Method for preparing nano composite permanent magnetic material by adding chromium in waste magnetic steel

Abstract

The invention discloses a method for preparing a nano composite permanent magnetic material by adding chromium in waste magnetic steel. The method comprises the following steps of pre-classifying the collected waste magnetic steel according to the classification standard that the waste magnetic steel, containing the same rare earth elements, of the same batch and the same model are classified together to obtain a pre-treated magnetic material, and directly conducting hydrogen decrepitation pulverization on the obtained pre-treated magnetic material to obtain rare earth hydrogen decrepitation magnetic powder; and then conducting sampling analysis on the rare earth hydrogen decrepitation magnetic powder, adding chromium in the rare earth hydrogen decrepitation magnetic powder according to requirements to obtain mixed powder, and finally carrying out isopressing, sintering and annealing to prepare the required nano composite permanent magnetic material. The method effectively solves the problem that an alloy ingot obtained after smelting is segregated, which is caused by factors, such as different melting points of all the components and manual operation, and has the beneficial effects that through the pre-classification, not only is the recovering time shortened, but also the processing step of extracting the rare earth elements is omitted; chromium is added in the rare earth hydrogen decrepitation magnetic powder to facilitate changing the hard magnetic phase of the nano composite permanent magnetic material; and the nano composite permanent magnetic material obtained by a precipitation separation method is high in magnetism and low in rare earth content.

Description

technical field [0001] The invention relates to the technical field of nanocomposite permanent magnet materials, in particular to a method for preparing nanocomposite permanent magnet materials by adding chromium to magnetic steel waste. Background technique [0002] In recent years, with the continuous expansion of the application field of nanocomposite permanent magnet materials, the demand for raw materials has increased. However, due to the high cost of rare earth mining and the increase in national regulation, the cost of materials has gradually increased. . However, under the current situation of excessive price increase, the price tolerance of downstream enterprises is relatively limited, so some downstream enterprises choose to use cheaper ferrite or aluminum nickel chromium, samarium chromium and other materials to replace the rare earth in the raw materials of NdFeB magnets , which brings greater instability to the NdFeB magnet market. At the same time, due to th...

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Problems solved by technology

However, although these methods can also adjust the microstructure of the composite material, it is difficult to precisely control the grain size and distribution of the hard magnetic phase and the soft magnetic phase, especially the size and composition of the two phases.

Therefore, it is difficult to increase the maximum energy product of isotropic nanomaterials