Rare earth permanent magnetic powder and preparation method thereof

Abstract

The invention discloses a rare earth permanent magnetic powder and a preparation method thereof. The magnetic powder is a multi-crystal powder containing columnar crystal and comprises the following component of R-T-B, wherein the R represents at least one kind of 17 kinds of elements including Sc and Y and accounts for 26.1-37.0 wt percent, the B represents at least boron or hydrogen and accounts for 0.8-1.5 wt percent, and the balance is T, and the T represents Fe and at least one kind of other transitional elements including Al, Ga, Si, Ge, Sn, Pb, Mg and Ca. The magnetic powder has high proportion of the column crystal, uniform particle size distribution and low oxygen content, and the prepared sintered permanent neodymium-iron-boron magnet has large coercive force and high magnetic energy product. The preparation method of the rare earth permanent magnetic powder comprises the following steps of precursor alloy preparation, hydrogen absorption or precursor alloy preparation, hydrogen absorption and dehydrogenation.

Description

technical field [0001] The invention belongs to the field of rare earth permanent magnet materials, and relates to an R-T-B series permanent magnet powder and a preparation method thereof. technical background [0002] The preparation process of sintered NdFeB magnets generally includes five major steps: ingot / cast sheet→coarse crushing→jet milling→press molding→sintering, among which coarse crushing and jet milling belong to the powder making process. The performance of magnetic powder is crucial to the preparation of high-performance NdFeB magnets. Generally, it is required that the magnetic powder particles should be evenly distributed, and should be single-crystal particles as much as possible, with few crystal defects and low impurities and oxygen content. In the powder making process, coarse crushing has an important impact on the performance of the magnetic powder. Proper coarse crushing of the master alloy is the prerequisite for ensuring the crystal shape of the ma...

AI Technical Summary

Problems solved by technology

In 1999, the Japanese patent JP11050110 disclosed an alloy powder for the preparation of rare earth magnets, using a rapid solidification technology to first prepare R-T-B flakes, and then at 0.10kg / cm 2 Hydrogen fragmentation under hydrogen pressure or above, but the crystallization state and hydrogen and oxygen content of the magnetic powder are not mentioned

In 2003, Japanese patent JP2003297622 disclosed a hydrogen absorption, hydrogenation ball milling method and a preparation process of rare earth permanent magnets. It mainly disclosed the gas composition of hydrogen absorption and dehydrogenation, and did not involve the crystallization state of magnetic powder, hydrogen and oxygen content and specific process parameters.

In 2004, Japanese patent JP2004285480 disclosed a method for preparing alloy powder for manufacturing Nd-Fe-B permanent magnets. The specific process is annealing at 800-1100°C, and ball milling in nitrogen after hydrogenation and dehydrogenation. The patent mainly discloses The process parameters and atmosphere of the ball mill are mentioned, but the crystallization state, hydrogen and oxygen content and process of the magnetic powder are not mentioned.

In 2006, the Japanese patent JP2006283095 disclosed a production method of rare earth alloy powder. The specific process is ball milling after hydrodehydrogenation. The patent mainly discloses the particle size of the rare earth alloy magnetic powder, but does not mention the crystallization state of the magnetic powder and the hydrogen and oxygen content.

Japanese patent JP2000303107 in 2000 and Japanese patent JP2003082406 in 2003 disclosed a hydrogenation device and rare earth magnetic powder and magnets prepared by it, mainly disclosing a hydrogenation device, without mentioning the hydrogen explosion process parameters and process of crushing rare earth alloy blocks

However, none of them involve the hydrogen and oxygen content, crystal shape, particle size and distribution in the composition of hydrogen crushing magnetic powder (HD magnetic powder), and these parameters directly determine the magnetic properties of hydrogen crushing magnetic powder