Method for preparing high-coercivity, high-toughness and high-corrosion-resistance sintered Nd-Fe-B permanent magnet

A high coercivity, NdFeB technology, used in magnetic objects, inductor/transformer/magnet manufacturing, magnetic materials, etc., can solve problems such as material fracture and corrosion, achieve simple operation, save rare earth resources, and be easy to industrialize production. Effect

Active Publication Date: 2014-03-26
UNIV OF SCI & TECH BEIJING
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, the boundary structure has been significantly improved by the double alloy technology and the infiltration of dysprosium and terbium on the surface of the magnet. However, it is still impossible to make the grain boundary Nd-rich phase uniformly and continuously distributed around the 2:14:1 phase grains. Achieve complete decoupling
[0004] The Nd-rich phase at the grain boundary is the key to obtain high coercive force of sintered NdFeB magnets. However, the Nd-rich phase itself is a mechanically and corrosion-weakened phase, and the material is easily broken and corroded from the Nd-rich phase at the grain boundary.

Method used

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  • Method for preparing high-coercivity, high-toughness and high-corrosion-resistance sintered Nd-Fe-B permanent magnet

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Embodiment 1

[0021] The design is based on the NdFeB-based alloy composition Nd11.8Fe82.2B6 (atomic percentage) of the 2:14:1 phase, according to the composition of the design, and considering the burning loss of rare earth Nd 3% (weight percentage), using the scale ingot casting process Prepare NdFeB-based quick-setting flakes with a thickness of about 300 μm, and prepare 2:14:1 NdFeB-based powders with an average particle size of 3.5 μm by hydrogen breaking and jet milling, and add a weight fraction of 4%, an average particle size of Pure Cu nano-powder with a diameter of 40 nm. Mix the two powders uniformly in a mixer. The uniformly mixed powder is oriented and pressed in a 2.0T magnetic field and isostatically pressed. The obtained compact is placed in a vacuum In the sintering furnace, sinter at 1050°C for 2 hours, and finally carry out secondary heat treatment, that is, heat treatment at 750°C (primary heat treatment temperature) and 350°C (secondary heat treatment temperature) for 2 ...

Embodiment 2

[0024] The design is based on the NdFeB-based alloy composition Nd11.8Fe82.2B6 (atomic percentage) of the 2:14:1 phase, according to the composition of the design, and considering the burning loss of rare earth Nd 3% (weight percentage), using the scale ingot casting process Prepare NdFeB-based quick-setting flakes with a thickness of about 300 μm, and prepare 2:14:1 NdFeB-based powders with an average particle size of 3.5 μm by hydrogen breaking and jet milling, and add 3% by weight, average particle size Pure Cu nano-powder with a diameter of 60 nm, mix the two powders uniformly in a mixer, and the uniformly mixed powder is oriented and pressed in a 2.0T magnetic field and isostatically pressed, and the obtained compact is placed in a vacuum In the sintering furnace, sinter at 1050°C for 2 hours, and finally carry out secondary heat treatment, that is, heat treatment at 750°C (primary heat treatment temperature) and 350°C (secondary heat treatment temperature) for 2 hours res...

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Abstract

The invention belongs to the field of rare earth permanent magnetic materials, and particularly provides a method for preparing a high-coercivity, high-toughness and high-corrosion-resistance sintered Nd-Fe-B permanent magnet. The method is characterized in that pure Cu nanopowder is used for completely replacing a grain boundary Nd-rich phase to achieve isolation of a liquid phase and the magnet. The Cu nanopowder with the even grain size being 20-150nm is added in 3-5 microns of Nd-Fe-B base powder with the proportion being 2:14:1 to be evenly mixed, the adding proportion is 2-8% of the weight of the 2:14:1 Nd-Fe-B base powder, and orientation, briquetting and isostatic pressing are conducted on the mixture in a magnetic filed larger than 1.5T. The mixture is placed in a vacuum sintering furnace and is sintered for 2-5 hours at the temperature of 1000-1100 DEG C, at last, secondary heat treatment is conducted, namely heat treatment is conducted for 1-4 hours at the temperature of 600-800 DEG C (primary heat treatment temperature) and at the temperature of 300-500 DEG C (secondary heat treatment temperature) respectively, and Nd-Fe-B magnetic materials are obtained. The method has the advantages that the Cu nanopowder is used for completely replacing the grain boundary Nd-rich phase to achieve isolation of the liquid phase and the magnet, high coercivity, high toughness and high corrosion resistance can be achieved, the cost of raw materials can also be greatly lowered, and rare earth resources are saved. The method is simple in operation and facilitates industrial production.

Description

technical field [0001] The invention relates to a preparation method of a sintered NdFeB permanent magnet with high coercive force, high strength, toughness and high corrosion resistance, belonging to the field of rare earth permanent magnet materials. Background technique [0002] Sintered NdFeB permanent magnets are widely used in electronics, automobiles, computers, electric power, machinery, energy, environmental protection, and national defense due to their higher remanence and magnetic energy product than other permanent magnets, good dynamic recovery characteristics and high cost performance. , medical equipment and many other fields. In recent years, my country's sintered NdFeB manufacturing technology has made significant progress, permanent magnet equipment has been continuously developed and improved, new technologies have been adopted, and product grades have been rapidly improved. For example, the traditional ingot casting technology is changed to the scale ing...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F41/02H01F1/057H01F1/08B22F9/04B22F3/16
Inventor 包小倩高学绪汤明辉崔俊娟卢克超
Owner UNIV OF SCI & TECH BEIJING
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