Preparation method of high-coercive-force and high-stability neodymium iron boron magnet

Abstract

The invention provides a preparation method of a high-coercive-force and high-stability neodymium iron boron magnet. The preparation method comprises the following steps: preparing materials according to components of a NdFeB alloy to obtain a master alloy ingot and rapidly quenching to prepare a thin strip; preparing the rapidly-quenched thin strip into nano-crystal alloy powder; weighing and preparing materials according to an alloy nominal composition Sm2Fe17; carrying out high-energy ball milling to obtain nano-crystal alloy powder; carrying out nitriding treatment on the Sm2Fe17 nano-crystal alloy powder in high-purity N2 gas or NH3 gas to obtain Sm2Fe17Nx nano-crystal alloy powder; mixing the NdFeB and the Sm2Fe17Nx nano-crystal alloy powder at a ratio to obtain compound powder which is uniformly mixed; carrying out magnetic field orientation on the compound powder and press-molding to form a blank; and carrying out spark plasma sintering on the blank to prepare a NdFeB / Sm2Fe17Nx magnet. With the adoption of the preparation method of the high-coercive-force and high-stability neodymium iron boron magnet, the use amount of rare earth is reduced and the cost is relatively low; and high-temperature-resisting neodymium iron boron magnet can be prepared through the preparation method, so that the market requirements are met.

Description

technical field [0001] The invention relates to the technical field of magnetic material preparation, in particular to a preparation method of a high-coercivity and high-stability NdFeB magnet. Background technique [0002] High-performance permanent magnet materials have been widely used in military equipment, electro-acoustic devices, motors, generators, computer hard disk drives, voice coil motors, nuclear magnetic resonance imaging instruments, microwave communication technology, controllers, instruments and other devices that require permanent magnetic fields and in the device. Nd-Fe-B permanent magnet has the incomparable advantages of other types of permanent magnet materials such as high magnetic energy product and high cost performance, and is currently the most widely used rare earth permanent magnet material. [0003] Sagawa and Fujimura et al. used the sintering method to prepare NdFeB permanent magnets for the first time in the 1880s. Sintered NdFeB magnets ar...

AI Technical Summary

Problems solved by technology

At present, the method of combining SmFeN and NdFeB is mainly the bonding method, but this method is easy to cause the surface oxidation of NdFeB due to the large amount of organic solvent used, and at the same time, the outer surface of SmFeB particles and NdFeB particles has a low bonding density, resulting in magnetic The energy is not high; the most critical problem is that due to the existence of the interface binder, the distance between the SmFeB particles and the NdFeB particles is relatively large, and the magnetic coupling between the particles cannot be achieved, resulting in low performance of the bonded magnet.

[0006] With the introduction and advancement of my country's energy-saving emission reduction and carbon emission policies, the rapid development of energy-saving and environmental protection fields such as electric vehicles and wind power generation has a growing demand for high-performance, high-temperature-resistant magnets. The rare earth permanent magnets known as the "magnet king" NdFeB has obtained unprecedented magnetic properties, but its coercive force is relatively low, the Curie temperature is 583K, the upper limit temperature used as a permanent magnet functional material is low, and the magnet stability is poor, which greatly limits its application.

Although traditional alloying methods and grain boundary modification methods can improve the temperature stability of NdFeB magnets, there are still deficiencies.