Gadolinium/yttrium-ion-implanted zinc-plated neodymium-iron-boron magnet and preparation method thereof

Abstract

The invention discloses a gadolinium / yttrium-ion-implanted zinc-plated neodymium-iron-boron magnet which is composed of the following components in percentage by mass: 25-35% of Pr-Nd, 0.5-1.5% of B, 0.1-1% of Al, 0-0.2% of Cu, 1-2% of Co, 0.1-1% of Ga, 0.02-0.08% of Nb, 0.01-0.05% of Zr, 0.1-1% of mesoporous silicon dioxide, and the balance of Fe and small amounts of inevitable impurities in the material. The sintered neodymium-iron-boron magnet has uniform crystal form structure; the heavy rare earth content in the region adjacent to the magnet core is lower, thereby preventing the magnetic remanence of the magnet from being influenced basically; the heavy rare earth content in the region adjacent to the magnet surface is higher, thereby obviously enhancing the coercivity of the magnet; and the defects of the neodymium-iron-boron sintered magnet are comprehensively improved, and the advantages are greatly enhanced.

Description

technical field [0001] The invention relates to the technical field of rare earth permanent magnet materials, in particular to a galvanized neodymium-iron-boron magnet implanted with gadolinium-yttrium ions and a preparation method thereof. Background technique [0002] NdFeB permanent magnet material, as the latest result of the development of rare earth permanent magnet materials, is known as the magnet king because of its excellent magnetic properties. It is the permanent magnet with the strongest magnetic force at present, and its maximum magnetic energy product is 10 times higher than that of ferrite. Above, it has the advantages of small size, light weight, extremely high magnetic energy product and coercive force, and high energy density, which makes NdFeB permanent magnet materials widely used in modern industry and electronic technology. [0003] In recent years, with the rapid development of NdFeB magnets in many fields, sintered NdFeB magnets have been widely used...

AI Technical Summary

Problems solved by technology

Due to the interaction of van der Waals force, London force and magnetic force among the raw material powders of micron-sized NdFeB magnets, the powders are easily agglomerated into secondary powder particles, forming small particle groups, resulting in poor fluidity and difficult orientation of the powder, resulting in final The rare earth-rich phase in the grain boundary of the magnet is absent or discontinuous, and the diffusion effect of heavy rare earth elements such as Dy / Tb along the grain boundary to the interior of the magnet will be affected when the grain boundary diffusion treatment is performed.

[0004] Chinese invention patent CN105702405A is the first to add nano-scale mesoporous materials to NdFeB magnet materials to improve its microstructure and structural defects, thereby increasing its coercive force and working temperature. Its advantages lie in simple processing technology, uniform crystal structure, The magnet material has strong coercivity and good temperature resistance, but it does not improve the shortcomings of NdFeB magnets that are easily oxidized and corroded

[0005] In order to meet the requirements of high magnetic energy product and high coercive force of NdFeB magnets, the most direct way is to add a large amount of heavy rare earth elements such as Dy / Tb. However, adding too much Dy to the magnet will cause antiferromagnetism between Dy and Fe. Coupled, the remanence of the magnet will decrease with the increase of Dy, and the resources of heavy rare earth elements are scarce and expensive. The production of high coercive force magnets by the existing technology will increase the cost and increase the consumption of resources.

The sintered NdFeB grain boundary diffusion process is to infiltrate from the surface to the inside of the sintered NdFeB blank, which avoids the problem of excessive heavy rare earth content in the main phase, and can greatly reduce the residual magnetism while hardly damaging the remanence. Increase the coercive force of the magnet, and at the same time significantly reduce the content of heavy rare earth elements; however, heavy rare earth elements can only diffuse on the surface of the sintered blank, resulting in limited diffusion depth of heavy rare earth elements inside the magnet, and the concentration of heavy rare earth elements presents a decaying gradient from the surface to the inside distributed

[0006] Chinese invention patent CN105742048A uses high-energy ions to inject rare earths and alloys into NdFeB pre-sintered blanks, which solves the problem that more rare earths and alloys remain on the surface of NdFeB magnets in the existing grain boundary diffusion technology, and the actual utilization rate of rare earths is not high. However, it only improves the diffusion efficiency of rare earth alloys. The arbitrary ratio of light and heavy rare earth metals and conventional metals not only makes the grain boundary structure of the magnet complex, the Nd-rich phase in the grain boundary is missing and discontinuous, and ultimately affects the Dy / Tb and other heavy rare earth. The effect of element diffusion along the grain boundary to the interior of the magnet does not actually greatly increase the coercive force of the NdFeB magnet