt% aluminum, the remainder being gallium) as the target material, it is subjected to a vacuum of 5×10⁻⁶. -4 At Pa, argon was used as the working gas, and an Al-Ga layer with a thickness of 0.5 μm was sputtered by magnetron sputtering at a flow rate of 40 sccm to obtain neodymium iron boron permanent magnet material A;

[0056] S2: The neodymium iron boron permanent magnet material A is polished, washed, dried, and transferred to the deposition solution. Using neodymium iron boron permanent magnet material A as the cathode and a stainless steel plate as the anode, with a cathode-anode distance of 3 mm, a TbF3 layer is electrophoretically deposited at a temperature of 2℃ and a voltage of 100V for 150 seconds. After washing and drying, the material is then placed under a vacuum of 2.5 × 10⁻⁶. -3 The material is first heat-treated at 860℃ for 9 hours, and then heat-treated at 510℃ for 2 hours to obtain neodymium iron boron permanent magnet material B; wherein, the preparation method of the deposition solution is to add terbium fluoride and magnesium chloride to anhydrous ethanol and ultrasonically disperse for 30 minutes to obtain a deposition solution containing 10 g / L terbium fluoride and 1.5 g / L magnesium chloride.

[0057] S3: Applying a current density of 1.5 A / dm² to the surface of neodymium iron boron permanent magnet material B. 2 A Ni-Co-Tb layer was formed by electroplating at 50℃ for 30 min, and then annealed at 510℃ for 2 h to obtain nickel-modified NdFeB permanent magnet material. The electroplating solution included the following raw materials: 230 g / L nickel sulfate hexahydrate, 36 g / L nickel chloride hexahydrate, 46 g / L cobalt sulfate heptahydrate, 1 g / L sodium saccharin, 20 g / L potassium chloride, 30 g / L boric acid, 0.1 g / L sodium dodecyl sulfate, and pH 5.

[0058] Performance testing: (1) The coercivity and performance of the samples prepared in Examples 1-3 and Comparative Examples 1-6 were measured using a permanent magnet material precision measurement system; (2) Electrochemical tests were performed on the samples prepared in Examples 1-3 and Comparative Examples 1-6 using a CS350H electrochemical workstation. The sample size was 10mm×10mm×5mm. The auxiliary electrode was a Pt electrode, the reference electrode was a saturated calomel electrode, the solution was a 3.5wt% NaCl solution, the scanning range was ±0.25V relative to the open circuit potential, the scanning speed was 0.5mV / s, and the test temperature was 25℃. The experimental data are shown in the table below.

[0059] Group Coercivity (kOe) Remanence (kGs) Corrosion current (pA / cm 2 )]> Example 1 21.25 14.65 0.34 Example 2 21.14 14.42 0.47 Example 3 20.89 14.49 0.52 Comparative Example 1 18.42 14.04 3.12 Comparative Example 2 17.84 14.24 2.74 Comparative Example 3 16.57 13.95 7.81 Comparative Example 4 19.78 14.42 6.78 Comparative Example 5 19.14 14.36 7.12 Comparative Example 6 15.74 13.75 2.47 Comparative Example 7 20.12 14.33 0.92 Initial magnet 14.12 14.78 38.24

[0060] Conclusion: As shown in Table 1, the present invention significantly improves the magnetic properties and corrosion resistance of NdFeB permanent magnet materials by sequentially magnetron sputtering an Al-Ga layer, electrophoretically depositing a TbF3 layer, and electroplating a Ni-Co-Tb layer on the surface of the NdFeB permanent magnet material.

