Method for preparing low-cost neodymium iron boron (NdFeB) by adding heavy rare earth oxide into ingot recasting sheet

Abstract

The invention discloses a method for preparing low-cost neodymium iron boron (NdFeB) by adding a heavy rare earth oxide into an ingot recasting sheet, which comprises the following steps of: putting didymium, boron, aluminum, copper, niobium, cobalt and iron into a vacuum induction furnace in an ingredient proportion, introducing argon. and refining and casting into a casting sheet; putting the casting sheet into a hydrogen breaking furnace to break the hydrogen; adding 1.04 to 5.05 weight percent of the heavy rare earth oxide in a powder weight ratio; stirring two kinds of powder in a mixer, pulverizing with an airflow grinding machine, and putting the powder into a mold of a molding press; orienting in a magnetic field and performing compression molding; putting blanks into an isostatic pressing machine for pressing, and making into green bodies after maintaining the pressure; and sintering the green bodies in a vacuum sintering furnace at the temperature of between 1,000 and 1,100 DEG C to prepare the NdFeB magnets. The ingot is modified into a casting sheet, so the coercive force of the magnet can be effectively improved. By adding heavy rare earth elements which are better distributed in the crystal boundary and on the grain crystal edge at the pulverizing stage, the capacity of improving the coercive force is far higher than that of directly adding the heavy rare earth elements at the smelting stage; and the formula cost can be reduced by replacing high-price heavy rare earth raw materials by lower-price heavy rare earth oxides.

Description

technical field [0001] The invention relates to a method for preparing a sintered NdFeB permanent magnet, in particular to a method for preparing low-cost NdFeB by adding heavy rare earth oxides to cast ingots. Background technique [0002] The existing high coercive force permanent magnet products are prepared by adding heavy rare earth elements, such as terbium, dysprosium, gadolinium, holmium, etc., to the master alloy to increase the coercive force of the magnet. The master alloy is usually smelted and cast into an ingot. Since the heavy rare earth elements are added during the smelting of the master alloy, some of the heavy rare earth elements are distributed to the component grains, so the content of the heavy rare earth elements is relatively high, and the heavy rare earth elements are expensive, resulting in high product formulation costs. [0003] CN200810227680 discloses a preparation method of heavy rare earth hydride nanoparticles doped sintered NdFeB permanent m...

AI Technical Summary

Problems solved by technology

However, since terbium hydride or dysprosium hydride nanopowders are ultra-fine powders, it is difficult to prepare hydride nanopowders, and the industrialization is difficult; and when mixing powders, due to the large size difference of powder particles, it is difficult to mix evenly, resulting in uneven product performance

The whole preparation process is technically difficult and needs further improvement

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