Method for improving performance of rare-earth permanent magnetic material by high temperature compressive stress

Abstract

The invention discloses a method for improving the performance of a rare-earth permanent magnetic material by high temperature compressive stress. The method for improving the performance of the rare-earth permanent magnetic material by high temperature compressive stress at least comprises the following steps: attaching heavy rare-earth compounds to the surface of the sintered magnet; and obtaining the magnet through heating and applying compressive stress at high temperature. According to the invention, the problems of the limitation of the magnet specification and dimension and the inconsistency of the heavy rare-earth diffusion in the traditional process can be overcome by improving the diffusion depth of magnet, therefore, the diffusion effect is enhanced, the magnet can obtain better magnetic performance, the equipment investment is simple, the cost is lower, and the invention is suitable for large-scale promotion.

Description

technical field [0001] The invention relates to a method for improving the performance of rare earth NdFeB magnetic materials, especially a method for improving the coercive force of magnets, especially a method for improving the performance of rare earth permanent magnet materials under high-temperature compressive stress. Background technique [0002] Since the invention of NdFeB magnets in the 1980s, due to their ultra-high performance characteristics, they have been widely used in electronics, new energy, aerospace, medical, and information fields. With the development of technology, the market demand for high-grade magnets is becoming more and more extensive. New technologies represented by pressureless sintering, grain refinement, and heavy rare earth diffusion are becoming the research and development focus of various research institutes and NdFeB enterprises. Due to the unstable price of rare earths in recent years, it is a consensus to develop low-heavy rare earths ...

AI Technical Summary

Problems solved by technology

[0005] We know that in the grain boundary diffusion of the magnet, the heavy rare earth enters the magnet from the surface, so the use of grain boundary diffusion to increase the coercive force of the magnet is limited by the thickness of the magnet, that is, when the magnet is thinner, the effect of increasing the coercive force of the magnet is more obvious, while For thicker magnets, the concentration of heavy rare earth atoms is distributed in a gradient from the surface to the center, and the effect of increasing the coercive force at the most central position is very limited, resulting in the overall coercive force of the magnet is not obvious, and the squareness is poor

In addition, the existing process has low dysprosium / terbium penetration efficiency, uneven magnet surface, and low degree of automation, which is not conducive to mass production

In the prior art, the addition and diffusion of heavy rare earth elements in magnets is achieved by mixing heavy rare earth powders (such as nano-scale or micron-scale powders with smaller particle sizes) with magnet alloy powders. This solution is limited by the specific gravity Factors such as different particle sizes make it difficult to achieve complete mixing uniformity during the mixing process, and in the sintering process, the particles in the form of powder are prone to flow and agglomerate due to the difference in melting point, which will greatly affect the magnet. Uniformity of Rare Earth Element Dispersion

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