[0061] In Comparative Example 1, magnetron sputtering only sputtered aluminum, lacking the refinement effect of gallium, resulting in a decrease in magnetic properties. In Comparative Example 2, magnetron sputtering only sputtered gallium, resulting in limited diffusion depth and decreased coercivity. In Comparative Example 3, direct electrophoretic deposition of the TbF3 layer lacked the promoting effect of Al-Ga, resulting in a lower diffusion depth and decreased magnetic properties. Furthermore, due to the lack of Al-Ga layer protection, the magnet absorbed hydrogen ions from the deposition solution, leading to a decrease in corrosion resistance. In Comparative Example 4, the TbF3 layer was first electrophoretically deposited, followed by the aluminum layer. This resulted in a decrease in the diffusion depth and uniformity of terbium, and the magnetic properties were not as good as those in the examples. 1; In Comparative Example 5, TbF3 and aluminum layers were deposited simultaneously via electrophoretic deposition. Due to the poor compatibility between aluminum and magnets during electrophoretic deposition, the aluminum layer detached under gravity. Essentially, the TbF3 layer was deposited first, followed by the aluminum layer via electrophoretic deposition. Therefore, the magnetic properties were not as good as in Example 1. Furthermore, due to the influence of aluminum, the overall coating was uneven, resulting in a further decline in performance compared to Comparative Example 4. In Comparative Example 6, increasing the thickness of magnetron sputtering significantly reduced the diffusion rate of terbium and affected the diffusion depth, leading to a decrease in magnetic properties. In Comparative Example 7, terbium was not introduced into the electroplating solution, resulting in a coating density lower than in Example 1 and a decrease in corrosion resistance.

[0062] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a nickel-plated modified NdFeB permanent magnet material, characterized in that: Includes the following steps: S1: The neodymium iron boron permanent magnet material is successively ground, polished, washed, dried, and magnetron sputtered with an Al-Ga layer to obtain neodymium iron boron permanent magnet material A; S2: The neodymium iron boron permanent magnet material A is successively polished, washed, dried, electrophoretically deposited with a TbF3 layer, and thermally diffused to obtain neodymium iron boron permanent magnet material B; S3: Electroplating a Ni-Co-Tb layer on the surface of NdFeB permanent magnet material B yields a nickel-modified NdFeB permanent magnet material; During the magnetron sputtering process, the coating thickness is 0.4~0.6μm; Specifically, the heat diffusion process involves operating under a vacuum of 2.5 × 10⁻⁶. -3 First, heat-treat at 850~875℃ for 9~9.5h, then heat-treat at 500~520℃ for 1.5~2h.

2. The method for preparing a nickel-plated modified NdFeB permanent magnet material according to claim 1, characterized in that: During the magnetron sputtering process, the target material is an Al-Ga alloy, and the vacuum level is 5×10⁻⁶. -4 Pa, the working gas is argon, and the flow rate is 35~45 sccm.

3. The method for preparing a nickel-plated modified NdFeB permanent magnet material according to claim 2, characterized in that: The Al-Ga alloy comprises 75-85 wt% aluminum, with the remainder being gallium.

4. The method for preparing a nickel-plated modified NdFeB permanent magnet material according to claim 1, characterized in that: During the electrophoretic deposition process, the deposition solution includes the following raw materials: 10~12g / L terbium fluoride, 1~1.5g / L magnesium chloride, and ethanol as the solvent.

5. The method for preparing a nickel-plated modified NdFeB permanent magnet material according to claim 1, characterized in that: During the electrophoretic deposition process, neodymium iron boron permanent magnet material A is used as the cathode, stainless steel plate is used as the anode, the distance between the cathode and the anode is 3 mm, the temperature is 25~30℃, the voltage is 100V, and the time is 140~160 seconds.

6. The method for preparing a nickel-plated modified NdFeB permanent magnet material according to claim 1, characterized in that: During the electroplating process, the electroplating solution includes the following raw materials: 220~240g / L nickel sulfate hexahydrate, 35~40g / L nickel chloride hexahydrate, 44~48g / L cobalt sulfate heptahydrate, 10~12g / L terbium nitrate hexahydrate, 1~1.5g / L sodium saccharin, 18~22g / L potassium chloride, 28~30g / L boric acid, 0.1~0.2g / L sodium dodecyl sulfate, and the pH is 4.5~5.

5.

7. The method for preparing a nickel-plated modified NdFeB permanent magnet material according to claim 1, characterized in that: During the electroplating process, the current density is 1.5~2A / dm³. 2 The time is 25~30 minutes and the temperature is 45~50℃.

8. The nickel-plated modified NdFeB permanent magnet material prepared by the method for preparing nickel-plated modified NdFeB permanent magnet material according to any one of claims 1 to 7.