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Glossary - S |
Samarium-Cobalt magnets
Saturation
Shear angle
Sintering
Soft magnetic material
Stabilisation
Samarium-Cobalt magnets
First rare-earth magnet, discovered in 1970. There are two main compositions: SmCo5 and Sm2Co17. They are characterised by a very high Br, HcJ, BHmax, and very good temperature behaviour. The cost of this compound limits its use; SmCo is now used only in special case, while NdFeB is preferred in most of cases.
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Saturation
The condition in which every magnetic moment of a ferromagnetic material is aligned in the same direction. The magnetization (M) and the intrinsic induction J is the maximum possible in the material. The saturation is easy for soft materials (up to few hundreds of gauss) and more difficult for hard magnets (up to 40 - 50 kG).
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Shear angle
Angle between loading line and B axis in B - H diagram.
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Sintering
Heat treatment procedure at high temperature during which powder pressed parts are compacted and homogenised. Hard ferrite and NdFeB are produced by sintering. The sintering temperature for ferrite is approx. 1220 °C ÷ 1250 °C, for NdFeB is approx. 1050 °C ÷ 1200 °C.
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Soft magnetic material
Ferromagnetic material with low coercivity (Hc < 1000 A/m). Soft magnetic material generally have also high permeability. The use of soft magnetic material are: amplification of magnetic field (electromagnets), low reluctance guide for magnetic flux (magnetic circuits), low magnetic loss devices (transformers).
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Stabilisation
A treatment of a magnetic material designed to increase the permanency of its magnetic properties or condition. Generally, it prevent modifications of the magnetic properties in time or under external influences.
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