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CN-121483786-B - GaCu co-doped sintered permanent magnet and production process thereof

CN121483786BCN 121483786 BCN121483786 BCN 121483786BCN-121483786-B

Abstract

The invention discloses a GaCu co-doped sintered permanent magnet and a production process thereof, wherein the production process comprises the following steps of smelting S1 raw materials, preparing S2 powder, processing the S2 powder for 2.5-3.5 hours at the pressure of 0.1-0.2 MPa and the temperature of 300 ℃ under the atmosphere of hydrogen, then grinding the powder with the air flow under the protection of inert gas to obtain anisotropic powder with the average particle diameter of 3-5 mu m, pressing and forming S3, and vacuum sintering the pressed blank under the vacuum condition, wherein the presintering temperature is 600-700 ℃, the heat preservation time is 0.8-1.2 hours, the temperature is continuously increased to 1040-1080 ℃, the temperature is 2-4 hours, the temperature is subsequently reduced to 500-600 ℃, the temperature is reduced to 1-2 hours, and the co-doped permanent magnet is obtained after cooling the pressed and formed by S4 vacuum sintering. By doping GaCu and realizing spontaneous passivation of grain boundaries in the vacuum sintering and low-temperature annealing processes, the corrosion resistance and structural stability of the magnet are obviously improved under the plating-free condition.

Inventors

  • LU XINCHUN
  • PEI GUOQING
  • ZHANG SHIWEI
  • GUO SHIHAN
  • TIAN YUNONG
  • XIE XUBO
  • CHENG YUKAI

Assignees

  • 宁波元辰新材料有限公司

Dates

Publication Date
20260505
Application Date
20260109

Claims (6)

  1. 1. A GaCu co-doped sintered permanent magnet production process is characterized by comprising the following steps: S1, smelting raw materials: The raw materials weighed according to the proportion comprise 25-35wt% of Ce, 15-25wt% of Nd+Pr, 0.9-1.1wt% of B, 0.2-0.3wt% of Ga, 0.1-0.2wt% of Cu and the balance of Fe, and the raw materials are heated to 1450-1500 ℃ to be completely melted under the protection of inert gas and cooled to form a master alloy ingot; S2, preparation of powder: Rapidly solidifying the master alloy ingot into an alloy sheet after melting, treating the alloy sheet for 2.5-3.5 hours at the temperature of 300 ℃ under the atmosphere of hydrogen and the pressure of 0.1-0.2MPa, and then carrying out air flow grinding under the protection of inert gas to obtain anisotropic powder, wherein the average particle size of the anisotropic powder is 3-5 mu m; S3, press forming: orientation cold press molding the anisotropic powder along the main axis direction under the action of a magnetic field to form a pressed compact; S4, vacuum sintering: presintering the pressed compact under the vacuum condition, wherein the presintering temperature is 600-700 ℃, the heat preservation time is 0.8-1.2 hours, continuously heating to 1040-1080 ℃, preserving heat for 2-4 hours, then cooling to 500-600 ℃, preserving heat for 1-2 hours, and cooling to obtain the GaCu co-doped sintered permanent magnet.
  2. 2. The process for producing GaCu co-doped sintered permanent magnets according to claim 1, characterized in that it comprises, in weight percent, 30wt% Ce, 20wt% nd+pr, 1wt% B, 0.3wt% Ga, 0.1wt% Cu and 48.4wt% Fe.
  3. 3. The production process of GaCu co-doped sintered permanent magnets according to claim 1, wherein step S1 is specifically to adopt an intermediate frequency vacuum induction melting furnace, heat to 1450-1500 ℃ under the protection of high purity argon gas to completely melt, and repeat melting for 3-4 times.
  4. 4. The process for producing GaCu co-doped sintered permanent magnets according to claim 1, wherein in step S2, after the master alloy ingot is melted, the master alloy ingot is rapidly solidified into alloy flakes by a strip melt-spinning machine, and the wheel speed of the strip melt-spinning machine is 25-30m/S, so that the average thickness of the alloy flakes is 30-50 μm.
  5. 5. The production process of GaCu co-doped sintered permanent magnets according to claim 1 is characterized in that in step S3, compression molding is specifically carried out by adopting an in-mold magnetic field orientation press, the magnetic field strength is 1.5-2.0T, orientation cold press molding is carried out along the main shaft direction under the action of a magnetic field, the pressure is 80-120MPa, an orientation pressed compact is obtained, the pressed compact is presintered under the vacuum condition, the temperature is 600-700 ℃, and the heat preservation is carried out for 1 hour.
  6. 6. A GaCu co-doped sintered permanent magnet produced by the process of any one of claims 1 to 5, wherein GaCu is co-doped sintered permanent magnet.

