Editors: | F. Kongoli, M.P. Brzezinska, M.A. Alario-Franco, F. Marquis, M.S. Noufal, E.Palomares, J.M. Poblet, D.M. Guldi, A.A. Popov, A.R. Puente Santiago, B. Raveau, D. G. Rodriguez, S. Stevenson, T. Torres, A. Tressaud, M. de Campos |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2023 |
Pages: | 166 pages |
ISBN: | 978-1-989820-78-0 (CD) |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
Rare-earth permanent magnets have a broad range of applications, in motors of electric and hybrid cars, in wind turbines, and in any machine where efficiency is important [1]. Many countries are establishing rigorous standards for electric motors efficiency, as IE4 and IE5 [1,2].
A rotating machine as an electric motor has two main components: a rotor and a stator. In essence, by using a permanent magnet in the rotor, the efficiency of the machine can be increased. This save an energy that would be used to magnetize the rotor. This also makes possible that the motor can be of the brushless type, thus avoiding friction.
In the electrical motors, the magnets need to present high resistance against reversal of magnetization. The motor heats during the motor operation. As consequence, the magnets embedded in the stator also heats. There is much research on increasing motor efficiency [3], especially in the case of electric cars, where automony is an important issue, and where batteries are very expensive.
Nanocrystalline magnets display better resistance against reversal of magnetization. Here this subject is discussed by considering magnetostatic and exchange energy terms.
The mechanisms of reversal of magnetization in nanocrystalline permanent magnets are reviewed. Nanocrystalline Rare-earth magnets can be used in motors, or also in thin films [4]. Crystallographic texture effects on the coercivity are also discussed [5].