A kind of preparation method of rare earth permanent magnet with high homogeneity and high performance

Abstract

The invention discloses a preparation method of a high-homogeneity and high-performance rare earth permanent magnet. The distribution of magnetic lines of force is optimized by adding a magnetic concentrating plate inside the female mold and selecting materials with near magnetic permeability for the upper and lower pressure heads; and by controlling the orientation of the product. At this time, the position of the powder is on the same plane as the centerline of the orientation pole head, so that the powder in the mold cavity can be fully oriented, and the magnetic declination angle and NS pole surface magnetic difference of the final magnet can be reduced and improved. When passing through the jet mill, the pulse spray method is adopted, and the mixed liquid additive is evenly added to improve the fluidity of the powder for preparing the magnet, and improve the density of the green body and the uniformity of the orientation of the local magnetic domain; it adopts the progressive pre-pressing process of multiple magnetization opposite directions , Repeated multiple times of orientation, step by step two-way preloading method, so that the consistency of density, surface magnetism, magnetic flux and magnetic moment of the final magnet is improved. The secondary sintering process is adopted, combined with liquid-phase sintering of nano-rare earth hydrides, to increase the coercive force of the magnet.

Description

technical field [0001] The invention belongs to the technical field of rare earth permanent magnet preparation, and in particular relates to a preparation method of high homogeneity and high performance rare earth permanent magnet, which is especially suitable for the preparation of high performance and high coercive force sintered NdFeB magnets. Background technique [0002] At present, servo motors are widely used in inkjet printers, cutting plotters, photo machines, spraying equipment, textile machinery equipment, medical instruments and equipment, precision instruments, industrial control systems, office automation, robots and other fields. High-precision servo motors are even widely used in robotics, aviation, aerospace, weapons, ships, electronics and other fields. With the increasing automation of all walks of life, the demand for high-precision servo motors is also increasing. The high-precision servo motor, in conjunction with the servo controller, can precisely con...

AI Technical Summary

Problems solved by technology

At present, the industry generally pursues high magnetic performance and low cost, but there are few studies on the high homogeneity of magnets, such as the magnetic declination angle of magnets, the magnetic difference of NS pole surface of magnets, and the consistency of magnetic flux and magnetic moments of magnets. The homogeneity of the magnet is poor, which is not conducive to the application of high-precision servo motors

At present, the Chinese patent with the patent publication number CN203044894U discloses a mold for improving the degree of orientation, but the magnetically conductive side plate described in this method cannot solve the problem of uniform distribution of magnetic force lines

At present, the Chinese patent with the patent publication number CN203076587U discloses a molding die for improving the density of magnetic lines of force at corners. The magnetic strips are embedded on the non-magnetic side plates, which can only improve the distribution of magnetic lines to a limited extent, and this method does not pay attention to As an important part of the mold, the upper and lower pressure heads will also affect the distribution of magnetic force lines

At present, the Chinese patent with the patent publication number CN101996721A discloses a method for improving the coercive force of NdFeB, but in this method, the rare earth hydride is ground to 1-10um by jet milling, and the jet mill will cause hydrogen in the rare earth hydride It is released in the violent collision of the gas, and the particle size of 1-10um is difficult to achieve uniform mixing by stirring. In addition, this method does not take advantage of the low melting point of rare earth hydrides to achieve liquid-phase sintering of the grain boundary phase at a lower sintering temperature. , so that the rare earth elements brought in by the hydride are evenly distributed on the grain boundary, so as to avoid the replacement of heavy rare earth elements with the main phase during high temperature sintering

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