Description

GaCu co-doped sintered permanent magnet and production process thereof Technical Field The invention relates to the technical field of rare earth permanent magnet material preparation, in particular to a production process of GaCu co-doped sintered permanent magnets. Background The sintered NdFeB permanent magnet has excellent magnetic performance, but the Nd-rich phase at the grain boundary has high activity, is extremely easy to oxidize or corrode, and particularly causes rapid decay of the magnetic performance in a high-humidity or salt fog environment. At present, the protection is carried out in a mode of chemically plating Ni, zn or epoxy coating and the like in industry. The documents surface technology (49 th 8 th period in 2020) and rare earth (40 th 6 th period in 2019) indicate that although the corrosion resistance of the outer plating layer can be improved, the difference of the thermal expansion coefficients between the plating layer and a substrate is large, cracks are easy to generate in thermal circulation, protection failure is caused, and the process is complex, high in cost and not environment-friendly. The prior art has the following technical problems that 1, the grain boundary of a high cerium magnet is easy to corrode and lacks a plating-free protection scheme, 2, an outer plating layer is complex and has large environmental burden, and 3, single doping improvement is limited. Disclosure of Invention In order to overcome the defects of the related art, the application provides a GaCu co-doped sintered permanent magnet and a production process thereof, wherein GaCu is doped in a Ce-Fe-B magnet system, and spontaneous passivation of a crystal boundary is realized in the vacuum sintering and low-temperature annealing processes, so that the corrosion resistance and structural stability of the magnet are obviously improved under the plating-free condition. The application provides GaCu co-doped sintered permanent magnet which comprises, by weight, 25-35% of Ce, 15-25% of Nd+Pr, 0.9-1.1% of B, 0.2-0.3% of Ga, 0.1-0.2% of Cu and the balance of Fe. Preferably, the alloy comprises, in weight percent, 30wt% Ce, 20wt% Nd+Pr, 1wt% B, 0.3wt% Ga, 0.1wt% Cu and 48.4wt% Fe. A GaCu co-doped sintered permanent magnet production process comprises the following steps: S1, smelting raw materials: the raw materials weighed according to the proportion are heated to 1450-1500 ℃ under the protection of inert gas to be completely melted, and cooled to form a master alloy ingot; S2, preparation of powder: rapidly solidifying the master alloy ingot into an alloy sheet by a strip belt casting machine after melting, treating the alloy sheet for 2.5-3.5 hours at the temperature of 300 ℃ under the hydrogen atmosphere and the pressure of 0.1-0.2 MPa, and then carrying out air flow grinding under the protection of inert gas to obtain anisotropic powder, wherein the average grain diameter of the anisotropic powder is 3-5 mu m; S3, press forming: orientation cold press molding the anisotropic powder along the main axis direction under the action of a magnetic field to form a pressed compact; S4, vacuum sintering: Presintering the pressed compact under the vacuum condition, wherein the presintering temperature is 600-700 ℃, the heat preservation time is 0.8-1.2 hours, continuously heating to 1040-1080 ℃, preserving heat for 2-4 hours, then cooling to 500-600 ℃, preserving heat for 1-2 hours, and cooling to obtain the GaCu co-doped sintered permanent magnet. Preferably, the step S1 is specifically to adopt an intermediate frequency vacuum induction melting furnace, heat the furnace to 1450-1500 ℃ under the protection of high-purity argon to be completely melted, and repeatedly melt the furnace for 3-4 times. Preferably, the wheel speed of the strip material melt-spinning machine in the step S2 is 25-30 m/S, and the average thickness of the obtained alloy sheet is 30-50 mu m. Preferably, the step S3 of compression molding is specifically to adopt an in-mold magnetic field orientation press, wherein the magnetic field strength is 1.5-2.0T, orientation cold press molding is carried out along the main shaft direction under the action of a magnetic field, the pressure is 80-120 MPa, an orientation pressed compact is obtained, the pressed compact is presintered under the vacuum condition, the temperature is 600-700 ℃, and the heat preservation is carried out for 1 hour. Compared with the related art, the invention has the following advantages: According to the invention, by introducing the cooperative doping of trace Ga and Cu into the high cerium Ce-Fe-B magnet system, spontaneous passivation of the grain boundary is realized in the vacuum sintering and low-temperature annealing processes, so that the corrosion resistance and structural stability of the magnet are obviously improved under the plating-free condition. The salt spray test service life of the magnet prepared by the invention in an uncoated state can be prolonged