The effects of the pressing step on the microstructure and aging of NdFeB bonded magnets

Abstracts:

The effects of the compaction step on the (micro) structural features and aging behavior of polymer coated NdFeB-based bonded magnets is reported. Due to the fracture of the material during pressing, it is estimated an increase of at least 14% in the particles\’ area which is not coated. Such uncoated surfaces, when exposed to the environment, reduce the magnetic performance of the magnets aged/cured in air by 19% in the conditions evaluated in this investigation. Furthermore, XRD results interpreted by Rietveld analyses show a lattice parameter change in the tetragonal structure of the hard magnetic phase after pressing. Such change varies as a function of the height of the compacted part and it is ascribed to macro-elastic stress arising from the pressure distribution in the magnet. An aging/curing step during 24 h is able to relief such macro-elastic stress.


Reference:

PÉRIGO, E.A.; CAMPOS, M.F. de; FARIA, R.N. ; LANDGRAF, Fernando José Gomes. The effects of the pressing step on the microstructure and aging of NdFeB bonded magnets. Powder Technology, v. 224, p. 291-296, jul., 2012.

Access the article by signature, in the ScienceDirect site:
http://www.sciencedirect.com/science/article/pii/S0032591012001647

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